/*

 * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * bitstream writer API

 */

#ifndef AVCODEC_PUT_BITS_H

#define AVCODEC_PUT_BITS_H

#include <stdint.h>

#include <stddef.h>

#include "config.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/avassert.h"

#include "libavutil/common.h"

#if ARCH_X86_64

// TODO: Benchmark and optionally enable on other 64-bit architectures.

typedef uint64_t BitBuf;

#define AV_WBBUF AV_WB64

#define AV_WLBUF AV_WL64

#define BUF_BITS 64

#else

typedef uint32_t BitBuf;

#define AV_WBBUF AV_WB32

#define AV_WLBUF AV_WL32

#define BUF_BITS 32

#endif

typedef struct PutBitContext {

    BitBuf bit_buf;

    int bit_left;

    uint8_t *buf, *buf_ptr, *buf_end;

} PutBitContext;

/**

 * Initialize the PutBitContext s.

 *

 * @param buffer the buffer where to put bits

 * @param buffer_size the size in bytes of buffer

 */

static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,

                                 int buffer_size)

{

    if (buffer_size < 0) {

        buffer_size = 0;

        buffer      = NULL;

    }

    s->buf          = buffer;

    s->buf_end      = s->buf + buffer_size;

    s->buf_ptr      = s->buf;

    s->bit_left     = BUF_BITS;

    s->bit_buf      = 0;

}

/**

 * Inform the compiler that a PutBitContext is flushed (i.e. if it has just

 * been initialized or flushed). Undefined behaviour occurs if this is used

 * with a PutBitContext for which this is not true.

 */

static inline void put_bits_assume_flushed(const PutBitContext *s)

{

    av_assume(s->bit_left == BUF_BITS);

}

/**

 * @return the total number of bits written to the bitstream.

 */

static inline int put_bits_count(PutBitContext *s)

{

    return (s->buf_ptr - s->buf) * 8 + BUF_BITS - s->bit_left;

}

/**

 * @return the number of bytes output so far; may only be called

 *         when the PutBitContext is freshly initialized or flushed.

 */

static inline int put_bytes_output(const PutBitContext *s)

{

    av_assert2(s->bit_left == BUF_BITS);

    return s->buf_ptr - s->buf;

}

/**

 * @param  round_up  When set, the number of bits written so far will be

 *                   rounded up to the next byte.

 * @return the number of bytes output so far.

 */

static inline int put_bytes_count(const PutBitContext *s, int round_up)

{

    return s->buf_ptr - s->buf + ((BUF_BITS - s->bit_left + (round_up ? 7 : 0)) >> 3);

}

/**

 * Rebase the bit writer onto a reallocated buffer.

 *

 * @param buffer the buffer where to put bits

 * @param buffer_size the size in bytes of buffer,

 *                    must be large enough to hold everything written so far

 */

static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer,

                                   int buffer_size)

{

    av_assert0(8*buffer_size >= put_bits_count(s));

    s->buf_end = buffer + buffer_size;

    s->buf_ptr = buffer + (s->buf_ptr - s->buf);

    s->buf     = buffer;

}

/**

 * @return the number of bits available in the bitstream.

 */

static inline int put_bits_left(PutBitContext* s)

{

    return (s->buf_end - s->buf_ptr) * 8 - BUF_BITS + s->bit_left;

}

/**

 * @param  round_up  When set, the number of bits written will be

 *                   rounded up to the next byte.

 * @return the number of bytes left.

 */

static inline int put_bytes_left(const PutBitContext *s, int round_up)

{

    return s->buf_end - s->buf_ptr - ((BUF_BITS - s->bit_left + (round_up ? 7 : 0)) >> 3);

}

/**

 * Pad the end of the output stream with zeros.

