1 /* eval.c expression evaluator for the Netwide Assembler
3 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
4 * Julian Hall. All rights reserved. The software is
5 * redistributable under the licence given in the file "Licence"
6 * distributed in the NASM archive.
8 * initial version 27/iii/95 by Simon Tatham
23 #define TEMPEXPRS_DELTA 128
24 #define TEMPEXPR_DELTA 8
26 static scanner scan; /* Address of scanner routine */
27 static efunc error; /* Address of error reporting routine */
28 static lfunc labelfunc; /* Address of label routine */
30 static struct ofmt *outfmt; /* Structure of addresses of output routines */
32 static expr **tempexprs = NULL;
33 static int ntempexprs;
34 static int tempexprs_size = 0;
36 static expr *tempexpr;
38 static int tempexpr_size;
40 static struct tokenval *tokval; /* The current token */
41 static int i; /* The t_type of tokval */
44 static loc_t *location; /* Pointer to current line's segment,offset */
47 static struct eval_hints *hint;
49 extern int in_abs_seg; /* ABSOLUTE segment flag */
50 extern int32_t abs_seg; /* ABSOLUTE segment */
51 extern int32_t abs_offset; /* ABSOLUTE segment offset */
54 * Unimportant cleanup is done to avoid confusing people who are trying
55 * to debug real memory leaks
57 void eval_cleanup(void)
60 nasm_free(tempexprs[--ntempexprs]);
65 * Construct a temporary expression.
67 static void begintemp(void)
70 tempexpr_size = ntempexpr = 0;
73 static void addtotemp(int32_t type, int64_t value)
75 while (ntempexpr >= tempexpr_size) {
76 tempexpr_size += TEMPEXPR_DELTA;
77 tempexpr = nasm_realloc(tempexpr,
78 tempexpr_size * sizeof(*tempexpr));
80 tempexpr[ntempexpr].type = type;
81 tempexpr[ntempexpr++].value = value;
84 static expr *finishtemp(void)
86 addtotemp(0L, 0L); /* terminate */
87 while (ntempexprs >= tempexprs_size) {
88 tempexprs_size += TEMPEXPRS_DELTA;
89 tempexprs = nasm_realloc(tempexprs,
90 tempexprs_size * sizeof(*tempexprs));
92 return tempexprs[ntempexprs++] = tempexpr;
96 * Add two vector datatypes. We have some bizarre behaviour on far-
97 * absolute segment types: we preserve them during addition _only_
98 * if one of the segments is a truly pure scalar.
100 static expr *add_vectors(expr * p, expr * q)
104 preserve = is_really_simple(p) || is_really_simple(q);
108 while (p->type && q->type &&
109 p->type < EXPR_SEGBASE + SEG_ABS &&
110 q->type < EXPR_SEGBASE + SEG_ABS) {
113 if (p->type > q->type) {
114 addtotemp(q->type, q->value);
115 lasttype = q++->type;
116 } else if (p->type < q->type) {
117 addtotemp(p->type, p->value);
118 lasttype = p++->type;
119 } else { /* *p and *q have same type */
120 int32_t sum = p->value + q->value;
122 addtotemp(p->type, sum);
126 if (lasttype == EXPR_UNKNOWN) {
130 while (p->type && (preserve || p->type < EXPR_SEGBASE + SEG_ABS)) {
131 addtotemp(p->type, p->value);
134 while (q->type && (preserve || q->type < EXPR_SEGBASE + SEG_ABS)) {
135 addtotemp(q->type, q->value);
143 * Multiply a vector by a scalar. Strip far-absolute segment part
146 * Explicit treatment of UNKNOWN is not required in this routine,
147 * since it will silently do the Right Thing anyway.
149 * If `affect_hints' is set, we also change the hint type to
150 * NOTBASE if a MAKEBASE hint points at a register being
151 * multiplied. This allows [eax*1+ebx] to hint EBX rather than EAX
152 * as the base register.
