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1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
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2 <HTML
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3 ><HEAD
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4 ><TITLE
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5 >LW Tool Chain</TITLE
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6 ><META
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7 NAME="GENERATOR"
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8 CONTENT="Modular DocBook HTML Stylesheet Version 1.79"></HEAD
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9 ><BODY
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10 CLASS="BOOK"
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11 BGCOLOR="#FFFFFF"
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12 TEXT="#000000"
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13 LINK="#0000FF"
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14 VLINK="#840084"
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15 ALINK="#0000FF"
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16 ><DIV
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17 CLASS="BOOK"
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18 ><A
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19 NAME="AEN1"
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20 ></A
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21 ><DIV
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22 CLASS="TITLEPAGE"
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23 ><H1
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24 CLASS="TITLE"
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25 ><A
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26 NAME="AEN2"
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27 >LW Tool Chain</A
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28 ></H1
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29 ><H3
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30 CLASS="AUTHOR"
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31 ><A
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32 NAME="AEN4"
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33 ></A
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34 >William Astle</H3
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35 ><P
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36 CLASS="COPYRIGHT"
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37 >Copyright © 2009 William Astle</P
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38 ><HR></DIV
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39 ><DIV
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40 CLASS="TOC"
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41 ><DL
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42 ><DT
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43 ><B
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44 >Table of Contents</B
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45 ></DT
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46 ><DT
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47 >1. <A
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48 HREF="#AEN10"
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49 >Introduction</A
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50 ></DT
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51 ><DD
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52 ><DL
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53 ><DT
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54 >1.1. <A
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55 HREF="#AEN13"
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56 >History</A
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57 ></DT
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58 ></DL
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59 ></DD
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60 ><DT
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61 >2. <A
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62 HREF="#AEN18"
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63 >Output Formats</A
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64 ></DT
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65 ><DD
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66 ><DL
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67 ><DT
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68 >2.1. <A
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69 HREF="#AEN21"
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70 >Raw Binaries</A
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71 ></DT
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72 ><DT
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73 >2.2. <A
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74 HREF="#AEN24"
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75 >DECB Binaries</A
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76 ></DT
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77 ><DT
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78 >2.3. <A
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79 HREF="#AEN29"
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80 >OS9 Modules</A
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81 ></DT
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82 ><DT
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83 >2.4. <A
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84 HREF="#AEN35"
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85 >Object Files</A
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86 ></DT
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87 ></DL
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88 ></DD
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89 ><DT
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90 >3. <A
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91 HREF="#AEN43"
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92 >LWASM</A
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93 ></DT
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94 ><DD
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95 ><DL
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96 ><DT
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97 >3.1. <A
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98 HREF="#AEN46"
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99 >Command Line Options</A
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100 ></DT
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101 ><DT
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102 >3.2. <A
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103 HREF="#AEN152"
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104 >Dialects</A
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105 ></DT
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106 ><DT
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107 >3.3. <A
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108 HREF="#AEN159"
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109 >Source Format</A
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110 ></DT
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111 ><DT
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112 >3.4. <A
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113 HREF="#AEN168"
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114 >Symbols</A
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115 ></DT
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116 ><DT
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117 >3.5. <A
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118 HREF="#AEN173"
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119 >Numbers and Expressions</A
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120 ></DT
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121 ><DT
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122 >3.6. <A
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123 HREF="#AEN181"
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124 >Assembler Directives</A
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125 ></DT
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126 ><DD
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127 ><DL
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128 ><DT
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129 >3.6.1. <A
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130 HREF="#AEN184"
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131 >Data Directives</A
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132 ></DT
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133 ><DT
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134 >3.6.2. <A
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135 HREF="#AEN287"
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136 >Address Definition</A
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137 ></DT
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138 ><DT
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139 >3.6.3. <A
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140 HREF="#AEN334"
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141 >Conditional Assembly</A
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142 ></DT
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143 ><DT
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144 >3.6.4. <A
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145 HREF="#AEN398"
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146 >OS9 Target Directives</A
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147 ></DT
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148 ><DT
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149 >3.6.5. <A
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150 HREF="#AEN423"
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151 >Miscelaneous Directives</A
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152 ></DT
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153 ></DL
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154 ></DD
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155 ><DT
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156 >3.7. <A
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157 HREF="#AEN456"
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158 >Macros</A
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159 ></DT
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160 ><DT
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161 >3.8. <A
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162 HREF="#AEN478"
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163 >Structures</A
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164 ></DT
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165 ><DT
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166 >3.9. <A
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167 HREF="#AEN498"
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168 >Object Files and Sections</A
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169 ></DT
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170 ><DT
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171 >3.10. <A
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172 HREF="#AEN562"
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173 >Assembler Modes and Pragmas</A
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174 ></DT
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175 ></DL
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176 ></DD
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177 ><DT
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178 >4. <A
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179 HREF="#AEN607"
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180 >LWLINK</A
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181 ></DT
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182 ><DD
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183 ><DL
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184 ><DT
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185 >4.1. <A
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186 HREF="#AEN610"
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187 >Command Line Options</A
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188 ></DT
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189 ><DT
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190 >4.2. <A
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191 HREF="#AEN707"
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192 >Linker Operation</A
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193 ></DT
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194 ><DT
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195 >4.3. <A
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196 HREF="#AEN721"
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197 >Linking Scripts</A
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198 ></DT
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199 ></DL
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200 ></DD
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201 ><DT
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202 >5. <A
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203 HREF="#AEN755"
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204 >Libraries and LWAR</A
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205 ></DT
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206 ><DD
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207 ><DL
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208 ><DT
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209 >5.1. <A
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210 HREF="#AEN759"
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211 >Command Line Options</A
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212 ></DT
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213 ></DL
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214 ></DD
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215 ><DT
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216 >6. <A
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217 HREF="#OBJCHAP"
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218 >Object Files</A
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219 ></DT
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220 ></DL
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221 ></DIV
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222 ><DIV
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223 CLASS="LOT"
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224 ><DL
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225 CLASS="LOT"
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226 ><DT
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227 ><B
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228 >List of Tables</B
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229 ></DT
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230 ><DT
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231 >6-1. <A
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232 HREF="#AEN842"
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233 >Object File Term Types</A
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234 ></DT
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235 ><DT
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236 >6-2. <A
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237 HREF="#AEN872"
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238 >Object File Operator Numbers</A
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239 ></DT
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240 ></DL
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241 ></DIV
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242 ><DIV
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243 CLASS="CHAPTER"
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244 ><HR><H1
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245 ><A
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246 NAME="AEN10"
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247 ></A
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248 >Chapter 1. Introduction</H1
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249 ><P
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250 >The LW tool chain provides utilities for building binaries for MC6809 and
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251 HD6309 CPUs. The tool chain includes a cross-assembler and a cross-linker
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252 which support several styles of output.</P
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253 ><DIV
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254 CLASS="SECTION"
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255 ><HR><H2
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256 CLASS="SECTION"
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257 ><A
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258 NAME="AEN13"
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259 >1.1. History</A
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260 ></H2
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261 ><P
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262 >For a long time, I have had an interest in creating an operating system for
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263 the Coco3. I finally started working on that project around the beginning of
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264 2006. I had a number of assemblers I could choose from. Eventually, I settled
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265 on one and started tinkering. After a while, I realized that assembler was not
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266 going to be sufficient due to lack of macros and issues with forward references.
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267 Then I tried another which handled forward references correctly but still did
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268 not support macros. I looked around at other assemblers and they all lacked
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269 one feature or another that I really wanted for creating my operating system.</P
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270 ><P
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271 >The solution seemed clear at that point. I am a fair programmer so I figured
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272 I could write an assembler that would do everything I wanted an assembler to
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273 do. Thus the LWASM probject was born. After more than two years of on and off
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274 work, version 1.0 of LWASM was released in October of 2008.</P
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275 ><P
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276 >As the aforementioned operating system project progressed further, it became
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277 clear that while assembling the whole project through a single file was doable,
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278 it was not practical. When I found myself playing some fancy games with macros
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279 in a bid to simulate sections, I realized I needed a means of assembling
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280 source files separately and linking them later. This spawned a major development
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281 effort to add an object file support to LWASM. It also spawned the LWLINK
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282 project to provide a means to actually link the files.</P
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283 ></DIV
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284 ></DIV
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285 ><DIV
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286 CLASS="CHAPTER"
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287 ><HR><H1
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288 ><A
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289 NAME="AEN18"
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290 ></A
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291 >Chapter 2. Output Formats</H1
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292 ><P
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293 >The LW tool chain supports multiple output formats. Each format has its
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294 advantages and disadvantages. Each format is described below.</P
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295 ><DIV
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296 CLASS="SECTION"
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297 ><HR><H2
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298 CLASS="SECTION"
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299 ><A
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300 NAME="AEN21"
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301 >2.1. Raw Binaries</A
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302 ></H2
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303 ><P
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304 >A raw binary is simply a string of bytes. There are no headers or other
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305 niceties. Both LWLINK and LWASM support generating raw binaries. ORG directives
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306 in the source code only serve to set the addresses that will be used for
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307 symbols but otherwise have no direct impact on the resulting binary.</P
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308 ></DIV
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309 ><DIV
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310 CLASS="SECTION"
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311 ><HR><H2
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312 CLASS="SECTION"
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313 ><A
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314 NAME="AEN24"
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315 >2.2. DECB Binaries</A
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316 ></H2
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317 ><P
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318 >A DECB binary is compatible with the LOADM command in Disk Extended
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319 Color Basic on the CoCo. They are also compatible with CLOADM from Extended
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320 Color Basic. These binaries include the load address of the binary as well
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321 as encoding an execution address. These binaries may contain multiple loadable
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322 sections, each of which has its own load address.</P
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323 ><P
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324 >Each binary starts with a preamble. Each preamble is five bytes long. The
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325 first byte is zero. The next two bytes specify the number of bytes to load
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326 and the last two bytes specify the address to load the bytes at. Then, a
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327 string of bytes follows. After this string of bytes, there may be another
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328 preamble or a postamble. A postamble is also five bytes in length. The first
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329 byte of the postamble is $FF, the next two are zero, and the last two are
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330 the execution address for the binary.</P
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331 ><P
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332 >Both LWASM and LWLINK can output this format.</P
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333 ></DIV
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334 ><DIV
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335 CLASS="SECTION"
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336 ><HR><H2
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337 CLASS="SECTION"
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338 ><A
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339 NAME="AEN29"
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340 >2.3. OS9 Modules</A
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341 ></H2
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342 ><P
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343 > Since version 2.5, LWASM is able to generate OS9 modules. The syntax is
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344 basically the same as for other assemblers. A module starts with the MOD
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345 directive and ends with the EMOD directive. The OS9 directive is provided
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346 as a shortcut for writing system calls. </P
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347 ><P
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348 > LWASM does NOT provide an OS9Defs file. You must provide your own. Also note
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349 that the common practice of using "ifp1" around the inclusion of the OS9Defs
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350 file is discouraged as it is pointless and can lead to unintentional
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351 problems and phasing errors. Because LWASM reads each file exactly once,
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352 there is no benefit to restricting the inclusion to the first assembly pass. </P
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353 ><P
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354 > It is also critical to understand that unlike many OS9 assemblers, LWASM
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355 does NOT maintain a separate data address counter. Thus, you must define
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356 all your data offsets and so on outside of the mod/emod segment. It is,
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357 therefore, likely that source code targeted at other assemblers will require
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358 edits to build correctly. </P
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359 ><P
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360 > LWLINK does not, yet, have the ability to create OS9 modules from object
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361 files. </P
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362 ></DIV
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363 ><DIV
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364 CLASS="SECTION"
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365 ><HR><H2
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366 CLASS="SECTION"
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367 ><A
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368 NAME="AEN35"
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369 >2.4. Object Files</A
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370 ></H2
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371 ><P
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372 >LWASM supports generating a proprietary object file format which is
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373 described in <A
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374 HREF="#OBJCHAP"
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375 >Chapter 6</A
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376 >. LWLINK is then used to link these
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377 object files into a final binary in any of LWLINK's supported binary
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378 formats.</P
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379 ><P
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380 >Object files also support the concept of sections which are not valid
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381 for other output types. This allows related code from each object file
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382 linked to be collapsed together in the final binary.</P
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383 ><P
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384 >Object files are very flexible in that they allow references that are not
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385 known at assembly time to be resolved at link time. However, because the
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386 addresses of such references are not known at assembly time, there is no way
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387 for the assembler to deduce that an eight bit addressing mode is possible.
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388 That means the assember will default to using sixteen bit addressing
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389 whenever an external or cross-section reference is used.</P
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390 ><P
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391 >As of LWASM 2.4, it is possible to force direct page addressing for an
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392 external reference. Care must be taken to ensure the resulting addresses
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393 are really in the direct page since the linker does not know what the direct
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394 page is supposed to be and does not emit errors for byte overflows.</P
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395 ><P
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396 >It is also possible to use external references in an eight bit immediate
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397 mode instruction. In this case, only the low order eight bits will be used.
