ogmalloc.c

UNIX下SH的实现源码

#else

/* Snarfed directly from Emacs src/dispnew.c:
   XXX Should use system bcopy if it handles overlap.  */

/* Like bcopy except never gets confused by overlap.  */

void
__malloc_safe_bcopy (afrom, ato, size)
     __ptr_t afrom;
     __ptr_t ato;
     __malloc_size_t size;
{
  char *from = afrom, *to = ato;

  if (size <= 0 || from == to)
    return;

  /* If the source and destination don't overlap, then bcopy can
     handle it.  If they do overlap, but the destination is lower in
     memory than the source, we'll assume bcopy can handle that.  */
  if (to < from || from + size <= to)
    bcopy (from, to, size);

  /* Otherwise, we'll copy from the end.  */
  else
    {
      register char *endf = from + size;
      register char *endt = to + size;

      /* If TO - FROM is large, then we should break the copy into
	 nonoverlapping chunks of TO - FROM bytes each.  However, if
	 TO - FROM is small, then the bcopy function call overhead
	 makes this not worth it.  The crossover point could be about
	 anywhere.  Since I don't think the obvious copy loop is too
	 bad, I'm trying to err in its favor.  */
      if (to - from < 64)
	{
	  do
	    *--endt = *--endf;
	  while (endf != from);
	}
      else
	{
	  for (;;)
	    {
	      endt -= (to - from);
	      endf -= (to - from);

	      if (endt < to)
		break;

	      bcopy (endf, endt, to - from);
	    }

	  /* If SIZE wasn't a multiple of TO - FROM, there will be a
	     little left over.  The amount left over is
	     (endt + (to - from)) - to, which is endt - from.  */
	  bcopy (from, to, endt - from);
	}
    }
}
#endif /* emacs */

#ifndef memmove
extern void __malloc_safe_bcopy __P ((__ptr_t, __ptr_t, __malloc_size_t));
#define memmove(to, from, size) __malloc_safe_bcopy ((from), (to), (size))
#endif

#endif


#define min(A, B) ((A) < (B) ? (A) : (B))

/* Debugging hook for realloc.  */
__ptr_t (*__realloc_hook) __P ((__ptr_t __ptr, __malloc_size_t __size));

/* Resize the given region to the new size, returning a pointer
   to the (possibly moved) region.  This is optimized for speed;
   some benchmarks seem to indicate that greater compactness is
   achieved by unconditionally allocating and copying to a
   new region.  This module has incestuous knowledge of the
   internals of both free and malloc. */
__ptr_t
_realloc_internal (ptr, size)
     __ptr_t ptr;
     __malloc_size_t size;
{
  __ptr_t result;
  int type;
  __malloc_size_t block, blocks, oldlimit;

  if (size == 0)
    {
      _free_internal (ptr);
      return _malloc_internal (0);
    }
  else if (ptr == NULL)
    return _malloc_internal (size);

  block = BLOCK (ptr);

  type = _heapinfo[block].busy.type;
  switch (type)
    {
    case 0:
      /* Maybe reallocate a large block to a small fragment.  */
      if (size <= BLOCKSIZE / 2)
	{
	  result = _malloc_internal (size);
	  if (result != NULL)
	    {
	      memcpy (result, ptr, size);
	      _free_internal (ptr);
	      return result;
	    }
	}

      /* The new size is a large allocation as well;
	 see if we can hold it in place. */
      blocks = BLOCKIFY (size);
      if (blocks < _heapinfo[block].busy.info.size)
	{
	  /* The new size is smaller; return
	     excess memory to the free list. */
	  _heapinfo[block + blocks].busy.type = 0;
	  _heapinfo[block + blocks].busy.info.size
	    = _heapinfo[block].busy.info.size - blocks;
	  _heapinfo[block].busy.info.size = blocks;
	  /* We have just created a new chunk by splitting a chunk in two.
	     Now we will free this chunk; increment the statistics counter
	     so it doesn't become wrong when _free_internal decrements it.  */
	  ++_chunks_used;
	  _free_internal (ADDRESS (block + blocks));
	  result = ptr;
	}
      else if (blocks == _heapinfo[block].busy.info.size)
	/* No size change necessary.  */
	result = ptr;
      else
	{
	  /* Won't fit, so allocate a new region that will.
	     Free the old region first in case there is sufficient
	     adjacent free space to grow without moving. */
	  blocks = _heapinfo[block].busy.info.size;
	  /* Prevent free from actually returning memory to the system.  */
	  oldlimit = _heaplimit;
	  _heaplimit = 0;
	  _free_internal (ptr);
	  result = _malloc_internal (size);
	  if (_heaplimit == 0)
	    _heaplimit = oldlimit;
	  if (result == NULL)
	    {
	      /* Now we're really in trouble.  We have to unfree
		 the thing we just freed.  Unfortunately it might
		 have been coalesced with its neighbors.  */
	      if (_heapindex == block)
	        (void) _malloc_internal (blocks * BLOCKSIZE);
	      else
		{
		  __ptr_t previous
		    = _malloc_internal ((block - _heapindex) * BLOCKSIZE);
		  (void) _malloc_internal (blocks * BLOCKSIZE);
		  _free_internal (previous);
		}
	      return NULL;
	    }
	  if (ptr != result)
	    memmove (result, ptr, blocks * BLOCKSIZE);
	}
      break;

