| 1 | /* Copyright (c) 1982 Regents of the University of California */ |
| 2 | |
| 3 | static char sccsid[] = "@(#)eval.c 1.4 %G%"; |
| 4 | |
| 5 | /* |
| 6 | * Parse tree evaluation. |
| 7 | */ |
| 8 | |
| 9 | #include "defs.h" |
| 10 | #include "tree.h" |
| 11 | #include "sym.h" |
| 12 | #include "process.h" |
| 13 | #include "source.h" |
| 14 | #include "mappings.h" |
| 15 | #include "breakpoint.h" |
| 16 | #include "machine.h" |
| 17 | #include "tree.rep" |
| 18 | |
| 19 | /* |
| 20 | * Evaluate a parse tree using a stack; value is left at top. |
| 21 | */ |
| 22 | |
| 23 | #define STACKSIZE 2000 |
| 24 | |
| 25 | STACK stack[STACKSIZE]; |
| 26 | STACK *sp = &stack[0]; |
| 27 | |
| 28 | eval(p) |
| 29 | register NODE *p; |
| 30 | { |
| 31 | long r0, r1; |
| 32 | double fr0, fr1; |
| 33 | |
| 34 | if (p == NULL) { |
| 35 | return; |
| 36 | } |
| 37 | switch(degree(p->op)) { |
| 38 | case BINARY: |
| 39 | eval(p->right); |
| 40 | if (isreal(p->op)) { |
| 41 | fr1 = pop(double); |
| 42 | } else if (isint(p->op)) { |
| 43 | r1 = pop(long); |
| 44 | } |
| 45 | /* fall through */ |
| 46 | case UNARY: |
| 47 | eval(p->left); |
| 48 | if (isreal(p->op)) { |
| 49 | fr0 = pop(double); |
| 50 | } else if (isint(p->op)) { |
| 51 | r0 = pop(long); |
| 52 | } |
| 53 | break; |
| 54 | |
| 55 | default: |
| 56 | /* do nothing */; |
| 57 | } |
| 58 | switch(p->op) { |
| 59 | case O_NAME: { |
| 60 | SYM *s, *f; |
| 61 | |
| 62 | s = p->nameval; |
| 63 | if (!isvariable(s)) { |
| 64 | error("cannot evaluate a %s", classname(s)); |
| 65 | } else { |
| 66 | f = container(s); |
| 67 | if (!isactive(f)) { |
| 68 | error("\"%s\" is not active", name(f)); |
| 69 | } |
| 70 | push(int, address(s, NIL)); |
| 71 | } |
| 72 | break; |
| 73 | } |
| 74 | |
| 75 | case O_LCON: |
| 76 | switch (size(p->nodetype)) { |
| 77 | case sizeof(char): |
| 78 | push(char, p->lconval); |
| 79 | break; |
| 80 | |
| 81 | case sizeof(short): |
| 82 | push(short, p->lconval); |
| 83 | break; |
| 84 | |
| 85 | case sizeof(long): |
| 86 | push(long, p->lconval); |
| 87 | break; |
| 88 | |
| 89 | default: |
| 90 | panic("bad size %d for LCON", size(p->nodetype)); |
| 91 | } |
| 92 | break; |
| 93 | |
| 94 | case O_FCON: |
| 95 | push(double, p->fconval); |
| 96 | break; |
| 97 | |
| 98 | case O_SCON: { |
| 99 | int len; |
| 100 | |
| 101 | len = size(p->nodetype); |
| 102 | mov(p->sconval, sp, len); |
| 103 | sp += len; |
| 104 | break; |
| 105 | } |
| 106 | |
| 107 | case O_INDEX: { |
| 108 | int n; |
| 109 | long i; |
| 110 | |
| 111 | n = pop(int); |
| 112 | i = evalindex(p->left->nodetype, popsmall(p->right->nodetype)); |
| 113 | push(int, n + i*size(p->nodetype)); |
| 114 | break; |
| 115 | } |
| 116 | |
| 117 | case O_INDIR: { |
| 118 | ADDRESS a; |
| 119 | |
| 120 | a = pop(ADDRESS); |
| 121 | if (a == 0) { |
