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annotate lwasm/expr.c @ 205:42df94f30d82
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| author | lost |
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| date | Sun, 19 Apr 2009 17:44:46 +0000 |
| parents | 2c1afbdb2de0 |
| children | bae1e3ecdce1 |
| rev | line source |
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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 /* |
| 18 | 22 This file contains the actual expression evaluator |
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23 */ |
| 14 | 24 |
| 25 #define __expr_c_seen__ | |
| 15 | 26 |
| 18 | 27 #include <ctype.h> |
| 15 | 28 #include <stdlib.h> |
| 18 | 29 #include <string.h> |
| 15 | 30 |
| 14 | 31 #include "expr.h" |
| 17 | 32 #include "util.h" |
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33 #include "lwasm.h" |
| 39 | 34 |
| 17 | 35 lwasm_expr_stack_t *lwasm_expr_stack_create(void) |
| 36 { | |
| 37 lwasm_expr_stack_t *s; | |
| 38 | |
| 39 s = lwasm_alloc(sizeof(lwasm_expr_stack_t)); | |
| 40 s -> head = NULL; | |
| 41 s -> tail = NULL; | |
| 42 return s; | |
| 43 } | |
| 15 | 44 |
| 17 | 45 void lwasm_expr_stack_free(lwasm_expr_stack_t *s) |
| 46 { | |
| 47 while (s -> head) | |
| 48 { | |
| 49 s -> tail = s -> head; | |
| 50 s -> head = s -> head -> next; | |
| 51 lwasm_expr_term_free(s -> tail -> term); | |
| 52 lwasm_free(s -> tail); | |
| 53 } | |
| 54 lwasm_free(s); | |
| 55 } | |
| 14 | 56 |
| 17 | 57 void lwasm_expr_term_free(lwasm_expr_term_t *t) |
| 58 { | |
| 59 if (t) | |
| 60 { | |
| 44 | 61 if (t -> term_type == LWASM_TERM_SYM) |
| 17 | 62 lwasm_free(t -> symbol); |
| 63 lwasm_free(t); | |
| 64 } | |
| 65 } | |
| 66 | |
| 67 lwasm_expr_term_t *lwasm_expr_term_create_oper(int oper) | |
| 68 { | |
| 69 lwasm_expr_term_t *t; | |
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70 |
| 39 | 71 debug_message(10, "Creating operator term: %d", oper); |
| 17 | 72 |
| 73 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); | |
| 74 t -> term_type = LWASM_TERM_OPER; | |
| 75 t -> value = oper; | |
| 76 return t; | |
| 77 } | |
| 15 | 78 |
| 17 | 79 lwasm_expr_term_t *lwasm_expr_term_create_int(int val) |
| 14 | 80 { |
| 17 | 81 lwasm_expr_term_t *t; |
| 39 | 82 debug_message(10, "Creating integer term: %d", val); |
| 17 | 83 |
| 84 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); | |
| 85 t -> term_type = LWASM_TERM_INT; | |
| 86 t -> value = val; | |
| 87 return t; | |
| 88 } | |
| 89 | |
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90 lwasm_expr_term_t *lwasm_expr_term_create_secbase(void) |
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91 { |
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92 lwasm_expr_term_t *t; |
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93 debug_message(10, "Creating section base term"); |
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94 |
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95 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); |
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96 t -> term_type = LWASM_TERM_SECBASE; |
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97 return t; |
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98 } |
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99 |
| 17 | 100 lwasm_expr_term_t *lwasm_expr_term_create_sym(char *sym) |
| 101 { | |
| 102 lwasm_expr_term_t *t; | |
| 14 | 103 |
| 39 | 104 debug_message(10, "Creating symbol term: %s", sym); |
| 105 | |
| 17 | 106 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); |
| 107 t -> term_type = LWASM_TERM_SYM; | |
| 108 t -> symbol = lwasm_strdup(sym); | |
| 109 return t; | |
| 110 } | |
| 15 | 111 |
| 17 | 112 lwasm_expr_term_t *lwasm_expr_term_dup(lwasm_expr_term_t *t) |
| 113 { | |
| 114 switch (t -> term_type) | |
| 15 | 115 { |
| 17 | 116 case LWASM_TERM_INT: |
| 117 return lwasm_expr_term_create_int(t -> value); | |
| 118 | |
| 119 case LWASM_TERM_OPER: | |
| 120 return lwasm_expr_term_create_oper(t -> value); | |
| 121 | |
| 122 case LWASM_TERM_SYM: | |
| 123 return lwasm_expr_term_create_sym(t -> symbol); | |
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124 |
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125 case LWASM_TERM_SECBASE: |
