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339
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1 /*
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2 expr.c
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3 Copyright © 2008 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 /*
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22 This file contains the actual expression evaluator
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23 */
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24
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25 #define __expr_c_seen__
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26
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27 #include <config.h>
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28
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29 #include <ctype.h>
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30 #include <stdlib.h>
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31 #include <string.h>
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32
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33 #include "expr.h"
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34 #include "util.h"
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35 #include "lwasm.h"
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36
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37 lwasm_expr_stack_t *lwasm_expr_stack_create(void)
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38 {
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39 lwasm_expr_stack_t *s;
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40
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41 s = lwasm_alloc(sizeof(lwasm_expr_stack_t));
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42 s -> head = NULL;
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43 s -> tail = NULL;
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44 return s;
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45 }
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46
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47 void lwasm_expr_stack_free(lwasm_expr_stack_t *s)
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48 {
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49 while (s -> head)
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50 {
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51 s -> tail = s -> head;
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52 s -> head = s -> head -> next;
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53 lwasm_expr_term_free(s -> tail -> term);
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54 lwasm_free(s -> tail);
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55 }
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56 lwasm_free(s);
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57 }
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58
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59 void lwasm_expr_term_free(lwasm_expr_term_t *t)
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60 {
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61 if (t)
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62 {
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63 if (t -> term_type == LWASM_TERM_SYM)
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64 lwasm_free(t -> symbol);
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65 lwasm_free(t);
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66 }
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67 }
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68
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69 lwasm_expr_term_t *lwasm_expr_term_create_oper(int oper)
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70 {
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71 lwasm_expr_term_t *t;
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72
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73 debug_message(10, "Creating operator term: %d", oper);
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74
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75 t = lwasm_alloc(sizeof(lwasm_expr_term_t));
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76 t -> term_type = LWASM_TERM_OPER;
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77 t -> value = oper;
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78 return t;
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79 }
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80
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81 lwasm_expr_term_t *lwasm_expr_term_create_int(int val)
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82 {
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83 lwasm_expr_term_t *t;
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84 debug_message(10, "Creating integer term: %d", val);
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85
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86 t = lwasm_alloc(sizeof(lwasm_expr_term_t));
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87 t -> term_type = LWASM_TERM_INT;
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88 t -> value = val;
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89 return t;
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90 }
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91
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92 lwasm_expr_term_t *lwasm_expr_term_create_secbase(void)
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93 {
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94 lwasm_expr_term_t *t;
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95 debug_message(10, "Creating section base term");
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96
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97 t = lwasm_alloc(sizeof(lwasm_expr_term_t));
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98 t -> term_type = LWASM_TERM_SECBASE;
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99 return t;
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100 }
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101
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102 lwasm_expr_term_t *lwasm_expr_term_create_sym(char *sym)
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103 {
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104 lwasm_expr_term_t *t;
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105
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106 debug_message(10, "Creating symbol term: %s", sym);
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107
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108 t = lwasm_alloc(sizeof(lwasm_expr_term_t));
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109 t -> term_type = LWASM_TERM_SYM;
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110 t -> symbol = lwasm_strdup(sym);
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111 return t;
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112 }
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113
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114 lwasm_expr_term_t *lwasm_expr_term_dup(lwasm_expr_term_t *t)
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115 {
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116 switch (t -> term_type)
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117 {
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118 case LWASM_TERM_INT:
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119 return lwasm_expr_term_create_int(t -> value);
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120
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121 case LWASM_TERM_OPER:
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122 return lwasm_expr_term_create_oper(t -> value);
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123
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124 case LWASM_TERM_SYM:
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125 return lwasm_expr_term_create_sym(t -> symbol);
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126
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127 case LWASM_TERM_SECBASE:
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128 return lwasm_expr_term_create_secbase();
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129
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130 default:
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131 debug_message(0, "lwasm_expr_term_dup(): invalid term type %d", t -> term_type);
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132 exit(1);
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133 }
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134 // can't get here
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135 }
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136
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137 void lwasm_expr_stack_push(lwasm_expr_stack_t *s, lwasm_expr_term_t *t)
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138 {
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139 lwasm_expr_stack_node_t *n;
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140
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141 if (!s)
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142 {
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143 debug_message(0, "lwasm_expr_stack_push(): invalid stack pointer");
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144 exit(1);
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145 }
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146
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147 n = lwasm_alloc(sizeof(lwasm_expr_stack_node_t));
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148 n -> next = NULL;
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149 n -> prev = s -> tail;
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150 n -> term = lwasm_expr_term_dup(t);
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151
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152 if (s -> head)
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153 {
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154 s -> tail -> next = n;
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155 s -> tail = n;
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156 }
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157 else
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158 {
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159 s -> head = n;
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160 s -> tail = n;
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161 }
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162 }
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163
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164 lwasm_expr_term_t *lwasm_expr_stack_pop(lwasm_expr_stack_t *s)
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165 {
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166 lwasm_expr_term_t *t;
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167 lwasm_expr_stack_node_t *n;
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168
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169 if (!(s -> tail))
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170 return NULL;
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171
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172 n = s -> tail;
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173 s -> tail = n -> prev;
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174 if (!(n -> prev))
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175 {
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176 s -> head = NULL;
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177 }
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178
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179 t = n -> term;
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180 n -> term = NULL;
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181
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182 lwasm_free(n);
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183
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184 return t;
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185 }
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186
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187 // the following two functions are co-routines which actually parse
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188 // an infix expression onto the expression stack, each returns -1
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189 // if an error is encountered
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190
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191 /*
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192 parse a term and push it onto the stack
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193
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194 this function handles unary prefix operators (-, +, .not., .com.)
