Mercurial > hg-old > index.cgi
annotate src/expr.c @ 44:2330b88f9600
Added simple output listing
author | lost |
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date | Sun, 04 Jan 2009 06:52:18 +0000 |
parents | 7eafdb3a8074 |
children | 804d7465e0f9 |
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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 | |
90 lwasm_expr_term_t *lwasm_expr_term_create_sym(char *sym) | |
91 { | |
92 lwasm_expr_term_t *t; | |
14 | 93 |
39 | 94 debug_message(10, "Creating symbol term: %s", sym); |
95 | |
17 | 96 t = lwasm_alloc(sizeof(lwasm_expr_term_t)); |
97 t -> term_type = LWASM_TERM_SYM; | |
98 t -> symbol = lwasm_strdup(sym); | |
99 return t; | |
100 } | |
15 | 101 |
17 | 102 lwasm_expr_term_t *lwasm_expr_term_dup(lwasm_expr_term_t *t) |
103 { | |
104 switch (t -> term_type) | |
15 | 105 { |
17 | 106 case LWASM_TERM_INT: |
107 return lwasm_expr_term_create_int(t -> value); | |
108 | |
109 case LWASM_TERM_OPER: | |
110 return lwasm_expr_term_create_oper(t -> value); | |
111 | |
112 case LWASM_TERM_SYM: | |
113 return lwasm_expr_term_create_sym(t -> symbol); | |
114 | |
115 default: | |
39 | 116 debug_message(0, "lwasm_expr_term_dup(): invalid term type %d", t -> term_type); |
17 | 117 exit(1); |
118 } | |
119 // can't get here | |
120 } | |
121 | |
122 void lwasm_expr_stack_push(lwasm_expr_stack_t *s, lwasm_expr_term_t *t) | |
123 { | |
124 lwasm_expr_stack_node_t *n; | |
125 | |
126 if (!s) | |
127 { | |
39 | 128 debug_message(0, "lwasm_expr_stack_push(): invalid stack pointer"); |
17 | 129 exit(1); |
15 | 130 } |
131 | |
17 | 132 n = lwasm_alloc(sizeof(lwasm_expr_stack_node_t)); |
133 n -> next = NULL; | |
134 n -> prev = s -> tail; | |
135 n -> term = lwasm_expr_term_dup(t); | |
136 | |
137 if (s -> head) | |
138 { | |
139 s -> tail -> next = n; | |
140 s -> tail = n; | |
141 } | |
142 else | |
15 | 143 { |
17 | 144 s -> head = n; |
145 s -> tail = n; | |
146 } | |
147 } | |
148 | |
149 lwasm_expr_term_t *lwasm_expr_stack_pop(lwasm_expr_stack_t *s) | |
150 { | |
151 lwasm_expr_term_t *t; | |
152 lwasm_expr_stack_node_t *n; | |
153 | |
154 if (!(s -> tail)) | |
155 return NULL; | |
156 | |
157 n = s -> tail; | |
158 s -> tail = n -> prev; | |
159 if (!(n -> prev)) | |
160 { | |
161 s -> head = NULL; | |
15 | 162 } |
14 | 163 |
17 | 164 t = n -> term; |
165 n -> term = NULL; | |
166 | |
167 lwasm_free(n); | |
168 | |
169 return t; | |
14 | 170 } |
18 | 171 |
172 // the following two functions are co-routines which actually parse | |
173 // an infix expression onto the expression stack, each returns -1 | |
174 // if an error is encountered | |
175 | |
176 /* | |
177 parse a term and push it onto the stack | |
178 | |
179 this function handles unary prefix operators (-, +, .not., .com.) | |
180 as well as () | |
181 */ | |
182 int lwasm_expr_parse_term(lwasm_expr_stack_t *s, const char **p) | |
183 { | |
184 lwasm_expr_term_t *t; | |
39 | 185 debug_message(2, "Expression string %s", *p); |
186 | |
18 | 187 eval_next: |
188 if (**p == '(') | |
189 { | |
39 | 190 debug_message(3, "Starting paren"); |
18 | 191 (*p)++; |
192 lwasm_expr_parse_expr(s, p, 0); | |
193 if (**p != ')') | |
194 return -1; | |
195 (*p)++; | |
196 return 0; | |
197 } | |
198 | |
199 if (**p == '+') | |
200 { | |
39 | 201 debug_message(3, "Unary +"); |
18 | 202 (*p)++; |
203 goto eval_next; | |
204 } | |
205 | |
206 if (**p == '-') | |
207 { | |
208 // parse expression following "-" | |
209 (*p)++; | |