154 static expr *scalar_mult(expr * vect, int32_t scalar, int affect_hints)
158 while (p->type && p->type < EXPR_SEGBASE + SEG_ABS) {
159 p->value = scalar * (p->value);
160 if (hint && hint->type == EAH_MAKEBASE &&
161 p->type == hint->base && affect_hints)
162 hint->type = EAH_NOTBASE;
170 static expr *scalarvect(int32_t scalar)
173 addtotemp(EXPR_SIMPLE, scalar);
177 static expr *unknown_expr(void)
180 addtotemp(EXPR_UNKNOWN, 1L);
185 * The SEG operator: calculate the segment part of a relocatable
186 * value. Return NULL, as usual, if an error occurs. Report the
189 static expr *segment_part(expr * e)
194 return unknown_expr();
197 error(ERR_NONFATAL, "cannot apply SEG to a non-relocatable value");
203 error(ERR_NONFATAL, "cannot apply SEG to a non-relocatable value");
205 } else if (seg & SEG_ABS) {
206 return scalarvect(seg & ~SEG_ABS);
207 } else if (seg & 1) {
208 error(ERR_NONFATAL, "SEG applied to something which"
209 " is already a segment base");
212 int32_t base = outfmt->segbase(seg + 1);
215 addtotemp((base == NO_SEG ? EXPR_UNKNOWN : EXPR_SEGBASE + base),
222 * Recursive-descent parser. Called with a single boolean operand,
223 * which is TRUE if the evaluation is critical (i.e. unresolved
224 * symbols are an error condition). Must update the global `i' to
225 * reflect the token after the parsed string. May return NULL.
227 * evaluate() should report its own errors: on return it is assumed
228 * that if NULL has been returned, the error has already been
235 * expr : bexpr [ WRT expr6 ]
236 * bexpr : rexp0 or expr0 depending on relative-mode setting
237 * rexp0 : rexp1 [ {||} rexp1...]
238 * rexp1 : rexp2 [ {^^} rexp2...]
239 * rexp2 : rexp3 [ {&&} rexp3...]
240 * rexp3 : expr0 [ {=,==,<>,!=,<,>,<=,>=} expr0 ]
241 * expr0 : expr1 [ {|} expr1...]
242 * expr1 : expr2 [ {^} expr2...]
243 * expr2 : expr3 [ {&} expr3...]
244 * expr3 : expr4 [ {<<,>>} expr4...]
245 * expr4 : expr5 [ {+,-} expr5...]
246 * expr5 : expr6 [ {*,/,%,//,%%} expr6...]
247 * expr6 : { ~,+,-,SEG } expr6
254 static expr *rexp0(int), *rexp1(int), *rexp2(int), *rexp3(int);
256 static expr *expr0(int), *expr1(int), *expr2(int), *expr3(int);
257 static expr *expr4(int), *expr5(int), *expr6(int);
259 static expr *(*bexpr) (int);
261 static expr *rexp0(int critical)
269 while (i == TOKEN_DBL_OR) {
270 i = scan(scpriv, tokval);
274 if (!(is_simple(e) || is_just_unknown(e)) ||
275 !(is_simple(f) || is_just_unknown(f))) {
276 error(ERR_NONFATAL, "`|' operator may only be applied to"
280 if (is_just_unknown(e) || is_just_unknown(f))
283 e = scalarvect((int32_t)(reloc_value(e) || reloc_value(f)));
288 static expr *rexp1(int critical)
296 while (i == TOKEN_DBL_XOR) {
297 i = scan(scpriv, tokval);
301 if (!(is_simple(e) || is_just_unknown(e)) ||
302 !(is_simple(f) || is_just_unknown(f))) {
303 error(ERR_NONFATAL, "`^' operator may only be applied to"
307 if (is_just_unknown(e) || is_just_unknown(f))
310 e = scalarvect((int32_t)(!reloc_value(e) ^ !reloc_value(f)));
315 static expr *rexp2(int critical)
322 while (i == TOKEN_DBL_AND) {
323 i = scan(scpriv, tokval);
327 if (!(is_simple(e) || is_just_unknown(e)) ||
328 !(is_simple(f) || is_just_unknown(f))) {
329 error(ERR_NONFATAL, "`&' operator may only be applied to"
332 if (is_just_unknown(e) || is_just_unknown(f))
335 e = scalarvect((int32_t)(reloc_value(e) && reloc_value(f)));
340 static expr *rexp3(int critical)