| 122 | error("reference through nil pointer"); |
| 123 | } |
| 124 | dread(sp, a, sizeof(ADDRESS)); |
| 125 | sp += sizeof(ADDRESS); |
| 126 | break; |
| 127 | } |
| 128 | |
| 129 | /* |
| 130 | * Get the value of the expression addressed by the top of the stack. |
| 131 | * Push the result back on the stack. Never push less than a long. |
| 132 | */ |
| 133 | |
| 134 | case O_RVAL: { |
| 135 | ADDRESS addr, len; |
| 136 | long i; |
| 137 | |
| 138 | addr = pop(int); |
| 139 | if (addr == 0) { |
| 140 | error("reference through nil pointer"); |
| 141 | } |
| 142 | len = size(p->nodetype); |
| 143 | if (!rpush(addr, len)) { |
| 144 | error("expression too large to evaluate"); |
| 145 | } |
| 146 | break; |
| 147 | } |
| 148 | |
| 149 | case O_COMMA: |
| 150 | break; |
| 151 | |
| 152 | case O_ITOF: |
| 153 | push(double, (double) r0); |
| 154 | break; |
| 155 | |
| 156 | case O_ADD: |
| 157 | push(long, r0+r1); |
| 158 | break; |
| 159 | |
| 160 | case O_ADDF: |
| 161 | push(double, fr0+fr1); |
| 162 | break; |
| 163 | |
| 164 | case O_SUB: |
| 165 | push(long, r0-r1); |
| 166 | break; |
| 167 | |
| 168 | case O_SUBF: |
| 169 | push(double, fr0-fr1); |
| 170 | break; |
| 171 | |
| 172 | case O_NEG: |
| 173 | push(long, -r0); |
| 174 | break; |
| 175 | |
| 176 | case O_NEGF: |
| 177 | push(double, -fr0); |
| 178 | break; |
| 179 | |
| 180 | case O_MUL: |
| 181 | push(long, r0*r1); |
| 182 | break; |
| 183 | |
| 184 | case O_MULF: |
| 185 | push(double, fr0*fr1); |
| 186 | break; |
| 187 | |
| 188 | case O_DIVF: |
| 189 | if (fr1 == 0) { |
| 190 | error("error: division by 0"); |
| 191 | } |
| 192 | push(double, fr0/fr1); |
| 193 | break; |
| 194 | |
| 195 | case O_DIV: |
| 196 | if (r1 == 0) { |
| 197 | error("error: div by 0"); |
| 198 | } |
| 199 | push(long, r0/r1); |
| 200 | break; |
| 201 | |
| 202 | case O_MOD: |
| 203 | if (r1 == 0) { |
| 204 | error("error: mod by 0"); |
| 205 | } |
| 206 | push(long, r0%r1); |
| 207 | break; |
| 208 | |
| 209 | case O_LT: |
| 210 | push(BOOLEAN, r0 < r1); |
| 211 | break; |
| 212 | |
| 213 | case O_LTF: |
| 214 | push(BOOLEAN, fr0 < fr1); |
| 215 | break; |
| 216 | |
| 217 | case O_LE: |
| 218 | push(BOOLEAN, r0 <= r1); |
| 219 | break; |
| 220 | |
| 221 | case O_LEF: |
| 222 | push(BOOLEAN, fr0 <= fr1); |
| 223 | break; |
| 224 | |
| 225 | case O_GT: |
| 226 | push(BOOLEAN, r0 > r1); |
| 227 | break; |
| 228 | |
| 229 | case O_GTF: |
| 230 | push(BOOLEAN, fr0 > fr1); |
| 231 | break; |
| 232 | |
| 233 | case O_EQ: |
| 234 | push(BOOLEAN, r0 == r1); |
| 235 | break; |
| 236 | |
| 237 | case O_EQF: |
| 238 | push(BOOLEAN, fr0 == fr1); |
| 239 | break; |
| 240 | |
| 241 | case O_NE: |
| 242 | push(BOOLEAN, r0 != r1); |
| 243 | break; |
| 244 | |
| 245 | case O_NEF: |
| 246 | push(BOOLEAN, fr0 != fr1); |
| 247 | break; |
| 248 | |
| 249 | case O_AND: |
| 250 | push(BOOLEAN, r0 && r1); |
