/*

 * Copyright 2008-2009 Katholieke Universiteit Leuven

 *

 * Use of this software is governed by the MIT license

 *

 * Written by Sven Verdoolaege, K.U.Leuven, Departement

 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium

 */

#include <isl_blk.h>

#include <isl_ctx_private.h>

/* The maximal number of cache misses before first element is evicted */

#define ISL_BLK_MAX_MISS	100

struct isl_blk isl_blk_empty()

{

	struct isl_blk block;

	block.size = 0;

	block.data = NULL;

	return block;

}

static int isl_blk_is_empty(struct isl_blk block)

{

	return block.size == 0 && block.data == NULL;

}

static struct isl_blk isl_blk_error()

{

	struct isl_blk block;

	block.size = -1;

	block.data = NULL;

	return block;

}

int isl_blk_is_error(struct isl_blk block)

{

	return block.size == -1 && block.data == NULL;

}

static struct isl_blk extend(struct isl_ctx *ctx, struct isl_blk block,

				size_t new_n)

{

	int i;

	isl_int *p;

	if (block.size >= new_n)

		return block;

	p = block.data;

	block.data = isl_realloc_array(ctx, block.data, isl_int, new_n);

	if (!block.data) {

		free(p);

		return isl_blk_error();

	}

	for (i = block.size; i < new_n; ++i)

		isl_int_init(block.data[i]);

	block.size = new_n;

	return block;

}

static void isl_blk_free_force(struct isl_ctx *ctx, struct isl_blk block)

{

	int i;

	for (i = 0; i < block.size; ++i)

		isl_int_clear(block.data[i]);

	free(block.data);

}

struct isl_blk isl_blk_alloc(struct isl_ctx *ctx, size_t n)

{

	int i;

	struct isl_blk block;

	block = isl_blk_empty();

	if (n && ctx->n_cached) {

		int best = 0;

		for (i = 1; ctx->cache[best].size != n && i < ctx->n_cached; ++i) {

			if (ctx->cache[best].size < n) {

				if (ctx->cache[i].size > ctx->cache[best].size)

					best = i;

			} else if (ctx->cache[i].size >= n &&

				   ctx->cache[i].size < ctx->cache[best].size)

					best = i;

		}

		if (ctx->cache[best].size < 2 * n + 100) {

			block = ctx->cache[best];

			if (--ctx->n_cached != best)

				ctx->cache[best] = ctx->cache[ctx->n_cached];

			if (best == 0)

				ctx->n_miss = 0;

		} else if (ctx->n_miss++ >= ISL_BLK_MAX_MISS) {

			isl_blk_free_force(ctx, ctx->cache[0]);

			if (--ctx->n_cached != 0)

				ctx->cache[0] = ctx->cache[ctx->n_cached];

			ctx->n_miss = 0;

		}

	}

	return extend(ctx, block, n);

}

struct isl_blk isl_blk_extend(struct isl_ctx *ctx, struct isl_blk block,

				size_t new_n)

{

	if (isl_blk_is_empty(block))

		return isl_blk_alloc(ctx, new_n);

	return extend(ctx, block, new_n);

}

void isl_blk_free(struct isl_ctx *ctx, struct isl_blk block)

{

	if (isl_blk_is_empty(block) || isl_blk_is_error(block))

		return;

	if (ctx->n_cached < ISL_BLK_CACHE_SIZE)

		ctx->cache[ctx->n_cached++] = block;

	else

		isl_blk_free_force(ctx, block);

}

void isl_blk_clear_cache(struct isl_ctx *ctx)

{

	int i;

	for (i = 0; i < ctx->n_cached; ++i)

		isl_blk_free_force(ctx, ctx->cache[i]);

	ctx->n_cached = 0;

}