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nasm/labels.c

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/* labels.c label handling 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.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include "nasm.h"
#include "nasmlib.h"
/*
* A local label is one that begins with exactly one period. Things
* that begin with _two_ periods are NASM-specific things.
*
* If TASM compatibility is enabled, a local label can also begin with
* @@, so @@local is a TASM compatible local label. Note that we only
* check for the first @ symbol, although TASM requires both.
*/
#define islocal(l) \
(tasm_compatible_mode ? \
(((l)[0] == '.' || (l)[0] == '@') && (l)[1] != '.') : \
((l)[0] == '.' && (l)[1] != '.'))
#define islocalchar(c) \
(tasm_compatible_mode ? \
((c) == '.' || (c) == '@') : \
((c) == '.'))
#define LABEL_BLOCK 32 /* no. of labels/block */
#define LBLK_SIZE (LABEL_BLOCK*sizeof(union label))
#define LABEL_HASHES 37 /* no. of hash table entries */
#define END_LIST -3 /* don't clash with NO_SEG! */
#define END_BLOCK -2
#define BOGUS_VALUE -4
#define PERMTS_SIZE 4096 /* size of text blocks */
#if (PERMTS_SIZE > IDLEN_MAX)
#error "IPERMTS_SIZE must be less than or equal to IDLEN_MAX"
#endif
/* values for label.defn.is_global */
#define DEFINED_BIT 1
#define GLOBAL_BIT 2
#define EXTERN_BIT 4
#define NOT_DEFINED_YET 0
#define TYPE_MASK 3
#define LOCAL_SYMBOL (DEFINED_BIT)
#define GLOBAL_PLACEHOLDER (GLOBAL_BIT)
#define GLOBAL_SYMBOL (DEFINED_BIT|GLOBAL_BIT)
union label { /* actual label structures */
struct {
int32_t segment, offset;
char *label, *special;
int is_global, is_norm;
} defn;
struct {
int32_t movingon, dummy;
union label *next;
} admin;
};
struct permts { /* permanent text storage */
struct permts *next; /* for the linked list */
int size, usage; /* size and used space in ... */
char data[PERMTS_SIZE]; /* ... the data block itself */
};
extern int global_offset_changed; /* defined in nasm.c */
static union label *ltab[LABEL_HASHES]; /* using a hash table */
static union label *lfree[LABEL_HASHES]; /* pointer into the above */
static struct permts *perm_head; /* start of perm. text storage */
static struct permts *perm_tail; /* end of perm. text storage */
static void init_block(union label *blk);
static char *perm_copy(char *string1, char *string2);
static char *prevlabel;
static int initialized = FALSE;
char lprefix[PREFIX_MAX] = { 0 };
char lpostfix[PREFIX_MAX] = { 0 };
/*
* Internal routine: finds the `union label' corresponding to the
* given label name. Creates a new one, if it isn't found, and if
* `create' is TRUE.
*/
static union label *find_label(char *label, int create)
{
int hash = 0;
char *p, *prev;
int prevlen;
union label *lptr;
if (islocal(label))
prev = prevlabel;
else
prev = "";
prevlen = strlen(prev);
p = prev;
while (*p)
hash += *p++;
p = label;
while (*p)
hash += *p++;
hash %= LABEL_HASHES;
lptr = ltab[hash];
while (lptr->admin.movingon != END_LIST) {
if (lptr->admin.movingon == END_BLOCK) {
lptr = lptr->admin.next;
if (!lptr)
break;
}
if (!strncmp(lptr->defn.label, prev, prevlen) &&
!strcmp(lptr->defn.label + prevlen, label))
return lptr;
lptr++;
}
if (create) {
if (lfree[hash]->admin.movingon == END_BLOCK) {
/*
* must allocate a new block
*/
lfree[hash]->admin.next =
(union label *)nasm_malloc(LBLK_SIZE);
lfree[hash] = lfree[hash]->admin.next;
init_block(lfree[hash]);
}
lfree[hash]->admin.movingon = BOGUS_VALUE;
lfree[hash]->defn.label = perm_copy(prev, label);
lfree[hash]->defn.special = NULL;
lfree[hash]->defn.is_global = NOT_DEFINED_YET;
return lfree[hash]++;
} else
return NULL;
}
int lookup_label(char *label, int32_t *segment, int32_t *offset)
{
union label *lptr;
if (!initialized)
return 0;
lptr = find_label(label, 0);
if (lptr && (lptr->defn.is_global & DEFINED_BIT)) {
*segment = lptr->defn.segment;
*offset = lptr->defn.offset;
return 1;
} else
return 0;
}
int is_extern(char *label)
{
union label *lptr;
if (!initialized)
return 0;
lptr = find_label(label, 0);
if (lptr && (lptr->defn.is_global & EXTERN_BIT))
return 1;
else
return 0;
}
void redefine_label(char *label, int32_t segment, int32_t offset, char *special,
int is_norm, int isextrn, struct ofmt *ofmt,
efunc error)
{
union label *lptr;
int exi;
/* This routine possibly ought to check for phase errors. Most assemblers
