/* Support routines for the various generation passes.
- Copyright (C) 2000 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2002, 2003
+ Free Software Foundation, Inc.
- This file is part of GNU CC.
+ This file is part of GCC.
- GNU CC is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
+ GCC is free software; you can redistribute it and/or modify it
+ under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
- GNU CC is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
+ GCC is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ License for more details.
You should have received a copy of the GNU General Public License
- along with GNU CC; see the file COPYING. If not, write to
- the Free Software Foundation, 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
+ along with GCC; see the file COPYING. If not, write to the Free
+ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+ 02111-1307, USA. */
-#include "hconfig.h"
+#include "bconfig.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "rtl.h"
#include "obstack.h"
#include "errors.h"
+#include "hashtab.h"
#include "gensupport.h"
+/* In case some macros used by files we include need it, define this here. */
+int target_flags;
+
+int insn_elision = 1;
+
static struct obstack obstack;
struct obstack *rtl_obstack = &obstack;
-#define obstack_chunk_alloc xmalloc
-#define obstack_chunk_free free
-
static int sequence_num;
static int errors;
static const char *predicable_true;
static const char *predicable_false;
+static htab_t condition_table;
+
+static char *base_dir = NULL;
+
/* We initially queue all patterns, process the define_insn and
define_cond_exec patterns, then return them one at a time. */
struct queue_elem
{
rtx data;
+ const char *filename;
int lineno;
struct queue_elem *next;
};
static struct queue_elem *other_queue;
static struct queue_elem **other_tail = &other_queue;
-static void queue_pattern PARAMS ((rtx, struct queue_elem ***, int));
-static void remove_constraints PARAMS ((rtx));
-static void process_rtx PARAMS ((rtx, int));
-
-static int is_predicable PARAMS ((struct queue_elem *));
-static void identify_predicable_attribute PARAMS ((void));
-static int n_alternatives PARAMS ((const char *));
-static void collect_insn_data PARAMS ((rtx, int *, int *));
-static rtx alter_predicate_for_insn PARAMS ((rtx, int, int, int));
-static const char *alter_test_for_insn PARAMS ((struct queue_elem *,
- struct queue_elem *));
-static char *shift_output_template PARAMS ((char *, const char *, int));
-static const char *alter_output_for_insn PARAMS ((struct queue_elem *,
- struct queue_elem *,
- int, int));
-static void process_one_cond_exec PARAMS ((struct queue_elem *));
-static void process_define_cond_exec PARAMS ((void));
+static void queue_pattern (rtx, struct queue_elem ***,
+ const char *, int);
+
+/* Current maximum length of directory names in the search path
+ for include files. (Altered as we get more of them.) */
+
+size_t max_include_len;
+
+struct file_name_list
+ {
+ struct file_name_list *next;
+ const char *fname;
+ };
+
+struct file_name_list *first_dir_md_include = 0; /* First dir to search */
+ /* First dir to search for <file> */
+struct file_name_list *first_bracket_include = 0;
+struct file_name_list *last_dir_md_include = 0; /* Last in chain */
+
+static void remove_constraints (rtx);
+static void process_rtx (rtx, int);
+
+static int is_predicable (struct queue_elem *);
+static void identify_predicable_attribute (void);
+static int n_alternatives (const char *);
+static void collect_insn_data (rtx, int *, int *);
+static rtx alter_predicate_for_insn (rtx, int, int, int);
+static const char *alter_test_for_insn (struct queue_elem *,
+ struct queue_elem *);
+static char *shift_output_template (char *, const char *, int);
+static const char *alter_output_for_insn (struct queue_elem *,
+ struct queue_elem *,
+ int, int);
+static void process_one_cond_exec (struct queue_elem *);
+static void process_define_cond_exec (void);
+static void process_include (rtx, int);
+static char *save_string (const char *, int);
\f
void
-message_with_line VPARAMS ((int lineno, const char *msg, ...))
+message_with_line (int lineno, const char *msg, ...)
