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nasm/eval.c
H. Peter Anvin e2c80181b6 Apply Nindent to all .c and .h files
2005-01-15 22:15:51 +00:00

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/* eval.c expression evaluator for the Netwide Assembler
*
* The Netwide Assembler is copyright (C) 1996 Simon Tatham and
* Julian Hall. All rights reserved. The software is
* redistributable under the licence given in the file "Licence"
* distributed in the NASM archive.
*
* initial version 27/iii/95 by Simon Tatham
*/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <ctype.h>
#include "nasm.h"
#include "nasmlib.h"
#include "eval.h"
#include "labels.h"
#define TEMPEXPRS_DELTA 128
#define TEMPEXPR_DELTA 8
static scanner scan; /* Address of scanner routine */
static efunc error; /* Address of error reporting routine */
static lfunc labelfunc; /* Address of label routine */
static struct ofmt *outfmt; /* Structure of addresses of output routines */
static expr **tempexprs = NULL;
static int ntempexprs;
static int tempexprs_size = 0;
static expr *tempexpr;
static int ntempexpr;
static int tempexpr_size;
static struct tokenval *tokval; /* The current token */
static int i; /* The t_type of tokval */
static void *scpriv;
static loc_t *location; /* Pointer to current line's segment,offset */
static int *opflags;
static struct eval_hints *hint;
extern int in_abs_seg; /* ABSOLUTE segment flag */
extern long abs_seg; /* ABSOLUTE segment */
extern long abs_offset; /* ABSOLUTE segment offset */
/*
* Unimportant cleanup is done to avoid confusing people who are trying
* to debug real memory leaks
*/
void eval_cleanup(void)
{
while (ntempexprs)
nasm_free(tempexprs[--ntempexprs]);
nasm_free(tempexprs);
}
/*
* Construct a temporary expression.
*/
static void begintemp(void)
{
tempexpr = NULL;
tempexpr_size = ntempexpr = 0;
}
static void addtotemp(long type, long value)
{
while (ntempexpr >= tempexpr_size) {
tempexpr_size += TEMPEXPR_DELTA;
tempexpr = nasm_realloc(tempexpr,
tempexpr_size * sizeof(*tempexpr));
}
tempexpr[ntempexpr].type = type;
tempexpr[ntempexpr++].value = value;
}
static expr *finishtemp(void)
{
addtotemp(0L, 0L); /* terminate */
while (ntempexprs >= tempexprs_size) {
tempexprs_size += TEMPEXPRS_DELTA;
tempexprs = nasm_realloc(tempexprs,
tempexprs_size * sizeof(*tempexprs));
}
return tempexprs[ntempexprs++] = tempexpr;
}
/*
* Add two vector datatypes. We have some bizarre behaviour on far-
* absolute segment types: we preserve them during addition _only_
* if one of the segments is a truly pure scalar.
*/
static expr *add_vectors(expr * p, expr * q)
{
int preserve;
preserve = is_really_simple(p) || is_really_simple(q);
begintemp();
while (p->type && q->type &&
p->type < EXPR_SEGBASE + SEG_ABS &&
q->type < EXPR_SEGBASE + SEG_ABS) {
int lasttype;
if (p->type > q->type) {
addtotemp(q->type, q->value);
lasttype = q++->type;
} else if (p->type < q->type) {
addtotemp(p->type, p->value);
lasttype = p++->type;
} else { /* *p and *q have same type */
long sum = p->value + q->value;
if (sum)
addtotemp(p->type, sum);
lasttype = p->type;
p++, q++;
}
if (lasttype == EXPR_UNKNOWN) {
return finishtemp();
}
}
while (p->type && (preserve || p->type < EXPR_SEGBASE + SEG_ABS)) {
addtotemp(p->type, p->value);
p++;
}
while (q->type && (preserve || q->type < EXPR_SEGBASE + SEG_ABS)) {
addtotemp(q->type, q->value);
q++;
}
return finishtemp();
}
/*
* Multiply a vector by a scalar. Strip far-absolute segment part
* if present.
