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util_mem.c

/*
 *  Copyright (C) 2000 Takashi Iwai <tiwai@suse.de>
 *
 *  Generic memory management routines for soundcard memory allocation
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/util_mem.h>

MODULE_AUTHOR("Takashi Iwai");
MODULE_DESCRIPTION("Generic memory management routines for soundcard memory allocation");
MODULE_LICENSE("GPL");

#define get_memblk(p)   list_entry(p, struct snd_util_memblk, list)

/*
 * create a new memory manager
 */
struct snd_util_memhdr *
snd_util_memhdr_new(int memsize)
{
      struct snd_util_memhdr *hdr;

      hdr = kzalloc(sizeof(*hdr), GFP_KERNEL);
      if (hdr == NULL)
            return NULL;
      hdr->size = memsize;
      mutex_init(&hdr->block_mutex);
      INIT_LIST_HEAD(&hdr->block);

      return hdr;
}

/*
 * free a memory manager
 */
void snd_util_memhdr_free(struct snd_util_memhdr *hdr)
{
      struct list_head *p;

      snd_assert(hdr != NULL, return);
      /* release all blocks */
      while ((p = hdr->block.next) != &hdr->block) {
            list_del(p);
            kfree(get_memblk(p));
      }
      kfree(hdr);
}

/*
 * allocate a memory block (without mutex)
 */
struct snd_util_memblk *
__snd_util_mem_alloc(struct snd_util_memhdr *hdr, int size)
{
      struct snd_util_memblk *blk;
      unsigned int units, prev_offset;
      struct list_head *p;

      snd_assert(hdr != NULL, return NULL);
      snd_assert(size > 0, return NULL);

      /* word alignment */
      units = size;
      if (units & 1)
            units++;
      if (units > hdr->size)
            return NULL;

      /* look for empty block */
      prev_offset = 0;
      list_for_each(p, &hdr->block) {
            blk = get_memblk(p);
            if (blk->offset - prev_offset >= units)
                  goto __found;
            prev_offset = blk->offset + blk->size;
      }
      if (hdr->size - prev_offset < units)
            return NULL;

__found:
      return __snd_util_memblk_new(hdr, units, p->prev);
}


/*
 * create a new memory block with the given size
 * the block is linked next to prev
 */
struct snd_util_memblk *
__snd_util_memblk_new(struct snd_util_memhdr *hdr, unsigned int units,
                  struct list_head *prev)
{
      struct snd_util_memblk *blk;

      blk = kmalloc(sizeof(struct snd_util_memblk) + hdr->block_extra_size,
                  GFP_KERNEL);
      if (blk == NULL)
            return NULL;

      if (prev == &hdr->block)
            blk->offset = 0;
      else {
            struct snd_util_memblk *p = get_memblk(prev);
            blk->offset = p->offset + p->size;
      }
      blk->size = units;
      list_add(&blk->list, prev);
      hdr->nblocks++;
      hdr->used += units;
      return blk;
}


/*
 * allocate a memory block (with mutex)
 */
struct snd_util_memblk *
snd_util_mem_alloc(struct snd_util_memhdr *hdr, int size)
{
      struct snd_util_memblk *blk;
      mutex_lock(&hdr->block_mutex);
      blk = __snd_util_mem_alloc(hdr, size);
      mutex_unlock(&hdr->block_mutex);
      return blk;
}


/*
 * remove the block from linked-list and free resource
 * (without mutex)
 */
void
__snd_util_mem_free(struct snd_util_memhdr *hdr, struct snd_util_memblk *blk)
{
      list_del(&blk->list);
      hdr->nblocks--;
      hdr->used -= blk->size;
      kfree(blk);
}

/*
 * free a memory block (with mutex)
 */
int snd_util_mem_free(struct snd_util_memhdr *hdr, struct snd_util_memblk *blk)
{
      snd_assert(hdr && blk, return -EINVAL);

      mutex_lock(&hdr->block_mutex);
      __snd_util_mem_free(hdr, blk);
      mutex_unlock(&hdr->block_mutex);
      return 0;
}

/*
 * return available memory size
 */
int snd_util_mem_avail(struct snd_util_memhdr *hdr)
{
      unsigned int size;
      mutex_lock(&hdr->block_mutex);
      size = hdr->size - hdr->used;
      mutex_unlock(&hdr->block_mutex);
      return size;
}


EXPORT_SYMBOL(snd_util_memhdr_new);
EXPORT_SYMBOL(snd_util_memhdr_free);
EXPORT_SYMBOL(snd_util_mem_alloc);
EXPORT_SYMBOL(snd_util_mem_free);
EXPORT_SYMBOL(snd_util_mem_avail);
EXPORT_SYMBOL(__snd_util_mem_alloc);
EXPORT_SYMBOL(__snd_util_mem_free);
EXPORT_SYMBOL(__snd_util_memblk_new);

/*
 *  INIT part
 */

static int __init alsa_util_mem_init(void)
{
      return 0;
}

static void __exit alsa_util_mem_exit(void)
{
}

module_init(alsa_util_mem_init)
module_exit(alsa_util_mem_exit)

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