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398 Again, no byte overflows will be flagged.</P
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399 ></DIV
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400 ></DIV
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401 ><DIV
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402 CLASS="CHAPTER"
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403 ><HR><H1
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404 ><A
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405 NAME="AEN43"
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406 ></A
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407 >Chapter 3. LWASM</H1
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408 ><P
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409 >The LWTOOLS assembler is called LWASM. This chapter documents the various
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410 features of the assembler. It is not, however, a tutorial on 6x09 assembly
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411 language programming.</P
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412 ><DIV
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413 CLASS="SECTION"
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414 ><HR><H2
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415 CLASS="SECTION"
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416 ><A
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417 NAME="AEN46"
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418 >3.1. Command Line Options</A
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419 ></H2
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420 ><P
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421 >The binary for LWASM is called "lwasm". Note that the binary is in lower
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422 case. lwasm takes the following command line arguments.</P
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423 ><P
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424 ></P
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425 ><DIV
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426 CLASS="VARIABLELIST"
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427 ><DL
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428 ><DT
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429 ><CODE
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430 CLASS="OPTION"
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431 >--6309</CODE
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432 >, <CODE
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433 CLASS="OPTION"
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434 >-3</CODE
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435 ></DT
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436 ><DD
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437 ><P
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438 >This will cause the assembler to accept the additional instructions available
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439 on the 6309 processor. This is the default mode; this option is provided for
|
|
|
440 completeness and to override preset command arguments.</P
|
|
|
441 ></DD
|
|
|
442 ><DT
|
|
|
443 ><CODE
|
|
|
444 CLASS="OPTION"
|
|
|
445 >--6809</CODE
|
|
|
446 >, <CODE
|
|
|
447 CLASS="OPTION"
|
|
|
448 >-9</CODE
|
|
|
449 ></DT
|
|
|
450 ><DD
|
|
|
451 ><P
|
|
|
452 >This will cause the assembler to reject instructions that are only available
|
|
|
453 on the 6309 processor.</P
|
|
|
454 ></DD
|
|
|
455 ><DT
|
|
|
456 ><CODE
|
|
|
457 CLASS="OPTION"
|
|
|
458 >--decb</CODE
|
|
|
459 >, <CODE
|
|
|
460 CLASS="OPTION"
|
|
|
461 >-b</CODE
|
|
|
462 ></DT
|
|
|
463 ><DD
|
|
|
464 ><P
|
|
|
465 >Select the DECB output format target. Equivalent to <CODE
|
|
|
466 CLASS="OPTION"
|
|
|
467 >--format=decb</CODE
|
|
|
468 >.</P
|
|
|
469 ></DD
|
|
|
470 ><DT
|
|
|
471 ><CODE
|
|
|
472 CLASS="OPTION"
|
|
|
473 >--format=type</CODE
|
|
|
474 >, <CODE
|
|
|
475 CLASS="OPTION"
|
|
|
476 >-f type</CODE
|
|
|
477 ></DT
|
|
|
478 ><DD
|
|
|
479 ><P
|
|
|
480 >Select the output format. Valid values are <CODE
|
|
|
481 CLASS="OPTION"
|
|
|
482 >obj</CODE
|
|
|
483 > for the
|
|
|
484 object file target, <CODE
|
|
|
485 CLASS="OPTION"
|
|
|
486 >decb</CODE
|
|
|
487 > for the DECB LOADM format,
|
|
|
488 <CODE
|
|
|
489 CLASS="OPTION"
|
|
|
490 >os9</CODE
|
|
|
491 > for creating OS9 modules, and <CODE
|
|
|
492 CLASS="OPTION"
|
|
|
493 >raw</CODE
|
|
|
494 > for
|
|
|
495 a raw binary.</P
|
|
|
496 ></DD
|
|
|
497 ><DT
|
|
|
498 ><CODE
|
|
|
499 CLASS="OPTION"
|
|
|
500 >--list[=file]</CODE
|
|
|
501 >, <CODE
|
|
|
502 CLASS="OPTION"
|
|
|
503 >-l[file]</CODE
|
|
|
504 ></DT
|
|
|
505 ><DD
|
|
|
506 ><P
|
|
|
507 >Cause LWASM to generate a listing. If <CODE
|
|
|
508 CLASS="OPTION"
|
|
|
509 >file</CODE
|
|
|
510 > is specified,
|
|
|
511 the listing will go to that file. Otherwise it will go to the standard output
|
|
|
512 stream. By default, no listing is generated.</P
|
|
|
513 ></DD
|
|
|
514 ><DT
|
|
|
515 ><CODE
|
|
|
516 CLASS="OPTION"
|
|
|
517 >--obj</CODE
|
|
|
518 ></DT
|
|
|
519 ><DD
|
|
|
520 ><P
|
|
|
521 >Select the proprietary object file format as the output target.</P
|
|
|
522 ></DD
|
|
|
523 ><DT
|
|
|
524 ><CODE
|
|
|
525 CLASS="OPTION"
|
|
|
526 >--output=FILE</CODE
|
|
|
527 >, <CODE
|
|
|
528 CLASS="OPTION"
|
|
|
529 >-o FILE</CODE
|
|
|
530 ></DT
|
|
|
531 ><DD
|
|
|
532 ><P
|
|
|
533 >This option specifies the name of the output file. If not specified, the
|
|
|
534 default is <CODE
|
|
|
535 CLASS="OPTION"
|
|
|
536 >a.out</CODE
|
|
|
537 >.</P
|
|
|
538 ></DD
|
|
|
539 ><DT
|
|
|
540 ><CODE
|
|
|
541 CLASS="OPTION"
|
|
|
542 >--pragma=pragma</CODE
|
|
|
543 >, <CODE
|
|
|
544 CLASS="OPTION"
|
|
|
545 >-p pragma</CODE
|
|
|
546 ></DT
|
|
|
547 ><DD
|
|
|
548 ><P
|
|
|
549 >Specify assembler pragmas. Multiple pragmas are separated by commas. The
|
|
|
550 pragmas accepted are the same as for the PRAGMA assembler directive described
|
|
|
551 below.</P
|
|
|
552 ></DD
|
|
|
553 ><DT
|
|
|
554 ><CODE
|
|
|
555 CLASS="OPTION"
|
|
|
556 >--raw</CODE
|
|
|
557 >, <CODE
|
|
|
558 CLASS="OPTION"
|
|
|
559 >-r</CODE
|
|
|
560 ></DT
|
|
|
561 ><DD
|
|
|
562 ><P
|
|
|
563 >Select raw binary as the output target.</P
|
|
|
564 ></DD
|
|
|
565 ><DT
|
|
|
566 ><CODE
|
|
|
567 CLASS="OPTION"
|
|
|
568 >--includedir=path</CODE
|
|
|
569 >, <CODE
|
|
|
570 CLASS="OPTION"
|
|
|
571 >-I path</CODE
|
|
|
572 ></DT
|
|
|
573 ><DD
|
|
|
574 ><P
|
|
|
575 >Add <CODE
|
|
|
576 CLASS="OPTION"
|
|
|
577 >path</CODE
|
|
|
578 > to the end of the include path.</P
|
|
|
579 ></DD
|
|
|
580 ><DT
|
|
|
581 ><CODE
|
|
|
582 CLASS="OPTION"
|
|
|
583 >--help</CODE
|
|
|
584 >, <CODE
|
|
|
585 CLASS="OPTION"
|
|
|
586 >-?</CODE
|
|
|
587 ></DT
|
|
|
588 ><DD
|
|
|
589 ><P
|
|
|
590 >Present a help screen describing the command line options.</P
|
|
|
591 ></DD
|
|
|
592 ><DT
|
|
|
593 ><CODE
|
|
|
594 CLASS="OPTION"
|
|
|
595 >--usage</CODE
|
|
|
596 ></DT
|
|
|
597 ><DD
|
|
|
598 ><P
|
|
|
599 >Provide a summary of the command line options.</P
|
|
|
600 ></DD
|
|
|
601 ><DT
|
|
|
602 ><CODE
|
|
|
603 CLASS="OPTION"
|
|
|
604 >--version</CODE
|
|
|
605 >, <CODE
|
|
|
606 CLASS="OPTION"
|
|
|
607 >-V</CODE
|
|
|
608 ></DT
|
|
|
609 ><DD
|
|
|
610 ><P
|
|
|
611 >Display the software version.</P
|
|
|
612 ></DD
|
|
|
613 ><DT
|
|
|
614 ><CODE
|
|
|
615 CLASS="OPTION"
|
|
|
616 >--debug</CODE
|
|
|
617 >, <CODE
|
|
|
618 CLASS="OPTION"
|
|
|
619 >-d</CODE
|
|
|
620 ></DT
|
|
|
621 ><DD
|
|
|
622 ><P
|
|
|
623 >Increase the debugging level. Only really useful to people hacking on the
|
|
|
624 LWASM source code itself.</P
|
|
|
625 ></DD
|
|
|
626 ></DL
|
|
|
627 ></DIV
|
|
|
628 ></DIV
|
|
|
629 ><DIV
|
|
|
630 CLASS="SECTION"
|
|
|
631 ><HR><H2
|
|
|
632 CLASS="SECTION"
|
|
|
633 ><A
|
|
|
634 NAME="AEN152"
|
|
|
635 >3.2. Dialects</A
|
|
|
636 ></H2
|
|
|
637 ><P
|
|
|
638 >LWASM supports all documented MC6809 instructions as defined by Motorola.
|
|
|
639 It also supports all known HD6309 instructions. While there is general
|
|
|
640 agreement on the pneumonics for most of the 6309 instructions, there is some
|
|
|
641 variance with the block transfer instructions. TFM for all four variations
|
|
|
642 seems to have gained the most traction and, thus, this is the form that is
|
|
|
643 recommended for LWASM. However, it also supports COPY, COPY-, IMP, EXP,
|
|
|
644 TFRP, TFRM, TFRS, and TFRR. It further adds COPY+ as a synomym for COPY,
|
|
|
645 IMPLODE for IMP, and EXPAND for EXP.</P
|
|
|
646 ><P
|
|
|
647 >By default, LWASM accepts 6309 instructions. However, using the
|
|
|
648 <CODE
|
|
|
649 CLASS="PARAMETER"
|
|
|
650 >--6809</CODE
|
|
|
651 > parameter, you can cause it to throw errors on
|
|
|
652 6309 instructions instead.</P
|
|
|
653 ><P
|
|
|
654 >The standard addressing mode specifiers are supported. These are the
|
|
|
655 hash sign ("#") for immediate mode, the less than sign ("<") for forced
|
|
|
656 eight bit modes, and the greater than sign (">") for forced sixteen bit modes.</P
|
|
|
657 ><P
|
|
|
658 >Additionally, LWASM supports using the asterisk ("*") to indicate
|
|
|
659 base page addressing. This should not be used in hand-written source code,
|
|
|
660 however, because it is non-standard and may or may not be present in future
|
|
|
661 versions of LWASM.</P
|
|
|
662 ></DIV
|
|
|
663 ><DIV
|
|
|
664 CLASS="SECTION"
|
|
|
665 ><HR><H2
|
|
|
666 CLASS="SECTION"
|
|
|
667 ><A
|
|
|
668 NAME="AEN159"
|
|
|
669 >3.3. Source Format</A
|
|
|
670 ></H2
|
|
|
671 ><P
|
|
|
672 >LWASM accepts plain text files in a relatively free form. It can handle
|
|
|
673 lines terminated with CR, LF, CRLF, or LFCR which means it should be able
|
|
|
674 to assemble files on any platform on which it compiles.</P
|
|
|
675 ><P
|
|
|
676 >Each line may start with a symbol. If a symbol is present, there must not
|
|
|
677 be any whitespace preceding it. It is legal for a line to contain nothing
|
|
|
678 but a symbol.</P
|
|
|
679 ><P
|
|
|
680 >The op code is separated from the symbol by whitespace. If there is
|
|
|
681 no symbol, there must be at least one white space character preceding it.
|
|
|
682 If applicable, the operand follows separated by whitespace. Following the
|
|
|
683 opcode and operand is an optional comment.</P
|
|
|
684 ><P
|
|
|
685 >A comment can also be introduced with a * or a ;. The comment character is
|
|
|
686 optional for end of statement comments. However, if a symbol is the only
|
|
|
687 thing present on the line other than the comment, the comment character is
|
|
|
688 mandatory to prevent the assembler from interpreting the comment as an opcode.</P
|
|
|
689 ><P
|
|
|
690 >For compatibility with the output generated by some C preprocessors, LWASM
|
|
|
691 will also ignore lines that begin with a #. This should not be used as a general
|
|
|
692 comment character, however.</P
|
|
|
693 ><P
|
|
|
694 >The opcode is not treated case sensitively. Neither are register names in
|
|
|
695 the operand fields. Symbols, however, are case sensitive.</P
|
|
|
696 ><P
|
|
|
697 > As of version 2.6, LWASM supports files with line numbers. If line
|
|
|
698 numbers are present, the line must start with a digit. The line number
|
|
|
699 itself must consist only of digits. The line number must then be followed
|
|
|
700 by either the end of the line or exactly one white space character. After
|
|
|
701 that white space character, the lines are interpreted exactly as above. </P
|
|
|
702 ></DIV
|
|
|
703 ><DIV
|
|
|
704 CLASS="SECTION"
|
|
|
705 ><HR><H2
|
|
|
706 CLASS="SECTION"
|
|
|
707 ><A
|
|
|
708 NAME="AEN168"
|
|
|
709 >3.4. Symbols</A
|
|
|
710 ></H2
|
|
|
711 ><P
|
|
|
712 >Symbols have no length restriction. They may contain letters, numbers, dots,
|
|
|
713 dollar signs, and underscores. They must start with a letter, dot, or
|
|
|
714 underscore.</P
|
|
|
715 ><P
|
|
|
716 >LWASM also supports the concept of a local symbol. A local symbol is one
|
|
|
717 which contains either a "?" or a "@", which can appear anywhere in the symbol.
|
|
|
718 The scope of a local symbol is determined by a number of factors. First,
|
|
|
719 each included file gets its own local symbol scope. A blank line will also
|
|
|
720 be considered a local scope barrier. Macros each have their own local symbol
|
|
|
721 scope as well (which has a side effect that you cannot use a local symbol
|
|
|
722 as an argument to a macro). There are other factors as well. In general,
|
|
|
723 a local symbol is restricted to the block of code it is defined within.</P
|
|
|
724 ><P
|
|
|
725 >By default, unless assembling to the os9 target, a "$" in the symbol will
|
|
|
726 also make it local. This can be controlled by the "dollarlocal" and
|
|
|
727 "nodollarlocal" pragmas. In the absence of a pragma to the contrary, For
|
|
|
728 the os9 target, a "$" in the symbol will not make it considered local while
|
|
|
729 for all other targets it will.</P
|
|
|
730 ></DIV
|
|
|
731 ><DIV
|
|
|
732 CLASS="SECTION"
|
|
|
733 ><HR><H2
|
|
|
734 CLASS="SECTION"
|
|
|
735 ><A
|
|
|
736 NAME="AEN173"
|
|
|
737 >3.5. Numbers and Expressions</A
|
|
|
738 ></H2
|
|
|
739 ><P
|
|
|
740 > Numbers can be expressed in binary, octal, decimal, or hexadecimal. Binary
|
|
|
741 numbers may be prefixed with a "%" symbol or suffixed with a "b" or "B".
|
|
|
742 Octal numbers may be prefixed with "@" or suffixed with "Q", "q", "O", or
|
|
|
743 "o". Hexadecimal numbers may be prefixed with "$", "0x" or "0X", or suffixed
|
|
|
744 with "H". No prefix or suffix is required for decimal numbers but they can
|
|
|
745 be prefixed with "&" if desired. Any constant which begins with a letter
|
|
|
746 must be expressed with the correct prefix base identifier or be prefixed
|
|
|
747 with a 0. Thus hexadecimal FF would have to be written either 0FFH or $FF.
|
|
|
748 Numbers are not case sensitive. </P
|
|
|
749 ><P
|
|
|
750 > A symbol may appear at any point where a number is acceptable. The
|
|
|
751 special symbol "*" can be used to represent the starting address of the
|
|
|
752 current source line within expressions. </P
|
|
|
753 ><P
|
|
|
754 >The ASCII value of a character can be included by prefixing it with a
|
|
|
755 single quote ('). The ASCII values of two characters can be included by
|
|
|
756 prefixing the characters with a quote (").</P
|
|
|
757 ><P
|
|
|
758 > LWASM supports the following basic binary operators: +, -, *, /, and %.
|
|
|
759 These represent addition, subtraction, multiplication, division, and
|
|
|
760 modulus. It also supports unary negation and unary 1's complement (- and ^
|
|
|
761 respectively). It is also possible to use ~ for the unary 1's complement
|
|
|
762 operator. For completeness, a unary positive (+) is supported though it is
|
|
|
763 a no-op. LWASM also supports using |, &, and ^ for bitwise or, bitwise and,
|
|
|
764 and bitwise exclusive or respectively. </P
|
|
|
765 ><P
|
|
|
766 > Operator precedence follows the usual rules. Multiplication, division, and
|
|
|
767 modulus take precedence over addition and subtraction. Unary operators take
|
|
|
768 precedence over binary operators. Bitwise operators are lower precdence
|
|
|
769 than addition and subtraction. To force a specific order of evaluation,
|
|
|
770 parentheses can be used in the usual manner. </P
|
|
|
771 ><P
|
|
|
772 > As of LWASM 2.5, the operators && and || are recognized for boolean and and
|
|
|
773 boolean or respectively. They will return either 0 or 1 (false or true).