210 if (lwasm_expr_parse_expr(s, p, 200) < 0) | |
211 return -1; | |
212 t = lwasm_expr_term_create_oper(LWASM_OPER_NEG); | |
213 lwasm_expr_stack_push(s, t); | |
214 lwasm_expr_term_free(t); | |
215 return 0; | |
216 } | |
217 | |
23 | 218 if (**p == '^') |
219 { | |
220 // parse expression following "^" | |
221 (*p)++; | |
222 if (lwasm_expr_parse_expr(s, p, 200) < 0) | |
223 return -1; | |
224 t = lwasm_expr_term_create_oper(LWASM_OPER_COM); | |
225 lwasm_expr_stack_push(s, t); | |
226 lwasm_expr_term_free(t); | |
227 return 0; | |
228 } | |
229 | |
18 | 230 /* |
231 we have an actual term here so evaluate it | |
232 | |
233 it could be one of the following: | |
234 | |
235 1. a decimal constant | |
236 2. a hexadecimal constant | |
237 3. an octal constant | |
238 4. a binary constant | |
239 5. a symbol reference | |
240 6. the "current" instruction address (*) | |
241 7. the "current" data address (.) | |
242 8. a "back reference" (<) | |
243 9. a "forward reference" (>) | |
244 | |
245 items 6 through 9 are stored as symbol references | |
246 | |
247 (a . followed by a . or a alpha char or number is a symbol) | |
248 */ | |
249 if (**p == '*' | |
250 || ( | |
251 **p == '.' | |
252 && (*p)[1] != '.' | |
253 && !((*p)[1] >= 'A' && (*p)[1] <= 'Z') | |
254 && !((*p)[1] >= 'a' && (*p)[1] <= 'z') | |
255 && !((*p)[1] >= '0' && (*p)[1] <= '9') | |
256 ) | |
257 || **p == '<' | |
258 || **p == '>') | |
259 { | |
260 char tstr[2]; | |
261 tstr[0] = **p; | |
262 tstr[1] = '\0'; | |
263 t = lwasm_expr_term_create_sym(tstr); | |
264 lwasm_expr_stack_push(s, t); | |
265 lwasm_expr_term_free(t); | |
266 (*p)++; | |
267 return 0; | |
268 } | |
269 | |
270 /* | |
271 - a symbol will be a string of characters introduced by a letter, ".", | |
272 "_" but NOT a number | |
273 - a decimal constant will consist of only digits, optionally prefixed | |
274 with "&" | |
275 - a binary constant will consist of only 0s and 1s either prefixed with % | |
276 or suffixed with "B" | |
277 - a hex constant will consist of 0-9A-F either prefixed with $ or | |
278 suffixed with "H"; a hex number starting with A-F must be prefixed | |
279 with $ or start with 0 and end with H | |
280 - an octal constant will consist of 0-7 either prefixed with @ or | |
281 suffixed with "O" or "Q" | |
282 - an ascii constant will be a single character prefixed with a ' | |
283 - a double ascii constant will be two characters prefixed with a " | |
284 | |
285 */ | |
286 if (**p == '"') | |
287 { | |
288 // double ascii constant | |
289 int val; | |
290 (*p)++; | |
291 if (!**p) | |
292 return -1; | |
293 if (!*((*p)+1)) | |
294 return -1; | |
295 val = **p << 8 | *((*p) + 1); | |
296 (*p) += 2; | |
297 t = lwasm_expr_term_create_int(val); | |
298 lwasm_expr_stack_push(s, t); | |
299 lwasm_expr_term_free(t); | |
300 return 0; | |
301 } | |
302 else if (**p == '\'') | |
303 { | |
304 // single ascii constant | |
305 int val; | |
306 (*p)++; | |
307 if (!**p) | |
308 return -1; | |
309 val = **p; | |
310 (*p)++; | |
311 t = lwasm_expr_term_create_int(val); | |
312 lwasm_expr_stack_push(s, t); | |
313 lwasm_expr_term_free(t); | |
314 } | |
315 else if (**p == '&') | |
316 { | |
317 // decimal constant | |
318 int val = 0; | |
319 | |
320 (*p)++; | |
321 while (strchr("0123456789", **p)) | |
322 { | |
323 val = val * 10 + (**p - '0'); | |
324 (*p)++; | |
325 } | |
326 t = lwasm_expr_term_create_int(val); | |
327 lwasm_expr_stack_push(s, t); | |
328 lwasm_expr_term_free(t); | |
329 return 0; | |