*
* Explicit treatment of UNKNOWN is not required in this routine,
* since it will silently do the Right Thing anyway.
*
* If `affect_hints' is set, we also change the hint type to
* NOTBASE if a MAKEBASE hint points at a register being
* multiplied. This allows [eax*1+ebx] to hint EBX rather than EAX
* as the base register.
*/
static expr *scalar_mult(expr * vect, long scalar, int affect_hints)
{
expr *p = vect;
while (p->type && p->type < EXPR_SEGBASE + SEG_ABS) {
p->value = scalar * (p->value);
if (hint && hint->type == EAH_MAKEBASE &&
p->type == hint->base && affect_hints)
hint->type = EAH_NOTBASE;
p++;
}
p->type = 0;
return vect;
}
static expr *scalarvect(long scalar)
{
begintemp();
addtotemp(EXPR_SIMPLE, scalar);
return finishtemp();
}
static expr *unknown_expr(void)
{
begintemp();
addtotemp(EXPR_UNKNOWN, 1L);
return finishtemp();
}
/*
* The SEG operator: calculate the segment part of a relocatable
* value. Return NULL, as usual, if an error occurs. Report the
* error too.
*/
static expr *segment_part(expr * e)
{
long seg;
if (is_unknown(e))
return unknown_expr();
if (!is_reloc(e)) {
error(ERR_NONFATAL, "cannot apply SEG to a non-relocatable value");
return NULL;
}
seg = reloc_seg(e);
if (seg == NO_SEG) {
error(ERR_NONFATAL, "cannot apply SEG to a non-relocatable value");
return NULL;
} else if (seg & SEG_ABS) {
return scalarvect(seg & ~SEG_ABS);
} else if (seg & 1) {
error(ERR_NONFATAL, "SEG applied to something which"
" is already a segment base");
return NULL;
} else {
long base = outfmt->segbase(seg + 1);
begintemp();
addtotemp((base == NO_SEG ? EXPR_UNKNOWN : EXPR_SEGBASE + base),
1L);
return finishtemp();
}
}
/*
* Recursive-descent parser. Called with a single boolean operand,
* which is TRUE if the evaluation is critical (i.e. unresolved
* symbols are an error condition). Must update the global `i' to
* reflect the token after the parsed string. May return NULL.
*
* evaluate() should report its own errors: on return it is assumed
* that if NULL has been returned, the error has already been
* reported.
*/
/*
* Grammar parsed is:
*
* expr : bexpr [ WRT expr6 ]
* bexpr : rexp0 or expr0 depending on relative-mode setting
* rexp0 : rexp1 [ {||} rexp1...]
* rexp1 : rexp2 [ {^^} rexp2...]
* rexp2 : rexp3 [ {&&} rexp3...]
* rexp3 : expr0 [ {=,==,<>,!=,<,>,<=,>=} expr0 ]
* expr0 : expr1 [ {|} expr1...]
* expr1 : expr2 [ {^} expr2...]
* expr2 : expr3 [ {&} expr3...]
* expr3 : expr4 [ {<<,>>} expr4...]
* expr4 : expr5 [ {+,-} expr5...]
* expr5 : expr6 [ {*,/,%,//,%%} expr6...]