* check for phase errors at this point. I don't know whether phase errors
* are even possible, nor whether they are checked somewhere else
*/
(void)segment; /* Don't warn that this parameter is unused */
(void)special; /* Don't warn that this parameter is unused */
(void)is_norm; /* Don't warn that this parameter is unused */
(void)isextrn; /* Don't warn that this parameter is unused */
(void)ofmt; /* Don't warn that this parameter is unused */
#ifdef DEBUG
#if DEBUG<3
if (!strncmp(label, "debugdump", 9))
#endif
error(ERR_DEBUG, "redefine_label (%s, %ld, %08lx, %s, %d, %d)",
label, segment, offset, special, is_norm, isextrn);
#endif
lptr = find_label(label, 1);
if (!lptr)
error(ERR_PANIC, "can't find label `%s' on pass two", label);
if (!islocal(label)) {
if (!islocalchar(*label) && lptr->defn.is_norm)
prevlabel = lptr->defn.label;
}
global_offset_changed |= (lptr->defn.offset != offset);
lptr->defn.offset = offset;
if (pass0 == 1) {
exi = !!(lptr->defn.is_global & GLOBAL_BIT);
if (exi) {
char *xsymbol;
int slen;
slen = strlen(lprefix);
slen += strlen(lptr->defn.label);
slen += strlen(lpostfix);
slen++; /* room for that null char */
xsymbol = nasm_malloc(slen);
snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
lpostfix);
ofmt->symdef(xsymbol, segment, offset, exi,
special ? special : lptr->defn.special);
ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
exi,
special ? special : lptr->
defn.special);
/** nasm_free(xsymbol); ! outobj.c stores the pointer; ouch!!! **/
} else {
if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
EXTERN_BIT) {
ofmt->symdef(lptr->defn.label, segment, offset, exi,
special ? special : lptr->defn.special);
ofmt->current_dfmt->debug_deflabel(label, segment, offset,
exi,
special ? special :
lptr->defn.special);
}
}
}
/* if (pass0 == 1) */
}
void define_label(char *label, int32_t segment, int32_t offset, char *special,
int is_norm, int isextrn, struct ofmt *ofmt, efunc error)
{
union label *lptr;
int exi;
#ifdef DEBUG
#if DEBUG<3
if (!strncmp(label, "debugdump", 9))
#endif
error(ERR_DEBUG, "define_label (%s, %ld, %08lx, %s, %d, %d)",
label, segment, offset, special, is_norm, isextrn);
#endif
lptr = find_label(label, 1);
if (lptr->defn.is_global & DEFINED_BIT) {
error(ERR_NONFATAL, "symbol `%s' redefined", label);
return;
}
lptr->defn.is_global |= DEFINED_BIT;
if (isextrn)
lptr->defn.is_global |= EXTERN_BIT;
if (!islocalchar(label[0]) && is_norm) /* not local, but not special either */
prevlabel = lptr->defn.label;
else if (islocal(label) && !*prevlabel) {
error(ERR_NONFATAL, "attempt to define a local label before any"
" non-local labels");
}
lptr->defn.segment = segment;
lptr->defn.offset = offset;
lptr->defn.is_norm = (!islocalchar(label[0]) && is_norm);
if (pass0 == 1 || (!is_norm && !isextrn && (segment & 1))) {
exi = !!(lptr->defn.is_global & GLOBAL_BIT);
if (exi) {
char *xsymbol;
int slen;
slen = strlen(lprefix);
slen += strlen(lptr->defn.label);
slen += strlen(lpostfix);
slen++; /* room for that null char */
xsymbol = nasm_malloc(slen);
snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
lpostfix);
ofmt->symdef(xsymbol, segment, offset, exi,
special ? special : lptr->defn.special);
ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
exi,
special ? special : lptr->
defn.special);
/** nasm_free(xsymbol); ! outobj.c stores the pointer; ouch!!! **/
} else {
if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
EXTERN_BIT) {
ofmt->symdef(lptr->defn.label, segment, offset, exi,
special ? special : lptr->defn.special);
ofmt->current_dfmt->debug_deflabel(label, segment, offset,
exi,
special ? special :
lptr->defn.special);
}
}
} /* if (pass0 == 1) */
}
void define_common(char *label, int32_t segment, int32_t size, char *special,
struct ofmt *ofmt, efunc error)
{
union label *lptr;
lptr = find_label(label, 1);
if (lptr->defn.is_global & DEFINED_BIT) {
error(ERR_NONFATAL, "symbol `%s' redefined", label);
return;
}
lptr->defn.is_global |= DEFINED_BIT;
if (!islocalchar(label[0])) /* not local, but not special either */
prevlabel = lptr->defn.label;
else
error(ERR_NONFATAL, "attempt to define a local label as a "
"common variable");
lptr->defn.segment = segment;
lptr->defn.offset = 0;
ofmt->symdef(lptr->defn.label, segment, size, 2,
special ? special : lptr->defn.special);
ofmt->current_dfmt->debug_deflabel(lptr->defn.label, segment, size, 2,
special ? special : lptr->defn.
