/* symbols.c -symbol table-

   Copyright (C) 1987, 1990, 1991, 1992 Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS 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.

   GAS 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 GAS; see the file COPYING.  If not, write to
   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <ctype.h>

#include "as.h"

#include "obstack.h"		/* For "symbols.h" */
#include "subsegs.h"

#ifndef WORKING_DOT_WORD
extern int new_broken_words;
#endif
#ifdef VMS
extern char const_flag;
#endif

static
struct hash_control *
  sy_hash;			/* symbol-name => struct symbol pointer */

/* Below are commented in "symbols.h". */
symbolS *symbol_rootP;
symbolS *symbol_lastP;
symbolS abs_symbol;

symbolS *dot_text_symbol;
symbolS *dot_data_symbol;
symbolS *dot_bss_symbol;

struct obstack notes;

static void fb_label_init PARAMS ((void));

void
symbol_begin ()
{
  symbol_lastP = NULL;
  symbol_rootP = NULL;		/* In case we have 0 symbols (!!) */
  sy_hash = hash_new ();
  memset ((char *) (&abs_symbol), '\0', sizeof (abs_symbol));
  S_SET_SEGMENT (&abs_symbol, SEG_ABSOLUTE);	/* Can't initialise a union. Sigh. */
#ifdef LOCAL_LABELS_FB
  fb_label_init ();
#endif /* LOCAL_LABELS_FB */
}

/*
 *			symbol_new()
 *
 * Return a pointer to a new symbol.
 * Die if we can't make a new symbol.
 * Fill in the symbol's values.
 * Add symbol to end of symbol chain.
 *
 *
 * Please always call this to create a new symbol.
 *
 * Changes since 1985: Symbol names may not contain '\0'. Sigh.
 * 2nd argument is now a SEG rather than a TYPE.  The mapping between
 * segments and types is mostly encapsulated herein (actually, we inherit it
 * from macros in struc-symbol.h).
 */

symbolS *
symbol_new (name, segment, value, frag)
     char *name;		/* It is copied, the caller can destroy/modify */
     segT segment;		/* Segment identifier (SEG_<something>) */
     long value;		/* Symbol value */
     fragS *frag;		/* Associated fragment */
{
  unsigned int name_length;
  char *preserved_copy_of_name;
  symbolS *symbolP;

  name_length = strlen (name) + 1;	/* +1 for \0 */
  obstack_grow (&notes, name, name_length);
  preserved_copy_of_name = obstack_finish (&notes);
  symbolP = (symbolS *) obstack_alloc (&notes, sizeof (symbolS));

  /* symbol must be born in some fixed state.  This seems as good as any. */
  memset (symbolP, 0, sizeof (symbolS));

#ifdef STRIP_UNDERSCORE
  S_SET_NAME (symbolP, (*preserved_copy_of_name == '_'
			? preserved_copy_of_name + 1
			: preserved_copy_of_name));
#else /* STRIP_UNDERSCORE */
  S_SET_NAME (symbolP, preserved_copy_of_name);
#endif /* STRIP_UNDERSCORE */

  S_SET_SEGMENT (symbolP, segment);
  S_SET_VALUE (symbolP, value);
  /*	symbol_clear_list_pointers(symbolP); uneeded if symbol is born zeroed. */

  symbolP->sy_frag = frag;
  /* krm: uneeded if symbol is born zeroed.
	     symbolP->sy_forward = NULL; *//* JF */
  symbolP->sy_number = ~0;
  symbolP->sy_name_offset = ~0;

  /*
	 * Link to end of symbol chain.
	 */
  symbol_append (symbolP, symbol_lastP, &symbol_rootP, &symbol_lastP);

  obj_symbol_new_hook (symbolP);

#ifdef DEBUG
  /*	verify_symbol_chain(symbol_rootP, symbol_lastP); */
#endif /* DEBUG */

  return (symbolP);
}				/* symbol_new() */


/*
 *			colon()
 *
 * We have just seen "<name>:".
 * Creates a struct symbol unless it already exists.
 *
 * Gripes if we are redefining a symbol incompatibly (and ignores it).
 *
 */
void 
colon (sym_name)		/* just seen "x:" - rattle symbols & frags */
     register char *sym_name;	/* symbol name, as a cannonical string */
     /* We copy this string: OK to alter later. */
{
  register symbolS *symbolP;	/* symbol we are working with */