 */

static inline void flush_put_bits(PutBitContext *s)

{

#ifndef BITSTREAM_WRITER_LE

    if (s->bit_left < BUF_BITS)

        s->bit_buf <<= s->bit_left;

#endif

    while (s->bit_left < BUF_BITS) {

        av_assert0(s->buf_ptr < s->buf_end);

#ifdef BITSTREAM_WRITER_LE

        *s->buf_ptr++ = s->bit_buf;

        s->bit_buf  >>= 8;

#else

        *s->buf_ptr++ = s->bit_buf >> (BUF_BITS - 8);

        s->bit_buf  <<= 8;

#endif

        s->bit_left  += 8;

    }

    s->bit_left = BUF_BITS;

    s->bit_buf  = 0;

}

static inline void flush_put_bits_le(PutBitContext *s)

{

    while (s->bit_left < BUF_BITS) {

        av_assert0(s->buf_ptr < s->buf_end);

        *s->buf_ptr++ = s->bit_buf;

        s->bit_buf  >>= 8;

        s->bit_left  += 8;

    }

    s->bit_left = BUF_BITS;

    s->bit_buf  = 0;

}

#ifdef BITSTREAM_WRITER_LE

#define ff_put_string ff_put_string_unsupported_here

#define ff_copy_bits ff_copy_bits_unsupported_here

#else

/**

 * Put the string string in the bitstream.

 *

 * @param terminate_string 0-terminates the written string if value is 1

 */

void ff_put_string(PutBitContext *pb, const char *string,

                       int terminate_string);

/**

 * Copy the content of src to the bitstream.

 *

 * @param length the number of bits of src to copy

 */

void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);

#endif

static inline void put_bits_no_assert(PutBitContext *s, int n, BitBuf value)

{

    BitBuf bit_buf;

    int bit_left;

    bit_buf  = s->bit_buf;

    bit_left = s->bit_left;

    /* XXX: optimize */

#ifdef BITSTREAM_WRITER_LE

    bit_buf |= value << (BUF_BITS - bit_left);

    if (n >= bit_left) {

        if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {

            AV_WLBUF(s->buf_ptr, bit_buf);

            s->buf_ptr += sizeof(BitBuf);

        } else {

            av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");

            av_assert2(0);

        }

        bit_buf     = value >> bit_left;

        bit_left   += BUF_BITS;

    }

    bit_left -= n;

#else

    if (n < bit_left) {

        bit_buf     = (bit_buf << n) | value;

        bit_left   -= n;

    } else {

        bit_buf   <<= bit_left;

        bit_buf    |= value >> (n - bit_left);

        if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {

            AV_WBBUF(s->buf_ptr, bit_buf);

            s->buf_ptr += sizeof(BitBuf);

        } else {

            av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");

            av_assert2(0);

        }

        bit_left   += BUF_BITS - n;

        bit_buf     = value;

    }

#endif

    s->bit_buf  = bit_buf;

    s->bit_left = bit_left;

}

/**

 * Write up to 31 bits into a bitstream.

 * Use put_bits32 to write 32 bits.

 */

static inline void put_bits(PutBitContext *s, int n, BitBuf value)

{

    av_assert2(n <= 31 && value < (BitBuf)(1U << n));

    put_bits_no_assert(s, n, value);

}

static inline void put_bits_le(PutBitContext *s, int n, BitBuf value)

{

    BitBuf bit_buf;

    int bit_left;

    av_assert2(n <= 31 && value < (BitBuf)(1U << n));

    bit_buf  = s->bit_buf;

    bit_left = s->bit_left;

    bit_buf |= value << (BUF_BITS - bit_left);

    if (n >= bit_left) {

        if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {

            AV_WLBUF(s->buf_ptr, bit_buf);

            s->buf_ptr += sizeof(BitBuf);

        } else {

            av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");

            av_assert2(0);

        }

        bit_buf     = value >> bit_left;

        bit_left   += BUF_BITS;

    }

    bit_left -= n;

    s->bit_buf  = bit_buf;

    s->bit_left = bit_left;

}

static inline void put_sbits(PutBitContext *pb, int n, int32_t value)

{

    av_assert2(n >= 0 && n <= 31);

    put_bits(pb, n, av_zero_extend(value, n));

}

/**

 * Write exactly 32 bits into a bitstream.