* expr6 : { ~,+,-,SEG } expr6
* | (bexpr)
* | symbol
* | $
* | number
*/
static expr *rexp0(int), *rexp1(int), *rexp2(int), *rexp3(int);
static expr *expr0(int), *expr1(int), *expr2(int), *expr3(int);
static expr *expr4(int), *expr5(int), *expr6(int);
static expr *(*bexpr) (int);
static expr *rexp0(int critical)
{
expr *e, *f;
e = rexp1(critical);
if (!e)
return NULL;
while (i == TOKEN_DBL_OR) {
i = scan(scpriv, tokval);
f = rexp1(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "`|' operator may only be applied to"
" scalar values");
}
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect((long)(reloc_value(e) || reloc_value(f)));
}
return e;
}
static expr *rexp1(int critical)
{
expr *e, *f;
e = rexp2(critical);
if (!e)
return NULL;
while (i == TOKEN_DBL_XOR) {
i = scan(scpriv, tokval);
f = rexp2(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "`^' operator may only be applied to"
" scalar values");
}
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect((long)(!reloc_value(e) ^ !reloc_value(f)));
}
return e;
}
static expr *rexp2(int critical)
{
expr *e, *f;
e = rexp3(critical);
if (!e)
return NULL;
while (i == TOKEN_DBL_AND) {
i = scan(scpriv, tokval);
f = rexp3(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "`&' operator may only be applied to"
" scalar values");
}
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect((long)(reloc_value(e) && reloc_value(f)));
}
return e;
}
static expr *rexp3(int critical)
{
expr *e, *f;
long v;
e = expr0(critical);
if (!e)
return NULL;
while (i == TOKEN_EQ || i == TOKEN_LT || i == TOKEN_GT ||
i == TOKEN_NE || i == TOKEN_LE || i == TOKEN_GE) {
int j = i;
i = scan(scpriv, tokval);
f = expr0(critical);
if (!f)
return NULL;
e = add_vectors(e, scalar_mult(f, -1L, FALSE));
switch (j) {
case TOKEN_EQ:
case TOKEN_NE:
if (is_unknown(e))
v = -1; /* means unknown */
else if (!is_really_simple(e) || reloc_value(e) != 0)
v = (j == TOKEN_NE); /* unequal, so return TRUE if NE */
else
v = (j == TOKEN_EQ); /* equal, so return TRUE if EQ */
break;
default:
if (is_unknown(e))
v = -1; /* means unknown */
else if (!is_really_simple(e)) {
error(ERR_NONFATAL,
"`%s': operands differ by a non-scalar",
(j == TOKEN_LE ? "<=" : j == TOKEN_LT ? "<" : j ==
TOKEN_GE ? ">=" : ">"));
v = 0; /* must set it to _something_ */
} else {
int vv = reloc_value(e);
if (vv == 0)
v = (j == TOKEN_LE || j == TOKEN_GE);
else if (vv > 0)
v = (j == TOKEN_GE || j == TOKEN_GT);
else /* vv < 0 */
v = (j == TOKEN_LE || j == TOKEN_LT);
}
break;
}
if (v == -1)
e = unknown_expr();
else
e = scalarvect(v);
}
return e;
}
static expr *expr0(int critical)
{
expr *e, *f;
e = expr1(critical);
if (!e)
return NULL;
while (i == '|') {
i = scan(scpriv, tokval);
f = expr1(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "`|' operator may only be applied to"
" scalar values");
}
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(reloc_value(e) | reloc_value(f));
}
return e;
}
static expr *expr1(int critical)
{
expr *e, *f;
e = expr2(critical);
if (!e)
return NULL;
while (i == '^') {
i = scan(scpriv, tokval);
f = expr2(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "`^' operator may only be applied to"
" scalar values");
}
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(reloc_value(e) ^ reloc_value(f));
}
return e;
}
static expr *expr2(int critical)
{
expr *e, *f;
e = expr3(critical);
if (!e)
return NULL;
while (i == '&') {
i = scan(scpriv, tokval);
f = expr3(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "`&' operator may only be applied to"
" scalar values");
}
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(reloc_value(e) & reloc_value(f));
}
return e;
}
static expr *expr3(int critical)
{
expr *e, *f;
e = expr4(critical);
if (!e)
return NULL;
while (i == TOKEN_SHL || i == TOKEN_SHR) {
int j = i;
i = scan(scpriv, tokval);
