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Annotation of OpenXM_contrib/gmp/stack-alloc.c, Revision 1.1

1.1     ! maekawa     1: /* Stack allocation routines.  This is intended for machines without support
        !             2:    for the `alloca' function.
        !             3:
        !             4: Copyright (C) 1996 Free Software Foundation, Inc.
        !             5:
        !             6: This file is part of the GNU MP Library.
        !             7:
        !             8: The GNU MP Library is free software; you can redistribute it and/or modify
        !             9: it under the terms of the GNU Library General Public License as published by
        !            10: the Free Software Foundation; either version 2 of the License, or (at your
        !            11: option) any later version.
        !            12:
        !            13: The GNU MP Library is distributed in the hope that it will be useful, but
        !            14: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            15: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            16: License for more details.
        !            17:
        !            18: You should have received a copy of the GNU Library General Public License
        !            19: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            20: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            21: MA 02111-1307, USA. */
        !            22:
        !            23: #include "stack-alloc.h"
        !            24:
        !            25: typedef struct tmp_stack tmp_stack;
        !            26:
        !            27: void *malloc ();
        !            28: static unsigned long max_total_allocation = 0;
        !            29: static unsigned long current_total_allocation = 0;
        !            30:
        !            31: static tmp_stack xxx = {&xxx, &xxx, 0};
        !            32: static tmp_stack *current = &xxx;
        !            33:
        !            34: /* Allocate a block of exactly <size> bytes.  This should only be called
        !            35:    through the TMP_ALLOC macro, which takes care of rounding/alignment.  */
        !            36: void *
        !            37: __tmp_alloc (size)
        !            38:      unsigned long size;
        !            39: {
        !            40:   void *this;
        !            41:
        !            42:   if (size > (char *) current->end - (char *) current->alloc_point)
        !            43:     {
        !            44:       void *chunk;
        !            45:       tmp_stack *header;
        !            46:       unsigned long chunk_size;
        !            47:       unsigned long now;
        !            48:
        !            49:       /* Allocate a chunk that makes the total current allocation somewhat
        !            50:         larger than the maximum allocation ever.  If size is very large, we
        !            51:         allocate that much.  */
        !            52:
        !            53:       now = current_total_allocation + size;
        !            54:       if (now > max_total_allocation)
        !            55:        {
        !            56:          /* We need more temporary memory than ever before.  Increase
        !            57:             for future needs.  */
        !            58:          now = now * 3 / 2;
        !            59:          chunk_size = now - current_total_allocation + sizeof (tmp_stack);
        !            60:          current_total_allocation = now;
        !            61:          max_total_allocation = current_total_allocation;
        !            62:        }
        !            63:       else
        !            64:        {
        !            65:          chunk_size = max_total_allocation - current_total_allocation + sizeof (tmp_stack);
        !            66:          current_total_allocation = max_total_allocation;
        !            67:        }
        !            68:
        !            69:       chunk = malloc (chunk_size);
        !            70:       header = chunk;
        !            71:       header->end = (char *) chunk + chunk_size;
        !            72:       header->alloc_point = (char *) chunk + sizeof (tmp_stack);
        !            73:       header->prev = current;
        !            74:       current = header;
        !            75:     }
        !            76:
        !            77:   this = current->alloc_point;
        !            78:   current->alloc_point = (char *) this + size;
        !            79:   return this;
        !            80: }
        !            81:
        !            82: /* Typically called at function entry.  <mark> is assigned so that __tmp_free
        !            83:    can later be used to reclaim all subsecuently allocated storage.  */
        !            84: void
        !            85: __tmp_mark (mark)
        !            86:      tmp_marker *mark;
        !            87: {
        !            88:   mark->which_chunk = current;
        !            89:   mark->alloc_point = current->alloc_point;
        !            90: }
        !            91:
        !            92: /* Free everything allocated since <mark> was assigned by __tmp_mark */
        !            93: void
        !            94: __tmp_free (mark)
        !            95:      tmp_marker *mark;
        !            96: {
        !            97:   while (mark->which_chunk != current)
        !            98:     {
        !            99:       tmp_stack *tmp;
        !           100:
        !           101:       tmp = current;
        !           102:       current = tmp->prev;
        !           103:       current_total_allocation -= (((char *) (tmp->end) - (char *) tmp)
        !           104:                                   - sizeof (tmp_stack));
        !           105:       free (tmp);
        !           106:     }
        !           107:   current->alloc_point = mark->alloc_point;
        !           108: }