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195 as well as ()
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196 */
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197 int lwasm_expr_parse_term(lwasm_expr_stack_t *s, const char **p)
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198 {
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199 lwasm_expr_term_t *t;
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200 debug_message(2, "Expression string %s", *p);
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201
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202 eval_next:
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203 if (!**p || isspace(**p) || **p == ')' || **p == ']')
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204 return -1;
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205 if (**p == '(')
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206 {
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207 debug_message(3, "Starting paren");
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208 (*p)++;
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209 lwasm_expr_parse_expr(s, p, 0);
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210 if (**p != ')')
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211 return -1;
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212 (*p)++;
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213 return 0;
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214 }
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215
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216 if (**p == '+')
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217 {
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218 debug_message(3, "Unary +");
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219 (*p)++;
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220 goto eval_next;
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221 }
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222
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223 if (**p == '-')
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224 {
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225 // parse expression following "-"
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226 (*p)++;
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227 if (lwasm_expr_parse_expr(s, p, 200) < 0)
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228 return -1;
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229 t = lwasm_expr_term_create_oper(LWASM_OPER_NEG);
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230 lwasm_expr_stack_push(s, t);
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231 lwasm_expr_term_free(t);
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232 return 0;
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233 }
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234
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235 if (**p == '^' || **p == '~')
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236 {
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237 // parse expression following "^"
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238 (*p)++;
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239 if (lwasm_expr_parse_expr(s, p, 200) < 0)
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240 return -1;
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241 t = lwasm_expr_term_create_oper(LWASM_OPER_COM);
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242 lwasm_expr_stack_push(s, t);
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243 lwasm_expr_term_free(t);
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244 return 0;
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245 }
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246
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247 /*
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248 we have an actual term here so evaluate it
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249
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250 it could be one of the following:
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251
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252 1. a decimal constant
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253 2. a hexadecimal constant
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254 3. an octal constant
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255 4. a binary constant
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256 5. a symbol reference
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257 6. the "current" instruction address (*)
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258 7. the "current" data address (.)
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259 8. a "back reference" (<)
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260 9. a "forward reference" (>)
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261
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262 items 6 through 9 are stored as symbol references
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263
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264 (a . followed by a . or a alpha char or number is a symbol)
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265 */
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266 if (**p == '*'
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267 || (
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268 **p == '.'
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269 && (*p)[1] != '.'