    default:
      /* Old size is a fragment; type is logarithm
	 to base two of the fragment size.  */
      if (size > (__malloc_size_t) (1 << (type - 1)) &&
	  size <= (__malloc_size_t) (1 << type))
	/* The new size is the same kind of fragment.  */
	result = ptr;
      else
	{
	  /* The new size is different; allocate a new space,
	     and copy the lesser of the new size and the old. */
	  result = _malloc_internal (size);
	  if (result == NULL)
	    return NULL;
	  memcpy (result, ptr, min (size, (__malloc_size_t) 1 << type));
	  _free_internal (ptr);
	}
      break;
    }

  return result;
}

__ptr_t
realloc (ptr, size)
     __ptr_t ptr;
     __malloc_size_t size;
{
  if (!__malloc_initialized && !__malloc_initialize ())
    return NULL;

  return (__realloc_hook != NULL ? *__realloc_hook : _realloc_internal)
    (ptr, size);
}
/* Copyright (C) 1991, 1992, 1994 Free Software Foundation, Inc.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

This library 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111 USA.

   The author may be reached (Email) at the address [e-mail],
   or (US mail) as Mike Haertel c/o Free Software Foundation.  */

#ifndef	_MALLOC_INTERNAL
#define	_MALLOC_INTERNAL
#include <malloc.h>
#endif

/* Allocate an array of NMEMB elements each SIZE bytes long.
   The entire array is initialized to zeros.  */
__ptr_t
calloc (nmemb, size)
     register __malloc_size_t nmemb;
     register __malloc_size_t size;
{
  register __ptr_t result = malloc (nmemb * size);

  if (result != NULL)
    (void) memset (result, 0, nmemb * size);

  return result;
}
/* Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library 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.

The GNU C Library 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 the GNU C Library; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.  */

#ifndef	_MALLOC_INTERNAL
#define	_MALLOC_INTERNAL
#include <malloc.h>
#endif

#ifndef	__GNU_LIBRARY__
#define	__sbrk	sbrk
#endif

#ifdef __GNU_LIBRARY__
/* It is best not to declare this and cast its result on foreign operating
   systems with potentially hostile include files.  */

#include <stddef.h>
extern __ptr_t __sbrk __P ((ptrdiff_t increment));
#endif

#ifndef NULL
#define NULL 0
#endif

/* Allocate INCREMENT more bytes of data space,
   and return the start of data space, or NULL on errors.
   If INCREMENT is negative, shrink data space.  */
__ptr_t
__default_morecore (increment)
     __malloc_ptrdiff_t increment;
{
  __ptr_t result = (__ptr_t) __sbrk (increment);
  if (result == (__ptr_t) -1)
    return NULL;
  return result;
}
/* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

This library 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111 USA.  */

#ifndef	_MALLOC_INTERNAL
#define _MALLOC_INTERNAL
#include <malloc.h>
#endif

#if __DJGPP__ - 0 == 1

/* There is some problem with memalign in DJGPP v1 and we are supposed
   to omit it.  Noone told me why, they just told me to do it.  */

#else

__ptr_t (*__memalign_hook) __P ((size_t __size, size_t __alignment));

__ptr_t
memalign (alignment, size)
     __malloc_size_t alignment;
     __malloc_size_t size;
{
  __ptr_t result;
  unsigned long int adj, lastadj;

  if (__memalign_hook)
    return (*__memalign_hook) (alignment, size);

  /* Allocate a block with enough extra space to pad the block with up to
     (ALIGNMENT - 1) bytes if necessary.  */
  result = malloc (size + alignment - 1);
  if (result == NULL)
    return NULL;

  /* Figure out how much we will need to pad this particular block
     to achieve the required alignment.  */
  adj = (unsigned long int) ((char *) result - (char *) NULL) % alignment;

  do
    {
      /* Reallocate the block with only as much excess as it needs.  */
      free (result);
      result = malloc (adj + size);
      if (result == NULL)	/* Impossible unless interrupted.  */
	return NULL;

      lastadj = adj;
      adj = (unsigned long int) ((char *) result - (char *) NULL) % alignment;
      /* It's conceivable we might have been so unlucky as to get a
	 different block with weaker alignment.  If so, this block is too
	 short to contain SIZE after alignment correction.  So we must
	 try again and get another block, slightly larger.  */
    } while (adj > lastadj);

  if (adj != 0)
    {
      /* Record this block in the list of aligned blocks, so that `free'
	 can identify the pointer it is passed, which will be in the middle
	 of an allocated block.  */

      struct alignlist *l;
      for (l = _aligned_blocks; l != NULL; l = l->next)
	if (l->aligned == NULL)
	  /* This slot is free.  Use it.  */
	  break;
      if (l == NULL)
	{
	  l = (struct alignlist *) malloc (sizeof (struct alignlist));
	  if (l == NULL)
	    {
	      free (result);
	      return NULL;
	    }
	  l->next = _aligned_blocks;
	  _aligned_blocks = l;
	}
      l->exact = result;
      result = l->aligned = (char *) result + alignment - adj;
    }

  return result;
}

#endif /* Not DJGPP v1 */