339
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1 /*
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2 output.c
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3 Copyright © 2009 William Astle
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4
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5 This file is part of LWASM.
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6
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7 LWASM is free software: you can redistribute it and/or modify it under the
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8 terms of the GNU General Public License as published by the Free Software
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9 Foundation, either version 3 of the License, or (at your option) any later
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10 version.
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11
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12 This program is distributed in the hope that it will be useful, but WITHOUT
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 more details.
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16
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17 You should have received a copy of the GNU General Public License along with
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18 this program. If not, see <http://www.gnu.org/licenses/>.
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19
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20
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21 Contains the code for actually outputting the assembled code
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22 */
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23 #include <config.h>
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24 //#include <ctype.h>
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25 #include <errno.h>
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26 #include <stdio.h>
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27 //#include <stdlib.h>
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28 #include <string.h>
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29 #include <unistd.h>
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30 #define __output_c_seen__
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31 //#include "instab.h"
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32 #include "lwasm.h"
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33 #include "util.h"
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34
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35 void write_code_raw(asmstate_t *as, FILE *of);
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36 void write_code_decb(asmstate_t *as, FILE *of);
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37 void write_code_rawrel(asmstate_t *as, FILE *of);
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38 void write_code_obj(asmstate_t *as, FILE *of);
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39 void write_code_os9(asmstate_t *as, FILE *of);
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40
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41 // this prevents warnings about not using the return value of fwrite()
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42 #define writebytes(s, l, c, f) do { int r; r = fwrite((s), (l), (c), (f)); } while (0)
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43
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44 void lwasm_output(asmstate_t *as)
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45 {
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46 FILE *of;
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47
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48 if (as -> errorcount > 0)
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49 {
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50 fprintf(stderr, "Not doing output due to assembly errors.\n");
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51 return;
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52 }
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53
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54 of = fopen(as -> outfile, "wb");
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55 if (!of)
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56 {
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57 fprintf(stderr, "Cannot open '%s' for output", as -> outfile);
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58 perror("");
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59 return;
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60 }
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61
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62 switch (as -> outformat)
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63 {
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64 case OUTPUT_RAW:
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65 write_code_raw(as, of);
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66 break;
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67
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68 case OUTPUT_DECB:
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69 write_code_decb(as, of);
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70 break;
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71
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72 case OUTPUT_RAWREL:
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73 write_code_rawrel(as, of);
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74 break;
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75
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76 case OUTPUT_OBJ:
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77 write_code_obj(as, of);
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78 break;
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79
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80 case OUTPUT_OS9:
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81 write_code_os9(as, of);
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82 break;
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83
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84 default:
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85 fprintf(stderr, "BUG: unrecognized output format when generating output file\n");
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86 fclose(of);
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87 unlink(as -> outfile);
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88 return;
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89 }
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90
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91 fclose(of);
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92 }
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93
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94 /*
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95 rawrel output treats an ORG directive as an offset from the start of the
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96 file. Undefined results will occur if an ORG directive moves the output
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97 pointer backward. This particular implementation uses "fseek" to handle
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98 ORG requests and to skip over RMBs.
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99
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100 This simple brain damanged method simply does an fseek before outputting
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101 each instruction.
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102 */
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103 void write_code_rawrel(asmstate_t *as, FILE *of)
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104 {
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105 lwasm_line_t *cl;
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106
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107 for (cl = as -> lineshead; cl; cl = cl -> next)
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108 {
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109 if (cl -> codelen == 0)
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110 continue;
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111
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112 fseek(of, cl -> codeaddr, SEEK_SET);
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113 writebytes(cl -> bytes, cl -> codelen, 1, of);
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114 }
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115 }
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116
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117 /*
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118 raw merely writes all the bytes directly to the file as is. ORG is just a
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119 reference for the assembler to handle absolute references. Multiple ORG
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120 statements will produce mostly useless results
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121 */
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122 void write_code_raw(asmstate_t *as, FILE *of)
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123 {
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124 lwasm_line_t *cl;
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125
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126 for (cl = as -> lineshead; cl; cl = cl -> next)
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127 {
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128 if (cl -> nocodelen)
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129 {
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130 int i;
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131 for (i = 0; i < cl -> nocodelen; i++)
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132 writebytes("\0", 1, 1, of);
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133 continue;
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134 }
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135 writebytes(cl -> bytes, cl -> codelen, 1, of);
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136 }
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137 }
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138
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139
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140 /*
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141 OS9 target also just writes all the bytes in order. No need for anything
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142 else.
