/*
 * ***** BEGIN GPL 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.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2008 by Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Geoffery Bantle
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenlib/intern/BLI_mempool.c
 *  \ingroup bli
 */

/*
 * Simple, fast memory allocator for allocating many elements of the same size.
 */

#include "BLI_utildefines.h"
#include "BLI_listbase.h"

#include "BLI_mempool.h" /* own include */

#include "DNA_listBase.h"

#include "MEM_guardedalloc.h"

#include <string.h>
#include <stdlib.h>

/* note: copied from BKE_utildefines.h, don't use here because we're in BLI */
#ifdef __BIG_ENDIAN__
/* Big Endian */
#  define MAKE_ID(a,b,c,d) ( (int)(a)<<24 | (int)(b)<<16 | (c)<<8 | (d) )
#else
/* Little Endian */
#  define MAKE_ID(a,b,c,d) ( (int)(d)<<24 | (int)(c)<<16 | (b)<<8 | (a) )
#endif

#define FREEWORD MAKE_ID('f', 'r', 'e', 'e')

typedef struct BLI_freenode {
	struct BLI_freenode *next;
	int freeword; /* used to identify this as a freed node */
} BLI_freenode;

typedef struct BLI_mempool_chunk {
	struct BLI_mempool_chunk *next, *prev;
	void *data;
} BLI_mempool_chunk;

struct BLI_mempool {
	struct ListBase chunks;
	int esize;         /* element size in bytes */
	int csize;         /* chunk size in bytes */
	int pchunk;        /* number of elements per chunk */
	int flag;
	/* keeps aligned to 16 bits */

	BLI_freenode *free;    /* free element list. Interleaved into chunk datas. */
	int totalloc, totused; /* total number of elements allocated in total,
	                        * and currently in use */
};

#define MEMPOOL_ELEM_SIZE_MIN (sizeof(void *) * 2)

BLI_mempool *BLI_mempool_create(int esize, int totelem, int pchunk, int flag)
{
	BLI_mempool *pool = NULL;
	BLI_freenode *lasttail = NULL, *curnode = NULL;
	int i, j, maxchunks;
	char *addr;

	/* allocate the pool structure */
	if (flag & BLI_MEMPOOL_SYSMALLOC) {
		pool = malloc(sizeof(BLI_mempool));
	}
	else {
		pool = MEM_mallocN(sizeof(BLI_mempool), "memory pool");
	}

	/* set the elem size */
	if (esize < MEMPOOL_ELEM_SIZE_MIN) {
		esize = MEMPOOL_ELEM_SIZE_MIN;
	}

	if (flag & BLI_MEMPOOL_ALLOW_ITER) {
		pool->esize = MAX2(esize, sizeof(BLI_freenode));
	}
	else {
		pool->esize = esize;
	}

	pool->flag = flag;
	pool->pchunk = pchunk;
	pool->csize = esize * pchunk;
	pool->chunks.first = pool->chunks.last = NULL;
	pool->totused = 0;

	maxchunks = totelem / pchunk + 1;
	if (maxchunks == 0) {
		maxchunks = 1;
	}

	/* allocate the actual chunks */
	for (i = 0; i < maxchunks; i++) {
		BLI_mempool_chunk *mpchunk;

		if (flag & BLI_MEMPOOL_SYSMALLOC) {
			mpchunk = malloc(sizeof(BLI_mempool_chunk));
			mpchunk->data = malloc(pool->csize);
		}
		else {
			mpchunk = MEM_mallocN(sizeof(BLI_mempool_chunk), "BLI_Mempool Chunk");
			mpchunk->data = MEM_mallocN(pool->csize, "BLI Mempool Chunk Data");
		}

		mpchunk->next = mpchunk->prev = NULL;
		BLI_addtail(&(pool->chunks), mpchunk);

		if (i == 0) {
			pool->free = mpchunk->data; /* start of the list */
			if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
				pool->free->freeword = FREEWORD;
			}
		}

		/* loop through the allocated data, building the pointer structures */
		for (addr = mpchunk->data, j = 0; j < pool->pchunk; j++) {
			curnode = ((BLI_freenode *)addr);
			addr += pool->esize;
			curnode->next = (BLI_freenode *)addr;
			if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
				if (j != pool->pchunk - 1)
					curnode->next->freeword = FREEWORD;
				curnode->freeword = FREEWORD;
			}
		}
		/* final pointer in the previously allocated chunk is wrong */
		if (lasttail) {
			lasttail->next = mpchunk->data;
			if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
				lasttail->freeword = FREEWORD;
			}
		}

		/* set the end of this chunks memoryy to the new tail for next iteration */
		lasttail = curnode;

		pool->totalloc += pool->pchunk;
	}
	/* terminate the list */
	curnode->next = NULL;
	return pool;
}

void *BLI_mempool_alloc(BLI_mempool *pool)
{
	void *retval = NULL;

	pool->totused++;

	if (!(pool->free)) {
		BLI_freenode *curnode = NULL;
		char *addr;
		int j;