|
|
|
774 They have the lowest precedence of all the binary operators. </P
|
|
|
775 ></DIV
|
|
|
776 ><DIV
|
|
|
777 CLASS="SECTION"
|
|
|
778 ><HR><H2
|
|
|
779 CLASS="SECTION"
|
|
|
780 ><A
|
|
|
781 NAME="AEN181"
|
|
|
782 >3.6. Assembler Directives</A
|
|
|
783 ></H2
|
|
|
784 ><P
|
|
|
785 >Various directives can be used to control the behaviour of the
|
|
|
786 assembler or to include non-code/data in the resulting output. Those directives
|
|
|
787 that are not described in detail in other sections of this document are
|
|
|
788 described below.</P
|
|
|
789 ><DIV
|
|
|
790 CLASS="SECTION"
|
|
|
791 ><HR><H3
|
|
|
792 CLASS="SECTION"
|
|
|
793 ><A
|
|
|
794 NAME="AEN184"
|
|
|
795 >3.6.1. Data Directives</A
|
|
|
796 ></H3
|
|
|
797 ><P
|
|
|
798 ></P
|
|
|
799 ><DIV
|
|
|
800 CLASS="VARIABLELIST"
|
|
|
801 ><DL
|
|
|
802 ><DT
|
|
|
803 >FCB <CODE
|
|
|
804 CLASS="PARAMETER"
|
|
|
805 >expr[,...]</CODE
|
|
|
806 >, .DB <CODE
|
|
|
807 CLASS="PARAMETER"
|
|
|
808 >expr[,...]</CODE
|
|
|
809 >, .BYTE <CODE
|
|
|
810 CLASS="PARAMETER"
|
|
|
811 >expr[,...]</CODE
|
|
|
812 ></DT
|
|
|
813 ><DD
|
|
|
814 ><P
|
|
|
815 >Include one or more constant bytes (separated by commas) in the output.</P
|
|
|
816 ></DD
|
|
|
817 ><DT
|
|
|
818 >FDB <CODE
|
|
|
819 CLASS="PARAMETER"
|
|
|
820 >expr[,...]</CODE
|
|
|
821 >, .DW <CODE
|
|
|
822 CLASS="PARAMETER"
|
|
|
823 >expr[,...]</CODE
|
|
|
824 >, .WORD <CODE
|
|
|
825 CLASS="PARAMETER"
|
|
|
826 >expr[,...]</CODE
|
|
|
827 ></DT
|
|
|
828 ><DD
|
|
|
829 ><P
|
|
|
830 >Include one or more words (separated by commas) in the output.</P
|
|
|
831 ></DD
|
|
|
832 ><DT
|
|
|
833 >FQB <CODE
|
|
|
834 CLASS="PARAMETER"
|
|
|
835 >expr[,...]</CODE
|
|
|
836 >, .QUAD <CODE
|
|
|
837 CLASS="PARAMETER"
|
|
|
838 >expr[,...]</CODE
|
|
|
839 >, .4BYTE <CODE
|
|
|
840 CLASS="PARAMETER"
|
|
|
841 >expr[,...]</CODE
|
|
|
842 ></DT
|
|
|
843 ><DD
|
|
|
844 ><P
|
|
|
845 >Include one or more double words (separated by commas) in the output.</P
|
|
|
846 ></DD
|
|
|
847 ><DT
|
|
|
848 >FCC <CODE
|
|
|
849 CLASS="PARAMETER"
|
|
|
850 >string</CODE
|
|
|
851 >, .ASCII <CODE
|
|
|
852 CLASS="PARAMETER"
|
|
|
853 >string</CODE
|
|
|
854 >, .STR <CODE
|
|
|
855 CLASS="PARAMETER"
|
|
|
856 >string</CODE
|
|
|
857 ></DT
|
|
|
858 ><DD
|
|
|
859 ><P
|
|
|
860 >Include a string of text in the output. The first character of the operand
|
|
|
861 is the delimiter which must appear as the last character and cannot appear
|
|
|
862 within the string. The string is included with no modifications></P
|
|
|
863 ></DD
|
|
|
864 ><DT
|
|
|
865 >FCN <CODE
|
|
|
866 CLASS="PARAMETER"
|
|
|
867 >string</CODE
|
|
|
868 >, .ASCIZ <CODE
|
|
|
869 CLASS="PARAMETER"
|
|
|
870 >string</CODE
|
|
|
871 >, .STRZ <CODE
|
|
|
872 CLASS="PARAMETER"
|
|
|
873 >string</CODE
|
|
|
874 ></DT
|
|
|
875 ><DD
|
|
|
876 ><P
|
|
|
877 >Include a NUL terminated string of text in the output. The first character of
|
|
|
878 the operand is the delimiter which must appear as the last character and
|
|
|
879 cannot appear within the string. A NUL byte is automatically appended to
|
|
|
880 the string.</P
|
|
|
881 ></DD
|
|
|
882 ><DT
|
|
|
883 >FCS <CODE
|
|
|
884 CLASS="PARAMETER"
|
|
|
885 >string</CODE
|
|
|
886 >, .ASCIS <CODE
|
|
|
887 CLASS="PARAMETER"
|
|
|
888 >string</CODE
|
|
|
889 >, .STRS <CODE
|
|
|
890 CLASS="PARAMETER"
|
|
|
891 >string</CODE
|
|
|
892 ></DT
|
|
|
893 ><DD
|
|
|
894 ><P
|
|
|
895 >Include a string of text in the output with bit 7 of the final byte set. The
|
|
|
896 first character of the operand is the delimiter which must appear as the last
|
|
|
897 character and cannot appear within the string.</P
|
|
|
898 ></DD
|
|
|
899 ><DT
|
|
|
900 >ZMB <CODE
|
|
|
901 CLASS="PARAMETER"
|
|
|
902 >expr</CODE
|
|
|
903 ></DT
|
|
|
904 ><DD
|
|
|
905 ><P
|
|
|
906 >Include a number of NUL bytes in the output. The number must be fully resolvable
|
|
|
907 during pass 1 of assembly so no forward or external references are permitted.</P
|
|
|
908 ></DD
|
|
|
909 ><DT
|
|
|
910 >ZMD <CODE
|
|
|
911 CLASS="PARAMETER"
|
|
|
912 >expr</CODE
|
|
|
913 ></DT
|
|
|
914 ><DD
|
|
|
915 ><P
|
|
|
916 >Include a number of zero words in the output. The number must be fully
|
|
|
917 resolvable during pass 1 of assembly so no forward or external references are
|
|
|
918 permitted.</P
|
|
|
919 ></DD
|
|
|
920 ><DT
|
|
|
921 >ZMQ <CODE
|
|
|
922 CLASS="PARAMETER"
|
|
|
923 >expr<CODE
|
|
|
924 CLASS="PARAMETER"
|
|
|
925 ></CODE
|
|
|
926 ></CODE
|
|
|
927 ></DT
|
|
|
928 ><DD
|
|
|
929 ><P
|
|
|
930 >Include a number of zero double-words in the output. The number must be fully
|
|
|
931 resolvable during pass 1 of assembly so no forward or external references are
|
|
|
932 permitted.</P
|
|
|
933 ></DD
|
|
|
934 ><DT
|
|
|
935 >RMB <CODE
|
|
|
936 CLASS="PARAMETER"
|
|
|
937 >expr</CODE
|
|
|
938 >, .BLKB <CODE
|
|
|
939 CLASS="PARAMETER"
|
|
|
940 >expr</CODE
|
|
|
941 >, .DS <CODE
|
|
|
942 CLASS="PARAMETER"
|
|
|
943 >expr</CODE
|
|
|
944 >, .RS <CODE
|
|
|
945 CLASS="PARAMETER"
|
|
|
946 >expr</CODE
|
|
|
947 ></DT
|
|
|
948 ><DD
|
|
|
949 ><P
|
|
|
950 >Reserve a number of bytes in the output. The number must be fully resolvable
|
|
|
951 during pass 1 of assembly so no forward or external references are permitted.
|
|
|
952 The value of the bytes is undefined.</P
|
|
|
953 ></DD
|
|
|
954 ><DT
|
|
|
955 >RMD <CODE
|
|
|
956 CLASS="PARAMETER"
|
|
|
957 >expr</CODE
|
|
|
958 ></DT
|
|
|
959 ><DD
|
|
|
960 ><P
|
|
|
961 >Reserve a number of words in the output. The number must be fully
|
|
|
962 resolvable during pass 1 of assembly so no forward or external references are
|
|
|
963 permitted. The value of the words is undefined.</P
|
|
|
964 ></DD
|
|
|
965 ><DT
|
|
|
966 >RMQ <CODE
|
|
|
967 CLASS="PARAMETER"
|
|
|
968 >expr</CODE
|
|
|
969 ></DT
|
|
|
970 ><DD
|
|
|
971 ><P
|
|
|
972 >Reserve a number of double-words in the output. The number must be fully
|
|
|
973 resolvable during pass 1 of assembly so no forward or external references are
|
|
|
974 permitted. The value of the double-words is undefined.</P
|
|
|
975 ></DD
|
|
|
976 ><DT
|
|
|
977 >INCLUDEBIN <CODE
|
|
|
978 CLASS="PARAMETER"
|
|
|
979 >filename</CODE
|
|
|
980 ></DT
|
|
|
981 ><DD
|
|
|
982 ><P
|
|
|
983 >Treat the contents of <CODE
|
|
|
984 CLASS="PARAMETER"
|
|
|
985 >filename</CODE
|
|
|
986 > as a string of bytes to
|
|
|
987 be included literally at the current assembly point. This has the same effect
|
|
|
988 as converting the file contents to a series of FCB statements and including
|
|
|
989 those at the current assembly point.</P
|
|
|
990 ><P
|
|
|
991 > If <CODE
|
|
|
992 CLASS="PARAMETER"
|
|
|
993 >filename</CODE
|
|
|
994 > beings with a /, the file name
|
|
|
995 will be taken as absolute. Otherwise, the current directory will be
|
|
|
996 searched followed by the search path in the order specified.</P
|
|
|
997 ><P
|
|
|
998 > Please note that absolute path detection including drive letters will
|
|
|
999 not function correctly on Windows platforms. Non-absolute inclusion will
|
|
|
1000 work, however.</P
|
|
|
1001 ></DD
|
|
|
1002 ></DL
|
|
|
1003 ></DIV
|
|
|
1004 ></DIV
|
|
|
1005 ><DIV
|
|
|
1006 CLASS="SECTION"
|
|
|
1007 ><HR><H3
|
|
|
1008 CLASS="SECTION"
|
|
|
1009 ><A
|
|
|
1010 NAME="AEN287"
|
|
|
1011 >3.6.2. Address Definition</A
|
|
|
1012 ></H3
|
|
|
1013 ><P
|
|
|
1014 >The directives in this section all control the addresses of symbols
|
|
|
1015 or the assembly process itself.</P
|
|
|
1016 ><P
|
|
|
1017 ></P
|
|
|
1018 ><DIV
|
|
|
1019 CLASS="VARIABLELIST"
|
|
|
1020 ><DL
|
|
|
1021 ><DT
|
|
|
1022 >ORG <CODE
|
|
|
1023 CLASS="PARAMETER"
|
|
|
1024 >expr</CODE
|
|
|
1025 ></DT
|
|
|
1026 ><DD
|
|
|
1027 ><P
|
|
|
1028 >Set the assembly address. The address must be fully resolvable on the
|
|
|
1029 first pass so no external or forward references are permitted. ORG is not
|
|
|
1030 permitted within sections when outputting to object files. For the DECB
|
|
|
1031 target, each ORG directive after which output is generated will cause
|
|
|
1032 a new preamble to be output. ORG is only used to determine the addresses
|
|
|
1033 of symbols when the raw target is used.</P
|
|
|
1034 ></DD
|
|
|
1035 ><DT
|
|
|
1036 ><CODE
|
|
|
1037 CLASS="PARAMETER"
|
|
|
1038 >sym</CODE
|
|
|
1039 > EQU <CODE
|
|
|
1040 CLASS="PARAMETER"
|
|
|
1041 >expr</CODE
|
|
|
1042 >, <CODE
|
|
|
1043 CLASS="PARAMETER"
|
|
|
1044 >sym</CODE
|
|
|
1045 > = <CODE
|
|
|
1046 CLASS="PARAMETER"
|
|
|
1047 >expr</CODE
|
|
|
1048 ></DT
|
|
|
1049 ><DD
|
|
|
1050 ><P
|
|
|
1051 >Define the value of <CODE
|
|
|
1052 CLASS="PARAMETER"
|
|
|
1053 >sym</CODE
|
|
|
1054 > to be <CODE
|
|
|
1055 CLASS="PARAMETER"
|
|
|
1056 >expr</CODE
|
|
|
1057 >.</P
|
|
|
1058 ></DD
|
|
|
1059 ><DT
|
|
|
1060 ><CODE
|
|
|
1061 CLASS="PARAMETER"
|
|
|
1062 >sym</CODE
|
|
|
1063 > SET <CODE
|
|
|
1064 CLASS="PARAMETER"
|
|
|
1065 >expr</CODE
|
|
|
1066 ></DT
|
|
|
1067 ><DD
|
|
|
1068 ><P
|
|
|
1069 >Define the value of <CODE
|
|
|
1070 CLASS="PARAMETER"
|
|
|
1071 >sym</CODE
|
|
|
1072 > to be <CODE
|
|
|
1073 CLASS="PARAMETER"
|
|
|
1074 >expr</CODE
|
|
|
1075 >.
|
|
|
1076 Unlike EQU, SET permits symbols to be defined multiple times as long as SET
|
|
|
1077 is used for all instances. Use of the symbol before the first SET statement
|
|
|
1078 that sets its value is undefined.</P
|
|
|
1079 ></DD
|
|
|
1080 ><DT
|
|
|
1081 >SETDP <CODE
|
|
|
1082 CLASS="PARAMETER"
|
|
|
1083 >expr</CODE
|
|
|
1084 ></DT
|
|
|
1085 ><DD
|
|
|
1086 ><P
|
|
|
1087 >Inform the assembler that it can assume the DP register contains
|
|
|
1088 <CODE
|
|
|
1089 CLASS="PARAMETER"
|
|
|
1090 >expr</CODE
|
|
|
1091 >. This directive is only advice to the assembler
|
|
|
1092 to determine whether an address is in the direct page and has no effect
|
|
|
1093 on the contents of the DP register. The value must be fully resolved during
|
|
|
1094 the first assembly pass because it affects the sizes of subsequent instructions.</P
|
|
|
1095 ><P
|
|
|
1096 >This directive has no effect in the object file target.</P
|
|
|
1097 ></DD
|
|
|
1098 ><DT
|
|
|
1099 >ALIGN <CODE
|
|
|
1100 CLASS="PARAMETER"
|
|
|
1101 >expr</CODE
|
|
|
1102 >[,<CODE
|
|
|
1103 CLASS="PARAMETER"
|
|
|
1104 >value</CODE
|
|
|
1105 >]</DT
|
|
|
1106 ><DD
|
|
|
1107 ><P
|
|
|
1108 >Force the current assembly address to be a multiple of
|
|
|
1109 <CODE
|
|
|
1110 CLASS="PARAMETER"
|
|
|
1111 >expr</CODE
|
|
|
1112 >. If <CODE
|
|
|
1113 CLASS="PARAMETER"
|
|
|
1114 >value</CODE
|
|
|
1115 > is not
|
|
|
1116 specified, a series of NUL bytes is output to force the alignment, if
|
|
|
1117 required. Otherwise, the low order 8 bits of <CODE
|
|
|
1118 CLASS="PARAMETER"
|
|
|
1119 >value</CODE
|
|
|
1120 >
|
|
|
1121 will be used as the fill. The alignment value must be fully resolved on the
|
|
|
1122 first pass because it affects the addresses of subsquent instructions.
|
|
|
1123 However, <CODE
|
|
|
1124 CLASS="PARAMETER"
|
|
|
1125 >value</CODE
|
|
|
1126 > may include forward references; as
|
|
|
1127 long as it resolves to a constant for the second pass, the value will be
|
|
|
1128 accepted.</P
|
|
|
1129 ><P
|
|
|
1130 >Unless <CODE
|
|
|
1131 CLASS="PARAMETER"
|
|
|
1132 >value</CODE
|
|
|
1133 > is specified as something like $12,
|
|
|
1134 this directive is not suitable for inclusion in the middle of actual code.