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126 return lwasm_expr_term_create_secbase(); |
| 17 | 127 |
| 128 default: | |
| 39 | 129 debug_message(0, "lwasm_expr_term_dup(): invalid term type %d", t -> term_type); |
| 17 | 130 exit(1); |
| 131 } | |
| 132 // can't get here | |
| 133 } | |
| 134 | |
| 135 void lwasm_expr_stack_push(lwasm_expr_stack_t *s, lwasm_expr_term_t *t) | |
| 136 { | |
| 137 lwasm_expr_stack_node_t *n; | |
| 138 | |
| 139 if (!s) | |
| 140 { | |
| 39 | 141 debug_message(0, "lwasm_expr_stack_push(): invalid stack pointer"); |
| 17 | 142 exit(1); |
| 15 | 143 } |
| 144 | |
| 17 | 145 n = lwasm_alloc(sizeof(lwasm_expr_stack_node_t)); |
| 146 n -> next = NULL; | |
| 147 n -> prev = s -> tail; | |
| 148 n -> term = lwasm_expr_term_dup(t); | |
| 149 | |
| 150 if (s -> head) | |
| 151 { | |
| 152 s -> tail -> next = n; | |
| 153 s -> tail = n; | |
| 154 } | |
| 155 else | |
| 15 | 156 { |
| 17 | 157 s -> head = n; |
| 158 s -> tail = n; | |
| 159 } | |
| 160 } | |
| 161 | |
| 162 lwasm_expr_term_t *lwasm_expr_stack_pop(lwasm_expr_stack_t *s) | |
| 163 { | |
| 164 lwasm_expr_term_t *t; | |
| 165 lwasm_expr_stack_node_t *n; | |
| 166 | |
| 167 if (!(s -> tail)) | |
| 168 return NULL; | |
| 169 | |
| 170 n = s -> tail; | |
| 171 s -> tail = n -> prev; | |
| 172 if (!(n -> prev)) | |
| 173 { | |
| 174 s -> head = NULL; | |
| 15 | 175 } |
| 14 | 176 |
| 17 | 177 t = n -> term; |
| 178 n -> term = NULL; | |
| 179 | |
| 180 lwasm_free(n); | |
| 181 | |
| 182 return t; | |
| 14 | 183 } |
| 18 | 184 |
| 185 // the following two functions are co-routines which actually parse | |
| 186 // an infix expression onto the expression stack, each returns -1 | |
| 187 // if an error is encountered | |
| 188 | |
| 189 /* | |
| 190 parse a term and push it onto the stack | |
| 191 | |
| 192 this function handles unary prefix operators (-, +, .not., .com.) | |
| 193 as well as () | |
| 194 */ | |
| 195 int lwasm_expr_parse_term(lwasm_expr_stack_t *s, const char **p) | |
| 196 { | |
| 197 lwasm_expr_term_t *t; | |
| 39 | 198 debug_message(2, "Expression string %s", *p); |
| 199 | |
| 18 | 200 eval_next: |
| 61 | 201 if (!**p || isspace(**p) || **p == ')' || **p == ']') |
| 202 return -1; | |
| 18 | 203 if (**p == '(') |
| 204 { | |
| 39 | 205 debug_message(3, "Starting paren"); |
| 18 | 206 (*p)++; |
| 207 lwasm_expr_parse_expr(s, p, 0); | |
| 208 if (**p != ')') | |
| 209 return -1; | |
| 210 (*p)++; | |
| 211 return 0; | |
| 212 } | |
| 213 | |
| 214 if (**p == '+') | |
| 215 { | |
| 39 | 216 debug_message(3, "Unary +"); |
| 18 | 217 (*p)++; |
| 218 goto eval_next; | |
| 219 } | |
| 220 | |
| 221 if (**p == '-') | |
| 222 { | |
| 223 // parse expression following "-" | |
| 224 (*p)++; | |
| 225 if (lwasm_expr_parse_expr(s, p, 200) < 0) | |
| 226 return -1; | |
| 227 t = lwasm_expr_term_create_oper(LWASM_OPER_NEG); | |
| 228 lwasm_expr_stack_push(s, t); | |
| 229 lwasm_expr_term_free(t); | |
| 230 return 0; | |
| 231 } | |
| 232 | |
| 191 | 233 if (**p == '^' || **p == '~') |
| 23 | 234 { |
| 235 // parse expression following "^" | |
| 236 (*p)++; | |
| 237 if (lwasm_expr_parse_expr(s, p, 200) < 0) | |
| 238 return -1; | |
| 239 t = lwasm_expr_term_create_oper(LWASM_OPER_COM); | |
| 240 lwasm_expr_stack_push(s, t); | |
| 241 lwasm_expr_term_free(t); | |
| 242 return 0; | |
| 243 } | |
| 244 | |
| 18 | 245 /* |
| 246 we have an actual term here so evaluate it | |
| 247 | |
| 248 it could be one of the following: | |
| 249 | |
| 250 1. a decimal constant | |
| 251 2. a hexadecimal constant | |
| 252 3. an octal constant | |
| 253 4. a binary constant | |
| 254 5. a symbol reference | |
| 255 6. the "current" instruction address (*) | |
| 256 7. the "current" data address (.) | |
| 257 8. a "back reference" (<) | |
| 258 9. a "forward reference" (>) | |
| 259 | |
| 260 items 6 through 9 are stored as symbol references | |
| 261 | |
| 262 (a . followed by a . or a alpha char or number is a symbol) | |
| 263 */ | |
| 264 if (**p == '*' | |
| 265 || ( | |
| 266 **p == '.' | |
| 267 && (*p)[1] != '.' | |
| 268 && !((*p)[1] >= 'A' && (*p)[1] <= 'Z') | |
| 269 && !((*p)[1] >= 'a' && (*p)[1] <= 'z') | |
| 270 && !((*p)[1] >= '0' && (*p)[1] <= '9') | |