330 } | |
331 else if (**p == '%') | |
332 { | |
333 // binary constant | |
334 int val = 0; | |
335 | |
336 (*p)++; | |
337 while (**p == '0' || **p == '1') | |
338 { | |
339 val = val * 2 + (**p - '0'); | |
340 (*p)++; | |
341 } | |
342 t = lwasm_expr_term_create_int(val); | |
343 lwasm_expr_stack_push(s, t); | |
344 lwasm_expr_term_free(t); | |
345 return 0; | |
346 } | |
347 else if (**p == '$') | |
348 { | |
349 // hexadecimal constant | |
350 int val = 0, val2; | |
351 | |
352 (*p)++; | |
353 while (strchr("0123456789ABCDEFabcdef", **p)) | |
354 { | |
355 val2 = toupper(**p) - '0'; | |
356 if (val2 > 9) | |
357 val2 -= 7; | |
358 val = val * 16 + val2; | |
359 (*p)++; | |
360 } | |
361 t = lwasm_expr_term_create_int(val); | |
362 lwasm_expr_stack_push(s, t); | |
363 lwasm_expr_term_free(t); | |
364 return 0; | |
365 } | |
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366 // an @ followed by a digit is an octal number |
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367 // but if it's followed by anything else, it is a symbol |
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368 else if (**p == '@' && isdigit(*(*p + 1))) |
18 | 369 { |
370 // octal constant | |
371 int val = 0; | |
372 | |
373 (*p)++; | |
374 while (strchr("01234567", **p)) | |
375 { | |
376 val = val * 8 + (**p - '0'); | |
377 (*p)++; | |
378 } | |
379 t = lwasm_expr_term_create_int(val); | |
380 lwasm_expr_stack_push(s, t); | |
381 lwasm_expr_term_free(t); | |
382 return 0; | |
383 } | |
384 | |
385 // symbol or bare decimal or suffix identified constant here | |
386 // all numbers will start with a digit at this point | |
387 if (**p < '0' || **p > '9') | |
388 { | |
389 int l = 0; | |
390 char *sb; | |
391 | |
392 // evaluate a symbol here | |
41 | 393 static const char *symchars = "_.$@?abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; |
394 while ((*p)[l] && strchr(symchars, (*p)[l])) | |
18 | 395 l++; |
396 | |
397 if (l == 0) | |
398 return -1; | |
399 | |
400 sb = lwasm_alloc(l + 1); | |
401 sb[l] = '\0'; | |
402 memcpy(sb, *p, l); | |
403 t = lwasm_expr_term_create_sym(sb); | |
404 lwasm_expr_stack_push(s, t); | |
405 lwasm_expr_term_free(t); | |
41 | 406 (*p) += l; |
407 debug_message(3, "Symbol: '%s'; (%s)", sb, *p); | |
18 | 408 lwasm_free(sb); |
409 return 0; | |
410 } | |
411 | |
412 if (!**p) | |
413 return -1; | |
414 | |
415 // evaluate a suffix based constant | |
416 { | |
417 int decval = 0, binval = 0, hexval = 0, octval = 0; | |
418 int valtype = 15; // 1 = bin, 2 = oct, 4 = dec, 8 = hex | |
419 int bindone = 0; | |
420 int val; | |
421 int dval; | |
422 | |
423 while (1) | |
424 { | |
425 if (!**p || !strchr("0123456789ABCDEFabcdefqhoQHO", **p)) | |
426 { | |
427 // we can legally have bin or decimal here | |
428 if (bindone) | |
429 { | |
430 // we just finished a binary value | |
431 val = binval; | |
432 break; | |
433 } | |
434 else if (valtype & 4) | |
435 { | |
436 // otherwise we must be decimal (if we're still allowed one) | |
437 val = decval; | |
39 | 438 debug_message(3, "End of decimal value"); |
18 | 439 break; |
440 } | |
441 else | |
442 { | |
443 // bad value | |
444 return -1; | |
445 } | |
446 } | |
447 | |
448 dval = toupper(**p); | |
449 (*p)++; | |
450 | |
451 if (bindone) | |
452 { | |
453 // any characters past "B" means it is not binary | |
454 bindone = 0; | |
455 valtype &= 14; | |
456 } | |
457 | |
458 switch (dval) | |
459 { | |
460 case 'Q': | |
461 case 'O': | |
462 if (valtype & 2) | |
