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1.1 root 1: /*
2: * Copyright (c) 1980 Regents of the University of California.
3: * All rights reserved. The Berkeley software License Agreement
4: * specifies the terms and conditions for redistribution.
5: */
6:
7: #ifndef lint
8: static char sccsid[] = "@(#)eval.c 5.2 (Berkeley) 4/7/87";
9: #endif not lint
10:
11: /*
12: * Parse tree evaluation.
13: */
14:
15: #include "defs.h"
16: #include "tree.h"
17: #include "sym.h"
18: #include "process.h"
19: #include "source.h"
20: #include "mappings.h"
21: #include "breakpoint.h"
22: #include "machine.h"
23: #include "tree.rep"
24: #include "process/process.rep"
25: #include "process/pxinfo.h"
26:
27: #define Boolean char /* underlying representation type for booleans */
28:
29: /*
30: * Evaluate a parse tree using a stack; value is left at top.
31: */
32:
33: #define STACKSIZE 2000
34:
35: STACK stack[STACKSIZE];
36: STACK *sp = &stack[0];
37:
38: eval(p)
39: register NODE *p;
40: {
41: long r0, r1;
42: double fr0, fr1;
43: FILE *fp;
44:
45: if (p == NULL) {
46: return;
47: }
48: switch(degree(p->op)) {
49: case BINARY:
50: eval(p->right);
51: if (isreal(p->op)) {
52: fr1 = pop(double);
53: } else if (isint(p->op)) {
54: r1 = popsmall(p->right->nodetype);
55: }
56: /* fall through */
57: case UNARY:
58: eval(p->left);
59: if (isreal(p->op)) {
60: fr0 = pop(double);
61: } else if (isint(p->op)) {
62: r0 = popsmall(p->left->nodetype);
63: }
64: break;
65:
66: default:
67: /* do nothing */;
68: }
69: switch(p->op) {
70: case O_NAME: {
71: SYM *s, *f;
72:
73: s = p->nameval;
74: if (!isvariable(s)) {
75: error("cannot evaluate a %s", classname(s));
76: } else {
77: f = container(s);
78: if (!isactive(f)) {
79: error("\"%s\" is not active", name(f));
80: }
81: push(long, address(s, NIL));
82: }
83: break;
84: }
85:
86: case O_LCON:
87: switch (size(p->nodetype)) {
88: case sizeof(char):
89: push(char, p->lconval);
90: break;
91:
92: case sizeof(short):
93: push(short, p->lconval);
94: break;
95:
96: case sizeof(long):
97: push(long, p->lconval);
98: break;
99:
100: default:
101: panic("bad size %d for LCON", size(p->nodetype));
102: }
103: break;
104:
105: case O_FCON:
106: push(double, p->fconval);
107: break;
108:
109: case O_SCON: {
110: int len;
111:
112: len = size(p->nodetype);
113: mov(p->sconval, sp, len);
114: sp += len;
115: #ifdef tahoe
116: alignstack();
117: #endif tahoe
118: break;
119: }
120:
121: case O_INDEX: {
122: long n; /* base address for array */
123: long i; /* index - lower bound */
124: long evalindex();
125:
126: n = pop(long);
127: i = evalindex(p->left->nodetype, p->right);
128: push(long, n + i*size(p->nodetype));
129: break;
130: }
131:
132: case O_INDIR: {
133: ADDRESS a;
134:
135: a = pop(ADDRESS);
136: if (a == 0) {
137: error("reference through nil pointer");
138: }
139: dread(sp, a, sizeof(ADDRESS));
140: sp += sizeof(ADDRESS);
141: break;
142: }
143:
144: /*
145: * Get the value of the expression addressed by the top of the stack.
146: * Push the result back on the stack.