| 271 ) | |
| 272 || **p == '<' | |
| 273 || **p == '>') | |
| 274 { | |
| 275 char tstr[2]; | |
| 276 tstr[0] = **p; | |
| 277 tstr[1] = '\0'; | |
| 278 t = lwasm_expr_term_create_sym(tstr); | |
| 279 lwasm_expr_stack_push(s, t); | |
| 280 lwasm_expr_term_free(t); | |
| 281 (*p)++; | |
| 282 return 0; | |
| 283 } | |
| 284 | |
| 285 /* | |
| 286 - a symbol will be a string of characters introduced by a letter, ".", | |
|
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287 "_" but NOT a number OR it may start with a digit if it contains a $ |
| 18 | 288 - a decimal constant will consist of only digits, optionally prefixed |
| 289 with "&" | |
| 290 - a binary constant will consist of only 0s and 1s either prefixed with % | |
| 291 or suffixed with "B" | |
| 292 - a hex constant will consist of 0-9A-F either prefixed with $ or | |
| 293 suffixed with "H"; a hex number starting with A-F must be prefixed | |
| 294 with $ or start with 0 and end with H | |
| 295 - an octal constant will consist of 0-7 either prefixed with @ or | |
| 296 suffixed with "O" or "Q" | |
| 297 - an ascii constant will be a single character prefixed with a ' | |
| 298 - a double ascii constant will be two characters prefixed with a " | |
| 299 | |
| 300 */ | |
| 301 if (**p == '"') | |
| 302 { | |
| 303 // double ascii constant | |
| 304 int val; | |
| 305 (*p)++; | |
| 306 if (!**p) | |
| 307 return -1; | |
| 308 if (!*((*p)+1)) | |
| 309 return -1; | |
| 310 val = **p << 8 | *((*p) + 1); | |
| 311 (*p) += 2; | |
| 312 t = lwasm_expr_term_create_int(val); | |
| 313 lwasm_expr_stack_push(s, t); | |
| 314 lwasm_expr_term_free(t); | |
| 315 return 0; | |
| 316 } | |
| 317 else if (**p == '\'') | |
| 318 { | |
| 319 // single ascii constant | |
| 320 int val; | |
| 321 (*p)++; | |
| 61 | 322 debug_message(3, "Single ascii character constant '%c'", **p); |
| 18 | 323 if (!**p) |
| 324 return -1; | |
| 325 val = **p; | |
| 326 (*p)++; | |
| 327 t = lwasm_expr_term_create_int(val); | |
| 328 lwasm_expr_stack_push(s, t); | |
| 329 lwasm_expr_term_free(t); | |
| 61 | 330 return 0; |
| 18 | 331 } |
| 332 else if (**p == '&') | |
| 333 { | |
| 334 // decimal constant | |
| 335 int val = 0; | |
| 336 | |
| 337 (*p)++; | |
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338 while (**p && strchr("0123456789", **p)) |
| 18 | 339 { |
| 340 val = val * 10 + (**p - '0'); | |
| 341 (*p)++; | |
| 342 } | |
| 343 t = lwasm_expr_term_create_int(val); | |
| 344 lwasm_expr_stack_push(s, t); | |
| 345 lwasm_expr_term_free(t); | |
| 346 return 0; | |
| 347 } | |
| 348 else if (**p == '%') | |
| 349 { | |
| 350 // binary constant | |
| 351 int val = 0; | |
| 352 | |
| 353 (*p)++; | |
| 354 while (**p == '0' || **p == '1') | |
| 355 { | |
| 356 val = val * 2 + (**p - '0'); | |
| 357 (*p)++; | |
| 358 } | |
| 359 t = lwasm_expr_term_create_int(val); | |
| 360 lwasm_expr_stack_push(s, t); | |
| 361 lwasm_expr_term_free(t); | |
| 362 return 0; | |
| 363 } | |
| 364 else if (**p == '$') | |
| 365 { | |
| 366 // hexadecimal constant | |
| 367 int val = 0, val2; | |
| 368 | |
| 369 (*p)++; | |
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370 debug_message(3, "Found prefix hex constant: %s", *p); |
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371 while (**p && strchr("0123456789ABCDEFabcdef", **p)) |
| 18 | 372 { |
| 373 val2 = toupper(**p) - '0'; | |
| 374 if (val2 > 9) | |
| 375 val2 -= 7; | |
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376 debug_message(3, "Got char: %c (%d)", **p, val2); |
| 18 | 377 val = val * 16 + val2; |
| 378 (*p)++; | |
| 379 } | |
| 380 t = lwasm_expr_term_create_int(val); | |
| 381 lwasm_expr_stack_push(s, t); | |
| 382 lwasm_expr_term_free(t); | |
| 383 return 0; | |
| 384 } | |
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385 else if (**p == '0' && tolower(*(*p + 1)) == 'x') |
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386 { |
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387 // "C" style hexadecimal constant |
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388 int val = 0, val2; |
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389 |
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390 (*p)+=2; |
