mmalloc/mmemalign.c

   1 /* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include "mmalloc.h"
  20
  21 PTR
  22 mmemalign (md, alignment, size)
  23   PTR md;
  24   size_t alignment;
  25   size_t size;
  26 {
  27   PTR result;
  28   unsigned long int adj;
  29   struct alignlist *l;
  30   struct mdesc *mdp;
  31
  32   size = ((size + alignment - 1) / alignment) * alignment;
  33
  34   if ((result = mmalloc (md, size)) != NULL)
  35     {
  36       adj = RESIDUAL (result, alignment);
  37       if (adj != 0)
  38         {
  39           mdp = MD_TO_MDP (md);
  40           for (l = mdp -> aligned_blocks; l != NULL; l = l -> next)
  41             {
  42               if (l -> aligned == NULL)
  43                 {
  44                   /* This slot is free.  Use it.  */
  45                   break;
  46                 }
  47             }
  48           if (l == NULL)
  49             {
  50               l = (struct alignlist *) mmalloc (md, sizeof (struct alignlist));
  51               if (l == NULL)
  52                 {
  53                   mfree (md, result);
  54                   return (NULL);
  55                 }
  56             }
  57           l -> exact = result;
  58           result = l -> aligned = (char *) result + alignment - adj;
  59           l -> next = mdp -> aligned_blocks;
  60           mdp -> aligned_blocks = l;
  61         }
  62     }
  63   return (result);
  64 }