463 { | |
464 val = octval; | |
465 valtype = -1; | |
466 break; | |
467 } | |
468 else | |
469 { | |
470 // not a valid octal value | |
471 return -1; | |
472 } | |
473 /* can't get here */ | |
474 | |
475 case 'H': | |
476 if (valtype & 8) | |
477 { | |
478 val = hexval; | |
479 valtype = -1; | |
480 break; | |
481 } | |
482 else | |
483 { | |
484 // not a valid hex number | |
485 return -1; | |
486 } | |
487 /* can't get here */ | |
488 | |
489 case 'B': | |
490 // this is a bit of a sticky one since B is a legit hex | |
491 // digit so this may or may not be the end of the number | |
492 // so we fall through to the digit case | |
493 | |
494 if (valtype & 1) | |
495 { | |
496 // could still be binary | |
497 bindone = 1; | |
498 valtype = 9; // hex and binary | |
499 } | |
500 /* fall through intentional */ | |
501 | |
502 default: | |
503 // digit | |
504 dval -= '0'; | |
505 if (dval > 9) | |
506 dval -= 7; | |
39 | 507 debug_message(3, "Got digit: %d", dval); |
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508 // if (dval > 1) |
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509 // valtype &= 14; |
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510 // if (dval > 7) |
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511 // valtype &= 12; |
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512 // if (dval > 9) |
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513 // valtype &= 8; |
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514 |
18 | 515 if (valtype & 8) |
516 { | |
517 hexval = hexval * 16 + dval; | |
518 } | |
519 if (valtype & 4) | |
520 { | |
521 if (dval > 9) | |
522 valtype &= 11; | |
523 else | |
524 decval = decval * 10 + dval; | |
525 } | |
526 if (valtype & 2) | |
527 { | |
528 if (dval > 7) | |
529 valtype &= 13; | |
530 else | |
531 octval = octval * 8 + dval; | |
532 } | |
533 if (valtype & 1) | |
534 { | |
535 if (dval > 1) | |
536 valtype &= 14; | |
537 else | |
538 binval = binval * 2 + dval; | |
539 } | |
540 } | |
541 // break out if we have a return value | |
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542 if (valtype == -1) |
18 | 543 break; |
544 // return if no more valid possibilities! | |
545 if (valtype == 0) | |
546 return -1; | |
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547 val = decval; // in case we fall through |
18 | 548 } |
549 | |
550 // we get here when we have a value to return | |
551 t = lwasm_expr_term_create_int(val); | |
552 lwasm_expr_stack_push(s, t); | |
553 lwasm_expr_term_free(t); | |
554 return 0; | |
555 } | |
556 /* can't get here */ | |
557 } | |
558 | |
559 // parse an expression and push the result onto the stack | |
560 // if an operator of lower precedence than the value of "prec" is found, | |
561 int lwasm_expr_parse_expr(lwasm_expr_stack_t *s, const char **p, int prec) | |
562 { | |
563 static const struct operinfo | |
564 { | |
565 int opernum; | |
566 char *operstr; | |
567 int operprec; | |
568 } operators[] = | |
569 { | |
570 { LWASM_OPER_PLUS, "+", 100 }, | |
571 { LWASM_OPER_MINUS, "-", 100 }, | |
572 { LWASM_OPER_TIMES, "*", 150 }, | |
573 { LWASM_OPER_DIVIDE, "/", 150 }, | |
574 { LWASM_OPER_MOD, "%", 150 }, | |
575 { LWASM_OPER_INTDIV, "\\", 150 }, | |
576 | |
577 { LWASM_OPER_NONE, "", 0 } | |
578 }; | |
579 int opern, i; | |
580 lwasm_expr_term_t *operterm; | |
581 | |
582 // return if we are at the end of the expression or a subexpression | |