#ifdef LOCAL_LABELS_DOLLAR
  /* Sun local labels go out of scope whenever a non-local symbol is defined.  */

  if (*sym_name != 'L')
    dollar_label_clear ();
#endif /* LOCAL_LABELS_DOLLAR */

#ifndef WORKING_DOT_WORD
  if (new_broken_words)
    {
      struct broken_word *a;
      int possible_bytes;
      fragS *frag_tmp;
      char *frag_opcode;

      extern md_short_jump_size;
      extern md_long_jump_size;
      possible_bytes = md_short_jump_size + new_broken_words * md_long_jump_size;

      frag_tmp = frag_now;
      frag_opcode = frag_var (rs_broken_word,
			      possible_bytes,
			      possible_bytes,
			      (relax_substateT) 0,
			      (symbolS *) broken_words,
			      0L,
			      NULL);

      /* We want to store the pointer to where to insert the jump table in the
		   fr_opcode of the rs_broken_word frag.  This requires a little hackery */
      while (frag_tmp && (frag_tmp->fr_type != rs_broken_word || frag_tmp->fr_opcode))
	frag_tmp = frag_tmp->fr_next;
      know (frag_tmp);
      frag_tmp->fr_opcode = frag_opcode;
      new_broken_words = 0;

      for (a = broken_words; a && a->dispfrag == 0; a = a->next_broken_word)
	a->dispfrag = frag_tmp;
    }
#endif /* WORKING_DOT_WORD */

  if ((symbolP = symbol_find (sym_name)) != 0)
    {
#ifdef	VMS
      /*
		 *	If the new symbol is .comm AND it has a size of zero,
		 *	we ignore it (i.e. the old symbol overrides it)
		 */
      if ((SEGMENT_TO_SYMBOL_TYPE ((int) now_seg) == (N_UNDF | N_EXT)) &&
	  ((obstack_next_free (&frags) - frag_now->fr_literal) == 0))
	return;
      /*
		 *	If the old symbol is .comm and it has a size of zero,
		 *	we override it with the new symbol value.
		 */
      if ((symbolP->sy_type == (N_UNDF | N_EXT))
	  && (S_GET_VALUE (symbolP) == 0))
	{
	  symbolP->sy_frag = frag_now;
	  symbolP->sy_other = const_flag;
	  S_SET_VALUE (symbolP, obstack_next_free (&frags) - frag_now->fr_literal);
	  symbolP->sy_type |= SEGMENT_TO_SYMBOL_TYPE ((int) now_seg);	/* keep N_EXT bit */
	  return;
	}
#endif /* VMS */
      /*
		 *	Now check for undefined symbols
		 */
      if (!S_IS_DEFINED (symbolP))
	{
	  if (S_GET_VALUE (symbolP) == 0)
	    {
	      symbolP->sy_frag = frag_now;
#ifdef VMS
	      symbolP->sy_other = const_flag;
#endif
	      S_SET_VALUE (symbolP, obstack_next_free (&frags) - frag_now->fr_literal);
	      S_SET_SEGMENT (symbolP, now_seg);
#ifdef N_UNDF
	      know (N_UNDF == 0);
#endif /* if we have one, it better be zero. */

	    }
	  else
	    {
	      /*
				 *	There are still several cases to check:
				 *		A .comm/.lcomm symbol being redefined as
				 *			initialized data is OK
				 *		A .comm/.lcomm symbol being redefined with
				 *			a larger size is also OK
				 *
				 * This only used to be allowed on VMS gas, but Sun cc
				 * on the sparc also depends on it.
				 */
	      /*			  char New_Type = SEGMENT_TO_SYMBOL_TYPE((int) now_seg); */
#ifdef MANY_SEGMENTS
#define SEG_BSS SEG_E2
#define SEG_DATA SEG_E1
#endif

