/*
   *  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 <linux/module.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;
  
  	if (!hdr)
  		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;
  
  	if (snd_BUG_ON(!hdr || 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)
  {
  	if (snd_BUG_ON(!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)