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270 && !((*p)[1] >= 'A' && (*p)[1] <= 'Z')
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271 && !((*p)[1] >= 'a' && (*p)[1] <= 'z')
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272 && !((*p)[1] >= '0' && (*p)[1] <= '9')
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273 )
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274 || **p == '<'
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275 || **p == '>')
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276 {
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277 char tstr[2];
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278 tstr[0] = **p;
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279 tstr[1] = '\0';
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280 t = lwasm_expr_term_create_sym(tstr);
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281 lwasm_expr_stack_push(s, t);
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282 lwasm_expr_term_free(t);
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283 (*p)++;
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284 return 0;
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285 }
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286
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287 /*
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288 - a symbol will be a string of characters introduced by a letter, ".",
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289 "_" but NOT a number OR it may start with a digit if it contains a $
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290 - a decimal constant will consist of only digits, optionally prefixed
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291 with "&"
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292 - a binary constant will consist of only 0s and 1s either prefixed with %
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293 or suffixed with "B"
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294 - a hex constant will consist of 0-9A-F either prefixed with $ or
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295 suffixed with "H"; a hex number starting with A-F must be prefixed
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296 with $ or start with 0 and end with H
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297 - an octal constant will consist of 0-7 either prefixed with @ or
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298 suffixed with "O" or "Q"
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299 - an ascii constant will be a single character prefixed with a '
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300 - a double ascii constant will be two characters prefixed with a "
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301
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302 */
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303 if (**p == '"')
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304 {
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305 // double ascii constant
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306 int val;
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307 (*p)++;
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308 if (!**p)
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309 return -1;
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310 if (!*((*p)+1))
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311 return -1;
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312 val = **p << 8 | *((*p) + 1);
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313 (*p) += 2;
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314 t = lwasm_expr_term_create_int(val);
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315 lwasm_expr_stack_push(s, t);
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316 lwasm_expr_term_free(t);
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317 return 0;
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318 }
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319 else if (**p == '\'')
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320 {
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321 // single ascii constant
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322 int val;
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323 (*p)++;
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324 debug_message(3, "Single ascii character constant '%c'", **p);
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325 if (!**p)
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326 return -1;