	      if (((!S_IS_DEBUG (symbolP) && !S_IS_DEFINED (symbolP) && S_IS_EXTERNAL (symbolP))
		   || (S_GET_SEGMENT (symbolP) == SEG_BSS))
		  && ((now_seg == SEG_DATA)
		      || (now_seg == S_GET_SEGMENT (symbolP))))
		{
		  /*
					 *	Select which of the 2 cases this is
					 */
		  if (now_seg != SEG_DATA)
		    {
		      /*
						 *   New .comm for prev .comm symbol.
						 *	If the new size is larger we just
						 *	change its value.  If the new size
						 *	is smaller, we ignore this symbol
						 */
		      if (S_GET_VALUE (symbolP)
			  < ((unsigned) (obstack_next_free (&frags) - frag_now->fr_literal)))
			{
			  S_SET_VALUE (symbolP,
				       obstack_next_free (&frags) -
				       frag_now->fr_literal);
			}
		    }
		  else
		    {
		      /* It is a .comm/.lcomm being converted to initialized
			 data.  */
		      symbolP->sy_frag = frag_now;
#ifdef VMS
		      symbolP->sy_other = const_flag;
#endif /* VMS */
		      S_SET_VALUE (symbolP, obstack_next_free (&frags) - frag_now->fr_literal);
		      S_SET_SEGMENT (symbolP, now_seg);	/* keep N_EXT bit */
		    }
		}
	      else
		{
#ifdef OBJ_COFF
		  as_fatal ("Symbol \"%s\" is already defined as \"%s\"/%d.",
			    sym_name,
			    segment_name (S_GET_SEGMENT (symbolP)),
			    S_GET_VALUE (symbolP));
#else /* OBJ_COFF */
		  as_fatal ("Symbol \"%s\" is already defined as \"%s\"/%d.%d.%d.",
			    sym_name,
			    segment_name (S_GET_SEGMENT (symbolP)),
			    S_GET_OTHER (symbolP), S_GET_DESC (symbolP),
			    S_GET_VALUE (symbolP));
#endif /* OBJ_COFF */
		}
	    }			/* if the undefined symbol has no value */
	}
      else
	{
	  /* Don't blow up if the definition is the same */
	  if (!(frag_now == symbolP->sy_frag
		&& S_GET_VALUE (symbolP) == obstack_next_free (&frags) - frag_now->fr_literal
		&& S_GET_SEGMENT (symbolP) == now_seg))
	    as_fatal ("Symbol %s already defined.", sym_name);
	}			/* if this symbol is not yet defined */

    }
  else
    {
      symbolP = symbol_new (sym_name,
			    now_seg,
	       (valueT) (obstack_next_free (&frags) - frag_now->fr_literal),
			    frag_now);
#ifdef VMS
      S_SET_OTHER (symbolP, const_flag);
#endif /* VMS */

      symbol_table_insert (symbolP);
    }				/* if we have seen this symbol before */

  return;
}				/* colon() */


/*
 *			symbol_table_insert()
 *
 * Die if we can't insert the symbol.
 *
 */

void 
symbol_table_insert (symbolP)
     symbolS *symbolP;
{
  register char *error_string;

  know (symbolP);
  know (S_GET_NAME (symbolP));

  if (*(error_string = hash_jam (sy_hash, S_GET_NAME (symbolP), (char *) symbolP)))
    {
      as_fatal ("Inserting \"%s\" into symbol table failed: %s",
		S_GET_NAME (symbolP), error_string);
    }				/* on error */
}				/* symbol_table_insert() */

/*
 *			symbol_find_or_make()
 *
 * If a symbol name does not exist, create it as undefined, and insert
 * it into the symbol table. Return a pointer to it.
 */
symbolS *
symbol_find_or_make (name)
     char *name;
{
  register symbolS *symbolP;

  symbolP = symbol_find (name);

  if (symbolP == NULL)
    {
      symbolP = symbol_make (name);

      symbol_table_insert (symbolP);
    }				/* if symbol wasn't found */

  return (symbolP);
}				/* symbol_find_or_make() */

symbolS *
symbol_make (name)
     char *name;
{
  symbolS *symbolP;