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391 debug_message(3, "Found \"C\" style prefix hex constant: %s", *p); |
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392 while (**p && strchr("0123456789ABCDEFabcdef", **p)) |
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393 { |
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394 val2 = toupper(**p) - '0'; |
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395 if (val2 > 9) |
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396 val2 -= 7; |
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397 debug_message(3, "Got char: %c (%d)", **p, val2); |
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398 val = val * 16 + val2; |
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399 (*p)++; |
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400 } |
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401 t = lwasm_expr_term_create_int(val); |
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402 lwasm_expr_stack_push(s, t); |
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403 lwasm_expr_term_free(t); |
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404 return 0; |
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405 } |
|
40
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adjusted symbol rules to accept symbols starting with @ but not @<digit>
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406 // an @ followed by a digit is an octal number |
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407 // but if it's followed by anything else, it is a symbol |
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408 else if (**p == '@' && isdigit(*(*p + 1))) |
| 18 | 409 { |
| 410 // octal constant | |
| 411 int val = 0; | |
| 412 | |
| 413 (*p)++; | |
|
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Implemented ORG and fixed problems with constants using $, &, or @ to specify base
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414 while (**p && strchr("01234567", **p)) |
| 18 | 415 { |
| 416 val = val * 8 + (**p - '0'); | |
| 417 (*p)++; | |
| 418 } | |
| 419 t = lwasm_expr_term_create_int(val); | |
| 420 lwasm_expr_stack_push(s, t); | |
| 421 lwasm_expr_term_free(t); | |
| 422 return 0; | |
| 423 } | |
|
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424 |
| 18 | 425 // symbol or bare decimal or suffix identified constant here |
|
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426 |
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427 // find the end of a potential symbol |
|
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428 do |
| 18 | 429 { |
| 430 int l = 0; | |
| 431 char *sb; | |
|
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432 int havedol = 0; |
| 18 | 433 |
| 434 // evaluate a symbol here | |
| 41 | 435 static const char *symchars = "_.$@?abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; |
| 436 while ((*p)[l] && strchr(symchars, (*p)[l])) | |
|
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437 { |
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438 if ((*p)[l] == '$') |
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439 havedol = 1; |
| 18 | 440 l++; |
|
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441 } |
| 18 | 442 if (l == 0) |
| 443 return -1; | |
| 444 | |
|
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445 if (havedol || **p < '0' || **p > '9') |
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446 { |
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447 // have a symbol here |
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448 |
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449 sb = lwasm_alloc(l + 1); |
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450 sb[l] = '\0'; |
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451 memcpy(sb, *p, l); |
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452 t = lwasm_expr_term_create_sym(sb); |
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453 lwasm_expr_stack_push(s, t); |
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454 lwasm_expr_term_free(t); |
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455 (*p) += l; |
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456 debug_message(3, "Symbol: '%s'; (%s)", sb, *p); |