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327 val = **p;
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328 (*p)++;
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329 t = lwasm_expr_term_create_int(val);
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330 lwasm_expr_stack_push(s, t);
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331 lwasm_expr_term_free(t);
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332 return 0;
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333 }
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334 else if (**p == '&')
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335 {
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336 // decimal constant
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337 int val = 0;
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338
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339 (*p)++;
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340 while (**p && strchr("0123456789", **p))
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341 {
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342 val = val * 10 + (**p - '0');
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343 (*p)++;
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344 }
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345 t = lwasm_expr_term_create_int(val);
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346 lwasm_expr_stack_push(s, t);
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347 lwasm_expr_term_free(t);
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348 return 0;
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349 }
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350 else if (**p == '%')
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351 {
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352 // binary constant
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353 int val = 0;
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354
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355 (*p)++;
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356 while (**p == '0' || **p == '1')
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357 {
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358 val = val * 2 + (**p - '0');
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359 (*p)++;
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360 }
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361 t = lwasm_expr_term_create_int(val);
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362 lwasm_expr_stack_push(s, t);
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363 lwasm_expr_term_free(t);
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364 return 0;
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365 }
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366 else if (**p == '$')
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367 {
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368 // hexadecimal constant
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369 int val = 0, val2;
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370
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371 (*p)++;
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372 debug_message(3, "Found prefix hex constant: %s", *p);
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373 while (**p && strchr("0123456789ABCDEFabcdef", **p))
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374 {
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375 val2 = toupper(**p) - '0';
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376 if (val2 > 9)
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377 val2 -= 7;
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378 debug_message(3, "Got char: %c (%d)", **p, val2);
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379 val = val * 16 + val2;
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380 (*p)++;
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381 }
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382 t = lwasm_expr_term_create_int(val);
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383 lwasm_expr_stack_push(s, t);
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384 lwasm_expr_term_free(t);
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385 return 0;
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386 }
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387 else if (**p == '0' && tolower(*(*p + 1)) == 'x')
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388 {
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389 // "C" style hexadecimal constant