| 251 | break; |
| 252 | |
| 253 | case O_OR: |
| 254 | push(BOOLEAN, r0 || r1); |
| 255 | break; |
| 256 | |
| 257 | case O_ASSIGN: |
| 258 | assign(p->left, p->right); |
| 259 | break; |
| 260 | |
| 261 | case O_CHFILE: |
| 262 | if (p->sconval == NIL) { |
| 263 | printf("%s\n", cursource); |
| 264 | } else { |
| 265 | skimsource(p->sconval); |
| 266 | } |
| 267 | break; |
| 268 | |
| 269 | case O_CONT: |
| 270 | cont(); |
| 271 | printnews(); |
| 272 | break; |
| 273 | |
| 274 | case O_LIST: { |
| 275 | SYM *b; |
| 276 | |
| 277 | if (p->left->op == O_NAME) { |
| 278 | b = p->left->nameval; |
| 279 | if (!isblock(b)) { |
| 280 | error("\"%s\" is not a procedure or function", name(b)); |
| 281 | } |
| 282 | r0 = srcline(firstline(b)); |
| 283 | r1 = r0 + 5; |
| 284 | if (r1 > lastlinenum) { |
| 285 | r1 = lastlinenum; |
| 286 | } |
| 287 | r0 = r0 - 5; |
| 288 | if (r0 < 1) { |
| 289 | r0 = 1; |
| 290 | } |
| 291 | } else { |
| 292 | eval(p->left->right); |
| 293 | eval(p->left->left); |
| 294 | r0 = pop(long); |
| 295 | r1 = pop(long); |
| 296 | } |
| 297 | printlines((LINENO) r0, (LINENO) r1); |
| 298 | break; |
| 299 | } |
| 300 | |
| 301 | case O_XI: |
| 302 | case O_XD: |
| 303 | { |
| 304 | SYM *b; |
| 305 | |
| 306 | if (p->left->op == O_CALL) { |
| 307 | b = p->left->left->nameval; |
| 308 | r0 = codeloc(b); |
| 309 | r1 = firstline(b); |
| 310 | } else { |
| 311 | eval(p->left->right); |
| 312 | eval(p->left->left); |
| 313 | r0 = pop(long); |
| 314 | r1 = pop(long); |
| 315 | } |
| 316 | if (p->op == O_XI) { |
| 317 | printinst((ADDRESS) r0, (ADDRESS) r1); |
| 318 | } else { |
| 319 | printdata((ADDRESS) r0, (ADDRESS) r1); |
| 320 | } |
| 321 | break; |
| 322 | } |
| 323 | |
| 324 | case O_NEXT: |
| 325 | next(); |
| 326 | printnews(); |
| 327 | break; |
| 328 | |
| 329 | case O_PRINT: { |
| 330 | NODE *o; |
| 331 | |
| 332 | for (o = p->left; o != NIL; o = o->right) { |
| 333 | eval(o->left); |
| 334 | printval(o->left->nodetype); |
| 335 | putchar(' '); |
| 336 | } |
| 337 | putchar('\n'); |
| 338 | break; |
| 339 | } |
| 340 | |
| 341 | case O_STEP: |
| 342 | stepc(); |
| 343 | printnews(); |
| 344 | break; |
| 345 | |
| 346 | case O_WHATIS: |
| 347 | if (p->left->op == O_NAME) { |
| 348 | printdecl(p->left->nameval); |
| 349 | } else { |
| 350 | printdecl(p->left->nodetype); |
| 351 | } |
| 352 | break; |
| 353 | |
| 354 | case O_WHICH: |
| 355 | printwhich(p->nameval); |
| 356 | putchar('\n'); |
| 357 | break; |
| 358 | |
| 359 | case O_WHERE: |
| 360 | where(); |
| 361 | break; |
| 362 | |
| 363 | case O_ALIAS: |
| 364 | alias(p->left->sconval, p->right->sconval); |
| 365 | break; |
| 366 | |
| 367 | case O_CALL: |
| 368 | callproc(p->left, p->right); |
| 369 | break; |
| 370 | |
| 371 | case O_EDIT: |
| 372 | edit(p->sconval); |
| 373 | break; |
| 374 | |
