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/* Stack allocation routines. This is intended for machines without support
for the `alloca' function.
Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP 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.
The GNU MP 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 the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "stack-alloc.h"
typedef struct tmp_stack tmp_stack;
void *malloc ();
static unsigned long max_total_allocation = 0;
static unsigned long current_total_allocation = 0;
static tmp_stack xxx = {&xxx, &xxx, 0};
static tmp_stack *current = &xxx;
/* Allocate a block of exactly <size> bytes. This should only be called
through the TMP_ALLOC macro, which takes care of rounding/alignment. */
void *
__tmp_alloc (size)
unsigned long size;
{
void *this;
if (size > (char *) current->end - (char *) current->alloc_point)
{
void *chunk;
tmp_stack *header;
unsigned long chunk_size;
unsigned long now;
/* Allocate a chunk that makes the total current allocation somewhat
larger than the maximum allocation ever. If size is very large, we
allocate that much. */
now = current_total_allocation + size;
if (now > max_total_allocation)
{
/* We need more temporary memory than ever before. Increase
for future needs. */
now = now * 3 / 2;
chunk_size = now - current_total_allocation + sizeof (tmp_stack);
current_total_allocation = now;
max_total_allocation = current_total_allocation;
}
else
{
chunk_size = max_total_allocation - current_total_allocation + sizeof (tmp_stack);
current_total_allocation = max_total_allocation;
}
chunk = malloc (chunk_size);
header = chunk;
header->end = (char *) chunk + chunk_size;
header->alloc_point = (char *) chunk + sizeof (tmp_stack);
header->prev = current;
current = header;
}
this = current->alloc_point;
current->alloc_point = (char *) this + size;
return this;
}
/* Typically called at function entry. <mark> is assigned so that __tmp_free
can later be used to reclaim all subsecuently allocated storage. */
void
__tmp_mark (mark)
tmp_marker *mark;
{
mark->which_chunk = current;
mark->alloc_point = current->alloc_point;
}
/* Free everything allocated since <mark> was assigned by __tmp_mark */
void
__tmp_free (mark)
tmp_marker *mark;
{
while (mark->which_chunk != current)
{
tmp_stack *tmp;
tmp = current;
current = tmp->prev;
current_total_allocation -= (((char *) (tmp->end) - (char *) tmp)
- sizeof (tmp_stack));
free (tmp);
}
current->alloc_point = mark->alloc_point;
}
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