122 lines
3.8 KiB
C
122 lines
3.8 KiB
C
/* Stack allocation routines. This is intended for machines without support
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for the `alloca' function.
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Copyright 1996, 1997, 1999, 2000, 2001, 2006 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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struct tmp_stack
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{
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void *end;
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void *alloc_point;
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struct tmp_stack *prev;
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};
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typedef struct tmp_stack tmp_stack;
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static unsigned long max_total_allocation = 0;
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static unsigned long current_total_allocation = 0;
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static tmp_stack xxx = {&xxx, &xxx, 0};
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static tmp_stack *current = &xxx;
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/* The rounded size of the header of each allocation block. */
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#define HSIZ ROUND_UP_MULTIPLE (sizeof (tmp_stack), __TMP_ALIGN)
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/* Allocate a block of exactly <size> bytes. This should only be called
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through the TMP_ALLOC macro, which takes care of rounding/alignment. */
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void *
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__gmp_tmp_alloc (unsigned long size)
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{
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void *that;
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ASSERT ((size % __TMP_ALIGN) == 0);
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ASSERT (((unsigned) current->alloc_point % __TMP_ALIGN) == 0);
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if (size > (char *) current->end - (char *) current->alloc_point)
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{
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void *chunk;
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tmp_stack *header;
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unsigned long chunk_size;
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unsigned long now;
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/* Allocate a chunk that makes the total current allocation somewhat
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larger than the maximum allocation ever. If size is very large, we
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allocate that much. */
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now = current_total_allocation + size;
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if (now > max_total_allocation)
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{
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/* We need more temporary memory than ever before. Increase
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for future needs. */
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now = (now * 3 / 2 + __TMP_ALIGN - 1) & -__TMP_ALIGN;
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chunk_size = now - current_total_allocation + HSIZ;
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current_total_allocation = now;
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max_total_allocation = current_total_allocation;
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}
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else
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{
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chunk_size = max_total_allocation - current_total_allocation + HSIZ;
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current_total_allocation = max_total_allocation;
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}
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chunk = (*__gmp_allocate_func) (chunk_size);
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header = (tmp_stack *) chunk;
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header->end = (char *) chunk + chunk_size;
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header->alloc_point = (char *) chunk + HSIZ;
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header->prev = current;
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current = header;
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}
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that = current->alloc_point;
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current->alloc_point = (char *) that + size;
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ASSERT (((unsigned) that % __TMP_ALIGN) == 0);
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return that;
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}
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/* Typically called at function entry. <mark> is assigned so that
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__gmp_tmp_free can later be used to reclaim all subsequently allocated
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storage. */
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void
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__gmp_tmp_mark (struct tmp_marker *mark)
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{
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mark->which_chunk = current;
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mark->alloc_point = current->alloc_point;
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}
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/* Free everything allocated since <mark> was assigned by __gmp_tmp_mark */
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void
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__gmp_tmp_free (struct tmp_marker *mark)
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{
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while (mark->which_chunk != current)
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{
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tmp_stack *tmp;
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tmp = current;
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current = tmp->prev;
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current_total_allocation -= (((char *) (tmp->end) - (char *) tmp) - HSIZ);
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(*__gmp_free_func) (tmp, (char *) tmp->end - (char *) tmp);
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}
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current->alloc_point = mark->alloc_point;
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}
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