  /* Let the machine description default it, e.g. for register names. */
  symbolP = md_undefined_symbol (name);

  if (!symbolP)
    {
      symbolP = symbol_new (name,
			    SEG_UNKNOWN,
			    0,
			    &zero_address_frag);
    }				/* if md didn't build us a symbol */

  return (symbolP);
}				/* symbol_make() */

/*
 *			symbol_find()
 *
 * Implement symbol table lookup.
 * In:	A symbol's name as a string: '\0' can't be part of a symbol name.
 * Out:	NULL if the name was not in the symbol table, else the address
 *	of a struct symbol associated with that name.
 */

symbolS *
symbol_find (name)
     char *name;
{
#ifdef STRIP_UNDERSCORE
  return (symbol_find_base (name, 1));
#else /* STRIP_UNDERSCORE */
  return (symbol_find_base (name, 0));
#endif /* STRIP_UNDERSCORE */
}				/* symbol_find() */

symbolS *
symbol_find_base (name, strip_underscore)
     char *name;
     int strip_underscore;
{
  if (strip_underscore && *name == '_')
    name++;
  return ((symbolS *) hash_find (sy_hash, name));
}

/*
 * Once upon a time, symbols were kept in a singly linked list.  At
 * least coff needs to be able to rearrange them from time to time, for
 * which a doubly linked list is much more convenient.  Loic did these
 * as macros which seemed dangerous to me so they're now functions.
 * xoxorich.
 */

/* Link symbol ADDME after symbol TARGET in the chain. */
void 
symbol_append (addme, target, rootPP, lastPP)
     symbolS *addme;
     symbolS *target;
     symbolS **rootPP;
     symbolS **lastPP;
{
  if (target == NULL)
    {
      know (*rootPP == NULL);
      know (*lastPP == NULL);
      *rootPP = addme;
      *lastPP = addme;
      return;
    }				/* if the list is empty */

  if (target->sy_next != NULL)
    {
#ifdef SYMBOLS_NEED_BACKPOINTERS
      target->sy_next->sy_previous = addme;
#endif /* SYMBOLS_NEED_BACKPOINTERS */
    }
  else
    {
      know (*lastPP == target);
      *lastPP = addme;
    }				/* if we have a next */

  addme->sy_next = target->sy_next;
  target->sy_next = addme;

#ifdef SYMBOLS_NEED_BACKPOINTERS
  addme->sy_previous = target;
#endif /* SYMBOLS_NEED_BACKPOINTERS */

#ifdef DEBUG
  /*	verify_symbol_chain(*rootPP, *lastPP); */
#endif /* DEBUG */

  return;
}				/* symbol_append() */

#ifdef SYMBOLS_NEED_BACKPOINTERS
/* Remove SYMBOLP from the list. */
void 
symbol_remove (symbolP, rootPP, lastPP)
     symbolS *symbolP;
     symbolS **rootPP;
     symbolS **lastPP;
{
  if (symbolP == *rootPP)
    {
      *rootPP = symbolP->sy_next;
    }				/* if it was the root */

  if (symbolP == *lastPP)
    {
      *lastPP = symbolP->sy_previous;
    }				/* if it was the tail */

  if (symbolP->sy_next != NULL)
    {
      symbolP->sy_next->sy_previous = symbolP->sy_previous;
    }				/* if not last */

  if (symbolP->sy_previous != NULL)
    {
      symbolP->sy_previous->sy_next = symbolP->sy_next;
    }				/* if not first */

#ifdef DEBUG
  verify_symbol_chain (*rootPP, *lastPP);
#endif /* DEBUG */

  return;
}				/* symbol_remove() */

/* Set the chain pointers of SYMBOL to null. */
void 
symbol_clear_list_pointers (symbolP)
     symbolS *symbolP;
{
  symbolP->sy_next = NULL;
  symbolP->sy_previous = NULL;
}				/* symbol_clear_list_pointers() */

/* Link symbol ADDME before symbol TARGET in the chain. */
void 
symbol_insert (addme, target, rootPP, lastPP)
     symbolS *addme;
     symbolS *target;
     symbolS **rootPP;
     symbolS **lastPP;
{
  if (target->sy_previous != NULL)
    {
      target->sy_previous->sy_next = addme;
    }
  else
    {
      know (*rootPP == target);
      *rootPP = addme;
    }				/* if not first */

  addme->sy_previous = target->sy_previous;
  target->sy_previous = addme;
  addme->sy_next = target;

