/*
 * 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 "config.h"

#include <stddef.h>
#include <stdint.h>

#include <libavutil/avassert.h>
#include <libavutil/intreadwrite.h>

#if HAVE_FAST_64BIT
typedef uint64_t BitBuf;
#define AV_WBBUF AV_WB64
#define AV_WLBUF AV_WL64
#else
typedef uint32_t BitBuf;
#define AV_WBBUF AV_WB32
#define AV_WLBUF AV_WL32
#endif

static const int BUF_BITS = 8 * sizeof(BitBuf);

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;
}

/**
 * @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 < (1UL << 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 < (1UL << 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_mod_uintp2(value, n));
}

/**
 * Write exactly 32 bits into a bitstream.
 */
static void av_unused 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 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 < 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
  }
  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
  }
}

/**
 * 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 */