|
|
|
1135 The default padding value is $00 which is intended to be used within data
|
|
|
1136 blocks. </P
|
|
|
1137 ></DD
|
|
|
1138 ></DL
|
|
|
1139 ></DIV
|
|
|
1140 ></DIV
|
|
|
1141 ><DIV
|
|
|
1142 CLASS="SECTION"
|
|
|
1143 ><HR><H3
|
|
|
1144 CLASS="SECTION"
|
|
|
1145 ><A
|
|
|
1146 NAME="AEN334"
|
|
|
1147 >3.6.3. Conditional Assembly</A
|
|
|
1148 ></H3
|
|
|
1149 ><P
|
|
|
1150 >Portions of the source code can be excluded or included based on conditions
|
|
|
1151 known at assembly time. Conditionals can be nested arbitrarily deeply. The
|
|
|
1152 directives associated with conditional assembly are described in this section.</P
|
|
|
1153 ><P
|
|
|
1154 >All conditionals must be fully bracketed. That is, every conditional
|
|
|
1155 statement must eventually be followed by an ENDC at the same level of nesting.</P
|
|
|
1156 ><P
|
|
|
1157 >Conditional expressions are only evaluated on the first assembly pass.
|
|
|
1158 It is not possible to game the assembly process by having a conditional
|
|
|
1159 change its value between assembly passes. Thus there is not and never will
|
|
|
1160 be any equivalent of IFP1 or IFP2 as provided by other assemblers.</P
|
|
|
1161 ><P
|
|
|
1162 ></P
|
|
|
1163 ><DIV
|
|
|
1164 CLASS="VARIABLELIST"
|
|
|
1165 ><DL
|
|
|
1166 ><DT
|
|
|
1167 >IFEQ <CODE
|
|
|
1168 CLASS="PARAMETER"
|
|
|
1169 >expr</CODE
|
|
|
1170 ></DT
|
|
|
1171 ><DD
|
|
|
1172 ><P
|
|
|
1173 >If <CODE
|
|
|
1174 CLASS="PARAMETER"
|
|
|
1175 >expr</CODE
|
|
|
1176 > evaluates to zero, the conditional
|
|
|
1177 will be considered true.</P
|
|
|
1178 ></DD
|
|
|
1179 ><DT
|
|
|
1180 >IFNE <CODE
|
|
|
1181 CLASS="PARAMETER"
|
|
|
1182 >expr</CODE
|
|
|
1183 >, IF <CODE
|
|
|
1184 CLASS="PARAMETER"
|
|
|
1185 >expr</CODE
|
|
|
1186 ></DT
|
|
|
1187 ><DD
|
|
|
1188 ><P
|
|
|
1189 >If <CODE
|
|
|
1190 CLASS="PARAMETER"
|
|
|
1191 >expr</CODE
|
|
|
1192 > evaluates to a non-zero value, the conditional
|
|
|
1193 will be considered true.</P
|
|
|
1194 ></DD
|
|
|
1195 ><DT
|
|
|
1196 >IFGT <CODE
|
|
|
1197 CLASS="PARAMETER"
|
|
|
1198 >expr</CODE
|
|
|
1199 ></DT
|
|
|
1200 ><DD
|
|
|
1201 ><P
|
|
|
1202 >If <CODE
|
|
|
1203 CLASS="PARAMETER"
|
|
|
1204 >expr</CODE
|
|
|
1205 > evaluates to a value greater than zero, the conditional
|
|
|
1206 will be considered true.</P
|
|
|
1207 ></DD
|
|
|
1208 ><DT
|
|
|
1209 >IFGE <CODE
|
|
|
1210 CLASS="PARAMETER"
|
|
|
1211 >expr</CODE
|
|
|
1212 ></DT
|
|
|
1213 ><DD
|
|
|
1214 ><P
|
|
|
1215 >If <CODE
|
|
|
1216 CLASS="PARAMETER"
|
|
|
1217 >expr</CODE
|
|
|
1218 > evaluates to a value greater than or equal to zero, the conditional
|
|
|
1219 will be considered true.</P
|
|
|
1220 ></DD
|
|
|
1221 ><DT
|
|
|
1222 >IFLT <CODE
|
|
|
1223 CLASS="PARAMETER"
|
|
|
1224 >expr</CODE
|
|
|
1225 ></DT
|
|
|
1226 ><DD
|
|
|
1227 ><P
|
|
|
1228 >If <CODE
|
|
|
1229 CLASS="PARAMETER"
|
|
|
1230 >expr</CODE
|
|
|
1231 > evaluates to a value less than zero, the conditional
|
|
|
1232 will be considered true.</P
|
|
|
1233 ></DD
|
|
|
1234 ><DT
|
|
|
1235 >IFLE <CODE
|
|
|
1236 CLASS="PARAMETER"
|
|
|
1237 >expr</CODE
|
|
|
1238 ></DT
|
|
|
1239 ><DD
|
|
|
1240 ><P
|
|
|
1241 >If <CODE
|
|
|
1242 CLASS="PARAMETER"
|
|
|
1243 >expr</CODE
|
|
|
1244 > evaluates to a value less than or equal to zero , the conditional
|
|
|
1245 will be considered true.</P
|
|
|
1246 ></DD
|
|
|
1247 ><DT
|
|
|
1248 >IFDEF <CODE
|
|
|
1249 CLASS="PARAMETER"
|
|
|
1250 >sym</CODE
|
|
|
1251 ></DT
|
|
|
1252 ><DD
|
|
|
1253 ><P
|
|
|
1254 >If <CODE
|
|
|
1255 CLASS="PARAMETER"
|
|
|
1256 >sym</CODE
|
|
|
1257 > is defined at this point in the assembly
|
|
|
1258 process, the conditional
|
|
|
1259 will be considered true.</P
|
|
|
1260 ></DD
|
|
|
1261 ><DT
|
|
|
1262 >IFNDEF <CODE
|
|
|
1263 CLASS="PARAMETER"
|
|
|
1264 >sym</CODE
|
|
|
1265 ></DT
|
|
|
1266 ><DD
|
|
|
1267 ><P
|
|
|
1268 >If <CODE
|
|
|
1269 CLASS="PARAMETER"
|
|
|
1270 >sym</CODE
|
|
|
1271 > is not defined at this point in the assembly
|
|
|
1272 process, the conditional
|
|
|
1273 will be considered true.</P
|
|
|
1274 ></DD
|
|
|
1275 ><DT
|
|
|
1276 >ELSE</DT
|
|
|
1277 ><DD
|
|
|
1278 ><P
|
|
|
1279 >If the preceding conditional at the same level of nesting was false, the
|
|
|
1280 statements following will be assembled. If the preceding conditional at
|
|
|
1281 the same level was true, the statements following will not be assembled.
|
|
|
1282 Note that the preceding conditional might have been another ELSE statement
|
|
|
1283 although this behaviour is not guaranteed to be supported in future versions
|
|
|
1284 of LWASM.</P
|
|
|
1285 ></DD
|
|
|
1286 ><DT
|
|
|
1287 >ENDC</DT
|
|
|
1288 ><DD
|
|
|
1289 ><P
|
|
|
1290 >This directive marks the end of a conditional construct. Every conditional
|
|
|
1291 construct must end with an ENDC directive.</P
|
|
|
1292 ></DD
|
|
|
1293 ></DL
|
|
|
1294 ></DIV
|
|
|
1295 ></DIV
|
|
|
1296 ><DIV
|
|
|
1297 CLASS="SECTION"
|
|
|
1298 ><HR><H3
|
|
|
1299 CLASS="SECTION"
|
|
|
1300 ><A
|
|
|
1301 NAME="AEN398"
|
|
|
1302 >3.6.4. OS9 Target Directives</A
|
|
|
1303 ></H3
|
|
|
1304 ><P
|
|
|
1305 >This section includes directives that apply solely to the OS9
|
|
|
1306 target.</P
|
|
|
1307 ><P
|
|
|
1308 ></P
|
|
|
1309 ><DIV
|
|
|
1310 CLASS="VARIABLELIST"
|
|
|
1311 ><DL
|
|
|
1312 ><DT
|
|
|
1313 >OS9 <CODE
|
|
|
1314 CLASS="PARAMETER"
|
|
|
1315 >syscall</CODE
|
|
|
1316 ></DT
|
|
|
1317 ><DD
|
|
|
1318 ><P
|
|
|
1319 > This directive generates a call to the specified system call. <CODE
|
|
|
1320 CLASS="PARAMETER"
|
|
|
1321 >syscall</CODE
|
|
|
1322 > may be an arbitrary expression. </P
|
|
|
1323 ></DD
|
|
|
1324 ><DT
|
|
|
1325 >MOD <CODE
|
|
|
1326 CLASS="PARAMETER"
|
|
|
1327 >size</CODE
|
|
|
1328 >,<CODE
|
|
|
1329 CLASS="PARAMETER"
|
|
|
1330 >name</CODE
|
|
|
1331 >,<CODE
|
|
|
1332 CLASS="PARAMETER"
|
|
|
1333 >type</CODE
|
|
|
1334 >,<CODE
|
|
|
1335 CLASS="PARAMETER"
|
|
|
1336 >flags</CODE
|
|
|
1337 >,<CODE
|
|
|
1338 CLASS="PARAMETER"
|
|
|
1339 >execoff</CODE
|
|
|
1340 >,<CODE
|
|
|
1341 CLASS="PARAMETER"
|
|
|
1342 >datasize</CODE
|
|
|
1343 ></DT
|
|
|
1344 ><DD
|
|
|
1345 ><P
|
|
|
1346 > This tells LWASM that the beginning of the actual module is here. It will
|
|
|
1347 generate a module header based on the parameters specified. It will also
|
|
|
1348 begin calcuating the module CRC. </P
|
|
|
1349 ><P
|
|
|
1350 > The precise meaning of the various parameters is beyond the scope of this
|
|
|
1351 document since it is not a tutorial on OS9 module programming. </P
|
|
|
1352 ></DD
|
|
|
1353 ><DT
|
|
|
1354 >EMOD</DT
|
|
|
1355 ><DD
|
|
|
1356 ><P
|
|
|
1357 > This marks the end of a module and causes LWASM to emit the calculated CRC
|
|
|
1358 for the module. </P
|
|
|
1359 ></DD
|
|
|
1360 ></DL
|
|
|
1361 ></DIV
|
|
|
1362 ></DIV
|
|
|
1363 ><DIV
|
|
|
1364 CLASS="SECTION"
|
|
|
1365 ><HR><H3
|
|
|
1366 CLASS="SECTION"
|
|
|
1367 ><A
|
|
|
1368 NAME="AEN423"
|
|
|
1369 >3.6.5. Miscelaneous Directives</A
|
|
|
1370 ></H3
|
|
|
1371 ><P
|
|
|
1372 >This section includes directives that do not fit into the other
|
|
|
1373 categories.</P
|
|
|
1374 ><P
|
|
|
1375 ></P
|
|
|
1376 ><DIV
|
|
|
1377 CLASS="VARIABLELIST"
|
|
|
1378 ><DL
|
|
|
1379 ><DT
|
|
|
1380 >INCLUDE <CODE
|
|
|
1381 CLASS="PARAMETER"
|
|
|
1382 >filename</CODE
|
|
|
1383 >, USE <CODE
|
|
|
1384 CLASS="PARAMETER"
|
|
|
1385 >filename</CODE
|
|
|
1386 ></DT
|
|
|
1387 ><DD
|
|
|
1388 ><P
|
|
|
1389 > Include the contents of <CODE
|
|
|
1390 CLASS="PARAMETER"
|
|
|
1391 >filename</CODE
|
|
|
1392 > at
|
|
|
1393 this point in the assembly as though it were a part of the file currently
|
|
|
1394 being processed. Note that if whitespace appears in the name of the file,
|
|
|
1395 you must enclose <CODE
|
|
|
1396 CLASS="PARAMETER"
|
|
|
1397 >filename</CODE
|
|
|
1398 > in quotes.</P
|
|
|
1399 ><P
|
|
|
1400 >Note that the USE variation is provided only for compatibility with other
|
|
|
1401 assemblers. It is recommended to use the INCLUDE variation.</P
|
|
|
1402 ></DD
|
|
|
1403 ><DT
|
|
|
1404 >END <CODE
|
|
|
1405 CLASS="PARAMETER"
|
|
|
1406 >[expr]</CODE
|
|
|
1407 ></DT
|
|
|
1408 ><DD
|
|
|
1409 ><P
|
|
|
1410 >This directive causes the assembler to stop assembling immediately as though
|
|
|
1411 it ran out of input. For the DECB target only, <CODE
|
|
|
1412 CLASS="PARAMETER"
|
|
|
1413 >expr</CODE
|
|
|
1414 >
|
|
|
1415 can be used to set the execution address of the resulting binary. For all
|
|
|
1416 other targets, specifying <CODE
|
|
|
1417 CLASS="PARAMETER"
|
|
|
1418 >expr</CODE
|
|
|
1419 > will cause an error.</P
|
|
|
1420 ></DD
|
|
|
1421 ><DT
|
|
|
1422 >ERROR <CODE
|
|
|
1423 CLASS="PARAMETER"
|
|
|
1424 >string</CODE
|
|
|
1425 ></DT
|
|
|
1426 ><DD
|
|
|
1427 ><P
|
|
|
1428 >Causes a custom error message to be printed at this line. This will cause
|
|
|
1429 assembly to fail. This directive is most useful inside conditional constructs
|
|
|
1430 to cause assembly to fail if some condition that is known bad happens.</P
|
|
|
1431 ></DD
|
|
|
1432 ><DT
|
|
|
1433 >.MODULE <CODE
|
|
|
1434 CLASS="PARAMETER"
|
|
|
1435 >string</CODE
|
|
|
1436 ></DT
|
|
|
1437 ><DD
|
|
|
1438 ><P
|
|
|
1439 >This directive is ignored for most output targets. If the output target
|
|
|
1440 supports encoding a module name into it, <CODE
|
|
|
1441 CLASS="PARAMETER"
|
|
|
1442 >string</CODE
|
|
|
1443 >
|
|
|
1444 will be used as the module name.</P
|
|
|
1445 ><P
|
|
|
1446 >As of version 2.2, no supported output targets support this directive.</P
|
|
|
1447 ></DD
|
|
|
1448 ></DL
|
|
|
1449 ></DIV
|
|
|
1450 ></DIV
|
|
|
1451 ></DIV
|
|
|
1452 ><DIV
|
|
|
1453 CLASS="SECTION"
|
|
|
1454 ><HR><H2
|
|
|
1455 CLASS="SECTION"
|
|
|
1456 ><A
|
|
|
1457 NAME="AEN456"
|
|
|
1458 >3.7. Macros</A
|
|
|
1459 ></H2
|
|
|
1460 ><P
|
|
|
1461 >LWASM is a macro assembler. A macro is simply a name that stands in for a
|
|
|
1462 series of instructions. Once a macro is defined, it is used like any other
|
|
|
1463 assembler directive. Defining a macro can be considered equivalent to adding
|
|
|
1464 additional assembler directives.</P
|
|
|
1465 ><P
|
|
|
1466 >Macros my accept parameters. These parameters are referenced within
|
|
|
1467 a macro by the a backslash ("\") followed by a digit 1 through 9 for the first
|
|
|
1468 through ninth parameters. They may also be referenced by enclosing the
|
|
|
1469 decimal parameter number in braces ("{num}"). These parameter references
|
|
|
1470 are replaced with the verbatim text of the parameter passed to the macro. A
|
|
|
1471 reference to a non-existent parameter will be replaced by an empty string.
