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annotate lwasm/expr.c @ 264:61d1db1dfe2a 2.6
Build manual for release
| author | lost |
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| date | Tue, 22 Dec 2009 05:27:32 +0000 |
| parents | c8787fad0f9f |
| children | 1bdb4e256fc9 |
| 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 |
| 212 | 27 #include <config.h> |
| 28 | |
| 18 | 29 #include <ctype.h> |
| 15 | 30 #include <stdlib.h> |
| 18 | 31 #include <string.h> |
| 15 | 32 |
| 14 | 33 #include "expr.h" |
| 17 | 34 #include "util.h" |
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35 #include "lwasm.h" |
| 39 | 36 |
| 17 | 37 lwasm_expr_stack_t *lwasm_expr_stack_create(void) |
| 38 { | |
| 39 lwasm_expr_stack_t *s; | |
| 40 | |
| 41 s = lwasm_alloc(sizeof(lwasm_expr_stack_t)); | |
| 42 s -> head = NULL; | |
| 43 s -> tail = NULL; | |
| 44 return s; | |
| 45 } | |
| 15 | 46 |
| 17 | 47 void lwasm_expr_stack_free(lwasm_expr_stack_t *s) |
| 48 { | |
| 49 while (s -> head) | |
| 50 { | |
| 51 s -> tail = s -> head; | |
| 52 s -> head = s -> head -> next; | |
| 53 lwasm_expr_term_free(s -> tail -> term); | |
| 54 lwasm_free(s -> tail); | |
| 55 } | |
| 56 lwasm_free(s); | |
| 57 } | |
| 14 | 58 |
| 17 | 59 void lwasm_expr_term_free(lwasm_expr_term_t *t) |
| 60 { | |
| 61 if (t) | |
| 62 { | |
| 44 | 63 if (t -> term_type == LWASM_TERM_SYM) |
| 17 | 64 lwasm_free(t -> symbol); |
| 65 lwasm_free(t); | |
| 66 } | |
| 67 } | |
| 68 | |
| 69 lwasm_expr_term_t *lwasm_expr_term_create_oper(int oper) | |
| 70 { | |
| 71 lwasm_expr_term_t *t; | |
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72 |
| 39 | 73 debug_message(10, "Creating operator term: %d", oper); |
| 17 | 74 |
| 75 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); | |
| 76 t -> term_type = LWASM_TERM_OPER; | |
| 77 t -> value = oper; | |
| 78 return t; | |
| 79 } | |
| 15 | 80 |
| 17 | 81 lwasm_expr_term_t *lwasm_expr_term_create_int(int val) |
| 14 | 82 { |
| 17 | 83 lwasm_expr_term_t *t; |
| 39 | 84 debug_message(10, "Creating integer term: %d", val); |
| 17 | 85 |
| 86 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); | |
| 87 t -> term_type = LWASM_TERM_INT; | |
| 88 t -> value = val; | |
| 89 return t; | |
| 90 } | |
| 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 |
| 17 | 102 lwasm_expr_term_t *lwasm_expr_term_create_sym(char *sym) |
| 103 { | |
| 104 lwasm_expr_term_t *t; | |
| 14 | 105 |
| 39 | 106 debug_message(10, "Creating symbol term: %s", sym); |
| 107 | |
| 17 | 108 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); |
| 109 t -> term_type = LWASM_TERM_SYM; | |
| 110 t -> symbol = lwasm_strdup(sym); | |
| 111 return t; | |
| 112 } | |
| 15 | 113 |
| 17 | 114 lwasm_expr_term_t *lwasm_expr_term_dup(lwasm_expr_term_t *t) |
| 115 { | |
| 116 switch (t -> term_type) | |
| 15 | 117 { |
| 17 | 118 case LWASM_TERM_INT: |
| 119 return lwasm_expr_term_create_int(t -> value); | |
| 120 | |
| 121 case LWASM_TERM_OPER: | |
| 122 return lwasm_expr_term_create_oper(t -> value); | |
| 123 | |
| 124 case LWASM_TERM_SYM: | |
| 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(); |
| 17 | 129 |
| 130 default: | |
| 39 | 131 debug_message(0, "lwasm_expr_term_dup(): invalid term type %d", t -> term_type); |
| 17 | 132 exit(1); |
| 133 } | |
| 134 // can't get here | |
| 135 } | |
| 136 | |
| 137 void lwasm_expr_stack_push(lwasm_expr_stack_t *s, lwasm_expr_term_t *t) | |
| 138 { | |
| 139 lwasm_expr_stack_node_t *n; | |
| 140 | |
| 141 if (!s) | |
| 142 { | |
| 39 | 143 debug_message(0, "lwasm_expr_stack_push(): invalid stack pointer"); |
| 17 | 144 exit(1); |
| 15 | 145 } |
| 146 | |
| 17 | 147 n = lwasm_alloc(sizeof(lwasm_expr_stack_node_t)); |
| 148 n -> next = NULL; | |