#ifdef DEBUG
  verify_symbol_chain (*rootPP, *lastPP);
#endif /* DEBUG */

  return;
}				/* symbol_insert() */

#endif /* SYMBOLS_NEED_BACKPOINTERS */

void 
verify_symbol_chain (rootP, lastP)
     symbolS *rootP;
     symbolS *lastP;
{
  symbolS *symbolP = rootP;

  if (symbolP == NULL)
    {
      return;
    }				/* empty chain */

  for (; symbol_next (symbolP) != NULL; symbolP = symbol_next (symbolP))
    {
#ifdef SYMBOLS_NEED_BACKPOINTERS
      /*$if (symbolP->sy_previous) {
		  know(symbolP->sy_previous->sy_next == symbolP);
		  } else {
		  know(symbolP == rootP);
		        }$*//* both directions */
      know (symbolP->sy_next->sy_previous == symbolP);
#else /* SYMBOLS_NEED_BACKPOINTERS */
      ;
#endif /* SYMBOLS_NEED_BACKPOINTERS */
    }				/* verify pointers */

  know (lastP == symbolP);

  return;
}				/* verify_symbol_chain() */


#ifdef LOCAL_LABELS_DOLLAR

/* Dollar labels look like a number followed by a dollar sign.  Eg, "42$".
   They are *really* local.  That is, they go out of scope whenever we see a
   label that isn't local.  Also, like fb labels, there can be multiple
   instances of a dollar label.  Therefor, we name encode each instance with
   the instance number, keep a list of defined symbols separate from the real
   symbol table, and we treat these buggers as a sparse array.  */

static long *dollar_labels = NULL;
static long *dollar_label_instances = NULL;
static char *dollar_label_defines = NULL;
static long dollar_label_count = 0;
static long dollar_label_max = 0;

int 
dollar_label_defined (label)
     long label;
{
  long *i;

  know ((dollar_labels != NULL) || (dollar_label_count == 0));

  for (i = dollar_labels; i < dollar_labels + dollar_label_count; ++i)
    {
      if (*i == label)
	{
	  return (dollar_label_defines[i - dollar_labels]);
	}			/* found it */
    }				/* look for label */

  /* if we get here, label isn't defined */
  return (0);
}				/* dollar_label_defined() */

static int 
dollar_label_instance (label)
     long label;
{
  long *i;

  know ((dollar_labels != NULL) || (dollar_label_count == 0));

  for (i = dollar_labels; i < dollar_labels + dollar_label_count; ++i)
    {
      if (*i == label)
	{
	  return (dollar_label_instances[i - dollar_labels]);
	}			/* found it */
    }				/* look for (the union :-) label */

  /* if we get here, we haven't seen the label before, therefor it's instance
    count is zero.  */
  return (0);
}				/* dollar_label_instance() */

void 
dollar_label_clear ()
{
  memset (dollar_label_defines, '\0', dollar_label_count);
  return;
}				/* clear_dollar_labels() */

#define DOLLAR_LABEL_BUMP_BY 10

void 
define_dollar_label (label)
     long label;
{
  long *i;

  for (i = dollar_labels; i < dollar_labels + dollar_label_count; ++i)
    {
      if (*i == label)
	{
	  ++dollar_label_instances[i - dollar_labels];
	  dollar_label_defines[i - dollar_labels] = 1;
	  return;
	}			/* if we find it */
    }				/* for each existing label */

  /* if we get to here, we don't have label listed yet. */

  if (dollar_labels == NULL)
    {
      dollar_labels = (long *) xmalloc (DOLLAR_LABEL_BUMP_BY * sizeof (long));
      dollar_label_instances = (long *) xmalloc (DOLLAR_LABEL_BUMP_BY * sizeof (long));
      dollar_label_defines = xmalloc (DOLLAR_LABEL_BUMP_BY);
      dollar_label_max = DOLLAR_LABEL_BUMP_BY;
      dollar_label_count = 0;

    }
  else if (dollar_label_count == dollar_label_max)
    {
      dollar_label_max += DOLLAR_LABEL_BUMP_BY;
      dollar_labels = (long *) xrealloc ((char *) dollar_labels,
					 dollar_label_max * sizeof (long));
      dollar_label_instances = (long *) xrealloc ((char *) dollar_label_instances,
					  dollar_label_max * sizeof (long));
      dollar_label_defines = xrealloc (dollar_label_defines, dollar_label_max);
    }				/* if we needed to grow */

  dollar_labels[dollar_label_count] = label;
  dollar_label_instances[dollar_label_count] = 1;
  dollar_label_defines[dollar_label_count] = 1;
  ++dollar_label_count;
  return;
}				/* define_dollar_label() */