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583 if (!**p || isspace(**p) || **p == ')' || **p == ',') |
18 | 584 return 0; |
585 | |
586 if (lwasm_expr_parse_term(s, p) < 0) | |
587 return -1; | |
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588 |
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589 eval_next: |
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590 if (!**p || isspace(**p) || **p == ')' || **p == ',') |
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591 return 0; |
18 | 592 |
593 // expecting an operator here | |
594 for (opern = 0; operators[opern].opernum != LWASM_OPER_NONE; opern++) | |
595 { | |
596 for (i = 0; (*p)[i] && operators[opern].operstr[i] && (*p[i] == operators[opern].operstr[i]); i++) | |
597 /* do nothing */ ; | |
598 if (operators[opern].operstr[i] == '\0') | |
599 break; | |
600 } | |
601 if (operators[opern].opernum == LWASM_OPER_NONE) | |
602 { | |
603 // unrecognized operator | |
604 return -1; | |
605 } | |
606 | |
607 // the operator number in question is in opern; i is the length of the | |
608 // operator string | |
609 | |
610 // logic: | |
611 // if the precedence of this operation is <= to the "prec" flag, | |
612 // we simply return without advancing the input pointer; the operator | |
613 // will be evaluated again in the enclosing function call | |
614 if (operators[opern].operprec <= prec) | |
615 return 0; | |
616 | |
617 // logic: | |
618 // we have a higher precedence operator here so we will advance the | |
619 // input pointer to the next term and let the expression evaluator | |
620 // loose on it after which time we will push our operator onto the | |
621 // stack and then go on with the expression evaluation | |
622 (*p) += i; // advance input pointer | |
623 | |
624 // evaluate next expression(s) of higher precedence | |
625 if (lwasm_expr_parse_expr(s, p, operators[opern].operprec) < 0) | |
626 return -1; | |
627 | |
628 operterm = lwasm_expr_term_create_oper(operators[opern].opernum); | |
629 lwasm_expr_stack_push(s, operterm); | |
630 lwasm_expr_term_free(operterm); | |
631 | |
632 // return if we are at the end of the expression or a subexpression | |
633 if (!**p || isspace(**p) || **p == ')') | |
634 return 0; | |
635 | |
636 // continue evaluating | |
637 goto eval_next; | |
638 } | |
639 | |
640 /* | |
641 actually evaluate an expression | |
642 | |
643 This happens in two stages. The first stage merely parses the expression into | |
644 a lwasm_expr_stack_t * which is then evaluated as much as possible before the | |
645 result is returned. | |
646 | |
647 Returns NULL on a parse error or otherwise invalid expression. *outp will | |
648 contain the pointer to the next character after the expression if and only | |
649 if there is no error. In the case of an error, *outp is undefined. | |
650 */ | |
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651 lwasm_expr_stack_t *lwasm_expr_eval(const char *inp, const char **outp, int (*sfunc)(char *sym, void *state, int *val), void *state) |
18 | 652 { |
653 lwasm_expr_stack_t *s; | |
654 const char *p; | |
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655 int rval; |
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656 |
18 | 657 // actually parse the expression |
658 p = inp; | |
659 s = lwasm_expr_stack_create(); | |
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660 |
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661 rval = lwasm_expr_parse_expr(s, &p, 0); |
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662 if (rval < 0) |