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143 */
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144 void write_code_os9(asmstate_t *as, FILE *of)
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145 {
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146 lwasm_line_t *cl;
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147
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148 for (cl = as -> lineshead; cl; cl = cl -> next)
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149 {
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150 if (cl -> inmod == 0)
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151 continue;
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152 if (cl -> nocodelen)
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153 {
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154 int i;
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155 for (i = 0; i < cl -> nocodelen; i++)
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156 writebytes("\0", 1, 1, of);
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157 continue;
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158 }
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159 writebytes(cl -> bytes, cl -> codelen, 1, of);
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160 }
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161 }
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162
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163 void write_code_decb(asmstate_t *as, FILE *of)
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164 {
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165 long preambloc;
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166 lwasm_line_t *cl;
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167 int blocklen = -1;
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168 int nextcalc = -1;
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169 unsigned char outbuf[5];
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170
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171 for (cl = as -> lineshead; cl; cl = cl -> next)
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172 {
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173 if (cl -> nocodelen)
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174 continue;
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175 if (cl -> codeaddr != nextcalc && cl -> codelen > 0)
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176 {
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177 // need preamble here
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178 if (blocklen > 0)
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179 {
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180 // update previous preamble if needed
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181 fseek(of, preambloc, SEEK_SET);
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182 outbuf[0] = (blocklen >> 8) & 0xFF;
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183 outbuf[1] = blocklen & 0xFF;
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184 writebytes(outbuf, 2, 1, of);
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185 fseek(of, 0, SEEK_END);
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186 }
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187 blocklen = 0;
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188 nextcalc = cl -> codeaddr;
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189 outbuf[0] = 0x00;
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190 outbuf[1] = 0x00;
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191 outbuf[2] = 0x00;
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192 outbuf[3] = (nextcalc >> 8) & 0xFF;
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193 outbuf[4] = nextcalc & 0xFF;
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194 preambloc = ftell(of) + 1;
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195 writebytes(outbuf, 5, 1, of);
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196 }
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197 nextcalc += cl -> codelen;
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198 writebytes(cl -> bytes, cl -> codelen, 1, of);
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199 blocklen += cl -> codelen;
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200 }
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201 if (blocklen > 0)
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202 {
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203 fseek(of, preambloc, SEEK_SET);
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204 outbuf[0] = (blocklen >> 8) & 0xFF;
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205 outbuf[1] = blocklen & 0xFF;
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206 writebytes(outbuf, 2, 1, of);
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207 fseek(of, 0, SEEK_END);
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208 }
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209
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210 // now write postamble
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211 outbuf[0] = 0xFF;
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212 outbuf[1] = 0x00;
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213 outbuf[2] = 0x00;
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214 outbuf[3] = (as -> execaddr >> 8) & 0xFF;
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215 outbuf[4] = (as -> execaddr) & 0xFF;
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216 writebytes(outbuf, 5, 1, of);
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217 }
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218
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219 void write_code_obj_sbadd(sectiontab_t *s, unsigned char b)
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220 {
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221 if (s -> oblen >= s -> obsize)
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222 {
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223 s -> obytes = lwasm_realloc(s -> obytes, s -> obsize + 128);
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224 s -> obsize += 128;
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225 }
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226 s -> obytes[s -> oblen] = b;
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227 s -> oblen += 1;
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228 }
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229
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230 void write_code_obj(asmstate_t *as, FILE *of)
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231 {
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232 lwasm_line_t *l;
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233 sectiontab_t *s;
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234 lwasm_symbol_ent_t *se;
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235 export_list_t *ex;
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236 section_reloc_list_t *re;
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237 lwasm_expr_stack_node_t *sn;
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238
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239 int i;
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240 unsigned char buf[16];
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241
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242 // output the magic number and file header
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243 // the 8 is NOT an error
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244 writebytes("LWOBJ16", 8, 1, of);
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245
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246 // run through the entire system and build the byte streams for each
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247 // section; at the same time, generate a list of "local" symbols to
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248 // output for each section
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249 // NOTE: for "local" symbols, we will append \x01 and the ascii string
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250 // of the context identifier (so sym in context 1 would be "sym\x011"
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251 // we can do this because the linker can handle symbols with any
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252 // character other than NUL.