147: */
148:
149: case O_RVAL: {
150: ADDRESS addr, len;
151:
152: addr = pop(long);
153: if (addr == 0) {
154: error("reference through nil pointer");
155: }
156: len = size(p->nodetype);
157: if (!rpush(addr, len)) {
158: error("expression too large to evaluate");
159: }
160: break;
161: }
162:
163: case O_COMMA:
164: break;
165:
166: case O_ITOF:
167: push(double, (double) r0);
168: break;
169:
170: case O_ADD:
171: push(long, r0+r1);
172: break;
173:
174: case O_ADDF:
175: push(double, fr0+fr1);
176: break;
177:
178: case O_SUB:
179: push(long, r0-r1);
180: break;
181:
182: case O_SUBF:
183: push(double, fr0-fr1);
184: break;
185:
186: case O_NEG:
187: push(long, -r0);
188: break;
189:
190: case O_NEGF:
191: push(double, -fr0);
192: break;
193:
194: case O_MUL:
195: push(long, r0*r1);
196: break;
197:
198: case O_MULF:
199: push(double, fr0*fr1);
200: break;
201:
202: case O_DIVF:
203: if (fr1 == 0) {
204: error("error: division by 0");
205: }
206: push(double, fr0/fr1);
207: break;
208:
209: case O_DIV:
210: if (r1 == 0) {
211: error("error: div by 0");
212: }
213: push(long, r0/r1);
214: break;
215:
216: case O_MOD:
217: if (r1 == 0) {
218: error("error: mod by 0");
219: }
220: push(long, r0%r1);
221: break;
222:
223: case O_LT:
224: push(Boolean, r0 < r1);
225: break;
226:
227: case O_LTF:
228: push(Boolean, fr0 < fr1);
229: break;
230:
231: case O_LE:
232: push(Boolean, r0 <= r1);
233: break;
234:
235: case O_LEF:
236: push(Boolean, fr0 <= fr1);
237: break;
238:
239: case O_GT:
240: push(Boolean, r0 > r1);
241: break;
242:
243: case O_GTF:
244: push(Boolean, fr0 > fr1);
245: break;
246:
247: case O_EQ:
248: push(Boolean, r0 == r1);
249: break;
250:
251: case O_EQF:
252: push(Boolean, fr0 == fr1);
253: break;
254:
255: case O_NE:
256: push(Boolean, r0 != r1);
257: break;
258:
259: case O_NEF:
260: push(Boolean, fr0 != fr1);
261: break;
262:
263: case O_AND:
264: push(Boolean, r0 && r1);
265: break;
266:
267: case O_OR:
268: push(Boolean, r0 || r1);
269: break;
270:
271: case O_ASSIGN:
272: assign(p->left, p->right);
273: break;
274:
275: case O_CHFILE:
276: if (p->sconval == NIL) {
277: printf("%s\n", cursource);
278: } else {
279: fp = fopen(p->sconval, "r");
280: if (fp == NIL) {
281: error("can't read \"%s\"", p->sconval);
282: } else {
283: fclose(fp);
284: skimsource(p->sconval);
285: }
286: }
287: break;
288:
289: case O_CONT:
290: cont();
291: printnews();
292: break;
293:
294: case O_LIST: {
295: SYM *b;
296: ADDRESS addr;
297:
298: if (p->left->op == O_NAME) {
299: b = p->left->nameval;
300: if (!isblock(b)) {
301: error("\"%s\" is not a procedure or function", name(b));
302: }
303: addr = firstline(b);
304: if ((int)addr == -1) {
305: error("\"%s\" is empty", name(b));
306: }
307: skimsource(srcfilename(addr));
308: r0 = srcline(addr);
309: r1 = r0 + 5;
310: if (r1 > lastlinenum) {
311: r1 = lastlinenum;
312: }
313: r0 = r0 - 5;
314: if (r0 < 1) {
315: r0 = 1;
316: }
317: } else {
318: eval(p->left->right);
319: eval(p->left->left);
320: r0 = pop(long);
321: r1 = pop(long);
322: }
323: printlines((LINENO) r0, (LINENO) r1);
324: break;
325: }
326:
327: case O_XI:
328: case O_XD:
329: {
330: SYM *b;
331:
332: if (p->left->op == O_CALL) {
333: b = p->left->left->nameval;
334: r0 = codeloc(b);
335: r1 = firstline(b);
336: } else {
337: eval(p->left->right);
338: eval(p->left->left);
339: r0 = pop(long);
340: r1 = pop(long);
341: }
342: if (p->op == O_XI) {
343: printinst((ADDRESS) r0, (ADDRESS) r1);
344: } else {
345: printdata((ADDRESS) r0, (ADDRESS) r1);
346: }
347: break;
348: }
349:
350: case O_NEXT:
351: next();
352: printnews();
353: break;
354:
355: case O_PRINT: {
356: NODE *o;
