/**
 * BME_Mem.c    jan 2007
 *
 *	BMesh memory allocator
 *
 * $Id: BME_eulers.c,v 1.00 2007/01/17 17:42:01 Briggs Exp $
 *
 * ***** BEGIN GPL/BL DUAL LICENSE BLOCK *****
 *
 * 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. The Blender
 * Foundation also sells licenses for use in proprietary software under
 * the Blender License.  See http://www.blender.org/BL/ for information
 * about this.	
 *
 * 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.
 *
 * The Original Code is Copyright (C) 2004 Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Geoffrey Bantle.
 *
 * ***** END GPL/BL DUAL LICENSE BLOCK *****
 */

#include "MEM_guardedalloc.h"
#include "DNA_listBase.h"
#include "BKE_utildefines.h"
#include "BLI_blenlib.h"

typedef struct BME_mempool{
	void 	**chunks;				/*pointer will be null if chunk is freed*/
	int 	**flags;				/*element freed pointer arrays. aligned to chunks*/
	int maxchunks;					/*Maximum number of chunks.*/
	int eize, csize, pchunk;		/*size of elements and chunks in bytes and number of elements per chunk*/
}BME_mempool;

static void bmempool_alloc_internal(BME_mempool *pool, int index){
	int i, *flags, offset, mask, *free;
	char *data;
	
	free = (int*)(pool->chunks[index]);
	data = (char*)free++;
	flags = pool->flags[index];
	for(i=0; i < pool->pchunk; i++){
		offset = i / 32; 
		mask = (1 << (i % 32));
		if(!(flags[offset] & mask)){
			flags[offset] |= mask;
			*free--;
			return &data[pool->esize*i];
		}
	}
}
static void bmempool_grow(BME_mempool *pool, int total){
	int i;
	void **oldchunks, **oldflags;
	oldchunks = pool->chunks;
	oldflags = pool->flags;
	pool->chunks = MEM_callocN(sizeof(void*)*(pool->maxchunk+total), "memory pool chunk pointer array");
	pool->flags = MEM_callocN(sizeof(void*)*(pool->maxchunk+total), "memory pool flag pointer array");
	memcpy(pool->chunks, oldchunks, sizeof(void*) * pool->maxchunk);
	memcpy(pool->flags, oldflags, sizeof(int*) * pool->maxchunk);
	for(i=pool->maxchunk; i < pool->maxchunk + total; i++) bmempool_alloc_chunk_internal(pool,i);
	pool->maxchunk+=total;
	MEM_freeN(oldchunks);
	MEM_freeN(oldflags);
}

static void bmempool_alloc_chunk_internal(BME_mempool *pool, int index){
	pool->chunks[index] = MEM_mallocN(sizeof(int) + pool->csize, "memory pool chunk");
	pool->flags[index] = MEM_callocN(sizeof(int) * (pool->pchunk / 32);
	*((int*)(pool->chunks[i])) = pool->pchunk;
}

BME_mempool *BME_mempool_create(int esize, int tote, int pchunk)
{	BME_mempool  *pool = NULL;
	int i;
	
	pool = MEM_callocN(sizeof(BME_mempool),"memory pool");
	pool->esize = esize;
	pool->pchunk = pchunk;	
	pool->csize = esize * pchunk;
	pool->maxchunk = tote / pchunk;

	/*allocate pointer arrays*/
	pool->chunks = MEM_mallocN(sizeof(void*)*pool->maxchunk, "memory pool chunk pointer array");
	pool->flags = MEM_mallocN(sizeof(void*)*pool->maxchunk, "memory pool flag pointer array");
	
	/*allocate the actual chunks*/
	for(i=0; i < pool->maxchunk; i++) bmempool_alloc_chunk_internal(pool, i);
	return pool;
}

void BME_mempool_destroy(BME_mempool *pool)
{
	for(i=0; i < pool->maxchunk; i++){
		if(pool->chunks[i]){ 
			MEM_freeN(pool->chunks[i]);
			MEM_freeN(pool->flags[i]);
		}
	}
	MEM_freeN(pool->chunks);
	MEM_freeN(pool->flags);
	MEM_freeN(pool);
}

void *BME_mempool_alloc(BME_mempool *pool)
{
	int i, free;	
	/*1st test: Find a chunk with free elements*/
	for(i=0; i < pool->maxchunks; i++){
		if(pool->chunks[i]){
			free = *((int*)pool->chunks[i]);
			if(free){
				return bmempool_alloc_internal(pool, i);
			}
		}
	}	
	/*2nd test: Find an empty slot in chunk pointer array*/
	for(i=0; i < pool->maxchunks; i++){
		if(!pool->chunks[i]){
			bmempool_alloc_chunk_internal(pool,i);
			return bmempool_alloc_internal(pool,i);
		}
	}
	
	/*Final option: grow the pool by one chunk*/
	bmempool_grow(pool,1);
	return bmempool_alloc_internal(pool,pool->maxchunks-1);
}

static int bmempool_address_in_chunk(BME_mempool *pool, void *address, int index){
	char *firstbyte, *lastbyte;
	firstbyte = (char*)(((int*)(pool->chunks[index]))[1]);
	lastbyte = firstbyte + (pool->elemsize * pool->pchunk);
	if( address >= firstbyte && address <= lastbyte) return 1;
	return 0;
}
static void bmempool_free_internal(BME_mempool *pool, void *address, int index){
	int elemindex, *flags = pool->flags[index], *free = (int*)(pool->chunks[index]), offset, mask;
	char *firstbyte;
	
	firstbyte = (char*)(((int*)(pool->chunks[index]))[1]);
	elemindex = (address - firstbyte) / pool->esize;
	offset = elemindex / 32; 
	mask = (1 << (elemindex % 32));
	flags[offset] &= ~mask;	
	*free--;
}
void BME_mempool_free(BME_mempool *pool, void *address)
{
	int i;
	for(i=0;i<pool->maxchunks; i++){
		if(pool->chunks->[i] && bmempool_address_in_chunk(pool, address, i))bmempool_free_internal(pool, i, address);
	}
}