| 375 | case O_DUMP: |
| 376 | dump(); |
| 377 | break; |
| 378 | |
| 379 | case O_GRIPE: |
| 380 | gripe(); |
| 381 | break; |
| 382 | |
| 383 | case O_HELP: |
| 384 | help(); |
| 385 | break; |
| 386 | |
| 387 | case O_REMAKE: |
| 388 | remake(); |
| 389 | break; |
| 390 | |
| 391 | case O_RUN: |
| 392 | run(); |
| 393 | break; |
| 394 | |
| 395 | case O_SOURCE: |
| 396 | setinput(p->sconval); |
| 397 | break; |
| 398 | |
| 399 | case O_STATUS: |
| 400 | status(); |
| 401 | break; |
| 402 | |
| 403 | case O_TRACE: |
| 404 | case O_TRACEI: |
| 405 | trace(p->op, p->what, p->where, p->cond); |
| 406 | if (isstdin()) { |
| 407 | status(); |
| 408 | } |
| 409 | break; |
| 410 | |
| 411 | case O_STOP: |
| 412 | case O_STOPI: |
| 413 | stop(p->op, p->what, p->where, p->cond); |
| 414 | if (isstdin()) { |
| 415 | status(); |
| 416 | } |
| 417 | break; |
| 418 | |
| 419 | case O_DELETE: |
| 420 | eval(p->left); |
| 421 | delbp((unsigned int) pop(long)); |
| 422 | break; |
| 423 | |
| 424 | default: |
| 425 | panic("eval: bad op %d", p->op); |
| 426 | } |
| 427 | } |
| 428 | |
| 429 | /* |
| 430 | * Push "len" bytes onto the expression stack from address "addr" |
| 431 | * in the process. Normally TRUE is returned, however if there |
| 432 | * isn't enough room on the stack, rpush returns FALSE. |
| 433 | */ |
| 434 | |
| 435 | BOOLEAN rpush(addr, len) |
| 436 | ADDRESS addr; |
| 437 | int len; |
| 438 | { |
| 439 | BOOLEAN success; |
| 440 | |
| 441 | if (sp + len >= &stack[STACKSIZE]) { |
| 442 | success = FALSE; |
| 443 | } else { |
| 444 | dread(sp, addr, len); |
| 445 | sp += len; |
| 446 | success = TRUE; |
| 447 | } |
| 448 | return success; |
| 449 | } |
| 450 | |
| 451 | /* |
| 452 | * Pop an item of the given type which is assumed to be no larger |
| 453 | * than a long and return it expanded into a long. |
| 454 | */ |
| 455 | |
| 456 | long popsmall(t) |
| 457 | SYM *t; |
| 458 | { |
| 459 | long r; |
| 460 | |
| 461 | switch (size(t)) { |
| 462 | case sizeof(char): |
| 463 | r = (long) pop(char); |
| 464 | break; |
| 465 | |
| 466 | case sizeof(short): |
| 467 | r = (long) pop(short); |
| 468 | break; |
| 469 | |
| 470 | case sizeof(long): |
| 471 | r = pop(long); |
| 472 | break; |
| 473 | |
| 474 | default: |
| 475 | panic("popsmall: size is %d", size(t)); |
| 476 | } |
| 477 | return r; |
| 478 | } |
| 479 | |
| 480 | /* |
| 481 | * evaluate a conditional expression |
| 482 | */ |
| 483 | |
| 484 | BOOLEAN cond(p) |
| 485 | NODE *p; |
| 486 | { |
| 487 | if (p == NIL) { |
| 488 | return(TRUE); |
| 489 | } |
| 490 | eval(p); |
| 491 | return(pop(BOOLEAN)); |
| 492 | } |
| 493 | |
| 494 | /* |
| 495 | * Return the address corresponding to a given tree. |
| 496 | */ |
| 497 | |
| 498 | ADDRESS lval(p) |
| 499 | NODE *p; |
| 500 | { |
| 501 | eval(p); |
| 502 | return(pop(ADDRESS)); |
| 503 | } |