357:
358: for (o = p->left; o != NIL; o = o->right) {
359: eval(o->left);
360: printval(o->left->nodetype);
361: putchar(' ');
362: }
363: putchar('\n');
364: break;
365: }
366:
367: case O_STEP:
368: stepc();
369: printnews();
370: break;
371:
372: case O_WHATIS:
373: if (p->left->op == O_NAME) {
374: printdecl(p->left->nameval);
375: } else {
376: printdecl(p->left->nodetype);
377: }
378: break;
379:
380: case O_WHICH:
381: printwhich(p->nameval);
382: putchar('\n');
383: break;
384:
385: case O_WHERE:
386: where();
387: break;
388:
389: case O_ALIAS:
390: alias(p->left->sconval, p->right->sconval);
391: break;
392:
393: case O_CALL:
394: callproc(p->left, p->right);
395: break;
396:
397: case O_EDIT:
398: edit(p->sconval);
399: break;
400:
401: case O_DUMP:
402: dump();
403: break;
404:
405: case O_GRIPE:
406: gripe();
407: break;
408:
409: case O_HELP:
410: help();
411: break;
412:
413: case O_REMAKE:
414: remake();
415: break;
416:
417: case O_RUN:
418: run();
419: break;
420:
421: case O_SOURCE:
422: setinput(p->sconval);
423: break;
424:
425: case O_STATUS:
426: status();
427: break;
428:
429: case O_TRACE:
430: case O_TRACEI:
431: trace(p->op, p->what, p->where, p->cond);
432: if (isstdin()) {
433: status();
434: }
435: break;
436:
437: case O_STOP:
438: case O_STOPI:
439: stop(p->op, p->what, p->where, p->cond);
440: if (isstdin()) {
441: status();
442: }
443: break;
444:
445: case O_DELETE:
446: eval(p->left);
447: delbp((unsigned int) pop(long));
448: break;
449:
450: default:
451: panic("eval: bad op %d", p->op);
452: }
453: }
454:
455: /*
456: * Push "len" bytes onto the expression stack from address "addr"
457: * in the process. Normally TRUE is returned, however if there
458: * isn't enough room on the stack, rpush returns FALSE.
459: */
460:
461: BOOLEAN rpush(addr, len)
462: ADDRESS addr;
463: int len;
464: {
465: BOOLEAN success;
466: #ifdef tahoe
467: register char *savesp = sp;
468: #endif
469:
470: if (sp + len >= &stack[STACKSIZE]) {
471: success = FALSE;
472: } else {
473: dread(sp, addr, len);
474: sp += len;
475: #ifdef tahoe
476: alignstack();
477: if (sp >= &stack[STACKSIZE]) {
478: success = FALSE;
479: sp = savesp;
480: } else
481: #endif
482: success = TRUE;
483: }
484: return success;
485: }
486:
487: /*
488: * Pop an item of the given type which is assumed to be no larger
489: * than a long and return it expanded into a long.
490: */
491:
492: long popsmall(t)
493: SYM *t;
494: {
495: long r;
496:
497: switch (size(t)) {
498: case sizeof(char):
499: r = (long) pop(char);
500: break;
501:
502: case sizeof(short):
503: r = (long) pop(short);
504: break;
505:
506: case sizeof(long):
507: r = pop(long);
508: break;
509:
510: /*
511: * A bit of a kludge here. If an array element is a record,
512: * the dot operation will be converted into an addition with
513: * the record operand having a type whose size may be larger
514: * than a word. Now actually this is a pointer, but the subscript
515: * operation isn't aware of this, so it's just hacked here.
516: *
517: * The right thing to do is to make dot directly evaluated
518: * instead of changing it into addition.
519: */
520: default:
521: r = pop(ADDRESS);
522: break;
523: }
524: return r;
525: }
526:
527: /*
528: * evaluate a conditional expression
529: */
530:
531: BOOLEAN cond(p)
532: NODE *p;
533: {
534: if (p == NIL) {
535: return(TRUE);
536: }
537: eval(p);
538: return(pop(BOOLEAN));
539: }
540:
541: /*
542: * Return the address corresponding to a given tree.
543: */
544:
545: ADDRESS lval(p)
546: NODE *p;
547: {
548: eval(p);
549: return(pop(ADDRESS));
550: }
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