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253 // also we will generate a list of incomplete references for each
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254 // section along with the actual definition that will be output
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255
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256 // once all this information is generated, we will output each section
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257 // to the file
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258
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259 // NOTE: we build everything in memory then output it because the
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260 // assembler accepts multiple instances of the same section but the
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261 // linker expects only one instance of each section in the object file
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262 // so we need to collect all the various pieces of a section together
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263 // (also, the assembler treated multiple instances of the same section
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264 // as continuations of previous sections so we would need to collect
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265 // them together anyway.
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266
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267 for (l = as -> lineshead; l; l = l -> next)
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268 {
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269 if (l -> sect)
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270 {
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271 // we're in a section - need to output some bytes
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272 for (i = 0; i < l -> codelen; i++)
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273 write_code_obj_sbadd(l -> sect, l -> bytes[i]);
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274 for (i = 0; i < l -> nocodelen; i++)
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275 write_code_obj_sbadd(l -> sect, 0);
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276
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277 // do we have a "relocation"? If so, add a reference to the
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278 // relocation table
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279 if (l -> relocoff >= 0)
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280 {
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281 // build the relocation reference for the linker
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282 re = lwasm_alloc(sizeof(section_reloc_list_t));
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283 re -> next = l -> sect -> rl;
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284 l -> sect -> rl = re;
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285
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286 re -> offset = l -> codeaddr + l -> relocoff;
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287 re -> expr = l -> exprs[0];
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288 re -> context = l -> context;
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289 re -> relocsize = 2;
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290 if (l -> reloc8bit)
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291 re -> relocsize = 1;
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292 }
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293 }
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294 }
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295
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296 // run through the sections
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297 for (s = as -> sections; s; s = s -> next)
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298 {
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299 // write the name
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300 writebytes(s -> name, strlen(s -> name) + 1, 1, of);
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301
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302 // write the flags
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303 if (s -> flags & SECTION_BSS)
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304 writebytes("\x01", 1, 1, of);
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305
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306 // indicate end of flags - the "" is NOT an error
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307 writebytes("", 1, 1, of);
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308
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309
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310 // now the local symbols
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311 for (se = as -> symhead; se; se = se -> next)
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312 {
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313 // ignore symbols not in this section
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314 if (se -> sect != s)
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315 continue;
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316
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317 if (se -> flags & SYMBOL_SET)
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318 continue;
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319
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320 if (se -> flags & SYMBOL_EXTERN)
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321 continue;
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322
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323 writebytes(se -> sym, strlen(se -> sym), 1, of);
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324 if (se -> context >= 0)
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325 {
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326 writebytes("\x01", 1, 1, of);
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327 sprintf(buf, "%d", se -> context);
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328 writebytes(buf, strlen(buf), 1, of);
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329 }
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330 // the "" is NOT an error
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331 writebytes("", 1, 1, of);
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332
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333 // write the address
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334 buf[0] = (se -> value >> 8) & 0xff;
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335 buf[1] = se -> value & 0xff;
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336 writebytes(buf, 2, 1, of);
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337 }
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338 // flag end of local symbol table - "" is NOT an error
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339 writebytes("", 1, 1, of);
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340
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341 // now the exports
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342 for (ex = s -> exports; ex; ex = ex -> next)
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343 {
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344 writebytes(ex -> sym, strlen(ex -> sym) + 1, 1, of);
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345 buf[0] = (ex -> offset >> 8) & 0xff;
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346 buf[1] = ex -> offset & 0xff;
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347 writebytes(buf, 2, 1, of);
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348 }
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349
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350 // flag end of exported symbols - "" is NOT an error
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351 writebytes("", 1, 1, of);
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352
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353 // now output the "incomplete references"