349 while (i == TOKEN_EQ || i == TOKEN_LT || i == TOKEN_GT ||
350 i == TOKEN_NE || i == TOKEN_LE || i == TOKEN_GE) {
352 i = scan(scpriv, tokval);
357 e = add_vectors(e, scalar_mult(f, -1L, FALSE));
363 v = -1; /* means unknown */
364 else if (!is_really_simple(e) || reloc_value(e) != 0)
365 v = (j == TOKEN_NE); /* unequal, so return TRUE if NE */
367 v = (j == TOKEN_EQ); /* equal, so return TRUE if EQ */
371 v = -1; /* means unknown */
372 else if (!is_really_simple(e)) {
374 "`%s': operands differ by a non-scalar",
375 (j == TOKEN_LE ? "<=" : j == TOKEN_LT ? "<" : j ==
376 TOKEN_GE ? ">=" : ">"));
377 v = 0; /* must set it to _something_ */
379 int vv = reloc_value(e);
381 v = (j == TOKEN_LE || j == TOKEN_GE);
383 v = (j == TOKEN_GE || j == TOKEN_GT);
385 v = (j == TOKEN_LE || j == TOKEN_LT);
398 static expr *expr0(int critical)
407 i = scan(scpriv, tokval);
411 if (!(is_simple(e) || is_just_unknown(e)) ||
412 !(is_simple(f) || is_just_unknown(f))) {
413 error(ERR_NONFATAL, "`|' operator may only be applied to"
416 if (is_just_unknown(e) || is_just_unknown(f))
419 e = scalarvect(reloc_value(e) | reloc_value(f));
424 static expr *expr1(int critical)
433 i = scan(scpriv, tokval);
437 if (!(is_simple(e) || is_just_unknown(e)) ||
438 !(is_simple(f) || is_just_unknown(f))) {
439 error(ERR_NONFATAL, "`^' operator may only be applied to"
442 if (is_just_unknown(e) || is_just_unknown(f))
445 e = scalarvect(reloc_value(e) ^ reloc_value(f));
450 static expr *expr2(int critical)
459 i = scan(scpriv, tokval);
463 if (!(is_simple(e) || is_just_unknown(e)) ||
464 !(is_simple(f) || is_just_unknown(f))) {
465 error(ERR_NONFATAL, "`&' operator may only be applied to"
468 if (is_just_unknown(e) || is_just_unknown(f))
471 e = scalarvect(reloc_value(e) & reloc_value(f));
476 static expr *expr3(int critical)
484 while (i == TOKEN_SHL || i == TOKEN_SHR) {
486 i = scan(scpriv, tokval);
490 if (!(is_simple(e) || is_just_unknown(e)) ||
491 !(is_simple(f) || is_just_unknown(f))) {
492 error(ERR_NONFATAL, "shift operator may only be applied to"
494 } else if (is_just_unknown(e) || is_just_unknown(f)) {
499 e = scalarvect(reloc_value(e) << reloc_value(f));
502 e = scalarvect(((uint32_t)reloc_value(e)) >>
510 static expr *expr4(int critical)
517 while (i == '+' || i == '-') {
519 i = scan(scpriv, tokval);
525 e = add_vectors(e, f);
528 e = add_vectors(e, scalar_mult(f, -1L, FALSE));
535 static expr *expr5(int critical)
542 while (i == '*' || i == '/' || i == '%' ||
543 i == TOKEN_SDIV || i == TOKEN_SMOD) {
545 i = scan(scpriv, tokval);
549 if (j != '*' && (!(is_simple(e) || is_just_unknown(e)) ||
550 !(is_simple(f) || is_just_unknown(f)))) {
551 error(ERR_NONFATAL, "division operator may only be applied to"
555 if (j != '*' && !is_unknown(f) && reloc_value(f) == 0) {
556 error(ERR_NONFATAL, "division by zero");
562 e = scalar_mult(f, reloc_value(e), TRUE);
563 else if (is_simple(f))
564 e = scalar_mult(e, reloc_value(f), TRUE);
565 else if (is_just_unknown(e) && is_just_unknown(f))
568 error(ERR_NONFATAL, "unable to multiply two "
569 "non-scalar objects");
574 if (is_just_unknown(e) || is_just_unknown(f))
577 e = scalarvect(((uint32_t)reloc_value(e)) /
578 ((uint32_t)reloc_value(f)));
581 if (is_just_unknown(e) || is_just_unknown(f))
584 e = scalarvect(((uint32_t)reloc_value(e)) %
585 ((uint32_t)reloc_value(f)));
588 if (is_just_unknown(e) || is_just_unknown(f))