{
-#ifndef ANSI_PROTOTYPES
- int lineno;
- const char *msg;
-#endif
va_list ap;
- VA_START (ap, msg);
-
-#ifndef ANSI_PROTOTYPES
- lineno = va_arg (ap, int);
- msg = va_arg (ap, const char *);
-#endif
+ va_start (ap, msg);
fprintf (stderr, "%s:%d: ", read_rtx_filename, lineno);
vfprintf (stderr, msg, ap);
va_end (ap);
}
+
+/* Make a version of gen_rtx_CONST_INT so that GEN_INT can be used in
+ the gensupport programs. */
+
+rtx
+gen_rtx_CONST_INT (enum machine_mode mode ATTRIBUTE_UNUSED,
+ HOST_WIDE_INT arg)
+{
+ rtx rt = rtx_alloc (CONST_INT);
+
+ XWINT (rt, 0) = arg;
+ return rt;
+}
\f
/* Queue PATTERN on LIST_TAIL. */
static void
-queue_pattern (pattern, list_tail, lineno)
- rtx pattern;
- struct queue_elem ***list_tail;
- int lineno;
+queue_pattern (rtx pattern, struct queue_elem ***list_tail,
+ const char *filename, int lineno)
{
struct queue_elem *e = (struct queue_elem *) xmalloc (sizeof (*e));
e->data = pattern;
+ e->filename = filename;
e->lineno = lineno;
e->next = NULL;
**list_tail = e;
/* Recursively remove constraints from an rtx. */
static void
-remove_constraints (part)
- rtx part;
+remove_constraints (rtx part)
{
- register int i, j;
- register const char *format_ptr;
+ int i, j;
+ const char *format_ptr;
if (part == 0)
return;
}
}
+/* Process an include file assuming that it lives in gcc/config/{target}/
+ if the include looks like (include "file"). */
+
+static void
+process_include (rtx desc, int lineno)
+{
+ const char *filename = XSTR (desc, 0);
+ const char *old_filename;
+ int old_lineno;
+ char *pathname;
+ FILE *input_file;
+
+ /* If specified file name is absolute, skip the include stack. */
+ if (! IS_ABSOLUTE_PATHNAME (filename))
+ {
+ struct file_name_list *stackp;
+
+ /* Search directory path, trying to open the file. */
+ for (stackp = first_dir_md_include; stackp; stackp = stackp->next)
+ {
+ static const char sep[2] = { DIR_SEPARATOR, '\0' };
+
+ pathname = concat (stackp->fname, sep, filename, NULL);
+ input_file = fopen (pathname, "r");
+ if (input_file != NULL)
+ goto success;
+ free (pathname);
+ }
+ }
+
+ if (base_dir)
+ pathname = concat (base_dir, filename, NULL);
+ else
+ pathname = xstrdup (filename);
+ input_file = fopen (pathname, "r");
+ if (input_file == NULL)
+ {
+ free (pathname);
+ message_with_line (lineno, "include file `%s' not found", filename);
+ errors = 1;
+ return;
+ }
+ success:
+
+ /* Save old cursor; setup new for the new file. Note that "lineno" the
+ argument to this function is the beginning of the include statement,
+ while read_rtx_lineno has already been advanced. */
+ old_filename = read_rtx_filename;
+ old_lineno = read_rtx_lineno;
+ read_rtx_filename = pathname;
+ read_rtx_lineno = 1;
+
+ /* Read the entire file. */
+ while (1)
+ {
+ rtx desc;
+ int c;
+
+ c = read_skip_spaces (input_file);
+ if (c == EOF)
+ break;
+
+ ungetc (c, input_file);
+ lineno = read_rtx_lineno;
+ desc = read_rtx (input_file);
+ process_rtx (desc, lineno);
+ }
+
+ /* Do not free pathname. It is attached to the various rtx queue
+ elements. */
+
+ read_rtx_filename = old_filename;
+ read_rtx_lineno = old_lineno;
+
+ fclose (input_file);
+}
+
/* Process a top level rtx in some way, queueing as appropriate. */
static void
-process_rtx (desc, lineno)
- rtx desc;
- int lineno;
+process_rtx (rtx desc, int lineno)
{
switch (GET_CODE (desc))
{
case DEFINE_INSN:
- queue_pattern (desc, &define_insn_tail, lineno);
+ queue_pattern (desc, &define_insn_tail, read_rtx_filename, lineno);