/*
 *			dollar_label_name()
 *
 * Caller must copy returned name: we re-use the area for the next name.
 *
 * The mth occurence of label n: is turned into the symbol "Ln^Am" where
 * n is the label number and m is the instance number. "L" makes it a label discarded
 * unless debugging and "^A"('\1') ensures no ordinary symbol SHOULD get the
 * same name as a local label symbol. The first "4:" is "L4^A1" - the m
 * numbers begin at 1.
 *
 * fb labels get the same treatment, except that ^B is used in place of ^A.
 */

char *				/* Return local label name. */
dollar_label_name (n, augend)
     register long n;		/* we just saw "n$:" : n a number */
     register int augend;	/* 0 for current instance, 1 for new instance */
{
  long i;
  /* Returned to caller, then copied.  used for created names ("4f") */
  static char symbol_name_build[24];
  register char *p;
  register char *q;
  char symbol_name_temporary[20];	/* build up a number, BACKWARDS */

  know (n >= 0);
  know (augend == 0 || augend == 1);
  p = symbol_name_build;
  *p++ = 'L';

  /* Next code just does sprintf( {}, "%d", n); */
  /* label number */
  q = symbol_name_temporary;
  for (*q++ = 0, i = n; i; ++q)
    {
      *q = i % 10 + '0';
      i /= 10;
    }
  while ((*p = *--q) != '\0')
    ++p;

  *p++ = 1;			/* ^A */

  /* instance number */
  q = symbol_name_temporary;
  for (*q++ = 0, i = dollar_label_instance (n) + augend; i; ++q)
    {
      *q = i % 10 + '0';
      i /= 10;
    }
  while ((*p++ = *--q) != '\0');;

  /* The label, as a '\0' ended string, starts at symbol_name_build. */
  return (symbol_name_build);
}				/* dollar_label_name() */

#endif /* LOCAL_LABELS_DOLLAR */

#ifdef LOCAL_LABELS_FB

/*
 * Sombody else's idea of local labels. They are made by "n:" where n
 * is any decimal digit. Refer to them with
 *  "nb" for previous (backward) n:
 *  or "nf" for next (forward) n:.
 *
 * We do a little better and let n be any number, not just a single digit, but
 * since the other guy's assembler only does ten, we treat the first ten
 * specially.
 *
 * Like someone else's assembler, we have one set of local label counters for
 * entire assembly, not one set per (sub)segment like in most assemblers. This
 * implies that one can refer to a label in another segment, and indeed some
 * crufty compilers have done just that.
 *
 * Since there could be a LOT of these things, treat them as a sparse array.
 */

#define FB_LABEL_SPECIAL (10)

static long fb_low_counter[FB_LABEL_SPECIAL];
static long *fb_labels;
static long *fb_label_instances;
static long fb_label_count = 0;
static long fb_label_max = 0;

/* this must be more than FB_LABEL_SPECIAL */
#define FB_LABEL_BUMP_BY (FB_LABEL_SPECIAL + 6)

static void 
fb_label_init ()
{
  memset ((void *) fb_low_counter, '\0', sizeof (fb_low_counter));
}				/* fb_label_init() */

/* add one to the instance number of this fb label */
void 
fb_label_instance_inc (label)
     long label;
{
  long *i;

  if (label < FB_LABEL_SPECIAL)
    {
      ++fb_low_counter[label];
      return;
    }

  for (i = fb_labels + FB_LABEL_SPECIAL; i < fb_labels + fb_label_count; ++i)
    {
      if (*i == label)
	{
	  ++fb_label_instances[i - fb_labels];
	  return;
	}			/* if we find it */
    }				/* for each existing label */

  /* if we get to here, we don't have label listed yet. */

  if (fb_labels == NULL)
    {
      fb_labels = (long *) xmalloc (FB_LABEL_BUMP_BY * sizeof (long));
      fb_label_instances = (long *) xmalloc (FB_LABEL_BUMP_BY * sizeof (long));
      fb_label_max = FB_LABEL_BUMP_BY;
      fb_label_count = FB_LABEL_SPECIAL;