f = expr4(critical);
if (!f)
return NULL;
if (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f))) {
error(ERR_NONFATAL, "shift operator may only be applied to"
" scalar values");
} else if (is_just_unknown(e) || is_just_unknown(f)) {
e = unknown_expr();
} else
switch (j) {
case TOKEN_SHL:
e = scalarvect(reloc_value(e) << reloc_value(f));
break;
case TOKEN_SHR:
e = scalarvect(((unsigned long)reloc_value(e)) >>
reloc_value(f));
break;
}
}
return e;
}
static expr *expr4(int critical)
{
expr *e, *f;
e = expr5(critical);
if (!e)
return NULL;
while (i == '+' || i == '-') {
int j = i;
i = scan(scpriv, tokval);
f = expr5(critical);
if (!f)
return NULL;
switch (j) {
case '+':
e = add_vectors(e, f);
break;
case '-':
e = add_vectors(e, scalar_mult(f, -1L, FALSE));
break;
}
}
return e;
}
static expr *expr5(int critical)
{
expr *e, *f;
e = expr6(critical);
if (!e)
return NULL;
while (i == '*' || i == '/' || i == '%' ||
i == TOKEN_SDIV || i == TOKEN_SMOD) {
int j = i;
i = scan(scpriv, tokval);
f = expr6(critical);
if (!f)
return NULL;
if (j != '*' && (!(is_simple(e) || is_just_unknown(e)) ||
!(is_simple(f) || is_just_unknown(f)))) {
error(ERR_NONFATAL, "division operator may only be applied to"
" scalar values");
return NULL;
}
if (j != '*' && !is_unknown(f) && reloc_value(f) == 0) {
error(ERR_NONFATAL, "division by zero");
return NULL;
}
switch (j) {
case '*':
if (is_simple(e))
e = scalar_mult(f, reloc_value(e), TRUE);
else if (is_simple(f))
e = scalar_mult(e, reloc_value(f), TRUE);
else if (is_just_unknown(e) && is_just_unknown(f))
e = unknown_expr();
else {
error(ERR_NONFATAL, "unable to multiply two "
"non-scalar objects");
return NULL;
}
break;
case '/':
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(((unsigned long)reloc_value(e)) /
((unsigned long)reloc_value(f)));
break;
case '%':
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(((unsigned long)reloc_value(e)) %
((unsigned long)reloc_value(f)));
break;
case TOKEN_SDIV:
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(((signed long)reloc_value(e)) /
((signed long)reloc_value(f)));
break;
case TOKEN_SMOD:
if (is_just_unknown(e) || is_just_unknown(f))
e = unknown_expr();
else
e = scalarvect(((signed long)reloc_value(e)) %
((signed long)reloc_value(f)));
break;
}
}
return e;
}
static expr *expr6(int critical)
{
long type;
expr *e;
long label_seg, label_ofs;
if (i == '-') {
i = scan(scpriv, tokval);
e = expr6(critical);
if (!e)
return NULL;
return scalar_mult(e, -1L, FALSE);
} else if (i == '+') {
i = scan(scpriv, tokval);
return expr6(critical);
} else if (i == '~') {
i = scan(scpriv, tokval);
e = expr6(critical);
if (!e)
return NULL;
if (is_just_unknown(e))
return unknown_expr();
else if (!is_simple(e)) {
error(ERR_NONFATAL, "`~' operator may only be applied to"
" scalar values");
return NULL;
}
return scalarvect(~reloc_value(e));
} else if (i == TOKEN_SEG) {
i = scan(scpriv, tokval);
e = expr6(critical);
if (!e)
return NULL;
e = segment_part(e);
if (!e)
return NULL;
if (is_unknown(e) && critical) {
error(ERR_NONFATAL, "unable to determine segment base");
return NULL;
}
return e;
} else if (i == '(') {
i = scan(scpriv, tokval);
e = bexpr(critical);
if (!e)
return NULL;
if (i != ')') {
error(ERR_NONFATAL, "expecting `)'");
return NULL;
}
i = scan(scpriv, tokval);
return e;
} else if (i == TOKEN_NUM || i == TOKEN_REG || i == TOKEN_ID ||
i == TOKEN_HERE || i == TOKEN_BASE) {
begintemp();
switch (i) {
case TOKEN_NUM:
addtotemp(EXPR_SIMPLE, tokval->t_integer);
break;
case TOKEN_REG:
addtotemp(tokval->t_integer, 1L);
if (hint && hint->type == EAH_NOHINT)
hint->base = tokval->t_integer, hint->type = EAH_MAKEBASE;
break;
case TOKEN_ID:
case TOKEN_HERE:
case TOKEN_BASE:
/*
* If !location->known, this indicates that no
* symbol, Here or Base references are valid because we
* are in preprocess-only mode.
