// Copyright 2010 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// -----------------------------------------------------------------------------

//

// Boolean decoder non-inlined methods

//

// Author: Skal (pascal.massimino@gmail.com)

#ifdef HAVE_CONFIG_H

#include "src/webp/config.h"

#endif

#include "src/utils/bit_reader_inl_utils.h"

#include "src/utils/utils.h"

//------------------------------------------------------------------------------

// VP8BitReader

void VP8BitReaderSetBuffer(VP8BitReader* const br,

                           const uint8_t* const start,

                           size_t size) {

  br->buf_     = start;

  br->buf_end_ = start + size;

  br->buf_max_ =

      (size >= sizeof(lbit_t)) ? start + size - sizeof(lbit_t) + 1

                               : start;

}

void VP8InitBitReader(VP8BitReader* const br,

                      const uint8_t* const start, size_t size) {

  assert(br != NULL);

  assert(start != NULL);

  assert(size < (1u << 31));   // limit ensured by format and upstream checks

  br->range_   = 255 - 1;

  br->value_   = 0;

  br->bits_    = -8;   // to load the very first 8bits

  br->eof_     = 0;

  VP8BitReaderSetBuffer(br, start, size);

  VP8LoadNewBytes(br);

}

void VP8RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) {

  if (br->buf_ != NULL) {

    br->buf_ += offset;

    br->buf_end_ += offset;

    br->buf_max_ += offset;

  }

}

const uint8_t kVP8Log2Range[128] = {

     7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,

  3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,

  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,

  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,

  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,

  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,

  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,

  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,

  0

};

// range = ((range - 1) << kVP8Log2Range[range]) + 1

const uint8_t kVP8NewRange[128] = {

  127, 127, 191, 127, 159, 191, 223, 127,

  143, 159, 175, 191, 207, 223, 239, 127,

  135, 143, 151, 159, 167, 175, 183, 191,

  199, 207, 215, 223, 231, 239, 247, 127,

  131, 135, 139, 143, 147, 151, 155, 159,

  163, 167, 171, 175, 179, 183, 187, 191,

  195, 199, 203, 207, 211, 215, 219, 223,

  227, 231, 235, 239, 243, 247, 251, 127,

  129, 131, 133, 135, 137, 139, 141, 143,

  145, 147, 149, 151, 153, 155, 157, 159,

  161, 163, 165, 167, 169, 171, 173, 175,

  177, 179, 181, 183, 185, 187, 189, 191,

  193, 195, 197, 199, 201, 203, 205, 207,

  209, 211, 213, 215, 217, 219, 221, 223,

  225, 227, 229, 231, 233, 235, 237, 239,

  241, 243, 245, 247, 249, 251, 253, 127

};

void VP8LoadFinalBytes(VP8BitReader* const br) {

  assert(br != NULL && br->buf_ != NULL);

  // Only read 8bits at a time

  if (br->buf_ < br->buf_end_) {

    br->bits_ += 8;

    br->value_ = (bit_t)(*br->buf_++) | (br->value_ << 8);

  } else if (!br->eof_) {

    br->value_ <<= 8;

    br->bits_ += 8;

    br->eof_ = 1;

  } else {

    br->bits_ = 0;  // This is to avoid undefined behaviour with shifts.

  }

}

//------------------------------------------------------------------------------

// Higher-level calls

uint32_t VP8GetValue(VP8BitReader* const br, int bits) {

  uint32_t v = 0;

  while (bits-- > 0) {

    v |= VP8GetBit(br, 0x80) << bits;

  }

  return v;

}

int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) {

  const int value = VP8GetValue(br, bits);

  return VP8Get(br) ? -value : value;

}

//------------------------------------------------------------------------------

// VP8LBitReader

#define VP8L_LOG8_WBITS 4  // Number of bytes needed to store VP8L_WBITS bits.

#if defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || \

    defined(__i386__) || defined(_M_IX86) || \

    defined(__x86_64__) || defined(_M_X64)

#define VP8L_USE_FAST_LOAD

#endif

static const uint32_t kBitMask[VP8L_MAX_NUM_BIT_READ + 1] = {

  0,

  0x000001, 0x000003, 0x000007, 0x00000f,

  0x00001f, 0x00003f, 0x00007f, 0x0000ff,

  0x0001ff, 0x0003ff, 0x0007ff, 0x000fff,

  0x001fff, 0x003fff, 0x007fff, 0x00ffff,

  0x01ffff, 0x03ffff, 0x07ffff, 0x0fffff,

  0x1fffff, 0x3fffff, 0x7fffff, 0xffffff

};

void VP8LInitBitReader(VP8LBitReader* const br, const uint8_t* const start,

                       size_t length) {

  size_t i;

  vp8l_val_t value = 0;

  assert(br != NULL);

  assert(start != NULL);

  assert(length < 0xfffffff8u);   // can't happen with a RIFF chunk.

  br->len_ = length;

  br->val_ = 0;

  br->bit_pos_ = 0;

  br->eos_ = 0;

  if (length > sizeof(br->val_)) {

    length = sizeof(br->val_);

  }

  for (i = 0; i < length; ++i) {

    value |= (vp8l_val_t)start[i] << (8 * i);

  }

  br->val_ = value;

  br->pos_ = length;

  br->buf_ = start;

}

void VP8LBitReaderSetBuffer(VP8LBitReader* const br,

                            const uint8_t* const buf, size_t len) {

  assert(br != NULL);

  assert(buf != NULL);

  assert(len < 0xfffffff8u);   // can't happen with a RIFF chunk.

  br->buf_ = buf;

  br->len_ = len;

  // pos_ > len_ should be considered a param error.

  br->eos_ = (br->pos_ > br->len_) || VP8LIsEndOfStream(br);

}

static void VP8LSetEndOfStream(VP8LBitReader* const br) {

  br->eos_ = 1;

  br->bit_pos_ = 0;  // To avoid undefined behaviour with shifts.

}

// If not at EOS, reload up to VP8L_LBITS byte-by-byte

static void ShiftBytes(VP8LBitReader* const br) {

  while (br->bit_pos_ >= 8 && br->pos_ < br->len_) {

    br->val_ >>= 8;

    br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (VP8L_LBITS - 8);

    ++br->pos_;

    br->bit_pos_ -= 8;

  }

  if (VP8LIsEndOfStream(br)) {

    VP8LSetEndOfStream(br);

  }

}

void VP8LDoFillBitWindow(VP8LBitReader* const br) {

  assert(br->bit_pos_ >= VP8L_WBITS);

#if defined(VP8L_USE_FAST_LOAD)

  if (br->pos_ + sizeof(br->val_) < br->len_) {

    br->val_ >>= VP8L_WBITS;

    br->bit_pos_ -= VP8L_WBITS;

    br->val_ |= (vp8l_val_t)HToLE32(WebPMemToUint32(br->buf_ + br->pos_)) <<

                (VP8L_LBITS - VP8L_WBITS);

    br->pos_ += VP8L_LOG8_WBITS;

    return;

  }

#endif

  ShiftBytes(br);       // Slow path.

}

uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {

  assert(n_bits >= 0);

  // Flag an error if end_of_stream or n_bits is more than allowed limit.

  if (!br->eos_ && n_bits <= VP8L_MAX_NUM_BIT_READ) {

    const uint32_t val = VP8LPrefetchBits(br) & kBitMask[n_bits];

    const int new_bits = br->bit_pos_ + n_bits;

    br->bit_pos_ = new_bits;

    ShiftBytes(br);

    return val;

  } else {

    VP8LSetEndOfStream(br);

    return 0;

  }

}

//------------------------------------------------------------------------------