|
|
|
1472 Macro parameters are expanded everywhere on each source line. That means
|
|
|
1473 the parameter to a macro could be used as a symbol or it could even appear
|
|
|
1474 in a comment or could cause an entire source line to be commented out
|
|
|
1475 when the macro is expanded.</P
|
|
|
1476 ><P
|
|
|
1477 >Parameters passed to a macro are separated by commas and the parameter list
|
|
|
1478 is terminated by any whitespace. This means that neither a comma nor whitespace
|
|
|
1479 may be included in a macro parameter.</P
|
|
|
1480 ><P
|
|
|
1481 >Macro expansion is done recursively. That is, within a macro, macros are
|
|
|
1482 expanded. This can lead to infinite loops in macro expansion. If the assembler
|
|
|
1483 hangs for a long time while assembling a file that uses macros, this may be
|
|
|
1484 the reason.</P
|
|
|
1485 ><P
|
|
|
1486 >Each macro expansion receives its own local symbol context which is not
|
|
|
1487 inherited by any macros called by it nor is it inherited from the context
|
|
|
1488 the macro was instantiated in. That means it is possible to use local symbols
|
|
|
1489 within macros without having them collide with symbols in other macros or
|
|
|
1490 outside the macro itself. However, this also means that using a local symbol
|
|
|
1491 as a parameter to a macro, while legal, will not do what it would seem to do
|
|
|
1492 as it will result in looking up the local symbol in the macro's symbol context
|
|
|
1493 rather than the enclosing context where it came from, likely yielding either
|
|
|
1494 an undefined symbol error or bizarre assembly results.</P
|
|
|
1495 ><P
|
|
|
1496 >Note that there is no way to define a macro as local to a symbol context. All
|
|
|
1497 macros are part of the global macro namespace. However, macros have a separate
|
|
|
1498 namespace from symbols so it is possible to have a symbol with the same name
|
|
|
1499 as a macro.</P
|
|
|
1500 ><P
|
|
|
1501 >Macros are defined only during the first pass. Macro expansion also
|
|
|
1502 only occurs during the first pass. On the second pass, the macro
|
|
|
1503 definition is simply ignored. Macros must be defined before they are used.</P
|
|
|
1504 ><P
|
|
|
1505 >The following directives are used when defining macros.</P
|
|
|
1506 ><P
|
|
|
1507 ></P
|
|
|
1508 ><DIV
|
|
|
1509 CLASS="VARIABLELIST"
|
|
|
1510 ><DL
|
|
|
1511 ><DT
|
|
|
1512 ><CODE
|
|
|
1513 CLASS="PARAMETER"
|
|
|
1514 >macroname</CODE
|
|
|
1515 > MACRO</DT
|
|
|
1516 ><DD
|
|
|
1517 ><P
|
|
|
1518 >This directive is used to being the definition of a macro called
|
|
|
1519 <CODE
|
|
|
1520 CLASS="PARAMETER"
|
|
|
1521 >macroname</CODE
|
|
|
1522 >. If <CODE
|
|
|
1523 CLASS="PARAMETER"
|
|
|
1524 >macroname</CODE
|
|
|
1525 > already
|
|
|
1526 exists, it is considered an error. Attempting to define a macro within a
|
|
|
1527 macro is undefined. It may work and it may not so the behaviour should not
|
|
|
1528 be relied upon.</P
|
|
|
1529 ></DD
|
|
|
1530 ><DT
|
|
|
1531 >ENDM</DT
|
|
|
1532 ><DD
|
|
|
1533 ><P
|
|
|
1534 >This directive indicates the end of the macro currently being defined. It
|
|
|
1535 causes the assembler to resume interpreting source lines as normal.</P
|
|
|
1536 ></DD
|
|
|
1537 ></DL
|
|
|
1538 ></DIV
|
|
|
1539 ></DIV
|
|
|
1540 ><DIV
|
|
|
1541 CLASS="SECTION"
|
|
|
1542 ><HR><H2
|
|
|
1543 CLASS="SECTION"
|
|
|
1544 ><A
|
|
|
1545 NAME="AEN478"
|
|
|
1546 >3.8. Structures</A
|
|
|
1547 ></H2
|
|
|
1548 ><P
|
|
|
1549 > Structures are used to group related data in a fixed structure. A structure
|
|
|
1550 consists a number of fields, defined in sequential order and which take up
|
|
|
1551 specified size. The assembler does not enforce any means of access within a
|
|
|
1552 structure; it assumes that whatever you are doing, you intended to do.
|
|
|
1553 There are two pseudo ops that are used for defining structures. </P
|
|
|
1554 ><P
|
|
|
1555 ></P
|
|
|
1556 ><DIV
|
|
|
1557 CLASS="VARIABLELIST"
|
|
|
1558 ><DL
|
|
|
1559 ><DT
|
|
|
1560 ><CODE
|
|
|
1561 CLASS="PARAMETER"
|
|
|
1562 >structname</CODE
|
|
|
1563 > STRUCT</DT
|
|
|
1564 ><DD
|
|
|
1565 ><P
|
|
|
1566 > This directive is used to begin the definition of a structure with name
|
|
|
1567 <CODE
|
|
|
1568 CLASS="PARAMETER"
|
|
|
1569 >structname</CODE
|
|
|
1570 >. Subsequent statements all form part of
|
|
|
1571 the structure definition until the end of the structure is declared. </P
|
|
|
1572 ></DD
|
|
|
1573 ><DT
|
|
|
1574 >ENDSTRUCT</DT
|
|
|
1575 ><DD
|
|
|
1576 ><P
|
|
|
1577 >This directive ends the definition of the structure.</P
|
|
|
1578 ></DD
|
|
|
1579 ></DL
|
|
|
1580 ></DIV
|
|
|
1581 ><P
|
|
|
1582 > Within a structure definition, only reservation pseudo ops are permitted.
|
|
|
1583 Anything else will cause an assembly error.</P
|
|
|
1584 ><P
|
|
|
1585 > Once a structure is defined, you can reserve an area of memory in the
|
|
|
1586 same structure by using the structure name as the opcode. Structures can
|
|
|
1587 also contain fields that are themselves structures. See the example
|
|
|
1588 below.</P
|
|
|
1589 ><PRE
|
|
|
1590 CLASS="PROGRAMLISTING"
|
|
|
1591 >tstruct2 STRUCT
|
|
|
1592 f1 rmb 1
|
|
|
1593 f2 rmb 1
|
|
|
1594 ENDSTRUCT
|
|
|
1595
|
|
|
1596 tstruct STRUCT
|
|
|
1597 field1 rmb 2
|
|
|
1598 field2 rmb 3
|
|
|
1599 field3 tstruct2
|
|
|
1600 ENDSTRUCT
|
|
|
1601
|
|
|
1602 ORG $2000
|
|
|
1603 var1 tstruct
|
|
|
1604 var2 tstruct2</PRE
|
|
|
1605 ><P
|
|
|
1606 >Fields are referenced using a dot (.) as a separator. To refer to the
|
|
|
1607 generic offset within a structure, use the structure name to the left of the
|
|
|
1608 dot. If referring to a field within an actual variable, use the variable's
|
|
|
1609 symbol name to the left of the dot.</P
|
|
|
1610 ><P
|
|
|
1611 >You can also refer to the actual size of a structure (or a variable
|
|
|
1612 declared as a structure) using the special symbol sizeof{structname} where
|
|
|
1613 structname will be the name of the structure or the name of the
|
|
|
1614 variable.</P
|
|
|
1615 ><P
|
|
|
1616 >Essentially, structures are a shortcut for defining a vast number of
|
|
|
1617 symbols. When a structure is defined, the assembler creates symbols for the
|
|
|
1618 various fields in the form structname.fieldname as well as the appropriate
|
|
|
1619 sizeof{structname} symbol. When a variable is declared as a structure, the
|
|
|
1620 assembler does the same thing using the name of the variable. You will see
|
|
|
1621 these symbols in the symbol table when the assembler is instructed to
|
|
|
1622 provide a listing. For instance, the above listing will create the
|
|
|
1623 following symbols (symbol values in parentheses): tstruct2.f1 (0),
|
|
|
1624 tstruct2.f2 (1), sizeof{tstruct2} (2), tstruct.field1 (0), tstruct.field2
|
|
|
1625 (2), tstruct.field3 (5), tstruct.field3.f1 (5), tstruct.field3.f2 (6),
|
|
|
1626 sizeof{tstruct.field3} (2), sizeof{tstruct} (7), var1 {$2000}, var1.field1
|
|
|
1627 {$2000}, var1.field2 {$2002}, var1.field3 {$2005}, var1.field3.f1 {$2005},
|
|
|
1628 var1.field3.f2 {$2006}, sizeof(var1.field3} (2), sizeof{var1} (7), var2
|
|
|
1629 ($2007), var2.f1 ($2007), var2.f2 ($2008), sizeof{var2} (2). </P
|
|
|
1630 ></DIV
|
|
|
1631 ><DIV
|
|
|
1632 CLASS="SECTION"
|
|
|
1633 ><HR><H2
|
|
|
1634 CLASS="SECTION"
|
|
|
1635 ><A
|
|
|
1636 NAME="AEN498"
|
|
|
1637 >3.9. Object Files and Sections</A
|
|
|
1638 ></H2
|
|
|
1639 ><P
|
|
|
1640 >The object file target is very useful for large project because it allows
|
|
|
1641 multiple files to be assembled independently and then linked into the final
|
|
|
1642 binary at a later time. It allows only the small portion of the project
|
|
|
1643 that was modified to be re-assembled rather than requiring the entire set
|
|
|
1644 of source code to be available to the assembler in a single assembly process.
|
|
|
1645 This can be particularly important if there are a large number of macros,
|
|
|
1646 symbol definitions, or other metadata that uses resources at assembly time.
|
|
|
1647 By far the largest benefit, however, is keeping the source files small enough
|
|
|
1648 for a mere mortal to find things in them.</P
|
|
|
1649 ><P
|
|
|
1650 >With multi-file projects, there needs to be a means of resolving references to
|
|
|
1651 symbols in other source files. These are known as external references. The
|
|
|
1652 addresses of these symbols cannot be known until the linker joins all the
|
|
|
1653 object files into a single binary. This means that the assembler must be
|
|
|
1654 able to output the object code without knowing the value of the symbol. This
|
|
|
1655 places some restrictions on the code generated by the assembler. For
|
|
|
1656 example, the assembler cannot generate direct page addressing for instructions
|
|
|
1657 that reference external symbols because the address of the symbol may not
|
|
|
1658 be in the direct page. Similarly, relative branches and PC relative addressing
|
|
|
1659 cannot be used in their eight bit forms. Everything that must be resolved
|
|
|
1660 by the linker must be assembled to use the largest address size possible to
|
|
|
1661 allow the linker to fill in the correct value at link time. Note that the
|
|
|
1662 same problem applies to absolute address references as well, even those in
|
|
|
1663 the same source file, because the address is not known until link time.</P
|
|
|
1664 ><P
|
|
|
1665 >It is often desired in multi-file projects to have code of various types grouped
|
|
|
1666 together in the final binary generated by the linker as well. The same applies
|
|
|
1667 to data. In order for the linker to do that, the bits that are to be grouped
|
|
|
1668 must be tagged in some manner. This is where the concept of sections comes in.
|
|
|
1669 Each chunk of code or data is part of a section in the object file. Then,
|
|
|
1670 when the linker reads all the object files, it coalesces all sections of the
|
|
|
1671 same name into a single section and then considers it as a unit.</P
|
|
|
1672 ><P
|
|
|
1673 >The existence of sections, however, raises a problem for symbols even
|
|
|
1674 within the same source file. Thus, the assembler must treat symbols from
|
|
|
1675 different sections within the same source file in the same manner as external
|
|
|
1676 symbols. That is, it must leave them for the linker to resolve at link time,
|
|
|
1677 with all the limitations that entails.</P
|
|
|
1678 ><P
|
|
|
1679 >In the object file target mode, LWASM requires all source lines that
|
|
|
1680 cause bytes to be output to be inside a section. Any directives that do
|
|
|
1681 not cause any bytes to be output can appear outside of a section. This includes
|
|
|
1682 such things as EQU or RMB. Even ORG can appear outside a section. ORG, however,
|
|
|
1683 makes no sense within a section because it is the linker that determines
|
|
|
1684 the starting address of the section's code, not the assembler.</P
|
|
|
1685 ><P
|
|
|
1686 >All symbols defined globally in the assembly process are local to the
|
|
|
1687 source file and cannot be exported. All symbols defined within a section are
|
|
|
1688 considered local to the source file unless otherwise explicitly exported.
|
|
|
1689 Symbols referenced from external source files must be declared external,
|
|
|
1690 either explicitly or by asking the assembler to assume that all undefined
|
|
|
1691 symbols are external.</P
|
|
|
1692 ><P
|
|
|
1693 >It is often handy to define a number of memory addresses that will be
|
|
|
1694 used for data at run-time but which need not be included in the binary file.
|
|
|
1695 These memory addresses are not initialized until run-time, either by the
|
|
|
1696 program itself or by the program loader, depending on the operating environment.
|
|
|
1697 Such sections are often known as BSS sections. LWASM supports generating
|
|
|
1698 sections with a BSS attribute set which causes the section definition including
|
|
|
1699 symbols exported from that section and those symbols required to resolve
|
|
|
1700 references from the local file, but with no actual code in the object file.
|
|
|
1701 It is illegal for any source lines within a BSS flagged section to cause any
|
|
|
1702 bytes to be output.</P
|
|
|
1703 ><P
|
|
|
1704 >The following directives apply to section handling.</P
|
|
|
1705 ><P
|
|
|
1706 ></P
|
|
|
1707 ><DIV
|
|
|
1708 CLASS="VARIABLELIST"
|
|
|
1709 ><DL
|
|
|
1710 ><DT
|
|
|
1711 >SECTION <CODE
|
|
|
1712 CLASS="PARAMETER"
|
|
|
1713 >name[,flags]</CODE
|
|
|
1714 >, SECT <CODE
|
|
|
1715 CLASS="PARAMETER"
|
|
|
1716 >name[,flags]</CODE
|
|
|
1717 >, .AREA <CODE
|
|
|
1718 CLASS="PARAMETER"
|
|
|
1719 >name[,flags]</CODE
|
|
|
1720 ></DT
|
|
|
1721 ><DD
|
|
|
1722 ><P
|
|
|
1723 >Instructs the assembler that the code following this directive is to be
|
|
|
1724 considered part of the section <CODE
|
|
|
1725 CLASS="PARAMETER"
|
|
|
1726 >name</CODE
|
|
|
1727 >. A section name
|
|
|
1728 may appear multiple times in which case it is as though all the code from
|
|
|
1729 all the instances of that section appeared adjacent within the source file.