| 149 n -> prev = s -> tail; | |
| 150 n -> term = lwasm_expr_term_dup(t); | |
| 151 | |
| 152 if (s -> head) | |
| 153 { | |
| 154 s -> tail -> next = n; | |
| 155 s -> tail = n; | |
| 156 } | |
| 157 else | |
| 15 | 158 { |
| 17 | 159 s -> head = n; |
| 160 s -> tail = n; | |
| 161 } | |
| 162 } | |
| 163 | |
| 164 lwasm_expr_term_t *lwasm_expr_stack_pop(lwasm_expr_stack_t *s) | |
| 165 { | |
| 166 lwasm_expr_term_t *t; | |
| 167 lwasm_expr_stack_node_t *n; | |
| 168 | |
| 169 if (!(s -> tail)) | |
| 170 return NULL; | |
| 171 | |
| 172 n = s -> tail; | |
| 173 s -> tail = n -> prev; | |
| 174 if (!(n -> prev)) | |
| 175 { | |
| 176 s -> head = NULL; | |
| 15 | 177 } |
| 14 | 178 |
| 17 | 179 t = n -> term; |
| 180 n -> term = NULL; | |
| 181 | |
| 182 lwasm_free(n); | |
| 183 | |
| 184 return t; | |
| 14 | 185 } |
| 18 | 186 |
| 187 // the following two functions are co-routines which actually parse | |
| 188 // an infix expression onto the expression stack, each returns -1 | |
| 189 // if an error is encountered | |
| 190 | |
| 191 /* | |
| 192 parse a term and push it onto the stack | |
| 193 | |
| 194 this function handles unary prefix operators (-, +, .not., .com.) | |
| 195 as well as () | |
| 196 */ | |
| 197 int lwasm_expr_parse_term(lwasm_expr_stack_t *s, const char **p) | |
| 198 { | |
| 199 lwasm_expr_term_t *t; | |
| 39 | 200 debug_message(2, "Expression string %s", *p); |
| 201 | |
| 18 | 202 eval_next: |
| 61 | 203 if (!**p || isspace(**p) || **p == ')' || **p == ']') |
| 204 return -1; | |
| 18 | 205 if (**p == '(') |
| 206 { | |
| 39 | 207 debug_message(3, "Starting paren"); |
| 18 | 208 (*p)++; |
| 209 lwasm_expr_parse_expr(s, p, 0); | |
| 210 if (**p != ')') | |
| 211 return -1; | |
| 212 (*p)++; | |
| 213 return 0; | |
| 214 } | |
| 215 | |
| 216 if (**p == '+') | |
| 217 { | |
| 39 | 218 debug_message(3, "Unary +"); |
| 18 | 219 (*p)++; |
| 220 goto eval_next; | |
| 221 } | |
| 222 | |
| 223 if (**p == '-') | |
| 224 { | |
| 225 // parse expression following "-" | |
| 226 (*p)++; | |
| 227 if (lwasm_expr_parse_expr(s, p, 200) < 0) | |
| 228 return -1; | |
| 229 t = lwasm_expr_term_create_oper(LWASM_OPER_NEG); | |
| 230 lwasm_expr_stack_push(s, t); | |
| 231 lwasm_expr_term_free(t); | |
| 232 return 0; | |
| 233 } | |
| 234 | |
| 191 | 235 if (**p == '^' || **p == '~') |
| 23 | 236 { |
| 237 // parse expression following "^" | |
| 238 (*p)++; | |
| 239 if (lwasm_expr_parse_expr(s, p, 200) < 0) | |
| 240 return -1; | |
| 241 t = lwasm_expr_term_create_oper(LWASM_OPER_COM); | |
| 242 lwasm_expr_stack_push(s, t); | |
| 243 lwasm_expr_term_free(t); | |
| 244 return 0; | |
| 245 } | |
| 246 | |
| 18 | 247 /* |
| 248 we have an actual term here so evaluate it | |
| 249 | |
| 250 it could be one of the following: | |
| 251 | |
| 252 1. a decimal constant | |
| 253 2. a hexadecimal constant | |
| 254 3. an octal constant | |
| 255 4. a binary constant | |
| 256 5. a symbol reference | |
| 257 6. the "current" instruction address (*) | |
| 258 7. the "current" data address (.) | |
| 259 8. a "back reference" (<) | |
| 260 9. a "forward reference" (>) | |
| 261 | |
| 262 items 6 through 9 are stored as symbol references | |
| 263 | |
| 264 (a . followed by a . or a alpha char or number is a symbol) | |
| 265 */ | |
| 266 if (**p == '*' | |
| 267 || ( | |
| 268 **p == '.' | |
| 269 && (*p)[1] != '.' | |
| 270 && !((*p)[1] >= 'A' && (*p)[1] <= 'Z') | |
| 271 && !((*p)[1] >= 'a' && (*p)[1] <= 'z') | |
| 272 && !((*p)[1] >= '0' && (*p)[1] <= '9') | |
| 273 ) | |
| 274 || **p == '<' | |
| 275 || **p == '>') | |
| 276 { | |
| 277 char tstr[2]; | |
| 278 tstr[0] = **p; | |
| 279 tstr[1] = '\0'; | |
| 280 t = lwasm_expr_term_create_sym(tstr); | |
| 281 lwasm_expr_stack_push(s, t); | |
