/*
 * Copyright 2010-2016, Tarantool AUTHORS, please see AUTHORS file.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * 1. Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the
 *    following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * <COPYRIGHT HOLDER> OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "bit/bit.h"

extern inline uint8_t
load_u8(const void *p);

extern inline uint16_t
load_u16(const void *p);

extern inline uint32_t
load_u32(const void *p);

extern inline uint64_t
load_u64(const void *p);

extern inline float
load_float(const void *p);

extern inline double
load_double(const void *p);

extern inline void
store_u8(void *p, uint8_t v);

extern inline void
store_u16(void *p, uint16_t v);

extern inline void
store_u32(void *p, uint32_t v);

extern inline void
store_u64(void *p, uint64_t v);

extern inline void
store_float(void *p, float v);

extern inline void
store_double(void *p, double v);

extern inline bool
bit_test(const void *data, size_t pos);

extern inline bool
bit_set(void *data, size_t pos);

extern inline bool
bit_clear(void *data, size_t pos);

extern inline int
bit_ctz_u32(uint32_t x);

extern inline int
bit_ctz_u64(uint64_t x);

extern inline int
bit_clz_u32(uint32_t x);

extern inline int
bit_clz_u64(uint64_t x);

extern inline int
bit_count_u32(uint32_t x);

extern inline int
bit_count_u64(uint64_t x);

extern inline uint32_t
bit_rotl_u32(uint32_t x, int r);

extern inline uint64_t
bit_rotl_u64(uint64_t x, int r);

extern inline uint32_t
bit_rotr_u32(uint32_t x, int r);

extern inline uint64_t
bit_rotr_u64(uint64_t x, int r);

extern inline uint16_t
bswap_u16(uint16_t x);

extern inline uint32_t
bswap_u32(uint32_t x);

extern inline uint64_t
bswap_u64(uint64_t x);

#define BITINDEX_NAIVE(type, x, bitsize) {				\
	/* naive generic implementation, worst case */			\
	type bit = 1;							\
	int i = 0;							\
	for (unsigned k = 0; k < bitsize; k++) {				\
		if (x & bit) {						\
			indexes[i++] = offset + k + 1;			\
		}							\
		bit <<= 1;						\
	}								\
									\
	indexes[i] = 0;							\
	return indexes + i;						\
}

int *
bit_index_u32(uint32_t x, int *indexes, int offset)
{
#if  defined(HAVE_BUILTIN_CTZ)
	int prev_pos = 0;
	int i = 0;

#if defined(HAVE_BUILTIN_POPCOUNT)
	/* fast implementation using built-in popcount function */
	const int count = bit_count_u32(x);
	while (i < count) {
#else
	/* sligtly slower implementation without using built-in popcount */
	while(x) {
#endif
		/* use ctz */
		const int a = bit_ctz_u32(x);

		prev_pos += a + 1;
		x >>= a;
		x >>= 1;
		indexes[i++] = offset + prev_pos;
	}

	indexes[i] = 0;
	return indexes + i;
#else /* !defined(HAVE_BUILTIN_CTZ) */
	BITINDEX_NAIVE(uint32_t, x, sizeof(uint32_t) * CHAR_BIT);
#endif
}

int *
bit_index_u64(uint64_t x, int *indexes, int offset) {
#if  defined(HAVE_BUILTIN_CTZLL)
	int prev_pos = 0;
	int i = 0;

#if defined(HAVE_BUILTIN_POPCOUNTLL)
	/* fast implementation using built-in popcount function */
	const int count = bit_count_u64(x);
	while (i < count) {
#else
	/* sligtly slower implementation without using built-in popcount */
	while(x) {
#endif
		/* use ctz */
		const int a = bit_ctz_u64(x);

		prev_pos += a + 1;
		x >>= a;
		x >>= 1;
		indexes[i++] = offset + prev_pos;
	}

	indexes[i] = 0;
	return indexes + i;
#else /* !defined(HAVE_CTZ) */
	BITINDEX_NAIVE(uint64_t, x, sizeof(uint64_t) * CHAR_BIT);
#endif
}

#undef BITINDEX_NAIVE

extern inline void
bit_iterator_init(struct bit_iterator *it, const void *data, size_t size,
		  bool set);

extern inline size_t
bit_iterator_next(struct bit_iterator *it);