    }
  else if (fb_label_count == fb_label_max)
    {
      fb_label_max += FB_LABEL_BUMP_BY;
      fb_labels = (long *) xrealloc ((char *) fb_labels,
				     fb_label_max * sizeof (long));
      fb_label_instances = (long *) xrealloc ((char *) fb_label_instances,
					      fb_label_max * sizeof (long));
    }				/* if we needed to grow */

  fb_labels[fb_label_count] = label;
  fb_label_instances[fb_label_count] = 1;
  ++fb_label_count;
  return;
}				/* fb_label_instance_inc() */

static long 
fb_label_instance (label)
     long label;
{
  long *i;

  if (label < FB_LABEL_SPECIAL)
    {
      return (fb_low_counter[label]);
    }

  for (i = fb_labels + FB_LABEL_SPECIAL; i < fb_labels + fb_label_count; ++i)
    {
      if (*i == label)
	{
	  return (fb_label_instances[i - fb_labels]);
	}			/* if we find it */
    }				/* for each existing label */

  /* NOTREACHED */
  know (0);
}				/* fb_label_instance() */

/*
 *			fb_label_name()
 *
 * Caller must copy returned name: we re-use the area for the next name.
 *
 * The mth occurence of label n: is turned into the symbol "Ln^Bm" where
 * n is the label number and m is the instance number. "L" makes it a label discarded
 * unless debugging and "^B"('\2') ensures no ordinary symbol SHOULD get the
 * same name as a local label symbol. The first "4:" is "L4^B1" - the m
 * numbers begin at 1.
 *
 * dollar labels get the same treatment, except that ^A is used in place of ^B.
 */

char *				/* Return local label name. */
fb_label_name (n, augend)
     long n;			/* we just saw "n:", "nf" or "nb" : n a number */
     long augend;		/* 0 for nb, 1 for n:, nf */
{
  long i;
  /* Returned to caller, then copied.  used for created names ("4f") */
  static char symbol_name_build[24];
  register char *p;
  register char *q;
  char symbol_name_temporary[20];	/* build up a number, BACKWARDS */

  know (n >= 0);
  know (augend == 0 || augend == 1);
  p = symbol_name_build;
  *p++ = 'L';

  /* Next code just does sprintf( {}, "%d", n); */
  /* label number */
  q = symbol_name_temporary;
  for (*q++ = 0, i = n; i; ++q)
    {
      *q = i % 10 + '0';
      i /= 10;
    }
  while ((*p = *--q) != '\0')
    ++p;

  *p++ = 2;			/* ^B */

  /* instance number */
  q = symbol_name_temporary;
  for (*q++ = 0, i = fb_label_instance (n) + augend; i; ++q)
    {
      *q = i % 10 + '0';
      i /= 10;
    }
  while ((*p++ = *--q) != '\0');;

  /* The label, as a '\0' ended string, starts at symbol_name_build. */
  return (symbol_name_build);
}				/* fb_label_name() */

#endif /* LOCAL_LABELS_FB */


/*
 * decode name that may have been generated by foo_label_name() above.  If
 * the name wasn't generated by foo_label_name(), then return it unaltered.
 * This is used for error messages.
 */

char *
decode_local_label_name (s)
     char *s;
{
  char *p;
  char *symbol_decode;
  int label_number;
  int instance_number;
  char *type;
  const char *message_format = "\"%d\" (instance number %d of a %s label)";

  if (s[0] != 'L')
    return (s);

  for (label_number = 0, p = s + 1; isdigit (*p); ++p)
    {
      label_number = (10 * label_number) + *p - '0';
    }

  if (*p == 1)
    {
      type = "dollar";
    }
  else if (*p == 2)
    {
      type = "fb";
    }
  else
    {
      return (s);
    }

  for (instance_number = 0, p = s + 1; isdigit (*p); ++p)
    {
      instance_number = (10 * instance_number) + *p - '0';
    }

  symbol_decode = obstack_alloc (&notes, strlen (message_format) + 30);
  (void) sprintf (symbol_decode, message_format, label_number,
		  instance_number, type);

  return (symbol_decode);
}				/* decode_local_label_name() */

/* end of symbols.c */