| 282 lwasm_expr_term_free(t); | |
| 283 (*p)++; | |
| 284 return 0; | |
| 285 } | |
| 286 | |
| 287 /* | |
| 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 $ |
| 18 | 290 - a decimal constant will consist of only digits, optionally prefixed |
| 291 with "&" | |
| 292 - a binary constant will consist of only 0s and 1s either prefixed with % | |
| 293 or suffixed with "B" | |
| 294 - a hex constant will consist of 0-9A-F either prefixed with $ or | |
| 295 suffixed with "H"; a hex number starting with A-F must be prefixed | |
| 296 with $ or start with 0 and end with H | |
| 297 - an octal constant will consist of 0-7 either prefixed with @ or | |
| 298 suffixed with "O" or "Q" | |
| 299 - an ascii constant will be a single character prefixed with a ' | |
| 300 - a double ascii constant will be two characters prefixed with a " | |
| 301 | |
| 302 */ | |
| 303 if (**p == '"') | |
| 304 { | |
| 305 // double ascii constant | |
| 306 int val; | |
| 307 (*p)++; | |
| 308 if (!**p) | |
| 309 return -1; | |
| 310 if (!*((*p)+1)) | |
| 311 return -1; | |
| 312 val = **p << 8 | *((*p) + 1); | |
| 313 (*p) += 2; | |
| 314 t = lwasm_expr_term_create_int(val); | |
| 315 lwasm_expr_stack_push(s, t); | |
| 316 lwasm_expr_term_free(t); | |
| 317 return 0; | |
| 318 } | |
| 319 else if (**p == '\'') | |
| 320 { | |
| 321 // single ascii constant | |
| 322 int val; | |
| 323 (*p)++; | |
| 61 | 324 debug_message(3, "Single ascii character constant '%c'", **p); |
| 18 | 325 if (!**p) |
| 326 return -1; | |
| 327 val = **p; | |
| 328 (*p)++; | |
| 329 t = lwasm_expr_term_create_int(val); | |
| 330 lwasm_expr_stack_push(s, t); | |
| 331 lwasm_expr_term_free(t); | |
| 61 | 332 return 0; |
| 18 | 333 } |
| 334 else if (**p == '&') | |
| 335 { | |
| 336 // decimal constant | |
| 337 int val = 0; | |
| 338 | |
| 339 (*p)++; | |
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340 while (**p && strchr("0123456789", **p)) |
| 18 | 341 { |
| 342 val = val * 10 + (**p - '0'); | |
| 343 (*p)++; | |
| 344 } | |
| 345 t = lwasm_expr_term_create_int(val); | |
| 346 lwasm_expr_stack_push(s, t); | |
| 347 lwasm_expr_term_free(t); | |
| 348 return 0; | |
| 349 } | |
| 350 else if (**p == '%') | |
| 351 { | |
| 352 // binary constant | |
| 353 int val = 0; | |
| 354 | |
| 355 (*p)++; | |
| 356 while (**p == '0' || **p == '1') | |
| 357 { | |
| 358 val = val * 2 + (**p - '0'); | |
| 359 (*p)++; | |
| 360 } | |
| 361 t = lwasm_expr_term_create_int(val); | |
| 362 lwasm_expr_stack_push(s, t); | |
| 363 lwasm_expr_term_free(t); | |
| 364 return 0; | |
| 365 } | |
| 366 else if (**p == '$') | |
| 367 { | |
| 368 // hexadecimal constant | |
| 369 int val = 0, val2; | |
| 370 | |
| 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)) |
| 18 | 374 { |
| 375 val2 = toupper(**p) - '0'; | |
| 376 if (val2 > 9) | |
| 377 val2 -= 7; | |
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378 debug_message(3, "Got char: %c (%d)", **p, val2); |
| 18 | 379 val = val * 16 + val2; |
| 380 (*p)++; | |
| 381 } | |
| 382 t = lwasm_expr_term_create_int(val); | |
| 383 lwasm_expr_stack_push(s, t); | |
| 384 lwasm_expr_term_free(t); | |
| 385 return 0; | |
| 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 } |
|
40
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adjusted symbol rules to accept symbols starting with @ but not @<digit>
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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))) |
| 18 | 411 { |
| 412 // octal constant | |
| 413 int val = 0; | |
| 414 | |
| 415 (*p)++; | |
|
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416 while (**p && strchr("01234567", **p)) |
| 18 | 417 { |
| 418 val = val * 8 + (**p - '0'); | |