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457 lwasm_free(sb); |
|
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458 return 0; |
|
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459 } |
|
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|
460 } while (0); |
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461 |
| 18 | 462 if (!**p) |
| 463 return -1; | |
| 464 | |
| 465 // evaluate a suffix based constant | |
| 466 { | |
| 467 int decval = 0, binval = 0, hexval = 0, octval = 0; | |
| 468 int valtype = 15; // 1 = bin, 2 = oct, 4 = dec, 8 = hex | |
| 469 int bindone = 0; | |
| 470 int val; | |
| 471 int dval; | |
| 472 | |
| 473 while (1) | |
| 474 { | |
| 475 if (!**p || !strchr("0123456789ABCDEFabcdefqhoQHO", **p)) | |
| 476 { | |
| 477 // we can legally have bin or decimal here | |
| 478 if (bindone) | |
| 479 { | |
| 480 // we just finished a binary value | |
| 481 val = binval; | |
| 482 break; | |
| 483 } | |
| 484 else if (valtype & 4) | |
| 485 { | |
| 486 // otherwise we must be decimal (if we're still allowed one) | |
| 487 val = decval; | |
| 39 | 488 debug_message(3, "End of decimal value"); |
| 18 | 489 break; |
| 490 } | |
| 491 else | |
| 492 { | |
| 493 // bad value | |
| 494 return -1; | |
| 495 } | |
| 496 } | |
| 497 | |
| 498 dval = toupper(**p); | |
| 499 (*p)++; | |
| 500 | |
| 501 if (bindone) | |
| 502 { | |
| 503 // any characters past "B" means it is not binary | |
| 504 bindone = 0; | |
| 505 valtype &= 14; | |
| 506 } | |
| 507 | |
| 508 switch (dval) | |
| 509 { | |
| 510 case 'Q': | |
| 511 case 'O': | |
| 512 if (valtype & 2) | |
| 513 { | |
| 514 val = octval; | |
| 515 valtype = -1; | |
| 516 break; | |
| 517 } | |
| 518 else | |
| 519 { | |
| 520 // not a valid octal value | |
| 521 return -1; | |
| 522 } | |
| 523 /* can't get here */ | |
| 524 | |
| 525 case 'H': | |
| 526 if (valtype & 8) | |
| 527 { | |
| 528 val = hexval; | |
| 529 valtype = -1; | |
| 530 break; | |
| 531 } | |
| 532 else | |
| 533 { | |
| 534 // not a valid hex number | |
| 535 return -1; | |
| 536 } | |
| 537 /* can't get here */ | |
| 538 | |
| 539 case 'B': | |
| 540 // this is a bit of a sticky one since B is a legit hex | |
| 541 // digit so this may or may not be the end of the number | |
| 542 // so we fall through to the digit case | |
| 543 | |
| 544 if (valtype & 1) | |
| 545 { | |
| 546 // could still be binary | |
| 547 bindone = 1; | |
| 548 valtype = 9; // hex and binary | |
| 549 } | |
| 550 /* fall through intentional */ | |
| 551 | |
| 552 default: | |
| 553 // digit | |
| 554 dval -= '0'; | |
| 555 if (dval > 9) | |
| 556 dval -= 7; | |
| 39 | 557 debug_message(3, "Got digit: %d", dval); |
|
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558 // if (dval > 1) |
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559 // valtype &= 14; |
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560 // if (dval > 7) |
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561 // valtype &= 12; |
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562 // if (dval > 9) |
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563 // valtype &= 8; |
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564 |
| 18 | 565 if (valtype & 8) |
| 566 { | |
| 567 hexval = hexval * 16 + dval; | |
| 568 } | |
| 569 if (valtype & 4) | |
| 570 { | |
| 571 if (dval > 9) | |
| 572 valtype &= 11; | |
| 573 else | |
| 574 decval = decval * 10 + dval; | |
| 575 } | |
| 576 if (valtype & 2) | |
| 577 { | |
| 578 if (dval > 7) | |
| 579 valtype &= 13; | |
| 580 else | |
| 581 octval = octval * 8 + dval; | |
| 582 } | |
| 583 if (valtype & 1) | |
| 584 { | |
| 585 if (dval > 1) | |
| 586 valtype &= 14; | |
| 587 else | |
| 588 binval = binval * 2 + dval; | |
| 589 } | |
| 590 } | |
| 591 // break out if we have a return value | |
|
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592 if (valtype == -1) |
| 18 | 593 break; |
| 594 // return if no more valid possibilities! | |
| 595 if (valtype == 0) | |
| 596 return -1; | |
|
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597 val = decval; // in case we fall through |
| 18 | 598 } |
| 599 | |
| 600 // we get here when we have a value to return | |