special);
}
void declare_as_global(char *label, char *special, efunc error)
{
union label *lptr;
if (islocal(label)) {
error(ERR_NONFATAL, "attempt to declare local symbol `%s' as"
" global", label);
return;
}
lptr = find_label(label, 1);
switch (lptr->defn.is_global & TYPE_MASK) {
case NOT_DEFINED_YET:
lptr->defn.is_global = GLOBAL_PLACEHOLDER;
lptr->defn.special = special ? perm_copy(special, "") : NULL;
break;
case GLOBAL_PLACEHOLDER: /* already done: silently ignore */
case GLOBAL_SYMBOL:
break;
case LOCAL_SYMBOL:
if (!lptr->defn.is_global & EXTERN_BIT)
error(ERR_NONFATAL, "symbol `%s': GLOBAL directive must"
" appear before symbol definition", label);
break;
}
}
int init_labels(void)
{
int i;
for (i = 0; i < LABEL_HASHES; i++) {
ltab[i] = (union label *)nasm_malloc(LBLK_SIZE);
if (!ltab[i])
return -1; /* can't initialise, panic */
init_block(ltab[i]);
lfree[i] = ltab[i];
}
perm_head =
perm_tail = (struct permts *)nasm_malloc(sizeof(struct permts));
if (!perm_head)
return -1;
perm_head->next = NULL;
perm_head->size = PERMTS_SIZE;
perm_head->usage = 0;
prevlabel = "";
initialized = TRUE;
return 0;
}
void cleanup_labels(void)
{
int i;
initialized = FALSE;
for (i = 0; i < LABEL_HASHES; i++) {
union label *lptr, *lhold;
lptr = lhold = ltab[i];
while (lptr) {
while (lptr->admin.movingon != END_BLOCK)
lptr++;
lptr = lptr->admin.next;
nasm_free(lhold);
lhold = lptr;
}
}
while (perm_head) {
perm_tail = perm_head;
perm_head = perm_head->next;
nasm_free(perm_tail);
}
}
static void init_block(union label *blk)
{
int j;
for (j = 0; j < LABEL_BLOCK - 1; j++)
blk[j].admin.movingon = END_LIST;
blk[LABEL_BLOCK - 1].admin.movingon = END_BLOCK;
blk[LABEL_BLOCK - 1].admin.next = NULL;
}
static char *perm_copy(char *string1, char *string2)
{
char *p, *q;
int len = strlen(string1) + strlen(string2) + 1;
if (perm_tail->size - perm_tail->usage < len) {
perm_tail->next =
(struct permts *)nasm_malloc(sizeof(struct permts));
perm_tail = perm_tail->next;
perm_tail->next = NULL;
perm_tail->size = PERMTS_SIZE;
perm_tail->usage = 0;
}
p = q = perm_tail->data + perm_tail->usage;
while ((*q = *string1++))
q++;
while ((*q++ = *string2++)) ;
perm_tail->usage = q - perm_tail->data;
return p;
}
/*
* Notes regarding bug involving redefinition of external segments.
*
* Up to and including v0.97, the following code didn't work. From 0.97
* developers release 2 onwards, it will generate an error.
*
* EXTERN extlabel
* newlabel EQU extlabel + 1
*
* The results of allowing this code through are that two import records
* are generated, one for 'extlabel' and one for 'newlabel'.
*
* The reason for this is an inadequacy in the defined interface between
* the label manager and the output formats. The problem lies in how the
* output format driver tells that a label is an external label for which
* a label import record must be produced. Most (all except bin?) produce
* the record if the segment number of the label is not one of the internal
* segments that the output driver is producing.
*
* A simple fix to this would be to make the output formats keep track of
* which symbols they've produced import records for, and make them not
* produce import records for segments that are already defined.
*
* The best way, which is slightly harder but reduces duplication of code
* and should therefore make the entire system smaller and more stable is
* to change the interface between assembler, define_label(), and
* the output module. The changes that are needed are:
*
* The semantics of the 'isextern' flag passed to define_label() need
* examining. This information may or may not tell us what we need to
* know (ie should we be generating an import record at this point for this
* label). If these aren't the semantics, the semantics should be changed
* to this.
*
* The output module interface needs changing, so that the `isextern' flag
* is passed to the module, so that it can be easily tested for.
*/
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