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390 int val = 0, val2;
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391
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392 (*p)+=2;
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393 debug_message(3, "Found \"C\" style prefix hex constant: %s", *p);
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394 while (**p && strchr("0123456789ABCDEFabcdef", **p))
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395 {
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396 val2 = toupper(**p) - '0';
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397 if (val2 > 9)
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398 val2 -= 7;
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399 debug_message(3, "Got char: %c (%d)", **p, val2);
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400 val = val * 16 + val2;
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401 (*p)++;
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402 }
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403 t = lwasm_expr_term_create_int(val);
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404 lwasm_expr_stack_push(s, t);
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405 lwasm_expr_term_free(t);
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406 return 0;
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407 }
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408 // an @ followed by a digit is an octal number
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409 // but if it's followed by anything else, it is a symbol
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410 else if (**p == '@' && isdigit(*(*p + 1)))
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411 {
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412 // octal constant
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413 int val = 0;
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414
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415 (*p)++;
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416 while (**p && strchr("01234567", **p))
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417 {
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418 val = val * 8 + (**p - '0');
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419 (*p)++;
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420 }
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421 t = lwasm_expr_term_create_int(val);
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422 lwasm_expr_stack_push(s, t);
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423 lwasm_expr_term_free(t);
|
|
|
424 return 0;
|
|
|
425 }
|
|
|
426
|
|
|
427 // symbol or bare decimal or suffix identified constant here
|
|
|
428
|
|
|
429 // find the end of a potential symbol
|
|
|
430 do
|
|
|
431 {
|
|
|
432 int l = 0;
|
|
|
433 char *sb;
|
|
|
434 int havedol = 0;
|
|
|
435
|
|
|
436 // evaluate a symbol here
|
|
|
437 static const char *symchars = "_.$@?abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
|
|
|
438 while ((*p)[l] && strchr(symchars, (*p)[l]))
|
|
|
439 {
|
|
|
440 if ((*p)[l] == '$')
|
|
|
441 havedol = 1;
|
|
|
442 l++;
|
|
|
443 }
|
|
|
444 if (l == 0)
|
|
|
445 return -1;
|
|
|
446
|
|
|
447 if (havedol || **p < '0' || **p > '9')
|
|
|
448 {
|
|
|
449 // have a symbol here
|
|
|
450
|
|
|
451 sb = lwasm_alloc(l + 1);
|
|
|
452 sb[l] = '\0';
|
|
|
453 memcpy(sb, *p, l);
|
|
|
454 t = lwasm_expr_term_create_sym(sb);
|
|
|
455 lwasm_expr_stack_push(s, t);
|
|
|
456 lwasm_expr_term_free(t);
|
|
|
457 (*p) += l;
|
|
|
458 debug_message(3, "Symbol: '%s'; (%s)", sb, *p);
|
|
|
459 lwasm_free(sb);
|
|
|
460 return 0;
|
|
|
461 }
|
|
|
462 } while (0);
|
|
|
463
|
|
|
464 if (!**p)
|
|
|
465 return -1;
|
|
|
466
|
|
|
467 // evaluate a suffix based constant
|
|
|
468 {
|
|
|
469 int decval = 0, binval = 0, hexval = 0, octval = 0;
|
|
|
470 int valtype = 15; // 1 = bin, 2 = oct, 4 = dec, 8 = hex
|
|
|
471 int bindone = 0;
|
|
|
472 int val;
|
|
|
473 int dval;
|
|
|
474
|
|
|
475 while (1)
|
|
|
476 {
|
|
|
477 if (!**p || !strchr("0123456789ABCDEFabcdefqhoQHO", **p))
|
|
|
478 {
|
|
|
479 // we can legally have bin or decimal here
|
|
|
480 if (bindone)
|
|
|
481 {
|
|
|
482 // we just finished a binary value
|
|
|
483 val = binval;
|
|
|
484 break;
|
|
|
485 }
|
|
|
486 else if (valtype & 4)
|
|
|
487 {
|
|
|
488 // otherwise we must be decimal (if we're still allowed one)
|
|
|
489 val = decval;
|
|
|
490 debug_message(3, "End of decimal value");
|
|
|
491 break;
|
|
|
492 }
|
|
|
493 else
|
|
|
494 {
|
|
|