18 | 663 goto cleanup_error; |
664 | |
665 // save end of expression | |
666 if (outp) | |
667 (*outp) = p; | |
668 | |
669 // return potentially partial expression | |
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670 if (lwasm_expr_reval(s, sfunc, state) < 0) |
18 | 671 goto cleanup_error; |
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672 |
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673 if (lwasm_expr_is_constant(s)) |
39 | 674 debug_message(3, "Constant expression evaluates to: %d", lwasm_expr_get_value(s)); |
18 | 675 |
676 return s; | |
677 | |
678 cleanup_error: | |
679 lwasm_expr_stack_free(s); | |
680 return NULL; | |
681 } | |
682 | |
683 /* | |
684 take an expression stack s and scan for operations that can be completed | |
685 | |
686 return -1 on error, 0 on no error | |
687 | |
688 possible errors are: division by zero or unknown operator | |
689 | |
690 theory of operation: | |
691 | |
692 scan the stack for an operator which has two constants preceding it (binary) | |
693 or 1 constant preceding it (unary) and if found, perform the calculation | |
694 and replace the operator and its operands with the result | |
695 | |
696 repeat the scan until no futher simplications are found or if there are no | |
697 further operators or only a single term remains | |
698 | |
699 */ | |
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700 int lwasm_expr_reval(lwasm_expr_stack_t *s, int (*sfunc)(char *sym, void *state, int *val), void *state) |
18 | 701 { |
702 lwasm_expr_stack_node_t *n; | |
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703 int sval; |
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704 |
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705 // resolve symbols |
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706 // symbols that do not resolve to a constant are left alone |
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707 for (n = s -> head; n; n = n -> next) |
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708 { |
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709 if (n -> term -> term_type == LWASM_TERM_SYM) |
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710 { |
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711 if (sfunc(n -> term -> symbol, state, &sval) == 0) |
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712 { |
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713 n -> term -> term_type = LWASM_TERM_INT; |
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714 n -> term -> value = sval; |
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715 lwasm_free(n -> term -> symbol); |
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716 n -> term -> symbol = NULL; |
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717 } |
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718 } |
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719 } |
18 | 720 |
721 next_iter: | |
722 // a single term | |
723 if (s -> head == s -> tail) | |
724 return 0; | |
725 | |
726 // search for an operator | |
727 for (n = s -> head; n; n = n -> next) | |
728 { | |
729 if (n -> term -> term_type == LWASM_TERM_OPER) | |
730 { | |
731 if (n -> term -> value == LWASM_OPER_NEG | |
732 || n -> term -> value == LWASM_OPER_COM | |
733 ) | |
734 { | |
735 // unary operator | |
736 if (n -> prev && n -> prev -> term -> term_type == LWASM_TERM_INT) | |
737 { | |
738 // a unary operator we can resolve | |