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354 // this being the most complex bit
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355 for (re = s -> rl; re; re = re -> next)
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356 {
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357 if (re -> expr == NULL)
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358 {
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359 // this is an error but we'll simply ignore it
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360 // and not output this expression
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361 continue;
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362 }
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363
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364 // work through each term in the expression and output
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365 // the proper equivalent to the object file
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366 if (re -> relocsize == 1)
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367 {
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368 // flag an 8 bit relocation (low 8 bits will be used)
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369 buf[0] = 0xFF;
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370 buf[1] = 0x01;
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371 writebytes(buf, 2, 1, of);
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372 }
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373 for (sn = re -> expr -> head; sn; sn = sn -> next)
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374 {
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375 switch (sn -> term -> term_type)
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376 {
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377 case LWASM_TERM_OPER:
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378 buf[0] = 0x04;
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379 buf[1] = sn -> term -> value;
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380 writebytes(buf, 2, 1, of);
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381 break;
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382
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383 case LWASM_TERM_INT:
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384 buf[0] = 0x01;
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385 buf[1] = (sn -> term -> value >> 8) & 0xff;
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386 buf[2] = sn -> term -> value & 0xff;
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387 writebytes(buf, 3, 1, of);
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388 break;
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389
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390 case LWASM_TERM_SECBASE:
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391 writebytes("\x05", 1, 1, of);
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392 break;
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393
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394 case LWASM_TERM_SYM:
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395 // now for the ugly part - resolve a symbol reference
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396 // and determine whether it's internal, external, or
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397 // a section base
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398 se = lwasm_find_symbol(as, sn -> term -> symbol, re -> context);
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399 if (!se)
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400 se = lwasm_find_symbol(as, sn -> term -> symbol, -1);
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401 if (!se || se -> flags & SYMBOL_EXTERN)
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402 {
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403 // not found - assume external reference
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404 // found but flagged external - handle it
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405 writebytes("\x02", 1, 1, of);
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406 writebytes(se -> sym, strlen(se -> sym) + 1, 1, of);
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407 break;
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408 }
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409 // a local symbol reference here
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410 writebytes("\x03", 1, 1, of);
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411 writebytes(se -> sym, strlen(se -> sym), 1, of);
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412 if (se -> context >= 0)
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413 {
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414 writebytes("\x01", 1, 1, of);
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415 sprintf(buf, "%d", se -> context);
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416 writebytes(buf, strlen(buf), 1, of);
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417 }
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418 writebytes("", 1, 1, of);
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419 break;
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420
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421 default:
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422 // unrecognized term type - replace with integer 0
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423 buf[0] = 0x01;
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424 buf[1] = 0x00;
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425 buf[2] = 0x00;
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426 writebytes(buf, 3, 1, of);
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427 break;
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428 }
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429 }
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430
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431 // flag end of expressions
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432 writebytes("", 1, 1, of);
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433
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434 // write the offset
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435 buf[0] = (re -> offset >> 8) & 0xff;
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436 buf[1] = re -> offset & 0xff;
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437 writebytes(buf, 2, 1, of);
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438 }
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439 // flag end of incomplete references list
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440 writebytes("", 1, 1, of);
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441
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442 // now blast out the code
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443
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444 // length
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445 buf[0] = s -> oblen >> 8 & 0xff;
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446 buf[1] = s -> oblen & 0xff;
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447 writebytes(buf, 2, 1, of);
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448
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449 if (!(s -> flags & SECTION_BSS))
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450 {
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451 writebytes(s -> obytes, s -> oblen, 1, of);
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452 }
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453 }
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454
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455 // flag no more sections
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456 // the "" is NOT an error
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457 writebytes("", 1, 1, of);
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458 }
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