495 // bad value
|
|
|
496 return -1;
|
|
|
497 }
|
|
|
498 }
|
|
|
499
|
|
|
500 dval = toupper(**p);
|
|
|
501 (*p)++;
|
|
|
502
|
|
|
503 if (bindone)
|
|
|
504 {
|
|
|
505 // any characters past "B" means it is not binary
|
|
|
506 bindone = 0;
|
|
|
507 valtype &= 14;
|
|
|
508 }
|
|
|
509
|
|
|
510 switch (dval)
|
|
|
511 {
|
|
|
512 case 'Q':
|
|
|
513 case 'O':
|
|
|
514 if (valtype & 2)
|
|
|
515 {
|
|
|
516 val = octval;
|
|
|
517 valtype = -1;
|
|
|
518 break;
|
|
|
519 }
|
|
|
520 else
|
|
|
521 {
|
|
|
522 // not a valid octal value
|
|
|
523 return -1;
|
|
|
524 }
|
|
|
525 /* can't get here */
|
|
|
526
|
|
|
527 case 'H':
|
|
|
528 if (valtype & 8)
|
|
|
529 {
|
|
|
530 val = hexval;
|
|
|
531 valtype = -1;
|
|
|
532 break;
|
|
|
533 }
|
|
|
534 else
|
|
|
535 {
|
|
|
536 // not a valid hex number
|
|
|
537 return -1;
|
|
|
538 }
|
|
|
539 /* can't get here */
|
|
|
540
|
|
|
541 case 'B':
|
|
|
542 // this is a bit of a sticky one since B is a legit hex
|
|
|
543 // digit so this may or may not be the end of the number
|
|
|
544 // so we fall through to the digit case
|
|
|
545
|
|
|
546 if (valtype & 1)
|
|
|
547 {
|
|
|
548 // could still be binary
|
|
|
549 bindone = 1;
|
|
|
550 valtype = 9; // hex and binary
|
|
|
551 }
|
|
|
552 /* fall through intentional */
|
|
|
553
|
|
|
554 default:
|
|
|
555 // digit
|
|
|
556 dval -= '0';
|
|
|
557 if (dval > 9)
|
|
|
558 dval -= 7;
|
|
|
559 debug_message(3, "Got digit: %d", dval);
|
|
|
560 // if (dval > 1)
|
|
|
561 // valtype &= 14;
|
|
|
562 // if (dval > 7)
|
|
|
563 // valtype &= 12;
|
|
|
564 // if (dval > 9)
|
|
|
565 // valtype &= 8;
|
|
|
566
|
|
|
567 if (valtype & 8)
|
|
|
568 {
|
|
|
569 hexval = hexval * 16 + dval;
|
|
|
570 }
|
|
|
571 if (valtype & 4)
|
|
|
572 {
|
|
|
573 if (dval > 9)
|
|
|
574 valtype &= 11;
|
|
|
575 else
|
|
|
576 decval = decval * 10 + dval;
|
|
|
577 }
|
|
|
578 if (valtype & 2)
|
|
|
579 {
|
|
|
580 if (dval > 7)
|
|
|
581 valtype &= 13;
|
|
|
582 else
|
|
|
583 octval = octval * 8 + dval;
|
|
|
584 }
|
|
|
585 if (valtype & 1)
|
|
|
586 {
|
|
|
587 if (dval > 1)
|
|
|
588 valtype &= 14;
|
|
|
589 else
|
|
|
590 binval = binval * 2 + dval;
|
|
|
591 }
|
|
|
592 }
|
|
|
593 // break out if we have a return value
|
|
|
594 if (valtype == -1)
|
|
|
595 break;
|
|
|
596 // return if no more valid possibilities!
|
|
|
597 if (valtype == 0)
|
|
|
598 return -1;
|
|
|
599 val = decval; // in case we fall through
|
|
|
600 }
|
|
|
601
|
|
|
602 // we get here when we have a value to return
|
|
|
603 t = lwasm_expr_term_create_int(val);
|
|
|
604 lwasm_expr_stack_push(s, t);
|
|
|
605 lwasm_expr_term_free(t);
|
|
|
606 return 0;
|
|
|
607 }
|
|
|
608 /* can't get here */
|
|
|
609 }
|
|
|
610
|
|
|
611 // parse an expression and push the result onto the stack
|
|
|
612 // if an operator of lower precedence than the value of "prec" is found,
|
|
|
613 int lwasm_expr_parse_expr(lwasm_expr_stack_t *s, const char **p, int prec)
|
|
|
614 {
|
|
|
615 static const struct operinfo
|
|
|
616 {
|
|
|
617 int opernum;
|
|
|
618 char *operstr;
|
|
|
619 int operprec;
|
|
|
620 } operators[] =
|
|
|
621 {
|
|
|
622 { LWASM_OPER_PLUS, "+", 100 },
|
|
|
623 { LWASM_OPER_MINUS, "-", 100 },
|
|
|
624 { LWASM_OPER_TIMES, "*", 150 },
|
|
|
625 { LWASM_OPER_DIVIDE, "/", 150 },
|
|
|
626 { LWASM_OPER_MOD, "%", 150 },
|
|
|
627 { LWASM_OPER_INTDIV, "\\", 150 },
|
|
|
628
|
|
|
629 // boolean AND/OR
|
|
|
630 { LWASM_OPER_AND, "&&", 25 },
|
|
|
631 { LWASM_OPER_OR, "||", 25 },
|
|
|
632
|
|
|
633 // bitwise ops
|
|
|
634 { LWASM_OPER_BWAND, "&", 50 },
|
|
|
635 { LWASM_OPER_BWOR, "|", 50 },
|
|
|
636
|
|
|
637 // this collides with the unary complement but shouldn't cause
|
|
|
638 // any trouble because of operator precedence
|
|
|
639 { LWASM_OPER_BWXOR, "^", 50 },
|
|
|
640
|
|
|
641 { LWASM_OPER_NONE, "", 0 }
|
|
|
642 };
|
|
|
643 int opern, i;
|
|
|
644 lwasm_expr_term_t *operterm;
|
|
|
645
|
|
|
646 // return if we are at the end of the expression or a subexpression
|
|
|
647 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']')
|
|
|
648 return 0;
|
|
|
649
|
|
|
650 if (lwasm_expr_parse_term(s, p) < 0)
|
|
|
651 return -1;
|
|
|
652
|
|
|
653 eval_next:
|
|
|
654 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']')
|
|
|
655 return 0;
|
|
|
656
|
|
|
657 // expecting an operator here
|
|
|
658 for (opern = 0; operators[opern].opernum != LWASM_OPER_NONE; opern++)
|
|
|
659 {
|
|
|
660 for (i = 0; (*p)[i] && operators[opern].operstr[i] && ((*p)[i] == operators[opern].operstr[i]); i++)
|
|
|
661 /* do nothing */ ;
|
|
|
662 if (operators[opern].operstr[i] == '\0')
|
|
|
663 break;
|
|
|
664 }
|
|
|