		/* need to allocate a new chunk */
		BLI_mempool_chunk *mpchunk;

		if (pool->flag & BLI_MEMPOOL_SYSMALLOC) {
			mpchunk       = malloc(sizeof(BLI_mempool_chunk));
			mpchunk->data = malloc(pool->csize);
		}
		else {
			mpchunk       = MEM_mallocN(sizeof(BLI_mempool_chunk), "BLI_Mempool Chunk");
			mpchunk->data = MEM_mallocN(pool->csize, "BLI_Mempool Chunk Data");
		}

		mpchunk->next = mpchunk->prev = NULL;
		BLI_addtail(&(pool->chunks), mpchunk);

		pool->free = mpchunk->data; /* start of the list */

		if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
			pool->free->freeword = FREEWORD;
		}

		for (addr = mpchunk->data, j = 0; j < pool->pchunk; j++) {
			curnode = ((BLI_freenode *)addr);
			addr += pool->esize;
			curnode->next = (BLI_freenode *)addr;

			if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
				curnode->freeword = FREEWORD;
				if (j != pool->pchunk - 1)
					curnode->next->freeword = FREEWORD;
			}
		}
		curnode->next = NULL; /* terminate the list */

		pool->totalloc += pool->pchunk;
	}

	retval = pool->free;

	if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
		pool->free->freeword = 0x7FFFFFFF;
	}

	pool->free = pool->free->next;
	//memset(retval, 0, pool->esize);
	return retval;
}

void *BLI_mempool_calloc(BLI_mempool *pool)
{
	void *retval = BLI_mempool_alloc(pool);
	memset(retval, 0, pool->esize);
	return retval;
}

/* doesnt protect against double frees, don't be stupid! */
void BLI_mempool_free(BLI_mempool *pool, void *addr)
{
	BLI_freenode *newhead = addr;

	if (pool->flag & BLI_MEMPOOL_ALLOW_ITER) {
		newhead->freeword = FREEWORD;
	}

	newhead->next = pool->free;
	pool->free = newhead;

	pool->totused--;

	/* nothing is in use; free all the chunks except the first */
	if (pool->totused == 0) {
		BLI_freenode *curnode = NULL;
		char *tmpaddr = NULL;
		int i;

		BLI_mempool_chunk *mpchunk = NULL;
		BLI_mempool_chunk *first = pool->chunks.first;

		BLI_remlink(&pool->chunks, first);

		if (pool->flag & BLI_MEMPOOL_SYSMALLOC) {
			for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
				free(mpchunk->data);
			}
			BLI_freelist(&(pool->chunks));
		}
		else {
			for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
				MEM_freeN(mpchunk->data);
			}
			BLI_freelistN(&(pool->chunks));
		}

		BLI_addtail(&pool->chunks, first);
		pool->totalloc = pool->pchunk;

		pool->free = first->data; /* start of the list */
		for (tmpaddr = first->data, i = 0; i < pool->pchunk; i++) {
			curnode = ((BLI_freenode *)tmpaddr);
			tmpaddr += pool->esize;
			curnode->next = (BLI_freenode *)tmpaddr;
		}
		curnode->next = NULL; /* terminate the list */
	}
}

int BLI_mempool_count(BLI_mempool *pool)
{
	return pool->totused;
}

void *BLI_mempool_findelem(BLI_mempool *pool, int index)
{
	if (!(pool->flag & BLI_MEMPOOL_ALLOW_ITER)) {
		fprintf(stderr, "%s: Error! you can't iterate over this mempool!\n", __func__);
		return NULL;
	}
	else if ((index >= 0) && (index < pool->totused)) {
		/* we could have some faster mem chunk stepping code inline */
		BLI_mempool_iter iter;
		void *elem;
		BLI_mempool_iternew(pool, &iter);
		for (elem = BLI_mempool_iterstep(&iter); index-- != 0; elem = BLI_mempool_iterstep(&iter)) {
			/* do nothing */
		};
		return elem;
	}

	return NULL;
}

void BLI_mempool_iternew(BLI_mempool *pool, BLI_mempool_iter *iter)
{
	if (!(pool->flag & BLI_MEMPOOL_ALLOW_ITER)) {
		fprintf(stderr, "%s: Error! you can't iterate over this mempool!\n", __func__);
		iter->curchunk = NULL;
		iter->curindex = 0;

		return;
	}

	iter->pool = pool;
	iter->curchunk = pool->chunks.first;
	iter->curindex = 0;
}

#if 0
/* unoptimized, more readable */

static void *bli_mempool_iternext(BLI_mempool_iter *iter)
{
	void *ret = NULL;

	if (!iter->curchunk || !iter->pool->totused) return NULL;

	ret = ((char *)iter->curchunk->data) + iter->pool->esize * iter->curindex;

	iter->curindex++;

	if (iter->curindex >= iter->pool->pchunk) {
		iter->curchunk = iter->curchunk->next;
		iter->curindex = 0;
	}

	return ret;
}

void *BLI_mempool_iterstep(BLI_mempool_iter *iter)
{
	BLI_freenode *ret;

	do {
		ret = bli_mempool_iternext(iter);
	} while (ret && ret->freeword == FREEWORD);

	return ret;
}

#else

/* optimized version of code above */

void *BLI_mempool_iterstep(BLI_mempool_iter *iter)
{
	BLI_freenode *ret;

	if (UNLIKELY(iter->pool->totused == 0)) {
		return NULL;
	}

	do {
		if (LIKELY(iter->curchunk)) {
			ret = (BLI_freenode *)(((char *)iter->curchunk->data) + iter->pool->esize * iter->curindex);
		}
		else {
			return NULL;
		}

		if (UNLIKELY(++iter->curindex >= iter->pool->pchunk)) {
			iter->curindex = 0;
			iter->curchunk = iter->curchunk->next;
		}
	} while (ret->freeword == FREEWORD);

	return ret;
}

#endif

void BLI_mempool_destroy(BLI_mempool *pool)
{
	BLI_mempool_chunk *mpchunk = NULL;

	if (pool->flag & BLI_MEMPOOL_SYSMALLOC) {
		for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
			free(mpchunk->data);
		}
		BLI_freelist(&(pool->chunks));
		free(pool);
	}
	else {
		for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
			MEM_freeN(mpchunk->data);
		}
		BLI_freelistN(&(pool->chunks));
		MEM_freeN(pool);
	}
}