break;
case DEFINE_COND_EXEC:
- queue_pattern (desc, &define_cond_exec_tail, lineno);
+ queue_pattern (desc, &define_cond_exec_tail, read_rtx_filename, lineno);
break;
case DEFINE_ATTR:
- queue_pattern (desc, &define_attr_tail, lineno);
+ queue_pattern (desc, &define_attr_tail, read_rtx_filename, lineno);
+ break;
+
+ case INCLUDE:
+ process_include (desc, lineno);
break;
case DEFINE_INSN_AND_SPLIT:
{
const char *split_cond;
rtx split;
+ rtvec attr;
int i;
- /* Create a split with values from the insn_and_split. */
+ /* Create a split with values from the insn_and_split. */
split = rtx_alloc (DEFINE_SPLIT);
i = XVECLEN (desc, 1);
- XEXP (split, 0) = rtvec_alloc (i);
+ XVEC (split, 0) = rtvec_alloc (i);
while (--i >= 0)
{
XVECEXP (split, 0, i) = copy_rtx (XVECEXP (desc, 1, i));
insn condition to create the new split condition. */
split_cond = XSTR (desc, 4);
if (split_cond[0] == '&' && split_cond[1] == '&')
- {
- const char *insn_cond = XSTR (desc, 2);
- size_t insn_cond_len = strlen (insn_cond);
- size_t split_cond_len = strlen (split_cond);
- char *combined;
-
- combined = (char *) xmalloc (insn_cond_len + split_cond_len + 1);
- memcpy (combined, insn_cond, insn_cond_len);
- memcpy (combined + insn_cond_len, split_cond, split_cond_len + 1);
-
- split_cond = combined;
- }
+ split_cond = concat (XSTR (desc, 2), split_cond, NULL);
XSTR (split, 1) = split_cond;
XVEC (split, 2) = XVEC (desc, 5);
XSTR (split, 3) = XSTR (desc, 6);
/* Fix up the DEFINE_INSN. */
+ attr = XVEC (desc, 7);
PUT_CODE (desc, DEFINE_INSN);
- XVEC (desc, 4) = XVEC (desc, 7);
+ XVEC (desc, 4) = attr;
/* Queue them. */
- queue_pattern (desc, &define_insn_tail, lineno);
- queue_pattern (split, &other_tail, lineno);
+ queue_pattern (desc, &define_insn_tail, read_rtx_filename, lineno);
+ queue_pattern (split, &other_tail, read_rtx_filename, lineno);
break;
}
default:
- queue_pattern (desc, &other_tail, lineno);
+ queue_pattern (desc, &other_tail, read_rtx_filename, lineno);
break;
}
}
a DEFINE_INSN. */
static int
-is_predicable (elem)
- struct queue_elem *elem;
+is_predicable (struct queue_elem *elem)
{
rtvec vec = XVEC (elem->data, 4);
const char *value;
return 0;
message_with_line (elem->lineno,
- "Unknown value `%s' for `predicable' attribute",
+ "unknown value `%s' for `predicable' attribute",
value);
errors = 1;
return 0;
and its default. */
static void
-identify_predicable_attribute ()
+identify_predicable_attribute (void)
{
struct queue_elem *elem;
- char *true, *false;
+ char *p_true, *p_false;
const char *value;
- size_t len;
/* Look for the DEFINE_ATTR for `predicable', which must exist. */
for (elem = define_attr_queue; elem ; elem = elem->next)
goto found;
message_with_line (define_cond_exec_queue->lineno,
- "Attribute `predicable' not defined");
+ "attribute `predicable' not defined");
errors = 1;
return;
found:
value = XSTR (elem->data, 1);
- len = strlen (value);
- false = (char *) xmalloc (len + 1);
- memcpy (false, value, len + 1);
-
- true = strchr (false, ',');
- if (true == NULL || strchr (++true, ',') != NULL)
+ p_false = xstrdup (value);
+ p_true = strchr (p_false, ',');
+ if (p_true == NULL || strchr (++p_true, ',') != NULL)
{
message_with_line (elem->lineno,
- "Attribute `predicable' is not a boolean");
+ "attribute `predicable' is not a boolean");
errors = 1;
return;
}
- true[-1] = '\0';
+ p_true[-1] = '\0';
- predicable_true = true;
- predicable_false = false;
+ predicable_true = p_true;
+ predicable_false = p_false;