665 if (operators[opern].opernum == LWASM_OPER_NONE)
|
|
|
666 {
|
|
|
667 // unrecognized operator
|
|
|
668 return -1;
|
|
|
669 }
|
|
|
670
|
|
|
671 // the operator number in question is in opern; i is the length of the
|
|
|
672 // operator string
|
|
|
673
|
|
|
674 // logic:
|
|
|
675 // if the precedence of this operation is <= to the "prec" flag,
|
|
|
676 // we simply return without advancing the input pointer; the operator
|
|
|
677 // will be evaluated again in the enclosing function call
|
|
|
678 if (operators[opern].operprec <= prec)
|
|
|
679 return 0;
|
|
|
680
|
|
|
681 // logic:
|
|
|
682 // we have a higher precedence operator here so we will advance the
|
|
|
683 // input pointer to the next term and let the expression evaluator
|
|
|
684 // loose on it after which time we will push our operator onto the
|
|
|
685 // stack and then go on with the expression evaluation
|
|
|
686 (*p) += i; // advance input pointer
|
|
|
687
|
|
|
688 // evaluate next expression(s) of higher precedence
|
|
|
689 if (lwasm_expr_parse_expr(s, p, operators[opern].operprec) < 0)
|
|
|
690 return -1;
|
|
|
691
|
|
|
692 operterm = lwasm_expr_term_create_oper(operators[opern].opernum);
|
|
|
693 lwasm_expr_stack_push(s, operterm);
|
|
|
694 lwasm_expr_term_free(operterm);
|
|
|
695
|
|
|
696 // return if we are at the end of the expression or a subexpression
|
|
|
697 if (!**p || isspace(**p) || **p == ')')
|
|
|
698 return 0;
|
|
|
699
|
|
|
700 // continue evaluating
|
|
|
701 goto eval_next;
|
|
|
702 }
|
|
|
703
|
|
|
704 /*
|
|
|
705 actually evaluate an expression
|
|
|
706
|
|
|
707 This happens in two stages. The first stage merely parses the expression into
|
|
|
708 a lwasm_expr_stack_t * which is then evaluated as much as possible before the
|
|
|
709 result is returned.
|
|
|
710
|
|
|
711 Returns NULL on a parse error or otherwise invalid expression. *outp will
|
|
|
712 contain the pointer to the next character after the expression if and only
|
|
|
713 if there is no error. In the case of an error, *outp is undefined.
|
|
|
714 */
|
|
|
715 lwasm_expr_stack_t *lwasm_expr_eval(const char *inp, const char **outp, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state)
|
|
|
716 {
|
|
|
717 lwasm_expr_stack_t *s;
|
|
|
718 const char *p;
|
|
|
719 int rval;
|
|
|
720
|
|
|
721 // actually parse the expression
|
|
|
722 p = inp;
|
|
|
723 s = lwasm_expr_stack_create();
|
|
|
724
|
|
|
725 rval = lwasm_expr_parse_expr(s, &p, 0);
|
|
|
726 if (rval < 0)
|
|
|
727 goto cleanup_error;
|
|
|
728
|
|
|
729 // save end of expression
|
|
|
730 if (outp)
|
|
|
731 (*outp) = p;
|
|
|
732
|
|
|
733 // return potentially partial expression
|
|
|
734 if (lwasm_expr_reval(s, sfunc, state) < 0)
|
|
|
735 goto cleanup_error;
|
|
|
736
|
|
|
737 if (lwasm_expr_is_constant(s))
|
|
|
738 debug_message(3, "Constant expression evaluates to: %d", lwasm_expr_get_value(s));
|
|
|
739
|
|
|
740 return s;
|
|
|
741
|
|
|
742 cleanup_error:
|
|
|
743 lwasm_expr_stack_free(s);
|
|
|
744 return NULL;
|
|
|
745 }
|
|
|
746
|
|
|
747 /*
|
|
|
748 take an expression stack s and scan for operations that can be completed
|
|
|
749
|
|
|
750 return -1 on error, 0 on no error
|
|
|
751
|
|
|
752 possible errors are: division by zero or unknown operator
|
|
|
753
|
|
|
754 theory of operation:
|
|
|
755
|
|
|
756 scan the stack for an operator which has two constants preceding it (binary)
|
|
|
757 or 1 constant preceding it (unary) and if found, perform the calculation
|
|
|
758 and replace the operator and its operands with the result
|
|
|
759
|
|
|
760 repeat the scan until no futher simplications are found or if there are no
|
|
|
761 further operators or only a single term remains
|
|
|
762
|
|
|
763 */
|
|
|
764 int lwasm_expr_reval(lwasm_expr_stack_t *s, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state)
|
|
|
765 {
|
|
|
766 lwasm_expr_stack_node_t *n, *n2;
|
|
|
767 lwasm_expr_stack_t *ss;
|
|
|
768 int c;
|
|
|
769
|
|
|
770 next_iter_sym:
|
|
|
771 // resolve symbols
|
|
|
772 // symbols that do not resolve to an expression are left alone
|
|
|
773 for (c = 0, n = s -> head; n; n = n -> next)
|
|
|
774 {
|
|
|
775 if (n -> term -> term_type == LWASM_TERM_SYM)
|
|
|
776 {
|
|
|
777 ss = sfunc(n -> term -> symbol, state);
|
|
|
778 if (ss)
|
|
|
779 {
|
|
|
780 c++;
|
|
|
781 // splice in the result stack
|
|
|
782 if (n -> prev)
|
|
|
783 {
|
|
|
784 n -> prev -> next = ss -> head;
|
|
|
785 }
|
|
|
786 else
|
|
|
787 {
|
|
|
788 s -> head = ss -> head;
|
|
|
789 }
|
|
|
790 ss -> head -> prev = n -> prev;
|
|
|
791 ss -> tail -> next = n -> next;
|
|
|
792 if (n -> next)
|
|
|
793 {
|
|
|
794 n -> next -> prev = ss -> tail;