| 601 t = lwasm_expr_term_create_int(val); | |
| 602 lwasm_expr_stack_push(s, t); | |
| 603 lwasm_expr_term_free(t); | |
| 604 return 0; | |
| 605 } | |
| 606 /* can't get here */ | |
| 607 } | |
| 608 | |
| 609 // parse an expression and push the result onto the stack | |
| 610 // if an operator of lower precedence than the value of "prec" is found, | |
| 611 int lwasm_expr_parse_expr(lwasm_expr_stack_t *s, const char **p, int prec) | |
| 612 { | |
| 613 static const struct operinfo | |
| 614 { | |
| 615 int opernum; | |
| 616 char *operstr; | |
| 617 int operprec; | |
| 618 } operators[] = | |
| 619 { | |
| 620 { LWASM_OPER_PLUS, "+", 100 }, | |
| 621 { LWASM_OPER_MINUS, "-", 100 }, | |
| 622 { LWASM_OPER_TIMES, "*", 150 }, | |
| 623 { LWASM_OPER_DIVIDE, "/", 150 }, | |
| 624 { LWASM_OPER_MOD, "%", 150 }, | |
| 625 { LWASM_OPER_INTDIV, "\\", 150 }, | |
| 626 | |
| 203 | 627 { LWASM_OPER_BWAND, "&", 50 }, |
| 628 { LWASM_OPER_BWOR, "|", 50 }, | |
| 629 | |
| 630 // this collides with the unary complement but shouldn't cause | |
| 631 // any trouble because of operator precedence | |
| 632 { LWASM_OPER_BWXOR, "^", 50 }, | |
| 633 | |
| 18 | 634 { LWASM_OPER_NONE, "", 0 } |
| 635 }; | |
| 636 int opern, i; | |
| 637 lwasm_expr_term_t *operterm; | |
| 638 | |
| 639 // return if we are at the end of the expression or a subexpression | |
| 61 | 640 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']') |
| 18 | 641 return 0; |
| 642 | |
| 643 if (lwasm_expr_parse_term(s, p) < 0) | |
| 644 return -1; | |
|
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645 |
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646 eval_next: |
| 61 | 647 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']') |
|
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648 return 0; |
| 18 | 649 |
| 650 // expecting an operator here | |
| 651 for (opern = 0; operators[opern].opernum != LWASM_OPER_NONE; opern++) | |
| 652 { | |
| 653 for (i = 0; (*p)[i] && operators[opern].operstr[i] && (*p[i] == operators[opern].operstr[i]); i++) | |
| 654 /* do nothing */ ; | |
| 655 if (operators[opern].operstr[i] == '\0') | |
| 656 break; | |
| 657 } | |
| 658 if (operators[opern].opernum == LWASM_OPER_NONE) | |
| 659 { | |
| 660 // unrecognized operator | |
| 661 return -1; | |
| 662 } | |
| 663 | |
| 664 // the operator number in question is in opern; i is the length of the | |
| 665 // operator string | |
| 666 | |
| 667 // logic: | |
| 668 // if the precedence of this operation is <= to the "prec" flag, | |
| 669 // we simply return without advancing the input pointer; the operator | |
| 670 // will be evaluated again in the enclosing function call | |
| 671 if (operators[opern].operprec <= prec) | |
| 672 return 0; | |
| 673 | |
| 674 // logic: | |
| 675 // we have a higher precedence operator here so we will advance the | |
| 676 // input pointer to the next term and let the expression evaluator | |
| 677 // loose on it after which time we will push our operator onto the | |
| 678 // stack and then go on with the expression evaluation | |
| 679 (*p) += i; // advance input pointer | |
| 680 | |
| 681 // evaluate next expression(s) of higher precedence | |
| 682 if (lwasm_expr_parse_expr(s, p, operators[opern].operprec) < 0) | |
| 683 return -1; | |
| 684 | |
| 685 operterm = lwasm_expr_term_create_oper(operators[opern].opernum); | |
| 686 lwasm_expr_stack_push(s, operterm); | |
| 687 lwasm_expr_term_free(operterm); | |
| 688 | |
| 689 // return if we are at the end of the expression or a subexpression | |
| 690 if (!**p || isspace(**p) || **p == ')') | |
| 691 return 0; | |
| 692 | |
| 693 // continue evaluating | |
| 694 goto eval_next; | |
| 695 } | |
| 696 | |
| 697 /* | |
| 698 actually evaluate an expression | |
| 699 | |
| 700 This happens in two stages. The first stage merely parses the expression into | |
| 701 a lwasm_expr_stack_t * which is then evaluated as much as possible before the | |
| 702 result is returned. | |
| 703 | |
| 704 Returns NULL on a parse error or otherwise invalid expression. *outp will | |
| 705 contain the pointer to the next character after the expression if and only | |
| 706 if there is no error. In the case of an error, *outp is undefined. | |
| 707 */ | |
