/*

 * Copyright (C) 2004 Michael Niedermayer

 *

 * This file may be used under the terms of the GNU Lesser General Public

 * License version 2.1, a copy of which is found in LICENSE included in the

 * packaging of this file.

 */

/* This was borrowed from FFmpeg */

#ifndef GET_BITS_H

#define GET_BITS_H

#include <stdint.h>

struct get_bit_context {

	const uint8_t *buffer, *buffer_end;

	unsigned index;

	unsigned size_in_bits;

};

static inline void skip_bits(struct get_bit_context *s, int n)

{

	unsigned index = s->index;

	index += n;

	s->index = index;

}

static inline void init_get_bits(struct get_bit_context *s, const uint8_t *buffer, unsigned bit_size)

{

	s->buffer = buffer;

	s->buffer_end = buffer + ((bit_size + 7) >> 3);

	s->size_in_bits = bit_size;

	s->index = 0;

}

static inline unsigned get_bits1(struct get_bit_context *s)

{

	unsigned index = s->index;

	uint8_t result = s->buffer[index >> 3];

	result <<= (index & 0x07);

	result >>= 8 - 1;

	index++;

	s->index = index;

	return result;

}

union unaligned_16 { uint16_t l; } __attribute__((packed));

union unaligned_32 { uint32_t l; } __attribute__((packed));

#define AV_RN(s, p) (((const union unaligned_##s *) (p))->l)

#if defined(__i386__)

static inline uint16_t av_bswap16(uint16_t x)

{

	__asm__("rorw $8, %0" : "+r"(x));

	return x;

}

static inline uint32_t av_bswap32(uint32_t x)

{

	__asm__("bswap   %0" : "+r" (x));

	return x;

}

#define AV_RB16(x) av_bswap16(AV_RN(16, x))

#define AV_RB32(x) av_bswap32(AV_RN(32, x))

#elif defined(__arm__)

static inline uint16_t av_read16_be(const uint8_t *p)

{

	uint16_t v;

	__asm__("ldrh %0, %1\n\trev16 %0, %0" : "=r"(v) : "m"(*(const uint16_t *)p));

	return v;

}

static inline uint32_t av_read32_be(const uint8_t *p)

{

	uint32_t v;

	__asm__("ldr %0, %1" : "=r"(v) : "m"(*(const uint32_t *)p));

	__asm__("rev %0, %0" : "+r"(v));

	return v;

}

#define AV_RB16(x) av_read16_be(x)

#define AV_RB32(x) av_read32_be(x)

#endif

#ifndef AV_RB16

#define AV_RB16(x) \

	((((const uint8_t *)(x))[0] << 8) | \

	 ((const uint8_t *)(x))[1])

#endif

#ifndef AV_RB32

#define AV_RB32(x) \

	((((const uint8_t *)(x))[0] << 24) | \

	 (((const uint8_t *)(x))[1] << 16) | \

	 (((const uint8_t *)(x))[2] <<  8) | \

	 ((const uint8_t *)(x))[3])

#endif

static inline unsigned get_bits(struct get_bit_context *s, int n)

{

	unsigned index = s->index;

	int re_cache = 0;

	register int tmp;

	re_cache = AV_RB32(((const uint8_t *)s->buffer) + (index >> 3)) << (index & 0x07);

	tmp = ((uint32_t)re_cache) >> (32 - n);

	index += n;

	s->index = index;

	return tmp;

}

static inline unsigned show_bits(struct get_bit_context *s, int n)

{

	unsigned index = s->index;

	int re_cache = 0;

	register int tmp;

	re_cache = AV_RB32(((const uint8_t *)s->buffer) + (index >> 3)) << (index & 0x07);

	tmp = ((uint32_t)re_cache) >> (32 - n);

	return tmp;

}

static inline unsigned get_bits_count(const struct get_bit_context *s)

{

	return s->index;

}

static inline int get_bits_left(const struct get_bit_context *s)

{

	return s->size_in_bits - get_bits_count(s);

}

#endif