591 e = scalarvect(((int32_t)reloc_value(e)) /
592 ((int32_t)reloc_value(f)));
595 if (is_just_unknown(e) || is_just_unknown(f))
598 e = scalarvect(((int32_t)reloc_value(e)) %
599 ((int32_t)reloc_value(f)));
606 static expr *expr6(int critical)
610 int32_t label_seg, label_ofs;
614 i = scan(scpriv, tokval);
618 return scalar_mult(e, -1L, FALSE);
622 i = scan(scpriv, tokval);
623 return expr6(critical);
626 i = scan(scpriv, tokval);
630 if (is_just_unknown(e))
631 return unknown_expr();
632 else if (!is_simple(e)) {
633 error(ERR_NONFATAL, "`~' operator may only be applied to"
637 return scalarvect(~reloc_value(e));
640 i = scan(scpriv, tokval);
644 if (is_just_unknown(e))
645 return unknown_expr();
646 else if (!is_simple(e)) {
647 error(ERR_NONFATAL, "`!' operator may only be applied to"
651 return scalarvect(!reloc_value(e));
654 i = scan(scpriv, tokval);
661 if (is_unknown(e) && critical) {
662 error(ERR_NONFATAL, "unable to determine segment base");
668 i = scan(scpriv, tokval);
673 error(ERR_NONFATAL, "expecting `)'");
676 i = scan(scpriv, tokval);
687 addtotemp(EXPR_SIMPLE, tokval->t_integer);
690 addtotemp(tokval->t_integer, 1L);
691 if (hint && hint->type == EAH_NOHINT)
692 hint->base = tokval->t_integer, hint->type = EAH_MAKEBASE;
698 * If !location->known, this indicates that no
699 * symbol, Here or Base references are valid because we
700 * are in preprocess-only mode.
702 if (!location->known) {
704 "%s not supported in preprocess-only mode",
705 (i == TOKEN_ID ? "symbol references" :
706 i == TOKEN_HERE ? "`$'" : "`$$'"));
707 addtotemp(EXPR_UNKNOWN, 1L);
711 type = EXPR_SIMPLE; /* might get overridden by UNKNOWN */
712 if (i == TOKEN_BASE) {
713 label_seg = in_abs_seg ? abs_seg : location->segment;
715 } else if (i == TOKEN_HERE) {
716 label_seg = in_abs_seg ? abs_seg : location->segment;
717 label_ofs = in_abs_seg ? abs_offset : location->offset;
719 if (!labelfunc(tokval->t_charptr, &label_seg, &label_ofs)) {
721 error(ERR_NONFATAL, "symbol `%s' undefined",
724 } else if (critical == 1) {
726 "symbol `%s' not defined before use",
737 if (opflags && is_extern(tokval->t_charptr))
738 *opflags |= OPFLAG_EXTERN;
740 addtotemp(type, label_ofs);
741 if (label_seg != NO_SEG)
742 addtotemp(EXPR_SEGBASE + label_seg, 1L);
745 i = scan(scpriv, tokval);
749 error(ERR_NONFATAL, "expression syntax error");
754 void eval_global_info(struct ofmt *output, lfunc lookup_label,
758 labelfunc = lookup_label;
762 expr *evaluate(scanner sc, void *scprivate, struct tokenval *tv,
763 int *fwref, int critical, efunc report_error,
764 struct eval_hints *hints)
771 hint->type = EAH_NOHINT;
773 if (critical & CRITICAL) {
774 critical &= ~CRITICAL;
782 error = report_error;
785 if (tokval->t_type == TOKEN_INVALID)
786 i = scan(scpriv, tokval);
790 while (ntempexprs) /* initialize temporary storage */
791 nasm_free(tempexprs[--ntempexprs]);
797 if (i == TOKEN_WRT) {
798 i = scan(scpriv, tokval); /* eat the WRT */
803 e = scalar_mult(e, 1L, FALSE); /* strip far-absolute segment part */
806 if (is_just_unknown(f))
812 error(ERR_NONFATAL, "invalid right-hand operand to WRT");
815 value = reloc_seg(f);
817 value = reloc_value(f) | SEG_ABS;
818 else if (!(value & SEG_ABS) && !(value % 2) && critical) {
819 error(ERR_NONFATAL, "invalid right-hand operand to WRT");
822 addtotemp(EXPR_WRT, value);
825 e = add_vectors(e, g);