| 419 (*p)++; | |
| 420 } | |
| 421 t = lwasm_expr_term_create_int(val); | |
| 422 lwasm_expr_stack_push(s, t); | |
| 423 lwasm_expr_term_free(t); | |
| 424 return 0; | |
| 425 } | |
|
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426 |
| 18 | 427 // symbol or bare decimal or suffix identified constant here |
|
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428 |
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429 // find the end of a potential symbol |
|
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430 do |
| 18 | 431 { |
| 432 int l = 0; | |
| 433 char *sb; | |
|
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434 int havedol = 0; |
| 18 | 435 |
| 436 // evaluate a symbol here | |
| 41 | 437 static const char *symchars = "_.$@?abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; |
| 438 while ((*p)[l] && strchr(symchars, (*p)[l])) | |
|
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439 { |
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440 if ((*p)[l] == '$') |
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441 havedol = 1; |
| 18 | 442 l++; |
|
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443 } |
| 18 | 444 if (l == 0) |
| 445 return -1; | |
| 446 | |
|
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447 if (havedol || **p < '0' || **p > '9') |
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448 { |
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449 // have a symbol here |
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450 |
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451 sb = lwasm_alloc(l + 1); |
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452 sb[l] = '\0'; |
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453 memcpy(sb, *p, l); |
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454 t = lwasm_expr_term_create_sym(sb); |
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455 lwasm_expr_stack_push(s, t); |
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456 lwasm_expr_term_free(t); |
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457 (*p) += l; |
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458 debug_message(3, "Symbol: '%s'; (%s)", sb, *p); |
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459 lwasm_free(sb); |
|
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460 return 0; |
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461 } |
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462 } while (0); |
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463 |
| 18 | 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; | |
| 39 | 490 debug_message(3, "End of decimal value"); |
| 18 | 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; | |
| 39 | 559 debug_message(3, "Got digit: %d", dval); |
|
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560 // if (dval > 1) |
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561 // valtype &= 14; |
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562 // if (dval > 7) |
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563 // valtype &= 12; |
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564 // if (dval > 9) |
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565 // valtype &= 8; |
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566 |
| 18 | 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 | |
|
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|
594 if (valtype == -1) |
| 18 | 595 break; |
| 596 // return if no more valid possibilities! | |
| 597 if (valtype == 0) | |
| 598 return -1; | |
|
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599 val = decval; // in case we fall through |
| 18 | 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 | |