| 76 | 708 lwasm_expr_stack_t *lwasm_expr_eval(const char *inp, const char **outp, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state) |
| 18 | 709 { |
| 710 lwasm_expr_stack_t *s; | |
| 711 const char *p; | |
|
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712 int rval; |
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713 |
| 18 | 714 // actually parse the expression |
| 715 p = inp; | |
| 716 s = lwasm_expr_stack_create(); | |
|
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|
717 |
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718 rval = lwasm_expr_parse_expr(s, &p, 0); |
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719 if (rval < 0) |
| 18 | 720 goto cleanup_error; |
| 721 | |
| 722 // save end of expression | |
| 723 if (outp) | |
| 724 (*outp) = p; | |
| 725 | |
| 726 // return potentially partial expression | |
|
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727 if (lwasm_expr_reval(s, sfunc, state) < 0) |
| 18 | 728 goto cleanup_error; |
|
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|
729 |
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|
730 if (lwasm_expr_is_constant(s)) |
| 39 | 731 debug_message(3, "Constant expression evaluates to: %d", lwasm_expr_get_value(s)); |
| 18 | 732 |
| 733 return s; | |
| 734 | |
| 735 cleanup_error: | |
| 736 lwasm_expr_stack_free(s); | |
| 737 return NULL; | |
| 738 } | |
| 739 | |
| 740 /* | |
| 741 take an expression stack s and scan for operations that can be completed | |
| 742 | |
| 743 return -1 on error, 0 on no error | |
| 744 | |
| 745 possible errors are: division by zero or unknown operator | |
| 746 | |
| 747 theory of operation: | |
| 748 | |
| 749 scan the stack for an operator which has two constants preceding it (binary) | |
| 750 or 1 constant preceding it (unary) and if found, perform the calculation | |
| 751 and replace the operator and its operands with the result | |
| 752 | |
| 753 repeat the scan until no futher simplications are found or if there are no | |
| 754 further operators or only a single term remains | |
| 755 | |
| 756 */ | |
| 76 | 757 int lwasm_expr_reval(lwasm_expr_stack_t *s, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state) |
| 18 | 758 { |
| 76 | 759 lwasm_expr_stack_node_t *n, *n2; |
| 760 lwasm_expr_stack_t *ss; | |
| 761 int c; | |
|
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|
762 |
| 76 | 763 next_iter_sym: |
|
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|
764 // resolve symbols |
| 76 | 765 // symbols that do not resolve to an expression are left alone |
| 766 for (c = 0, n = s -> head; n; n = n -> next) | |
|
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|
767 { |
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768 if (n -> term -> term_type == LWASM_TERM_SYM) |
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769 { |
| 76 | 770 ss = sfunc(n -> term -> symbol, state); |
| 771 if (ss) | |
|
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|
772 { |
| 76 | 773 c++; |
| 774 // splice in the result stack | |
| 775 if (n -> prev) | |
| 776 { | |
| 777 n -> prev -> next = ss -> head; | |
| 778 } | |
| 779 else | |
| 780 { | |
| 781 s -> head = ss -> head; | |
| 782 } | |
| 783 ss -> head -> prev = n -> prev; | |
| 784 ss -> tail -> next = n -> next; | |
| 785 if (n -> next) | |
| 786 { | |
| 787 n -> next -> prev = ss -> tail; | |
| 788 } | |
| 789 else | |
| 790 { | |
| 791 s -> tail = ss -> tail; | |
| 792 } | |
| 793 lwasm_expr_term_free(n -> term); | |
| 794 lwasm_free(n); | |
| 795 n = ss -> tail; | |
| 796 | |
| 797 ss -> head = NULL; | |
| 798 ss -> tail = NULL; | |
| 799 lwasm_expr_stack_free(ss); | |
|
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800 } |
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Added symbol handling to expression subsystem; adpated instruction handlers to the new scheme; misc fixes
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801 } |
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Added symbol handling to expression subsystem; adpated instruction handlers to the new scheme; misc fixes
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802 } |
| 76 | 803 if (c) |
| 804 goto next_iter_sym; | |
| 18 | 805 |
| 806 next_iter: | |
