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/* Stack allocation routines. This is intended for machines without support
for the `alloca' function.
Copyright 1996, 1997, 1999, 2000, 2001, 2006 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 Lesser General Public License as published by
the Free Software Foundation; either version 3 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
#include "gmp.h"
#include "gmp-impl.h"
struct tmp_stack
{
void *end;
void *alloc_point;
struct tmp_stack *prev;
};
typedef struct tmp_stack tmp_stack;
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;
/* The rounded size of the header of each allocation block. */
#define HSIZ ROUND_UP_MULTIPLE (sizeof (tmp_stack), __TMP_ALIGN)
/* Allocate a block of exactly <size> bytes. This should only be called
through the TMP_ALLOC macro, which takes care of rounding/alignment. */
void *
__gmp_tmp_alloc (unsigned long size)
{
void *that;
ASSERT ((size % __TMP_ALIGN) == 0);
ASSERT (((unsigned) current->alloc_point % __TMP_ALIGN) == 0);
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 + __TMP_ALIGN - 1) & -__TMP_ALIGN;
chunk_size = now - current_total_allocation + HSIZ;
current_total_allocation = now;
max_total_allocation = current_total_allocation;
}
else
{
chunk_size = max_total_allocation - current_total_allocation + HSIZ;
current_total_allocation = max_total_allocation;
}
chunk = (*__gmp_allocate_func) (chunk_size);
header = (tmp_stack *) chunk;
header->end = (char *) chunk + chunk_size;
header->alloc_point = (char *) chunk + HSIZ;
header->prev = current;
current = header;
}
that = current->alloc_point;
current->alloc_point = (char *) that + size;
ASSERT (((unsigned) that % __TMP_ALIGN) == 0);
return that;
}
/* Typically called at function entry. <mark> is assigned so that
__gmp_tmp_free can later be used to reclaim all subsequently allocated
storage. */
void
__gmp_tmp_mark (struct tmp_marker *mark)
{
mark->which_chunk = current;
mark->alloc_point = current->alloc_point;
}
/* Free everything allocated since <mark> was assigned by __gmp_tmp_mark */
void
__gmp_tmp_free (struct tmp_marker *mark)
{
while (mark->which_chunk != current)
{
tmp_stack *tmp;
tmp = current;
current = tmp->prev;
current_total_allocation -= (((char *) (tmp->end) - (char *) tmp) - HSIZ);
(*__gmp_free_func) (tmp, (char *) tmp->end - (char *) tmp);
}
current->alloc_point = mark->alloc_point;
}
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