|
|
|
1730 However, <CODE
|
|
|
1731 CLASS="PARAMETER"
|
|
|
1732 >flags</CODE
|
|
|
1733 > may only be specified on the first
|
|
|
1734 instance of the section.</P
|
|
|
1735 ><P
|
|
|
1736 >There is a single flag supported in <CODE
|
|
|
1737 CLASS="PARAMETER"
|
|
|
1738 >flags</CODE
|
|
|
1739 >. The
|
|
|
1740 flag <CODE
|
|
|
1741 CLASS="PARAMETER"
|
|
|
1742 >bss</CODE
|
|
|
1743 > will cause the section to be treated as a BSS
|
|
|
1744 section and, thus, no code will be included in the object file nor will any
|
|
|
1745 bytes be permitted to be output.</P
|
|
|
1746 ><P
|
|
|
1747 >If the section name is "bss" or ".bss" in any combination of upper and
|
|
|
1748 lower case, the section is assumed to be a BSS section. In that case,
|
|
|
1749 the flag <CODE
|
|
|
1750 CLASS="PARAMETER"
|
|
|
1751 >!bss</CODE
|
|
|
1752 > can be used to override this assumption.</P
|
|
|
1753 ><P
|
|
|
1754 >If assembly is already happening within a section, the section is implicitly
|
|
|
1755 ended and the new section started. This is not considered an error although
|
|
|
1756 it is recommended that all sections be explicitly closed.</P
|
|
|
1757 ></DD
|
|
|
1758 ><DT
|
|
|
1759 >ENDSECTION, ENDSECT, ENDS</DT
|
|
|
1760 ><DD
|
|
|
1761 ><P
|
|
|
1762 >This directive ends the current section. This puts assembly outside of any
|
|
|
1763 sections until the next SECTION directive.</P
|
|
|
1764 ></DD
|
|
|
1765 ><DT
|
|
|
1766 ><CODE
|
|
|
1767 CLASS="PARAMETER"
|
|
|
1768 >sym</CODE
|
|
|
1769 > EXTERN, <CODE
|
|
|
1770 CLASS="PARAMETER"
|
|
|
1771 >sym</CODE
|
|
|
1772 > EXTERNAL, <CODE
|
|
|
1773 CLASS="PARAMETER"
|
|
|
1774 >sym</CODE
|
|
|
1775 > IMPORT</DT
|
|
|
1776 ><DD
|
|
|
1777 ><P
|
|
|
1778 >This directive defines <CODE
|
|
|
1779 CLASS="PARAMETER"
|
|
|
1780 >sym</CODE
|
|
|
1781 > as an external symbol.
|
|
|
1782 This directive may occur at any point in the source code. EXTERN definitions
|
|
|
1783 are resolved on the first pass so an EXTERN definition anywhere in the
|
|
|
1784 source file is valid for the entire file. The use of this directive is
|
|
|
1785 optional when the assembler is instructed to assume that all undefined
|
|
|
1786 symbols are external. In fact, in that mode, if the symbol is referenced
|
|
|
1787 before the EXTERN directive, an error will occur.</P
|
|
|
1788 ></DD
|
|
|
1789 ><DT
|
|
|
1790 ><CODE
|
|
|
1791 CLASS="PARAMETER"
|
|
|
1792 >sym</CODE
|
|
|
1793 > EXPORT, <CODE
|
|
|
1794 CLASS="PARAMETER"
|
|
|
1795 >sym</CODE
|
|
|
1796 > .GLOBL, EXPORT <CODE
|
|
|
1797 CLASS="PARAMETER"
|
|
|
1798 >sym</CODE
|
|
|
1799 >, .GLOBL <CODE
|
|
|
1800 CLASS="PARAMETER"
|
|
|
1801 >sym</CODE
|
|
|
1802 ></DT
|
|
|
1803 ><DD
|
|
|
1804 ><P
|
|
|
1805 >This directive defines <CODE
|
|
|
1806 CLASS="PARAMETER"
|
|
|
1807 >sym</CODE
|
|
|
1808 > as an exported symbol.
|
|
|
1809 This directive may occur at any point in the source code, even before the
|
|
|
1810 definition of the exported symbol.</P
|
|
|
1811 ><P
|
|
|
1812 >Note that <CODE
|
|
|
1813 CLASS="PARAMETER"
|
|
|
1814 >sym</CODE
|
|
|
1815 > may appear as the operand or as the
|
|
|
1816 statement's symbol. If there is a symbol on the statement, that will
|
|
|
1817 take precedence over any operand that is present.</P
|
|
|
1818 ></DD
|
|
|
1819 ><DT
|
|
|
1820 ><CODE
|
|
|
1821 CLASS="PARAMETER"
|
|
|
1822 >sym</CODE
|
|
|
1823 >EXTDEP</DT
|
|
|
1824 ><DD
|
|
|
1825 ><P
|
|
|
1826 >This directive forces an external dependency on
|
|
|
1827 <CODE
|
|
|
1828 CLASS="PARAMETER"
|
|
|
1829 >sym</CODE
|
|
|
1830 >, even if it is never referenced anywhere else in
|
|
|
1831 this file.</P
|
|
|
1832 ></DD
|
|
|
1833 ></DL
|
|
|
1834 ></DIV
|
|
|
1835 ></DIV
|
|
|
1836 ><DIV
|
|
|
1837 CLASS="SECTION"
|
|
|
1838 ><HR><H2
|
|
|
1839 CLASS="SECTION"
|
|
|
1840 ><A
|
|
|
1841 NAME="AEN562"
|
|
|
1842 >3.10. Assembler Modes and Pragmas</A
|
|
|
1843 ></H2
|
|
|
1844 ><P
|
|
|
1845 >There are a number of options that affect the way assembly is performed.
|
|
|
1846 Some of these options can only be specified on the command line because
|
|
|
1847 they determine something absolute about the assembly process. These include
|
|
|
1848 such things as the output target. Other things may be switchable during
|
|
|
1849 the assembly process. These are known as pragmas and are, by definition,
|
|
|
1850 not portable between assemblers.</P
|
|
|
1851 ><P
|
|
|
1852 >LWASM supports a number of pragmas that affect code generation or
|
|
|
1853 otherwise affect the behaviour of the assembler. These may be specified by
|
|
|
1854 way of a command line option or by assembler directives. The directives
|
|
|
1855 are as follows.</P
|
|
|
1856 ><P
|
|
|
1857 ></P
|
|
|
1858 ><DIV
|
|
|
1859 CLASS="VARIABLELIST"
|
|
|
1860 ><DL
|
|
|
1861 ><DT
|
|
|
1862 >PRAGMA <CODE
|
|
|
1863 CLASS="PARAMETER"
|
|
|
1864 >pragma[,...]</CODE
|
|
|
1865 ></DT
|
|
|
1866 ><DD
|
|
|
1867 ><P
|
|
|
1868 >Specifies that the assembler should bring into force all <CODE
|
|
|
1869 CLASS="PARAMETER"
|
|
|
1870 >pragma</CODE
|
|
|
1871 >s
|
|
|
1872 specified. Any unrecognized pragma will cause an assembly error. The new
|
|
|
1873 pragmas will take effect immediately. This directive should be used when
|
|
|
1874 the program will assemble incorrectly if the pragma is ignored or not supported.</P
|
|
|
1875 ></DD
|
|
|
1876 ><DT
|
|
|
1877 >*PRAGMA <CODE
|
|
|
1878 CLASS="PARAMETER"
|
|
|
1879 >pragma[,...]</CODE
|
|
|
1880 ></DT
|
|
|
1881 ><DD
|
|
|
1882 ><P
|
|
|
1883 >This is identical to the PRAGMA directive except no error will occur with
|
|
|
1884 unrecognized or unsupported pragmas. This directive, by virtue of starting
|
|
|
1885 with a comment character, will also be ignored by assemblers that do not
|
|
|
1886 support this directive. Use this variation if the pragma is not required
|
|
|
1887 for correct functioning of the code.</P
|
|
|
1888 ></DD
|
|
|
1889 ></DL
|
|
|
1890 ></DIV
|
|
|
1891 ><P
|
|
|
1892 >Each pragma supported has a positive version and a negative version.
|
|
|
1893 The positive version enables the pragma while the negative version disables
|
|
|
1894 it. The negatitve version is simply the positive version with "no" prefixed
|
|
|
1895 to it. For instance, "pragma" vs. "nopragma". Only the positive version is
|
|
|
1896 listed below.</P
|
|
|
1897 ><P
|
|
|
1898 >Pragmas are not case sensitive.</P
|
|
|
1899 ><P
|
|
|
1900 ></P
|
|
|
1901 ><DIV
|
|
|
1902 CLASS="VARIABLELIST"
|
|
|
1903 ><DL
|
|
|
1904 ><DT
|
|
|
1905 >index0tonone</DT
|
|
|
1906 ><DD
|
|
|
1907 ><P
|
|
|
1908 >When in force, this pragma enables an optimization affecting indexed addressing
|
|
|
1909 modes. When the offset expression in an indexed mode evaluates to zero but is
|
|
|
1910 not explicity written as 0, this will replace the operand with the equivalent
|
|
|
1911 no offset mode, thus creating slightly faster code. Because of the advantages
|
|
|
1912 of this optimization, it is enabled by default.</P
|
|
|
1913 ></DD
|
|
|
1914 ><DT
|
|
|
1915 >cescapes</DT
|
|
|
1916 ><DD
|
|
|
1917 ><P
|
|
|
1918 >This pragma will cause strings in the FCC, FCS, and FCN pseudo operations to
|
|
|
1919 have C-style escape sequences interpreted. The one departure from the official
|
|
|
1920 spec is that unrecognized escape sequences will return either the character
|
|
|
1921 immediately following the backslash or some undefined value. Do not rely
|
|
|
1922 on the behaviour of undefined escape sequences.</P
|
|
|
1923 ></DD
|
|
|
1924 ><DT
|
|
|
1925 >importundefexport</DT
|
|
|
1926 ><DD
|
|
|
1927 ><P
|
|
|
1928 >This pragma is only valid for targets that support external references. When
|
|
|
1929 in force, it will cause the EXPORT directive to act as IMPORT if the symbol
|
|
|
1930 to be exported is not defined. This is provided for compatibility with the
|
|
|
1931 output of gcc6809 and should not be used in hand written code. Because of
|
|
|
1932 the confusion this pragma can cause, it is disabled by default.</P
|
|
|
1933 ></DD
|
|
|
1934 ><DT
|
|
|
1935 >undefextern</DT
|
|
|
1936 ><DD
|
|
|
1937 ><P
|
|
|
1938 >This pragma is only valid for targets that support external references. When in
|
|
|
1939 force, if the assembler sees an undefined symbol on the second pass, it will
|
|
|
1940 automatically define it as an external symbol. This automatic definition will
|
|
|
1941 apply for the remainder of the assembly process, even if the pragma is
|
|
|
1942 subsequently turned off. Because this behaviour would be potentially surprising,
|
|
|
1943 this pragma defaults to off.</P
|
|
|
1944 ><P
|
|
|
1945 >The primary use for this pragma is for projects that share a large number of
|
|
|
1946 symbols between source files. In such cases, it is impractical to enumerate
|
|
|
1947 all the external references in every source file. This allows the assembler
|
|
|
1948 and linker to do the heavy lifting while not preventing a particular source
|
|
|
1949 module from defining a local symbol of the same name as an external symbol
|
|
|
1950 if it does not need the external symbol. (This pragma will not cause an
|
|
|
1951 automatic external definition if there is already a locally defined symbol.)</P
|
|
|
1952 ><P
|
|
|
1953 >This pragma will often be specified on the command line for large projects.
|
|
|
1954 However, depending on the specific dynamics of the project, it may be sufficient
|
|
|
1955 for one or two files to use this pragma internally.</P
|
|
|
1956 ></DD
|
|
|
1957 ><DT
|
|
|
1958 >dollarlocal</DT
|
|
|
1959 ><DD
|
|
|
1960 ><P
|
|
|
1961 >When set, a "$" in a symbol makes it local. When not set, "$" does not
|
|
|
1962 cause a symbol to be local. It is set by default except when using the OS9
|
|
|
1963 target.</P
|
|
|
1964 ></DD
|
|
|
1965 ><DT
|
|
|
1966 >dollarnotlocal</DT
|
|
|
1967 ><DD
|
|
|
1968 ><P
|
|
|
1969 > This is the same as the "dollarlocal" pragma except its sense is
|
|
|
1970 reversed. That is, "dollarlocal" and "nodollarnotlocal" are equivalent and
|
|
|
1971 "nodollarlocal" and "dollarnotlocal" are equivalent. </P
|
|
|
1972 ></DD
|
|
|
1973 ></DL
|
|
|
1974 ></DIV
|
|
|
1975 ></DIV
|
|
|
1976 ></DIV
|
|
|
1977 ><DIV
|
|
|
1978 CLASS="CHAPTER"
|
|
|
1979 ><HR><H1
|
|
|
1980 ><A
|
|
|
1981 NAME="AEN607"
|
|
|
1982 ></A
|
|
|
1983 >Chapter 4. LWLINK</H1
|
|
|
1984 ><P
|
|
|
1985 >The LWTOOLS linker is called LWLINK. This chapter documents the various features
|
|
|
1986 of the linker.</P
|
|
|
1987 ><DIV
|
|
|
1988 CLASS="SECTION"
|
|
|
1989 ><HR><H2
|
|
|
1990 CLASS="SECTION"
|
|
|
1991 ><A
|
|
|
1992 NAME="AEN610"
|
|
|
1993 >4.1. Command Line Options</A
|
|
|
1994 ></H2
|
|
|
1995 ><P
|
|
|
1996 >The binary for LWLINK is called "lwlink". Note that the binary is in lower
|
|
|
1997 case. lwlink takes the following command line arguments.</P
|
|
|
1998 ><P
|
|
|
1999 ></P
|
|
|
2000 ><DIV
|
|
|
2001 CLASS="VARIABLELIST"
|
|
|
2002 ><DL
|
|
|
2003 ><DT
|
|
|
2004 ><CODE
|
|
|
2005 CLASS="OPTION"
|
|
|
2006 >--decb</CODE
|
|
|
2007 >, <CODE
|
|
|
2008 CLASS="OPTION"
|
|
|
2009 >-b</CODE
|
|
|
2010 ></DT
|
|
|
2011 ><DD
|
|
|
2012 ><P
|
|
|
2013 >Selects the DECB output format target. This is equivalent to <CODE
|
|
|
2014 CLASS="OPTION"
|
|
|
2015 >--format=decb</CODE
|
|
|
2016 ></P
|
|
|
2017 ></DD
|
|
|
2018 ><DT
|
|
|
2019 ><CODE
|
|
|
2020 CLASS="OPTION"
|
|
|
2021 >--output=FILE</CODE
|
|
|
2022 >, <CODE
|
|
|
2023 CLASS="OPTION"
|
|
|
2024 >-o FILE</CODE
|
|
|
2025 ></DT
|
|
|
2026 ><DD
|
|
|
2027 ><P
|
|
|
2028 >This option specifies the name of the output file. If not specified, the
|
|
|
2029 default is <CODE
|
|
|
2030 CLASS="OPTION"
|
|
|
2031 >a.out</CODE
|
|
|
2032 >.</P
|
|
|
2033 ></DD
|
|
|
2034 ><DT
|
|
|
2035 ><CODE
|
|
|
2036 CLASS="OPTION"
|
|
|
2037 >--format=TYPE</CODE
|
|
|
2038 >, <CODE
|
|
|
2039 CLASS="OPTION"
|
|
|
2040 >-f TYPE</CODE
|
|
|
2041 ></DT
|
|
|
2042 ><DD
|
|
|
2043 ><P
|
|
|
2044 >This option specifies the output format. Valid values are <CODE
|
|
|
2045 CLASS="OPTION"
|
|
|
2046 >decb</CODE
|
|
|
2047 >
|
|
|
2048 and <CODE
|
|
|
2049 CLASS="OPTION"
|
|
|
2050 >raw</CODE
|
|
|
2051 ></P
|
|
|
2052 ></DD
|
|
|
2053 ><DT
|
|
|
2054 ><CODE
|
|
|
2055 CLASS="OPTION"
|
|
|
2056 >--raw</CODE
|
|
|
2057 >, <CODE
|
|
|
2058 CLASS="OPTION"
|
|
|
2059 >-r</CODE
|
|
|
2060 ></DT
|
|
|
2061 ><DD
|
|
|
2062 ><P
|
|
|
2063 >This option specifies the raw output format.
|
|
|
2064 It is equivalent to <CODE
|
|
|
2065 CLASS="OPTION"
|
|
|
2066 >--format=raw</CODE
|
|
|
2067 >.