 */

av_unused static void put_bits32(PutBitContext *s, uint32_t value)

{

    BitBuf bit_buf;

    int bit_left;

    if (BUF_BITS > 32) {

        put_bits_no_assert(s, 32, value);

        return;

    }

    bit_buf  = s->bit_buf;

    bit_left = s->bit_left;

#ifdef BITSTREAM_WRITER_LE

    bit_buf |= (BitBuf)value << (BUF_BITS - bit_left);

    if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {

        AV_WLBUF(s->buf_ptr, bit_buf);

        s->buf_ptr += sizeof(BitBuf);

    } else {

        av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");

        av_assert2(0);

    }

    bit_buf     = (uint64_t)value >> bit_left;

#else

    bit_buf     = (uint64_t)bit_buf << bit_left;

    bit_buf    |= (BitBuf)value >> (BUF_BITS - bit_left);

    if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {

        AV_WBBUF(s->buf_ptr, bit_buf);

        s->buf_ptr += sizeof(BitBuf);

    } else {

        av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");

        av_assert2(0);

    }

    bit_buf     = value;

#endif

    s->bit_buf  = bit_buf;

    s->bit_left = bit_left;

}

/**

 * Write up to 63 bits into a bitstream.

 */

static inline void put_bits63(PutBitContext *s, int n, uint64_t value)

{

    av_assert2(n < 64U && value < (UINT64_C(1) << n));

#if BUF_BITS >= 64

    put_bits_no_assert(s, n, value);

#else

    if (n < 32)

        put_bits(s, n, value);

    else if (n == 32)

        put_bits32(s, value);

    else if (n < 64) {

        uint32_t lo = value & 0xffffffff;

        uint32_t hi = value >> 32;

#ifdef BITSTREAM_WRITER_LE

        put_bits32(s, lo);

        put_bits(s, n - 32, hi);

#else

        put_bits(s, n - 32, hi);

        put_bits32(s, lo);

#endif

    }

#endif

}

/**

 * Write up to 64 bits into a bitstream.

 */

static inline void put_bits64(PutBitContext *s, int n, uint64_t value)

{

    av_assert2((n == 64) || (n < 64 && value < (UINT64_C(1) << n)));

    if (n < 64) {

        put_bits63(s, n, value);

    } else {

        uint32_t lo = value & 0xffffffff;

        uint32_t hi = value >> 32;

#ifdef BITSTREAM_WRITER_LE

        put_bits32(s, lo);

        put_bits32(s, hi);

#else

        put_bits32(s, hi);

        put_bits32(s, lo);

#endif

    }

}

static inline void put_sbits63(PutBitContext *pb, int n, int64_t value)

{

    av_assert2(n >= 0 && n < 64);

    put_bits63(pb, n, (uint64_t)(value) & (~(UINT64_MAX << n)));

}

/**

 * Return the pointer to the byte where the bitstream writer will put

 * the next bit.

 */

static inline uint8_t *put_bits_ptr(PutBitContext *s)

{

    return s->buf_ptr;

}

/**

 * Skip the given number of bytes.

 * PutBitContext must be flushed & aligned to a byte boundary before calling this.

 */

static inline void skip_put_bytes(PutBitContext *s, int n)

{

    av_assert2((put_bits_count(s) & 7) == 0);

    av_assert2(s->bit_left == BUF_BITS);

    av_assert0(n <= s->buf_end - s->buf_ptr);

    s->buf_ptr += n;

}

/**

 * Skip the given number of bits.

 * Must only be used if the actual values in the bitstream do not matter.

 * If n is < 0 the behavior is undefined.

 */

static inline void skip_put_bits(PutBitContext *s, int n)

{

    unsigned bits = BUF_BITS - s->bit_left + n;

    s->buf_ptr += sizeof(BitBuf) * (bits / BUF_BITS);

    s->bit_left = BUF_BITS - (bits & (BUF_BITS - 1));

}

/**

 * Change the end of the buffer.

 *

 * @param size the new size in bytes of the buffer where to put bits

 */

static inline void set_put_bits_buffer_size(PutBitContext *s, int size)

{

    av_assert0(size <= INT_MAX/8 - BUF_BITS);

    s->buf_end = s->buf + size;

}

/**

 * Pad the bitstream with zeros up to the next byte boundary.

 */

static inline void align_put_bits(PutBitContext *s)

{

    put_bits(s, s->bit_left & 7, 0);

}

#undef AV_WBBUF

#undef AV_WLBUF

#endif /* AVCODEC_PUT_BITS_H */