sound/oss/emu10k1/emuadxmg.c

   1
   2 /*
   3  **********************************************************************
   4  *     emuadxmg.c - Address space manager for emu10k1 driver
   5  *     Copyright 1999, 2000 Creative Labs, Inc.
   6  *
   7  **********************************************************************
   8  *
   9  *     Date                 Author          Summary of changes
  10  *     ----                 ------          ------------------
  11  *     October 20, 1999     Bertrand Lee    base code release
  12  *
  13  **********************************************************************
  14  *
  15  *     This program is free software; you can redistribute it and/or
  16  *     modify it under the terms of the GNU General Public License as
  17  *     published by the Free Software Foundation; either version 2 of
  18  *     the License, or (at your option) any later version.
  19  *
  20  *     This program is distributed in the hope that it will be useful,
  21  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  *     GNU General Public License for more details.
  24  *
  25  *     You should have received a copy of the GNU General Public
  26  *     License along with this program; if not, write to the Free
  27  *     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
  28  *     USA.
  29  *
  30  **********************************************************************
  31  */
  32
  33 #include "hwaccess.h"
  34
  35 /* Allocates emu address space */
  36
  37 int emu10k1_addxmgr_alloc(u32 size, struct emu10k1_card *card)
  38 {
  39         u16 *pagetable = card->emupagetable;
  40         u16 index = 0;
  41         u16 numpages;
  42         unsigned long flags;
  43
  44         /* Convert bytes to pages */
  45         numpages = (size / EMUPAGESIZE) + ((size % EMUPAGESIZE) ? 1 : 0);
  46
  47         spin_lock_irqsave(&card->lock, flags);
  48
  49         while (index < (MAXPAGES - 1)) {
  50                 if (pagetable[index] & 0x8000) {
  51                         /* This block of pages is in use, jump to the start of the next block. */
  52                         index += (pagetable[index] & 0x7fff);
  53                 } else {
  54                         /* Found free block */
  55                         if (pagetable[index] >= numpages) {
  56
  57                                 /* Block is large enough */
  58
  59                                 /* If free block is larger than the block requested
  60                                  * then adjust the size of the block remaining */
  61                                 if (pagetable[index] > numpages)
  62                                         pagetable[index + numpages] = pagetable[index] - numpages;
  63
  64                                 pagetable[index] = (numpages | 0x8000); /* Mark block as used */
  65
  66                                 spin_unlock_irqrestore(&card->lock, flags);
  67
  68                                 return index;
  69                         } else {
  70                                 /* Block too small, jump to the start of the next block */
  71                                 index += pagetable[index];
  72                         }
  73                 }
  74         }
  75
  76         spin_unlock_irqrestore(&card->lock, flags);
  77
  78         return -1;
  79 }
  80
  81 /* Frees a previously allocated emu address space. */
  82
  83 void emu10k1_addxmgr_free(struct emu10k1_card *card, int index)
  84 {
  85         u16 *pagetable = card->emupagetable;
  86         u16 origsize = 0;
  87         unsigned long flags;
  88
  89         spin_lock_irqsave(&card->lock, flags);
  90
  91         if (pagetable[index] & 0x8000) {
  92                 /* Block is allocated - mark block as free */
  93                 origsize = pagetable[index] & 0x7fff;
  94                 pagetable[index] = origsize;
  95
  96                 /* If next block is free, we concat both blocks */
  97                 if (!(pagetable[index + origsize] & 0x8000))
  98                         pagetable[index] += pagetable[index + origsize] & 0x7fff;
  99         }
 100
 101         spin_unlock_irqrestore(&card->lock, flags);
 102
 103         return;
 104 }