|
|
|
2068 and <CODE
|
|
|
2069 CLASS="OPTION"
|
|
|
2070 >raw</CODE
|
|
|
2071 ></P
|
|
|
2072 ></DD
|
|
|
2073 ><DT
|
|
|
2074 ><CODE
|
|
|
2075 CLASS="OPTION"
|
|
|
2076 >--script=FILE</CODE
|
|
|
2077 >, <CODE
|
|
|
2078 CLASS="OPTION"
|
|
|
2079 >-s</CODE
|
|
|
2080 ></DT
|
|
|
2081 ><DD
|
|
|
2082 ><P
|
|
|
2083 >This option allows specifying a linking script to override the linker's
|
|
|
2084 built in defaults.</P
|
|
|
2085 ></DD
|
|
|
2086 ><DT
|
|
|
2087 ><CODE
|
|
|
2088 CLASS="OPTION"
|
|
|
2089 >--section-base=SECT=BASE</CODE
|
|
|
2090 ></DT
|
|
|
2091 ><DD
|
|
|
2092 ><P
|
|
|
2093 >Cause section SECT to load at base address BASE. This will be prepended
|
|
|
2094 to the built-in link script. It is ignored if a link script is provided.</P
|
|
|
2095 ></DD
|
|
|
2096 ><DT
|
|
|
2097 ><CODE
|
|
|
2098 CLASS="OPTION"
|
|
|
2099 >--map=FILE</CODE
|
|
|
2100 >, <CODE
|
|
|
2101 CLASS="OPTION"
|
|
|
2102 >-m FILE</CODE
|
|
|
2103 ></DT
|
|
|
2104 ><DD
|
|
|
2105 ><P
|
|
|
2106 >This will output a description of the link result to FILE.</P
|
|
|
2107 ></DD
|
|
|
2108 ><DT
|
|
|
2109 ><CODE
|
|
|
2110 CLASS="OPTION"
|
|
|
2111 >--library=LIBSPEC</CODE
|
|
|
2112 >, <CODE
|
|
|
2113 CLASS="OPTION"
|
|
|
2114 >-l LIBSPEC</CODE
|
|
|
2115 ></DT
|
|
|
2116 ><DD
|
|
|
2117 ><P
|
|
|
2118 >Load a library using the library search path. LIBSPEC will have "lib" prepended
|
|
|
2119 and ".a" appended.</P
|
|
|
2120 ></DD
|
|
|
2121 ><DT
|
|
|
2122 ><CODE
|
|
|
2123 CLASS="OPTION"
|
|
|
2124 >--library-path=DIR</CODE
|
|
|
2125 >, <CODE
|
|
|
2126 CLASS="OPTION"
|
|
|
2127 >-L DIR</CODE
|
|
|
2128 ></DT
|
|
|
2129 ><DD
|
|
|
2130 ><P
|
|
|
2131 >Add DIR to the library search path.</P
|
|
|
2132 ></DD
|
|
|
2133 ><DT
|
|
|
2134 ><CODE
|
|
|
2135 CLASS="OPTION"
|
|
|
2136 >--debug</CODE
|
|
|
2137 >, <CODE
|
|
|
2138 CLASS="OPTION"
|
|
|
2139 >-d</CODE
|
|
|
2140 ></DT
|
|
|
2141 ><DD
|
|
|
2142 ><P
|
|
|
2143 >This option increases the debugging level. It is only useful for LWTOOLS
|
|
|
2144 developers.</P
|
|
|
2145 ></DD
|
|
|
2146 ><DT
|
|
|
2147 ><CODE
|
|
|
2148 CLASS="OPTION"
|
|
|
2149 >--help</CODE
|
|
|
2150 >, <CODE
|
|
|
2151 CLASS="OPTION"
|
|
|
2152 >-?</CODE
|
|
|
2153 ></DT
|
|
|
2154 ><DD
|
|
|
2155 ><P
|
|
|
2156 >This provides a listing of command line options and a brief description
|
|
|
2157 of each.</P
|
|
|
2158 ></DD
|
|
|
2159 ><DT
|
|
|
2160 ><CODE
|
|
|
2161 CLASS="OPTION"
|
|
|
2162 >--usage</CODE
|
|
|
2163 ></DT
|
|
|
2164 ><DD
|
|
|
2165 ><P
|
|
|
2166 >This will display a usage summary.
|
|
|
2167 of each.</P
|
|
|
2168 ></DD
|
|
|
2169 ><DT
|
|
|
2170 ><CODE
|
|
|
2171 CLASS="OPTION"
|
|
|
2172 >--version</CODE
|
|
|
2173 >, <CODE
|
|
|
2174 CLASS="OPTION"
|
|
|
2175 >-V</CODE
|
|
|
2176 ></DT
|
|
|
2177 ><DD
|
|
|
2178 ><P
|
|
|
2179 >This will display the version of LWLINK.</P
|
|
|
2180 ></DD
|
|
|
2181 ></DL
|
|
|
2182 ></DIV
|
|
|
2183 ></DIV
|
|
|
2184 ><DIV
|
|
|
2185 CLASS="SECTION"
|
|
|
2186 ><HR><H2
|
|
|
2187 CLASS="SECTION"
|
|
|
2188 ><A
|
|
|
2189 NAME="AEN707"
|
|
|
2190 >4.2. Linker Operation</A
|
|
|
2191 ></H2
|
|
|
2192 ><P
|
|
|
2193 > LWLINK takes one or more files in supported input formats and links them
|
|
|
2194 into a single binary. Currently supported formats are the LWTOOLS object
|
|
|
2195 file format and the archive format used by LWAR. While the precise method is
|
|
|
2196 slightly different, linking can be conceptualized as the following steps. </P
|
|
|
2197 ><P
|
|
|
2198 ></P
|
|
|
2199 ><OL
|
|
|
2200 TYPE="1"
|
|
|
2201 ><LI
|
|
|
2202 ><P
|
|
|
2203 >First, the linker loads a linking script. If no script is specified, it
|
|
|
2204 loads a built-in default script based on the output format selected. This
|
|
|
2205 script tells the linker how to lay out the various sections in the final
|
|
|
2206 binary.</P
|
|
|
2207 ></LI
|
|
|
2208 ><LI
|
|
|
2209 ><P
|
|
|
2210 >Next, the linker reads all the input files into memory. At this time, it
|
|
|
2211 flags any format errors in those files. It constructs a table of symbols
|
|
|
2212 for each object at this time.</P
|
|
|
2213 ></LI
|
|
|
2214 ><LI
|
|
|
2215 ><P
|
|
|
2216 >The linker then proceeds with organizing the sections loaded from each file
|
|
|
2217 according to the linking script. As it does so, it is able to assign addresses
|
|
|
2218 to each symbol defined in each object file. At this time, the linker may
|
|
|
2219 also collapse different instances of the same section name into a single
|
|
|
2220 section by appending the data from each subsequent instance of the section
|
|
|
2221 to the first instance of the section.</P
|
|
|
2222 ></LI
|
|
|
2223 ><LI
|
|
|
2224 ><P
|
|
|
2225 >Next, the linker looks through every object file for every incomplete reference.
|
|
|
2226 It then attempts to fully resolve that reference. If it cannot do so, it
|
|
|
2227 throws an error. Once a reference is resolved, the value is placed into
|
|
|
2228 the binary code at the specified section. It should be noted that an
|
|
|
2229 incomplete reference can reference either a symbol internal to the object
|
|
|
2230 file or an external symbol which is in the export list of another object
|
|
|
2231 file.</P
|
|
|
2232 ></LI
|
|
|
2233 ><LI
|
|
|
2234 ><P
|
|
|
2235 >If all of the above steps are successful, the linker opens the output file
|
|
|
2236 and actually constructs the binary.</P
|
|
|
2237 ></LI
|
|
|
2238 ></OL
|
|
|
2239 ></DIV
|
|
|
2240 ><DIV
|
|
|
2241 CLASS="SECTION"
|
|
|
2242 ><HR><H2
|
|
|
2243 CLASS="SECTION"
|
|
|
2244 ><A
|
|
|
2245 NAME="AEN721"
|
|
|
2246 >4.3. Linking Scripts</A
|
|
|
2247 ></H2
|
|
|
2248 ><P
|
|
|
2249 >A linker script is used to instruct the linker about how to assemble the
|
|
|
2250 various sections into a completed binary. It consists of a series of
|
|
|
2251 directives which are considered in the order they are encountered.</P
|
|
|
2252 ><P
|
|
|
2253 >The sections will appear in the resulting binary in the order they are
|
|
|
2254 specified in the script file. If a referenced section is not found, the linker will behave as though the
|
|
|
2255 section did exist but had a zero size, no relocations, and no exports.
|
|
|
2256 A section should only be referenced once. Any subsequent references will have
|
|
|
2257 an undefined effect.</P
|
|
|
2258 ><P
|
|
|
2259 >All numbers are in linking scripts are specified in hexadecimal. All directives
|
|
|
2260 are case sensitive although the hexadecimal numbers are not.</P
|
|
|
2261 ><P
|
|
|
2262 >A section name can be specified as a "*", then any section not
|
|
|
2263 already matched by the script will be matched. The "*" can be followed
|
|
|
2264 by a comma and a flag to narrow the section down slightly, also.
|
|
|
2265 If the flag is "!bss", then any section that is not flagged as a bss section
|
|
|
2266 will be matched. If the flag is "bss", then any section that is flagged as
|
|
|
2267 bss will be matched.</P
|
|
|
2268 ><P
|
|
|
2269 >The following directives are understood in a linker script.</P
|
|
|
2270 ><P
|
|
|
2271 ></P
|
|
|
2272 ><DIV
|
|
|
2273 CLASS="VARIABLELIST"
|
|
|
2274 ><DL
|
|
|
2275 ><DT
|
|
|
2276 >section <CODE
|
|
|
2277 CLASS="PARAMETER"
|
|
|
2278 >name</CODE
|
|
|
2279 > load <CODE
|
|
|
2280 CLASS="PARAMETER"
|
|
|
2281 >addr</CODE
|
|
|
2282 ></DT
|
|
|
2283 ><DD
|
|
|
2284 ><P
|
|
|
2285 > This causes the section <CODE
|
|
|
2286 CLASS="PARAMETER"
|
|
|
2287 >name</CODE
|
|
|
2288 > to load at
|
|
|
2289 <CODE
|
|
|
2290 CLASS="PARAMETER"
|
|
|
2291 >addr</CODE
|
|
|
2292 >. For the raw target, only one "load at" entry is
|
|
|
2293 allowed for non-bss sections and it must be the first one. For raw targets,
|
|
|
2294 it affects the addresses the linker assigns to symbols but has no other
|
|
|
2295 affect on the output. bss sections may all have separate load addresses but
|
|
|
2296 since they will not appear in the binary anyway, this is okay.</P
|
|
|
2297 ><P
|
|
|
2298 >For the decb target, each "load" entry will cause a new "block" to be
|
|
|
2299 output to the binary which will contain the load address. It is legal for
|
|
|
2300 sections to overlap in this manner - the linker assumes the loader will sort
|
|
|
2301 everything out.</P
|
|
|
2302 ></DD
|
|
|
2303 ><DT
|
|
|
2304 >section <CODE
|
|
|
2305 CLASS="PARAMETER"
|
|
|
2306 >name</CODE
|
|
|
2307 ></DT
|
|
|
2308 ><DD
|
|
|
2309 ><P
|
|
|
2310 > This will cause the section <CODE
|
|
|
2311 CLASS="PARAMETER"
|
|
|
2312 >name</CODE
|
|
|
2313 > to load after the previously listed
|
|
|
2314 section.</P
|
|
|
2315 ></DD
|
|
|
2316 ><DT
|
|
|
2317 >exec <CODE
|
|
|
2318 CLASS="PARAMETER"
|
|
|
2319 >addr or sym</CODE
|
|
|
2320 ></DT
|
|
|
2321 ><DD
|
|
|
2322 ><P
|
|
|
2323 >This will cause the execution address (entry point) to be the address
|
|
|
2324 specified (in hex) or the specified symbol name. The symbol name must
|
|
|
2325 match a symbol that is exported by one of the object files being linked.
|
|
|
2326 This has no effect for targets that do not encode the entry point into the
|
|
|
2327 resulting file. If not specified, the entry point is assumed to be address 0
|
|
|
2328 which is probably not what you want. The default link scripts for targets
|
|
|
2329 that support this directive automatically starts at the beginning of the
|
|
|
2330 first section (usually "init" or "code") that is emitted in the binary.</P
|
|
|
2331 ></DD
|
|
|
2332 ><DT
|
|
|
2333 >pad <CODE
|
|
|
2334 CLASS="PARAMETER"
|
|
|
2335 >size</CODE
|
|
|
2336 ></DT
|
|
|
2337 ><DD
|
|
|
2338 ><P
|
|
|
2339 >This will cause the output file to be padded with NUL bytes to be exactly
|
|
|
2340 <CODE
|
|
|
2341 CLASS="PARAMETER"
|
|
|
2342 >size</CODE
|
|
|
2343 > bytes in length. This only makes sense for a raw target.</P
|
|
|
2344 ></DD
|
|
|
2345 ></DL
|
|
|
2346 ></DIV
|
|
|
2347 ></DIV
|
|
|
2348 ></DIV
|
|
|
2349 ><DIV
|
|
|
2350 CLASS="CHAPTER"
|
|
|
2351 ><HR><H1
|
|
|
2352 ><A
|
|
|
2353 NAME="AEN755"
|
|
|
2354 ></A
|
|
|
2355 >Chapter 5. Libraries and LWAR</H1
|
|
|
2356 ><P
|
|
|
2357 >LWTOOLS also includes a tool for managing libraries. These are analogous to
|
|
|
2358 the static libraries created with the "ar" tool on POSIX systems. Each library
|
|
|
2359 file contains one or more object files. The linker will treat the object
|
|
|
2360 files within a library as though they had been specified individually on
|
|
|
2361 the command line except when resolving external references. External references
|
|
|
2362 are looked up first within the object files within the library and then, if
|
|
|
2363 not found, the usual lookup based on the order the files are specified on
|
|
|
2364 the command line occurs.</P
|
|
|
2365 ><P
|
|
|
2366 >The tool for creating these libary files is called LWAR.</P
|
|
|
2367 ><DIV
|
|
|
2368 CLASS="SECTION"
|
|
|
2369 ><HR><H2
|
|
|
2370 CLASS="SECTION"
|
|
|
2371 ><A
|
|
|
2372 NAME="AEN759"
|
|
|
2373 >5.1. Command Line Options</A
|
|
|
2374 ></H2
|
|
|
2375 ><P
|
|
|
2376 >The binary for LWAR is called "lwar". Note that the binary is in lower
|
|
|
2377 case. The options lwar understands are listed below. For archive manipulation
|
|
|
2378 options, the first non-option argument is the name of the archive. All other
|
|
|
2379 non-option arguments are the names of files to operate on.</P
|
|
|
2380 ><P
|
|
|
2381 ></P
|
|
|
2382 ><DIV
|
|
|
2383 CLASS="VARIABLELIST"
|
|
|
2384 ><DL
|
|
|
2385 ><DT
|
|
|
2386 ><CODE
|
|
|
2387 CLASS="OPTION"
|
|
|
2388 >--add</CODE
|
|
|
2389 >, <CODE
|
|
|
2390 CLASS="OPTION"
|
|
|
2391 >-a</CODE
|
|
|
2392 ></DT
|
|
|
2393 ><DD
|
|
|
2394 ><P
|
|
|
2395 >This option specifies that an archive is going to have files added to it.