switch (GET_CODE (XEXP (elem->data, 2)))
{
case CONST:
message_with_line (elem->lineno,
- "Attribute `predicable' cannot be const");
+ "attribute `predicable' cannot be const");
errors = 1;
return;
default:
message_with_line (elem->lineno,
- "Attribute `predicable' must have a constant default");
+ "attribute `predicable' must have a constant default");
errors = 1;
return;
}
- if (strcmp (value, true) == 0)
+ if (strcmp (value, p_true) == 0)
predicable_default = 1;
- else if (strcmp (value, false) == 0)
+ else if (strcmp (value, p_false) == 0)
predicable_default = 0;
else
{
message_with_line (elem->lineno,
- "Unknown value `%s' for `predicable' attribute",
+ "unknown value `%s' for `predicable' attribute",
value);
errors = 1;
}
/* Return the number of alternatives in constraint S. */
static int
-n_alternatives (s)
- const char *s;
+n_alternatives (const char *s)
{
int n = 1;
operands. */
static void
-collect_insn_data (pattern, palt, pmax)
- rtx pattern;
- int *palt, *pmax;
+collect_insn_data (rtx pattern, int *palt, int *pmax)
{
const char *fmt;
enum rtx_code code;
switch (code)
{
case MATCH_OPERAND:
- *palt = n_alternatives (XSTR (pattern, 2));
+ i = n_alternatives (XSTR (pattern, 2));
+ *palt = (i > *palt ? i : *palt);
/* FALLTHRU */
case MATCH_OPERATOR:
collect_insn_data (XVECEXP (pattern, i, j), palt, pmax);
break;
- case 'i': case 'w': case '0': case 's': case 'S':
+ case 'i': case 'w': case '0': case 's': case 'S': case 'T':
break;
default:
}
static rtx
-alter_predicate_for_insn (pattern, alt, max_op, lineno)
- rtx pattern;
- int alt, max_op, lineno;
+alter_predicate_for_insn (rtx pattern, int alt, int max_op, int lineno)
{
const char *fmt;
enum rtx_code code;
if (n_alternatives (c) != 1)
{
message_with_line (lineno,
- "Too many alternatives for operand %d",
+ "too many alternatives for operand %d",
XINT (pattern, 0));
errors = 1;
return NULL;
}
static const char *
-alter_test_for_insn (ce_elem, insn_elem)
- struct queue_elem *ce_elem, *insn_elem;
+alter_test_for_insn (struct queue_elem *ce_elem,
+ struct queue_elem *insn_elem)
{
const char *ce_test, *insn_test;
- char *new_test;
- size_t len, ce_len, insn_len;
ce_test = XSTR (ce_elem->data, 1);
insn_test = XSTR (insn_elem->data, 2);
if (!insn_test || *insn_test == '\0')
return ce_test;
- ce_len = strlen (ce_test);
- insn_len = strlen (insn_test);
- len = 1 + ce_len + 1 + 4 + 1 + insn_len + 1 + 1;
- new_test = (char *) xmalloc (len);
-
- sprintf (new_test, "(%s) && (%s)", ce_test, insn_test);
-
- return new_test;
+ return concat ("(", ce_test, ") && (", insn_test, ")", NULL);
}
/* Adjust all of the operand numbers in OLD to match the shift they'll
adjusted string. */
static char *
-shift_output_template (new, old, disp)
- char *new;
- const char *old;
- int disp;
+shift_output_template (char *new, const char *old, int disp)
{
while (*old)
{
c = *old++;
if (ISDIGIT ((unsigned char) c))
c += disp;
- else if (ISUPPER ((unsigned char) c)
- || ISLOWER ((unsigned char) c))
+ else if (ISALPHA (c))
{
*new++ = c;
c = *old++ + disp;
}
static const char *
-alter_output_for_insn (ce_elem, insn_elem, alt, max_op)
- struct queue_elem *ce_elem, *insn_elem;
- int alt, max_op;
+alter_output_for_insn (struct queue_elem *ce_elem,
+ struct queue_elem *insn_elem,
+ int alt, int max_op)
{
const char *ce_out, *insn_out;
char *new, *p;
/* ??? Could coordinate with genoutput to not duplicate code here. */
ce_out = XSTR (ce_elem->data, 2);
- insn_out = XSTR (insn_elem->data, 3);