| 226 | 629 // boolean AND/OR |
| 630 { LWASM_OPER_AND, "&&", 25 }, | |
| 631 { LWASM_OPER_OR, "||", 25 }, | |
| 632 | |
| 633 // bitwise ops | |
| 203 | 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 | |
| 18 | 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 | |
| 61 | 647 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']') |
| 18 | 648 return 0; |
| 649 | |
| 650 if (lwasm_expr_parse_term(s, p) < 0) | |
| 651 return -1; | |
|
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652 |
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653 eval_next: |
| 61 | 654 if (!**p || isspace(**p) || **p == ')' || **p == ',' || **p == ']') |
|
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655 return 0; |
| 18 | 656 |
| 657 // expecting an operator here | |
| 658 for (opern = 0; operators[opern].opernum != LWASM_OPER_NONE; opern++) | |
| 659 { | |
| 226 | 660 for (i = 0; (*p)[i] && operators[opern].operstr[i] && ((*p)[i] == operators[opern].operstr[i]); i++) |
| 18 | 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 */ | |
| 76 | 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) |
| 18 | 716 { |
| 717 lwasm_expr_stack_t *s; | |
| 718 const char *p; | |
|
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|
719 int rval; |
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720 |
| 18 | 721 // actually parse the expression |
| 722 p = inp; | |
| 723 s = lwasm_expr_stack_create(); | |
|
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724 |
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725 rval = lwasm_expr_parse_expr(s, &p, 0); |
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726 if (rval < 0) |
| 18 | 727 goto cleanup_error; |
| 728 | |
| 729 // save end of expression | |
| 730 if (outp) | |
| 731 (*outp) = p; | |
| 732 | |
| 733 // return potentially partial expression | |
|
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734 if (lwasm_expr_reval(s, sfunc, state) < 0) |
| 18 | 735 goto cleanup_error; |
|
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|
736 |
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|
737 if (lwasm_expr_is_constant(s)) |
| 39 | 738 debug_message(3, "Constant expression evaluates to: %d", lwasm_expr_get_value(s)); |
| 18 | 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 */ | |
| 76 | 764 int lwasm_expr_reval(lwasm_expr_stack_t *s, lwasm_expr_stack_t *(*sfunc)(char *sym, void *state), void *state) |
| 18 | 765 { |
| 76 | 766 lwasm_expr_stack_node_t *n, *n2; |
| 767 lwasm_expr_stack_t *ss; | |
| 768 int c; | |
|
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769 |
| 76 | 770 next_iter_sym: |
|
37
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|
771 // resolve symbols |
| 76 | 772 // symbols that do not resolve to an expression are left alone |
| 773 for (c = 0, n = s -> head; n; n = n -> next) | |
|
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|
774 { |
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775 if (n -> term -> term_type == LWASM_TERM_SYM) |
|
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|
776 { |
| 76 | 777 ss = sfunc(n -> term -> symbol, state); |
| 778 if (ss) | |
|
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|
779 { |
| 76 | 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); | |
|
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807 } |
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808 } |
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Added symbol handling to expression subsystem; adpated instruction handlers to the new scheme; misc fixes
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809 } |
| 76 | 810 if (c) |
| 811 goto next_iter_sym; | |
| 18 | 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 } |