| 807 // a single term | |
| 808 if (s -> head == s -> tail) | |
| 809 return 0; | |
| 810 | |
| 811 // search for an operator | |
| 812 for (n = s -> head; n; n = n -> next) | |
| 813 { | |
| 814 if (n -> term -> term_type == LWASM_TERM_OPER) | |
| 815 { | |
| 816 if (n -> term -> value == LWASM_OPER_NEG | |
| 817 || n -> term -> value == LWASM_OPER_COM | |
| 818 ) | |
| 819 { | |
| 820 // unary operator | |
| 821 if (n -> prev && n -> prev -> term -> term_type == LWASM_TERM_INT) | |
| 822 { | |
| 823 // a unary operator we can resolve | |
| 824 // we do the op then remove the term "n" is pointing at | |
| 825 if (n -> term -> value == LWASM_OPER_NEG) | |
| 826 { | |
| 827 n -> prev -> term -> value = -(n -> prev -> term -> value); | |
| 828 } | |
| 829 else if (n -> term -> value == LWASM_OPER_COM) | |
| 830 { | |
| 831 n -> prev -> term -> value = ~(n -> prev -> term -> value); | |
| 832 } | |
| 833 n -> prev -> next = n -> next; | |
| 834 if (n -> next) | |
| 835 n -> next -> prev = n -> prev; | |
| 836 else | |
| 837 s -> tail = n -> prev; | |
| 838 | |
| 839 lwasm_expr_term_free(n -> term); | |
| 840 lwasm_free(n); | |
| 841 break; | |
| 842 } | |
| 843 } | |
| 844 else | |
| 845 { | |
| 846 // binary operator | |
| 847 if (n -> prev && n -> prev -> prev && n -> prev -> term -> term_type == LWASM_TERM_INT && n -> prev -> prev -> term -> term_type == LWASM_TERM_INT) | |
| 848 { | |
| 849 // a binary operator we can resolve | |
| 850 switch (n -> term -> value) | |
| 851 { | |
| 852 case LWASM_OPER_PLUS: | |
| 853 n -> prev -> prev -> term -> value += n -> prev -> term -> value; | |
| 854 break; | |
| 855 | |
| 856 case LWASM_OPER_MINUS: | |
| 857 n -> prev -> prev -> term -> value -= n -> prev -> term -> value; | |
| 858 break; | |
| 859 | |
| 860 case LWASM_OPER_TIMES: | |
| 861 n -> prev -> prev -> term -> value *= n -> prev -> term -> value; | |
| 862 break; | |
| 863 | |
| 864 case LWASM_OPER_DIVIDE: | |
| 865 if (n -> prev -> term -> value == 0) | |
| 866 return -1; | |
| 867 n -> prev -> prev -> term -> value /= n -> prev -> term -> value; | |
| 868 break; | |
| 869 | |
| 870 case LWASM_OPER_MOD: | |
| 871 if (n -> prev -> term -> value == 0) | |
| 872 return -1; | |
| 873 n -> prev -> prev -> term -> value %= n -> prev -> term -> value; | |
| 874 break; | |
| 875 | |
| 876 case LWASM_OPER_INTDIV: | |
| 877 if (n -> prev -> term -> value == 0) | |
| 878 return -1; | |
| 879 n -> prev -> prev -> term -> value /= n -> prev -> term -> value; | |
| 880 break; | |
| 881 | |
| 882 case LWASM_OPER_BWAND: | |
| 883 n -> prev -> prev -> term -> value &= n -> prev -> term -> value; | |
| 884 break; | |
| 885 | |
| 886 case LWASM_OPER_BWOR: | |
| 887 n -> prev -> prev -> term -> value |= n -> prev -> term -> value; | |
| 888 break; | |
| 889 | |
| 890 case LWASM_OPER_BWXOR: | |
| 891 n -> prev -> prev -> term -> value ^= n -> prev -> term -> value; | |
| 892 break; | |
| 893 | |
| 894 case LWASM_OPER_AND: | |
| 895 n -> prev -> prev -> term -> value = (n -> prev -> term -> value && n -> prev -> prev -> term -> value) ? 1 : 0; | |
| 896 break; | |
| 897 | |
| 898 case LWASM_OPER_OR: | |
| 899 n -> prev -> prev -> term -> value = (n -> prev -> term -> value || n -> prev -> prev -> term -> value) ? 1 : 0; | |
| 900 break; | |
| 901 | |
| 902 default: | |
| 903 // return error if unknown operator! | |
| 904 return -1; | |
| 905 } | |
| 906 | |
| 907 // now remove the two unneeded entries from the stack | |
| 908 n -> prev -> prev -> next = n -> next; | |
| 909 if (n -> next) | |
| 910 n -> next -> prev = n -> prev -> prev; | |
| 911 else | |
| 912 s -> tail = n -> prev -> prev; | |
| 913 | |
| 914 lwasm_expr_term_free(n -> term); | |
| 915 lwasm_expr_term_free(n -> prev -> term); | |
| 916 lwasm_free(n -> prev); | |
| 917 lwasm_free(n); | |
| 918 break; | |
| 919 } | |
| 920 } | |
| 921 } | |
| 922 } | |
| 923 // note for the terminally confused about dynamic memory and pointers: | |
| 924 // n will not be NULL even after the lwasm_free calls above so | |
| 925 // this test will still work (n will be a dangling pointer) | |
| 926 // (n will only be NULL if we didn't find any operators to simplify) | |
| 927 if (n) | |
| 928 goto next_iter; | |
| 929 | |
| 930 return 0; | |
| 931 } |