+ insn_out = XTMPL (insn_elem->data, 3);
if (!ce_out || *ce_out == '\0')
return insn_out;
/* Replicate insns as appropriate for the given DEFINE_COND_EXEC. */
static void
-process_one_cond_exec (ce_elem)
- struct queue_elem *ce_elem;
+process_one_cond_exec (struct queue_elem *ce_elem)
{
struct queue_elem *insn_elem;
for (insn_elem = define_insn_queue; insn_elem ; insn_elem = insn_elem->next)
}
XSTR (insn, 2) = alter_test_for_insn (ce_elem, insn_elem);
- XSTR (insn, 3) = alter_output_for_insn (ce_elem, insn_elem,
+ XTMPL (insn, 3) = alter_output_for_insn (ce_elem, insn_elem,
alternatives, max_operand);
/* ??? Set `predicable' to false. Not crucial since it's really
patterns into the define_insn chain just after their generator
is something we'll have to experiment with. */
- queue_pattern (insn, &other_tail, insn_elem->lineno);
+ queue_pattern (insn, &other_tail, insn_elem->filename,
+ insn_elem->lineno);
}
}
patterns appropriately. */
static void
-process_define_cond_exec ()
+process_define_cond_exec (void)
{
struct queue_elem *elem;
for (elem = define_cond_exec_queue; elem ; elem = elem->next)
process_one_cond_exec (elem);
}
+
+static char *
+save_string (const char *s, int len)
+{
+ register char *result = xmalloc (len + 1);
+
+ memcpy (result, s, len);
+ result[len] = 0;
+ return result;
+}
+
\f
/* The entry point for initializing the reader. */
int
-init_md_reader (filename)
- const char *filename;
+init_md_reader_args (int argc, char **argv)
+{
+ int i;
+ const char *in_fname;
+
+ max_include_len = 0;
+ in_fname = NULL;
+ for (i = 1; i < argc; i++)
+ {
+ if (argv[i][0] != '-')
+ {
+ if (in_fname == NULL)
+ in_fname = argv[i];
+ }
+ else
+ {
+ int c = argv[i][1];
+ switch (c)
+ {
+ case 'I': /* Add directory to path for includes. */
+ {
+ struct file_name_list *dirtmp;
+
+ dirtmp = (struct file_name_list *)
+ xmalloc (sizeof (struct file_name_list));
+ dirtmp->next = 0; /* New one goes on the end */
+ if (first_dir_md_include == 0)
+ first_dir_md_include = dirtmp;
+ else
+ last_dir_md_include->next = dirtmp;
+ last_dir_md_include = dirtmp; /* Tail follows the last one */
+ if (argv[i][1] == 'I' && argv[i][2] != 0)
+ dirtmp->fname = argv[i] + 2;
+ else if (i + 1 == argc)
+ fatal ("directory name missing after -I option");
+ else
+ dirtmp->fname = argv[++i];
+ if (strlen (dirtmp->fname) > max_include_len)
+ max_include_len = strlen (dirtmp->fname);
+ }
+ break;
+ default:
+ fatal ("invalid option `%s'", argv[i]);
+
+ }
+ }
+ }
+ return init_md_reader (in_fname);
+}
+\f
+/* The entry point for initializing the reader. */
+
+int
+init_md_reader (const char *filename)
{
FILE *input_file;
int c;
+ size_t i;
+ char *lastsl;
+
+ lastsl = strrchr (filename, '/');
+ if (lastsl != NULL)
+ base_dir = save_string (filename, lastsl - filename + 1 );
read_rtx_filename = filename;
input_file = fopen (filename, "r");
return FATAL_EXIT_CODE;
}
+ /* Initialize the table of insn conditions. */
+ condition_table = htab_create (n_insn_conditions,
+ hash_c_test, cmp_c_test, NULL);
+
+ for (i = 0; i < n_insn_conditions; i++)
+ *(htab_find_slot (condition_table, (PTR) &insn_conditions[i], INSERT))
+ = (PTR) &insn_conditions[i];
+
obstack_init (rtl_obstack);
errors = 0;
sequence_num = 0;
c = read_skip_spaces (input_file);
if (c == EOF)
- break;
+ break;
ungetc (c, input_file);
lineno = read_rtx_lineno;
/* The entry point for reading a single rtx from an md file. */
rtx
-read_md_rtx (lineno, seqnr)
- int *lineno;