|
|
|
795 }
|
|
|
796 else
|
|
|
797 {
|
|
|
798 s -> tail = ss -> tail;
|
|
|
799 }
|
|
|
800 lwasm_expr_term_free(n -> term);
|
|
|
801 lwasm_free(n);
|
|
|
802 n = ss -> tail;
|
|
|
803
|
|
|
804 ss -> head = NULL;
|
|
|
805 ss -> tail = NULL;
|
|
|
806 lwasm_expr_stack_free(ss);
|
|
|
807 }
|
|
|
808 }
|
|
|
809 }
|
|
|
810 if (c)
|
|
|
811 goto next_iter_sym;
|
|
|
812
|
|
|
813 next_iter:
|
|
|
814 // a single term
|
|
|
815 if (s -> head == s -> tail)
|
|
|
816 return 0;
|
|
|
817
|
|
|
818 // search for an operator
|
|
|
819 for (n = s -> head; n; n = n -> next)
|
|
|
820 {
|
|
|
821 if (n -> term -> term_type == LWASM_TERM_OPER)
|
|
|
822 {
|
|
|
823 if (n -> term -> value == LWASM_OPER_NEG
|
|
|
824 || n -> term -> value == LWASM_OPER_COM
|
|
|
825 )
|
|
|
826 {
|
|
|
827 // unary operator
|
|
|
828 if (n -> prev && n -> prev -> term -> term_type == LWASM_TERM_INT)
|
|
|
829 {
|
|
|
830 // a unary operator we can resolve
|
|
|
831 // we do the op then remove the term "n" is pointing at
|
|
|
832 if (n -> term -> value == LWASM_OPER_NEG)
|
|
|
833 {
|
|
|
834 n -> prev -> term -> value = -(n -> prev -> term -> value);
|
|
|
835 }
|
|
|
836 else if (n -> term -> value == LWASM_OPER_COM)
|
|
|
837 {
|
|
|
838 n -> prev -> term -> value = ~(n -> prev -> term -> value);
|
|
|
839 }
|
|
|
840 n -> prev -> next = n -> next;
|
|
|
841 if (n -> next)
|
|
|
842 n -> next -> prev = n -> prev;
|
|
|
843 else
|
|
|
844 s -> tail = n -> prev;
|
|
|
845
|
|
|
846 lwasm_expr_term_free(n -> term);
|
|
|
847 lwasm_free(n);
|
|
|
848 break;
|
|
|
849 }
|
|
|
850 }
|
|
|
851 else
|
|
|
852 {
|
|
|
853 // binary operator
|
|
|
854 if (n -> prev && n -> prev -> prev && n -> prev -> term -> term_type == LWASM_TERM_INT && n -> prev -> prev -> term -> term_type == LWASM_TERM_INT)
|
|
|
855 {
|
|
|
856 // a binary operator we can resolve
|
|
|
857 switch (n -> term -> value)
|
|
|
858 {
|
|
|
859 case LWASM_OPER_PLUS:
|
|
|
860 n -> prev -> prev -> term -> value += n -> prev -> term -> value;
|
|
|
861 break;
|
|
|
862
|
|
|
863 case LWASM_OPER_MINUS:
|
|
|
864 n -> prev -> prev -> term -> value -= n -> prev -> term -> value;
|
|
|
865 break;
|
|
|
866
|
|
|
867 case LWASM_OPER_TIMES:
|
|
|
868 n -> prev -> prev -> term -> value *= n -> prev -> term -> value;
|
|
|
869 break;
|
|
|
870
|
|
|
871 case LWASM_OPER_DIVIDE:
|
|
|
872 if (n -> prev -> term -> value == 0)
|
|
|
873 return -1;
|
|
|
874 n -> prev -> prev -> term -> value /= n -> prev -> term -> value;
|
|
|
875 break;
|
|
|
876
|
|
|
877 case LWASM_OPER_MOD:
|
|
|
878 if (n -> prev -> term -> value == 0)
|
|
|
879 return -1;
|
|
|
880 n -> prev -> prev -> term -> value %= n -> prev -> term -> value;
|
|
|
881 break;
|
|
|
882
|
|
|
883 case LWASM_OPER_INTDIV:
|
|
|
884 if (n -> prev -> term -> value == 0)
|
|
|
885 return -1;
|
|
|
886 n -> prev -> prev -> term -> value /= n -> prev -> term -> value;
|
|
|
887 break;
|
|
|
888
|
|
|
889 case LWASM_OPER_BWAND:
|
|
|
890 n -> prev -> prev -> term -> value &= n -> prev -> term -> value;
|
|
|
891 break;
|
|
|
892
|
|
|
893 case LWASM_OPER_BWOR:
|
|
|
894 n -> prev -> prev -> term -> value |= n -> prev -> term -> value;
|
|
|
895 break;
|
|
|
896
|
|
|
897 case LWASM_OPER_BWXOR:
|
|
|
898 n -> prev -> prev -> term -> value ^= n -> prev -> term -> value;
|
|
|
899 break;
|
|
|
900
|
|
|
901 case LWASM_OPER_AND:
|
|
|
902 n -> prev -> prev -> term -> value = (n -> prev -> term -> value && n -> prev -> prev -> term -> value) ? 1 : 0;
|
|
|
903 break;
|
|
|
904
|
|
|
905 case LWASM_OPER_OR:
|
|
|
906 n -> prev -> prev -> term -> value = (n -> prev -> term -> value || n -> prev -> prev -> term -> value) ? 1 : 0;
|
|
|
907 break;
|
|
|
908
|
|
|
909 default:
|
|
|
910 // return error if unknown operator!
|
|
|
911 return -1;
|
|
|
912 }
|
|
|
913
|
|
|
914 // now remove the two unneeded entries from the stack
|
|
|
915 n -> prev -> prev -> next = n -> next;
|
|
|
916 if (n -> next)
|
|
|
917 n -> next -> prev = n -> prev -> prev;
|
|
|
918 else
|
|
|
919 s -> tail = n -> prev -> prev;
|
|
|
920
|
|
|
921 lwasm_expr_term_free(n -> term);
|
|
|
922 lwasm_expr_term_free(n -> prev -> term);
|
|
|
923 lwasm_free(n -> prev);
|
|
|
924 lwasm_free(n);
|
|
|
925 break;
|
|
|
926 }
|
|
|
927 }
|
|
|
928 }
|
|
|
929 }
|
|
|
930 // note for the terminally confused about dynamic memory and pointers:
|
|
|
931 // n will not be NULL even after the lwasm_free calls above so
|
|
|
932 // this test will still work (n will be a dangling pointer)
|
|
|
933 // (n will only be NULL if we didn't find any operators to simplify)
|
|
|
934 if (n)
|
|
|
935 goto next_iter;
|
|
|
936
|
|
|
937 return 0;
|
|
|
938 }
|