739 // we do the op then remove the term "n" is pointing at | |
740 if (n -> term -> value == LWASM_OPER_NEG) | |
741 { | |
742 n -> prev -> term -> value = -(n -> prev -> term -> value); | |
743 } | |
744 else if (n -> term -> value == LWASM_OPER_COM) | |
745 { | |
746 n -> prev -> term -> value = ~(n -> prev -> term -> value); | |
747 } | |
748 n -> prev -> next = n -> next; | |
749 if (n -> next) | |
750 n -> next -> prev = n -> prev; | |
751 else | |
752 s -> tail = n -> prev; | |
753 | |
754 lwasm_expr_term_free(n -> term); | |
755 lwasm_free(n); | |
756 break; | |
757 } | |
758 } | |
759 else | |
760 { | |
761 // binary operator | |
762 if (n -> prev && n -> prev -> prev && n -> prev -> term -> term_type == LWASM_TERM_INT && n -> prev -> prev -> term -> term_type == LWASM_TERM_INT) | |
763 { | |
764 // a binary operator we can resolve | |
765 switch (n -> term -> value) | |
766 { | |
767 case LWASM_OPER_PLUS: | |
768 n -> prev -> prev -> term -> value += n -> prev -> term -> value; | |
769 break; | |
770 | |
771 case LWASM_OPER_MINUS: | |
772 n -> prev -> prev -> term -> value -= n -> prev -> term -> value; | |
773 break; | |
774 | |
775 case LWASM_OPER_TIMES: | |
776 n -> prev -> prev -> term -> value *= n -> prev -> term -> value; | |
777 break; | |
778 | |
779 case LWASM_OPER_DIVIDE: | |
780 if (n -> prev -> term -> value == 0) | |
781 return -1; | |
782 n -> prev -> prev -> term -> value /= n -> prev -> term -> value; | |
783 break; | |
784 | |
785 case LWASM_OPER_MOD: | |
786 if (n -> prev -> term -> value == 0) | |
787 return -1; | |
788 n -> prev -> prev -> term -> value %= n -> prev -> term -> value; | |
789 break; | |
790 | |
791 case LWASM_OPER_INTDIV: | |
792 if (n -> prev -> term -> value == 0) | |
793 return -1; | |
794 n -> prev -> prev -> term -> value /= n -> prev -> term -> value; | |
795 break; | |
796 | |
797 case LWASM_OPER_BWAND: | |
798 n -> prev -> prev -> term -> value &= n -> prev -> term -> value; | |
799 break; | |
800 | |
801 case LWASM_OPER_BWOR: | |
802 n -> prev -> prev -> term -> value |= n -> prev -> term -> value; | |
803 break; | |
804 | |
805 case LWASM_OPER_BWXOR: | |
806 n -> prev -> prev -> term -> value ^= n -> prev -> term -> value; | |
807 break; | |
808 | |
809 case LWASM_OPER_AND: | |
810 n -> prev -> prev -> term -> value = (n -> prev -> term -> value && n -> prev -> prev -> term -> value) ? 1 : 0; | |
811 break; | |
812 | |
813 case LWASM_OPER_OR: | |
814 n -> prev -> prev -> term -> value = (n -> prev -> term -> value || n -> prev -> prev -> term -> value) ? 1 : 0; | |
815 break; | |
816 | |
817 default: | |
818 // return error if unknown operator! | |
819 return -1; | |
820 } | |
821 | |
822 // now remove the two unneeded entries from the stack | |
823 n -> prev -> prev -> next = n -> next; | |
824 if (n -> next) | |
825 n -> next -> prev = n -> prev -> prev; | |
826 else | |
827 s -> tail = n -> prev -> prev; | |
828 | |
829 lwasm_expr_term_free(n -> term); | |
830 lwasm_expr_term_free(n -> prev -> term); | |
831 lwasm_free(n -> prev); | |
832 lwasm_free(n); | |
833 break; | |
834 } | |
835 } | |
836 } | |
837 } | |
838 // note for the terminally confused about dynamic memory and pointers: | |
839 // n will not be NULL even after the lwasm_free calls above so | |
840 // this test will still work (n will be a dangling pointer) | |
841 // (n will only be NULL if we didn't find any operators to simplify) | |
842 if (n) | |
843 goto next_iter; | |
844 | |
845 return 0; | |
846 } |