- int *seqnr;
+read_md_rtx (int *lineno, int *seqnr)
{
struct queue_elem **queue, *elem;
rtx desc;
+ discard:
+
/* Read all patterns from a given queue before moving on to the next. */
if (define_attr_queue != NULL)
queue = &define_attr_queue;
elem = *queue;
*queue = elem->next;
desc = elem->data;
+ read_rtx_filename = elem->filename;
*lineno = elem->lineno;
*seqnr = sequence_num;
free (elem);
+ /* Discard insn patterns which we know can never match (because
+ their C test is provably always false). If insn_elision is
+ false, our caller needs to see all the patterns. Note that the
+ elided patterns are never counted by the sequence numbering; it
+ it is the caller's responsibility, when insn_elision is false, not
+ to use elided pattern numbers for anything. */
switch (GET_CODE (desc))
{
case DEFINE_INSN:
case DEFINE_EXPAND:
+ if (maybe_eval_c_test (XSTR (desc, 2)) != 0)
+ sequence_num++;
+ else if (insn_elision)
+ goto discard;
+ break;
+
case DEFINE_SPLIT:
case DEFINE_PEEPHOLE:
case DEFINE_PEEPHOLE2:
- sequence_num++;
+ if (maybe_eval_c_test (XSTR (desc, 1)) != 0)
+ sequence_num++;
+ else if (insn_elision)
+ goto discard;
break;
default:
return desc;
}
+
+/* Helper functions for insn elision. */
+
+/* Compute a hash function of a c_test structure, which is keyed
+ by its ->expr field. */
+hashval_t
+hash_c_test (const void *x)
+{
+ const struct c_test *a = (const struct c_test *) x;
+ const unsigned char *base, *s = (const unsigned char *) a->expr;
+ hashval_t hash;
+ unsigned char c;
+ unsigned int len;
+
+ base = s;
+ hash = 0;
+
+ while ((c = *s++) != '\0')
+ {
+ hash += c + (c << 17);
+ hash ^= hash >> 2;
+ }
+
+ len = s - base;
+ hash += len + (len << 17);
+ hash ^= hash >> 2;
+
+ return hash;
+}
+
+/* Compare two c_test expression structures. */
+int
+cmp_c_test (const void *x, const void *y)
+{
+ const struct c_test *a = (const struct c_test *) x;
+ const struct c_test *b = (const struct c_test *) y;
+
+ return !strcmp (a->expr, b->expr);
+}
+
+/* Given a string representing a C test expression, look it up in the
+ condition_table and report whether or not its value is known
+ at compile time. Returns a tristate: 1 for known true, 0 for
+ known false, -1 for unknown. */
+int
+maybe_eval_c_test (const char *expr)
+{
+ const struct c_test *test;
+ struct c_test dummy;
+
+ if (expr[0] == 0)
+ return 1;
+
+ if (insn_elision_unavailable)
+ return -1;
+
+ dummy.expr = expr;
+ test = (const struct c_test *) htab_find (condition_table, &dummy);
+ if (!test)
+ abort ();
+
+ return test->value;
+}
+
+/* Given a string, return the number of comma-separated elements in it.
+ Return 0 for the null string. */
+int
+n_comma_elts (const char *s)
+{
+ int n;
+
+ if (*s == '\0')
+ return 0;
+
+ for (n = 1; *s; s++)
+ if (*s == ',')
+ n++;
+
+ return n;
+}
+
+/* Given a pointer to a (char *), return a pointer to the beginning of the
+ next comma-separated element in the string. Advance the pointer given
+ to the end of that element. Return NULL if at end of string. Caller
+ is responsible for copying the string if necessary. White space between
+ a comma and an element is ignored. */
+
+const char *
+scan_comma_elt (const char **pstr)
+{
+ const char *start;
+ const char *p = *pstr;
+
+ if (*p == ',')
+ p++;
+ while (ISSPACE(*p))
+ p++;
+
+ if (*p == '\0')
+ return NULL;
+
+ start = p;
+
+ while (*p != ',' && *p != '\0')
+ p++;
+
+ *pstr = p;
+ return start;
+}
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