|
|
|
2396 If the archive does not already exist, it is created. New files are added
|
|
|
2397 to the end of the archive.</P
|
|
|
2398 ></DD
|
|
|
2399 ><DT
|
|
|
2400 ><CODE
|
|
|
2401 CLASS="OPTION"
|
|
|
2402 >--create</CODE
|
|
|
2403 >, <CODE
|
|
|
2404 CLASS="OPTION"
|
|
|
2405 >-c</CODE
|
|
|
2406 ></DT
|
|
|
2407 ><DD
|
|
|
2408 ><P
|
|
|
2409 >This option specifies that an archive is going to be created and have files
|
|
|
2410 added to it. If the archive already exists, it is truncated.</P
|
|
|
2411 ></DD
|
|
|
2412 ><DT
|
|
|
2413 ><CODE
|
|
|
2414 CLASS="OPTION"
|
|
|
2415 >--merge</CODE
|
|
|
2416 >, <CODE
|
|
|
2417 CLASS="OPTION"
|
|
|
2418 >-m</CODE
|
|
|
2419 ></DT
|
|
|
2420 ><DD
|
|
|
2421 ><P
|
|
|
2422 >If specified, any files specified to be added to an archive will be checked
|
|
|
2423 to see if they are archives themselves. If so, their constituent members are
|
|
|
2424 added to the archive. This is useful for avoiding archives containing archives.</P
|
|
|
2425 ></DD
|
|
|
2426 ><DT
|
|
|
2427 ><CODE
|
|
|
2428 CLASS="OPTION"
|
|
|
2429 >--list</CODE
|
|
|
2430 >, <CODE
|
|
|
2431 CLASS="OPTION"
|
|
|
2432 >-l</CODE
|
|
|
2433 ></DT
|
|
|
2434 ><DD
|
|
|
2435 ><P
|
|
|
2436 >This will display a list of the files contained in the archive.</P
|
|
|
2437 ></DD
|
|
|
2438 ><DT
|
|
|
2439 ><CODE
|
|
|
2440 CLASS="OPTION"
|
|
|
2441 >--debug</CODE
|
|
|
2442 >, <CODE
|
|
|
2443 CLASS="OPTION"
|
|
|
2444 >-d</CODE
|
|
|
2445 ></DT
|
|
|
2446 ><DD
|
|
|
2447 ><P
|
|
|
2448 >This option increases the debugging level. It is only useful for LWTOOLS
|
|
|
2449 developers.</P
|
|
|
2450 ></DD
|
|
|
2451 ><DT
|
|
|
2452 ><CODE
|
|
|
2453 CLASS="OPTION"
|
|
|
2454 >--help</CODE
|
|
|
2455 >, <CODE
|
|
|
2456 CLASS="OPTION"
|
|
|
2457 >-?</CODE
|
|
|
2458 ></DT
|
|
|
2459 ><DD
|
|
|
2460 ><P
|
|
|
2461 >This provides a listing of command line options and a brief description
|
|
|
2462 of each.</P
|
|
|
2463 ></DD
|
|
|
2464 ><DT
|
|
|
2465 ><CODE
|
|
|
2466 CLASS="OPTION"
|
|
|
2467 >--usage</CODE
|
|
|
2468 ></DT
|
|
|
2469 ><DD
|
|
|
2470 ><P
|
|
|
2471 >This will display a usage summary.
|
|
|
2472 of each.</P
|
|
|
2473 ></DD
|
|
|
2474 ><DT
|
|
|
2475 ><CODE
|
|
|
2476 CLASS="OPTION"
|
|
|
2477 >--version</CODE
|
|
|
2478 >, <CODE
|
|
|
2479 CLASS="OPTION"
|
|
|
2480 >-V</CODE
|
|
|
2481 ></DT
|
|
|
2482 ><DD
|
|
|
2483 ><P
|
|
|
2484 >This will display the version of LWLINK.
|
|
|
2485 of each.</P
|
|
|
2486 ></DD
|
|
|
2487 ></DL
|
|
|
2488 ></DIV
|
|
|
2489 ></DIV
|
|
|
2490 ></DIV
|
|
|
2491 ><DIV
|
|
|
2492 CLASS="CHAPTER"
|
|
|
2493 ><HR><H1
|
|
|
2494 ><A
|
|
|
2495 NAME="OBJCHAP"
|
|
|
2496 ></A
|
|
|
2497 >Chapter 6. Object Files</H1
|
|
|
2498 ><P
|
|
|
2499 >LWTOOLS uses a proprietary object file format. It is proprietary in the sense
|
|
|
2500 that it is specific to LWTOOLS, not that it is a hidden format. It would be
|
|
|
2501 hard to keep it hidden in an open source tool chain anyway. This chapter
|
|
|
2502 documents the object file format.</P
|
|
|
2503 ><P
|
|
|
2504 >An object file consists of a series of sections each of which contains a
|
|
|
2505 list of exported symbols, a list of incomplete references, and a list of
|
|
|
2506 "local" symbols which may be used in calculating incomplete references. Each
|
|
|
2507 section will obviously also contain the object code.</P
|
|
|
2508 ><P
|
|
|
2509 >Exported symbols must be completely resolved to an address within the
|
|
|
2510 section it is exported from. That is, an exported symbol must be a constant
|
|
|
2511 rather than defined in terms of other symbols.</P
|
|
|
2512 ><P
|
|
|
2513 >Each object file starts with a magic number and version number. The magic
|
|
|
2514 number is the string "LWOBJ16" for this 16 bit object file format. The only
|
|
|
2515 defined version number is currently 0. Thus, the first 8 bytes of the object
|
|
|
2516 file are <FONT
|
|
|
2517 COLOR="RED"
|
|
|
2518 >4C574F424A313600</FONT
|
|
|
2519 ></P
|
|
|
2520 ><P
|
|
|
2521 >Each section has the following items in order:</P
|
|
|
2522 ><P
|
|
|
2523 ></P
|
|
|
2524 ><UL
|
|
|
2525 ><LI
|
|
|
2526 ><P
|
|
|
2527 >section name</P
|
|
|
2528 ></LI
|
|
|
2529 ><LI
|
|
|
2530 ><P
|
|
|
2531 >flags</P
|
|
|
2532 ></LI
|
|
|
2533 ><LI
|
|
|
2534 ><P
|
|
|
2535 >list of local symbols (and addresses within the section)</P
|
|
|
2536 ></LI
|
|
|
2537 ><LI
|
|
|
2538 ><P
|
|
|
2539 >list of exported symbols (and addresses within the section)</P
|
|
|
2540 ></LI
|
|
|
2541 ><LI
|
|
|
2542 ><P
|
|
|
2543 >list of incomplete references along with the expressions to calculate them</P
|
|
|
2544 ></LI
|
|
|
2545 ><LI
|
|
|
2546 ><P
|
|
|
2547 >the actual object code (for non-BSS sections)</P
|
|
|
2548 ></LI
|
|
|
2549 ></UL
|
|
|
2550 ><P
|
|
|
2551 >The section starts with the name of the section with a NUL termination
|
|
|
2552 followed by a series of flag bytes terminated by NUL. There are only two
|
|
|
2553 flag bytes defined. A NUL (0) indicates no more flags and a value of 1
|
|
|
2554 indicates the section is a BSS section. For a BSS section, no actual
|
|
|
2555 code is included in the object file.</P
|
|
|
2556 ><P
|
|
|
2557 >Either a NULL section name or end of file indicate the presence of no more
|
|
|
2558 sections.</P
|
|
|
2559 ><P
|
|
|
2560 >Each entry in the exported and local symbols table consists of the symbol
|
|
|
2561 (NUL terminated) followed by two bytes which contain the value in big endian
|
|
|
2562 order. The end of a symbol table is indicated by a NULL symbol name.</P
|
|
|
2563 ><P
|
|
|
2564 >Each entry in the incomplete references table consists of an expression
|
|
|
2565 followed by a 16 bit offset where the reference goes. Expressions are
|
|
|
2566 defined as a series of terms up to an "end of expression" term. Each term
|
|
|
2567 consists of a single byte which identifies the type of term (see below)
|
|
|
2568 followed by any data required by the term. Then end of the list is flagged
|
|
|
2569 by a NULL expression (only an end of expression term).</P
|
|
|
2570 ><DIV
|
|
|
2571 CLASS="TABLE"
|
|
|
2572 ><A
|
|
|
2573 NAME="AEN842"
|
|
|
2574 ></A
|
|
|
2575 ><P
|
|
|
2576 ><B
|
|
|
2577 >Table 6-1. Object File Term Types</B
|
|
|
2578 ></P
|
|
|
2579 ><TABLE
|
|
|
2580 BORDER="1"
|
|
|
2581 FRAME="border"
|
|
|
2582 CLASS="CALSTABLE"
|
|
|
2583 ><COL><COL><THEAD
|
|
|
2584 ><TR
|
|
|
2585 ><TH
|
|
|
2586 >TERMTYPE</TH
|
|
|
2587 ><TH
|
|
|
2588 >Meaning</TH
|
|
|
2589 ></TR
|
|
|
2590 ></THEAD
|
|
|
2591 ><TBODY
|
|
|
2592 ><TR
|
|
|
2593 ><TD
|
|
|
2594 >00</TD
|
|
|
2595 ><TD
|
|
|
2596 >end of expression</TD
|
|
|
2597 ></TR
|
|
|
2598 ><TR
|
|
|
2599 ><TD
|
|
|
2600 >01</TD
|
|
|
2601 ><TD
|
|
|
2602 >integer (16 bit in big endian order follows)</TD
|
|
|
2603 ></TR
|
|
|
2604 ><TR
|
|
|
2605 ><TD
|
|
|
2606 >02</TD
|
|
|
2607 ><TD
|
|
|
2608 > external symbol reference (NUL terminated symbol name follows)</TD
|
|
|
2609 ></TR
|
|
|
2610 ><TR
|
|
|
2611 ><TD
|
|
|
2612 >03</TD
|
|
|
2613 ><TD
|
|
|
2614 >local symbol reference (NUL terminated symbol name follows)</TD
|
|
|
2615 ></TR
|
|
|
2616 ><TR
|
|
|
2617 ><TD
|
|
|
2618 >04</TD
|
|
|
2619 ><TD
|
|
|
2620 >operator (1 byte operator number)</TD
|
|
|
2621 ></TR
|
|
|
2622 ><TR
|
|
|
2623 ><TD
|
|
|
2624 >05</TD
|
|
|
2625 ><TD
|
|
|
2626 >section base address reference</TD
|
|
|
2627 ></TR
|
|
|
2628 ><TR
|
|
|
2629 ><TD
|
|
|
2630 >FF</TD
|
|
|
2631 ><TD
|
|
|
2632 >This term will set flags for the expression. Each one of these terms will set a single flag. All of them should be specified first in an expression. If they are not, the behaviour is undefined. The byte following is the flag. Flag 01 indicates an 8 bit relocation. Flag 02 indicates a zero-width relocation (see the EXTDEP pseudo op in LWASM).</TD
|
|
|
2633 ></TR
|
|
|
2634 ></TBODY
|
|
|
2635 ></TABLE
|
|
|
2636 ></DIV
|
|
|
2637 ><P
|
|
|
2638 >External references are resolved using other object files while local
|
|
|
2639 references are resolved using the local symbol table(s) from this file. This
|
|
|
2640 allows local symbols that are not exported to have the same names as
|
|
|
2641 exported symbols or external references.</P
|
|
|
2642 ><DIV
|
|
|
2643 CLASS="TABLE"
|
|
|
2644 ><A
|
|
|
2645 NAME="AEN872"
|
|
|
2646 ></A
|
|
|
2647 ><P
|
|
|
2648 ><B
|
|
|
2649 >Table 6-2. Object File Operator Numbers</B
|
|
|
2650 ></P
|
|
|
2651 ><TABLE
|
|
|
2652 BORDER="1"
|
|
|
2653 FRAME="border"
|
|
|
2654 CLASS="CALSTABLE"
|
|
|
2655 ><COL><COL><THEAD
|
|
|
2656 ><TR
|
|
|
2657 ><TH
|
|
|
2658 >Number</TH
|
|
|
2659 ><TH
|
|
|
2660 >Operator</TH
|
|
|
2661 ></TR
|
|
|
2662 ></THEAD
|
|
|
2663 ><TBODY
|
|
|
2664 ><TR
|
|
|
2665 ><TD
|
|
|
2666 >01</TD
|
|
|
2667 ><TD
|
|
|
2668 >addition (+)</TD
|
|
|
2669 ></TR
|
|
|
2670 ><TR
|
|
|
2671 ><TD
|
|
|
2672 >02</TD
|
|
|
2673 ><TD
|
|
|
2674 >subtraction (-)</TD
|
|
|
2675 ></TR
|
|
|
2676 ><TR
|
|
|
2677 ><TD
|
|
|
2678 >03</TD
|
|
|
2679 ><TD
|
|
|
2680 >multiplication (*)</TD
|
|
|
2681 ></TR
|
|
|
2682 ><TR
|
|
|
2683 ><TD
|
|
|
2684 >04</TD
|
|
|
2685 ><TD
|
|
|
2686 >division (/)</TD
|
|
|
2687 ></TR
|
|
|
2688 ><TR
|
|
|
2689 ><TD
|
|
|
2690 >05</TD
|
|
|
2691 ><TD
|
|
|
2692 >modulus (%)</TD
|
|
|
2693 ></TR
|
|
|
2694 ><TR
|
|
|
2695 ><TD
|
|
|
2696 >06</TD
|
|
|
2697 ><TD
|
|
|
2698 >integer division (\) (same as division)</TD
|
|
|
2699 ></TR
|
|
|
2700 ><TR
|
|
|
2701 ><TD
|
|
|
2702 >07</TD
|
|
|
2703 ><TD
|
|
|
2704 >bitwise and</TD
|
|
|
2705 ></TR
|
|
|
2706 ><TR
|
|
|
2707 ><TD
|
|
|
2708 >08</TD
|
|
|
2709 ><TD
|
|
|
2710 >bitwise or</TD
|
|
|
2711 ></TR
|
|
|
2712 ><TR
|
|
|
2713 ><TD
|
|
|
2714 >09</TD
|
|
|
2715 ><TD
|
|
|
2716 >bitwise xor</TD
|
|
|
2717 ></TR
|
|
|
2718 ><TR
|
|
|
2719 ><TD
|
|
|
2720 >0A</TD
|
|
|
2721 ><TD
|
|
|
2722 >boolean and</TD
|
|
|
2723 ></TR
|
|
|
2724 ><TR
|
|
|
2725 ><TD
|
|
|
2726 >0B</TD
|
|
|
2727 ><TD
|
|
|
2728 >boolean or</TD
|
|
|
2729 ></TR
|
|
|
2730 ><TR
|
|
|
2731 ><TD
|
|
|
2732 >0C</TD
|
|
|
2733 ><TD
|
|
|
2734 >unary negation, 2's complement (-)</TD
|
|
|
2735 ></TR
|
|
|
2736 ><TR
|
|
|
2737 ><TD
|
|
|
2738 >0D</TD
|
|
|
2739 ><TD
|
|
|
2740 >unary 1's complement (^)</TD
|
|
|
2741 ></TR
|
|
|
2742 ></TBODY
|
|
|
2743 ></TABLE
|
|
|
2744 ></DIV
|
|
|
2745 ><P
|
|
|
2746 >An expression is represented in a postfix manner with both operands for
|
|
|
2747 binary operators preceding the operator and the single operand for unary
|
|
|
2748 operators preceding the operator.</P
|
|
|
2749 ></DIV
|
|
|
2750 ></DIV
|
|
|
2751 ></BODY
|
|
|
2752 ></HTML
|
|
|
2753 > |