*/
if (!location->known) {
error(ERR_NONFATAL,
"%s not supported in preprocess-only mode",
(i == TOKEN_ID ? "symbol references" :
i == TOKEN_HERE ? "`$'" : "`$$'"));
addtotemp(EXPR_UNKNOWN, 1L);
break;
}
type = EXPR_SIMPLE; /* might get overridden by UNKNOWN */
if (i == TOKEN_BASE) {
label_seg = in_abs_seg ? abs_seg : location->segment;
label_ofs = 0;
} else if (i == TOKEN_HERE) {
label_seg = in_abs_seg ? abs_seg : location->segment;
label_ofs = in_abs_seg ? abs_offset : location->offset;
} else {
if (!labelfunc(tokval->t_charptr, &label_seg, &label_ofs)) {
if (critical == 2) {
error(ERR_NONFATAL, "symbol `%s' undefined",
tokval->t_charptr);
return NULL;
} else if (critical == 1) {
error(ERR_NONFATAL,
"symbol `%s' not defined before use",
tokval->t_charptr);
return NULL;
} else {
if (opflags)
*opflags |= 1;
type = EXPR_UNKNOWN;
label_seg = NO_SEG;
label_ofs = 1;
}
}
if (opflags && is_extern(tokval->t_charptr))
*opflags |= OPFLAG_EXTERN;
}
addtotemp(type, label_ofs);
if (label_seg != NO_SEG)
addtotemp(EXPR_SEGBASE + label_seg, 1L);
break;
}
i = scan(scpriv, tokval);
return finishtemp();
} else {
error(ERR_NONFATAL, "expression syntax error");
return NULL;
}
}
void eval_global_info(struct ofmt *output, lfunc lookup_label,
loc_t * locp)
{
outfmt = output;
labelfunc = lookup_label;
location = locp;
}
expr *evaluate(scanner sc, void *scprivate, struct tokenval *tv,
int *fwref, int critical, efunc report_error,
struct eval_hints *hints)
{
expr *e;
expr *f = NULL;
hint = hints;
if (hint)
hint->type = EAH_NOHINT;
if (critical & CRITICAL) {
critical &= ~CRITICAL;
bexpr = rexp0;
} else
bexpr = expr0;
scan = sc;
scpriv = scprivate;
tokval = tv;
error = report_error;
opflags = fwref;
if (tokval->t_type == TOKEN_INVALID)
i = scan(scpriv, tokval);
else
i = tokval->t_type;
while (ntempexprs) /* initialise temporary storage */
nasm_free(tempexprs[--ntempexprs]);
e = bexpr(critical);
if (!e)
return NULL;
if (i == TOKEN_WRT) {
i = scan(scpriv, tokval); /* eat the WRT */
f = expr6(critical);
if (!f)
return NULL;
}
e = scalar_mult(e, 1L, FALSE); /* strip far-absolute segment part */
if (f) {
expr *g;
if (is_just_unknown(f))
g = unknown_expr();
else {
long value;
begintemp();
if (!is_reloc(f)) {
error(ERR_NONFATAL, "invalid right-hand operand to WRT");
return NULL;
}
value = reloc_seg(f);
if (value == NO_SEG)
value = reloc_value(f) | SEG_ABS;
else if (!(value & SEG_ABS) && !(value % 2) && critical) {
error(ERR_NONFATAL, "invalid right-hand operand to WRT");
return NULL;
}
addtotemp(EXPR_WRT, value);
g = finishtemp();
}
e = add_vectors(e, g);
}
return e;
}
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