// 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 <assert.h>

#include <stddef.h>

#include "src/dsp/cpu.h"

#include "src/utils/bit_reader_inl_utils.h"

#include "src/utils/bit_reader_utils.h"

#include "src/utils/bounds_safety.h"

#include "src/utils/endian_inl_utils.h"

#include "src/utils/utils.h"

#include "src/webp/types.h"

WEBP_ASSUME_UNSAFE_INDEXABLE_ABI

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

// VP8BitReader

void VP8BitReaderSetBuffer(VP8BitReader* const br,

                           const uint8_t* const WEBP_COUNTED_BY(size) start,

                           size_t size) {

  assert(start != NULL);

  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 WEBP_COUNTED_BY(size) 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);

    WEBP_SELF_ASSIGN(br->buf_end);

  } 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, const char label[]) {

  uint32_t v = 0;

  while (bits-- > 0) {

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

  }

  return v;

}

int32_t VP8GetSignedValue(VP8BitReader* const br, int bits,

                          const char label[]) {

  const int value = VP8GetValue(br, bits, label);

  return VP8Get(br, label) ? -value : value;

}

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

// VP8LBitReader

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

#if defined(__arm__) || defined(_M_ARM) || WEBP_AARCH64 ||          \

    defined(__i386__) || defined(_M_IX86) || defined(__x86_64__) || \

    defined(_M_X64) || defined(__wasm__)

#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 WEBP_COUNTED_BY(length) 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->buf = start;

  br->len = length;

  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;

}

void VP8LBitReaderSetBuffer(VP8LBitReader* const br,

                            const uint8_t* const WEBP_COUNTED_BY(len) 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;

  }

}

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

// Bit-tracing tool

#if (BITTRACE > 0)

#include <stdio.h>

#include <stdlib.h>  // for atexit()

#include <string.h>

#define MAX_NUM_LABELS 32

static struct {

  const char* label;

  int size;

  int count;

} kLabels[MAX_NUM_LABELS];

static int last_label = 0;

static int last_pos = 0;

static const uint8_t* buf_start = NULL;

static int init_done = 0;

static void PrintBitTraces(void) {

  int i;

  int scale = 1;

  int total = 0;

  const char* units = "bits";

#if (BITTRACE == 2)

  scale = 8;

  units = "bytes";

#endif

  for (i = 0; i < last_label; ++i) total += kLabels[i].size;

  if (total < 1) total = 1;  // avoid rounding errors

  printf("=== Bit traces ===\n");

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

    const int skip = 16 - (int)strlen(kLabels[i].label);

    const int value = (kLabels[i].size + scale - 1) / scale;

    assert(skip > 0);

    printf("%s \%*s: %6d %s   \t[%5.2f%%] [count: %7d]\n", kLabels[i].label,

           skip, "", value, units, 100.f * kLabels[i].size / total,

           kLabels[i].count);

  }

  total = (total + scale - 1) / scale;

  printf("Total: %d %s\n", total, units);

}

void BitTrace(const struct VP8BitReader* const br, const char label[]) {

  int i, pos;

  if (!init_done) {

    WEBP_UNSAFE_MEMSET(kLabels, 0, sizeof(kLabels));

    atexit(PrintBitTraces);

    buf_start = br->buf;

    init_done = 1;

  }

  pos = (int)(br->buf - buf_start) * 8 - br->bits;

  // if there's a too large jump, we've changed partition -> reset counter

  if (abs(pos - last_pos) > 32) {

    buf_start = br->buf;

    pos = 0;

    last_pos = 0;

  }

  if (br->range >= 0x7f) pos += kVP8Log2Range[br->range - 0x7f];

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

    if (!strcmp(label, kLabels[i].label)) break;

  }

  if (i == MAX_NUM_LABELS) abort();  // overflow!

  kLabels[i].label = label;

  kLabels[i].size += pos - last_pos;

  kLabels[i].count += 1;

  if (i == last_label) ++last_label;

  last_pos = pos;

}

#endif  // BITTRACE > 0

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