/src/brotli/c/dec/bit_reader.h

Source
/* Copyright 2013 Google Inc. All Rights Reserved.

   Distributed under MIT license.
   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/

/* Bit reading helpers */

#ifndef BROTLI_DEC_BIT_READER_H_
#define BROTLI_DEC_BIT_READER_H_

#include "../common/constants.h"
#include "../common/platform.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

#define BROTLI_SHORT_FILL_BIT_WINDOW_READ (sizeof(brotli_reg_t) >> 1)

/* 162 bits + 7 bytes */
#define BROTLI_FAST_INPUT_SLACK 28

BROTLI_INTERNAL extern const brotli_reg_t kBrotliBitMask[33];

static BROTLI_INLINE brotli_reg_t BitMask(brotli_reg_t n) {
  if (BROTLI_IS_CONSTANT(n) || BROTLI_HAS_UBFX) {
    /* Masking with this expression turns to a single
       "Unsigned Bit Field Extract" UBFX instruction on ARM. */
    return ~(~((brotli_reg_t)0) << n);
  } else {
    return kBrotliBitMask[n];
  }
}

typedef struct {
  brotli_reg_t val_;       /* pre-fetched bits */
  brotli_reg_t bit_pos_;   /* current bit-reading position in val_ */
  const uint8_t* next_in;  /* the byte we're reading from */
  const uint8_t* guard_in; /* position from which "fast-path" is prohibited */
  const uint8_t* last_in;  /* == next_in + avail_in */
} BrotliBitReader;

typedef struct {
  brotli_reg_t val_;
  brotli_reg_t bit_pos_;
  const uint8_t* next_in;
  size_t avail_in;
} BrotliBitReaderState;

/* Initializes the BrotliBitReader fields. */
BROTLI_INTERNAL void BrotliInitBitReader(BrotliBitReader* br);

/* Ensures that accumulator is not empty.
   May consume up to sizeof(brotli_reg_t) - 1 bytes of input.
   Returns BROTLI_FALSE if data is required but there is no input available.
   For !BROTLI_UNALIGNED_READ_FAST this function also prepares bit reader for
   aligned reading. */
BROTLI_INTERNAL BROTLI_BOOL BrotliWarmupBitReader(BrotliBitReader* br);

/* Fallback for BrotliSafeReadBits32. Extracted as noninlined method to unburden
   the main code-path. Never called for RFC brotli streams, required only for
   "large-window" mode and other extensions. */
BROTLI_INTERNAL BROTLI_NOINLINE BROTLI_BOOL BrotliSafeReadBits32Slow(
    BrotliBitReader* br, brotli_reg_t n_bits, brotli_reg_t* val);

static BROTLI_INLINE size_t
BrotliBitReaderGetAvailIn(BrotliBitReader* const br) {
  return (size_t)(br->last_in - br->next_in);
}

static BROTLI_INLINE void BrotliBitReaderSaveState(
    BrotliBitReader* const from, BrotliBitReaderState* to) {
  to->val_ = from->val_;
  to->bit_pos_ = from->bit_pos_;
  to->next_in = from->next_in;
  to->avail_in = BrotliBitReaderGetAvailIn(from);
}

static BROTLI_INLINE void BrotliBitReaderSetInput(
    BrotliBitReader* const br, const uint8_t* next_in, size_t avail_in) {
  br->next_in = next_in;
  br->last_in = (avail_in == 0) ? next_in : (next_in + avail_in);
  if (avail_in + 1 > BROTLI_FAST_INPUT_SLACK) {
    br->guard_in = next_in + (avail_in + 1 - BROTLI_FAST_INPUT_SLACK);
  } else {
    br->guard_in = next_in;
  }
}

static BROTLI_INLINE void BrotliBitReaderRestoreState(
    BrotliBitReader* const to, BrotliBitReaderState* from) {
  to->val_ = from->val_;
  to->bit_pos_ = from->bit_pos_;
  to->next_in = from->next_in;
  BrotliBitReaderSetInput(to, from->next_in, from->avail_in);
}

static BROTLI_INLINE brotli_reg_t BrotliGetAvailableBits(
    const BrotliBitReader* br) {
  return br->bit_pos_;
}

/* Returns amount of unread bytes the bit reader still has buffered from the
   BrotliInput, including whole bytes in br->val_. Result is capped with
   maximal ring-buffer size (larger number won't be utilized anyway). */
static BROTLI_INLINE size_t BrotliGetRemainingBytes(BrotliBitReader* br) {
  static const size_t kCap = (size_t)1 << BROTLI_LARGE_MAX_WBITS;
  size_t avail_in = BrotliBitReaderGetAvailIn(br);
  if (avail_in > kCap) return kCap;
  return avail_in + (BrotliGetAvailableBits(br) >> 3);
}

/* Checks if there is at least |num| bytes left in the input ring-buffer
   (excluding the bits remaining in br->val_). */
static BROTLI_INLINE BROTLI_BOOL BrotliCheckInputAmount(
    BrotliBitReader* const br) {
  return TO_BROTLI_BOOL(br->next_in < br->guard_in);
}

/* Load more bits into accumulator. */
static BROTLI_INLINE brotli_reg_t BrotliBitReaderLoadBits(brotli_reg_t val,
                                                          brotli_reg_t new_bits,
                                                          brotli_reg_t count,
                                                          brotli_reg_t offset) {
  BROTLI_DCHECK(
      !((val >> offset) & ~new_bits & ~(~((brotli_reg_t)0) << count)));
  (void)count;
  return val | (new_bits << offset);
}

/* Guarantees that there are at least |n_bits| + 1 bits in accumulator.
   Precondition: accumulator contains at least 1 bit.
   |n_bits| should be in the range [1..24] for regular build. For portable
   non-64-bit little-endian build only 16 bits are safe to request. */
static BROTLI_INLINE void BrotliFillBitWindow(
    BrotliBitReader* const br, brotli_reg_t n_bits) {
#if (BROTLI_64_BITS)
  if (BROTLI_UNALIGNED_READ_FAST && BROTLI_IS_CONSTANT(n_bits) &&
      (n_bits <= 8)) {
    brotli_reg_t bit_pos = br->bit_pos_;
    if (bit_pos <= 8) {
      br->val_ = BrotliBitReaderLoadBits(br->val_,
          BROTLI_UNALIGNED_LOAD64LE(br->next_in), 56, bit_pos);
      br->bit_pos_ = bit_pos + 56;
      br->next_in += 7;
    }
  } else if (BROTLI_UNALIGNED_READ_FAST && BROTLI_IS_CONSTANT(n_bits) &&
             (n_bits <= 16)) {
    brotli_reg_t bit_pos = br->bit_pos_;
    if (bit_pos <= 16) {
      br->val_ = BrotliBitReaderLoadBits(br->val_,
          BROTLI_UNALIGNED_LOAD64LE(br->next_in), 48, bit_pos);
      br->bit_pos_ = bit_pos + 48;
      br->next_in += 6;
    }
  } else {
    brotli_reg_t bit_pos = br->bit_pos_;
    if (bit_pos <= 32) {
      br->val_ = BrotliBitReaderLoadBits(br->val_,
          (uint64_t)BROTLI_UNALIGNED_LOAD32LE(br->next_in), 32, bit_pos);
      br->bit_pos_ = bit_pos + 32;
      br->next_in += BROTLI_SHORT_FILL_BIT_WINDOW_READ;
    }
  }
#else
  if (BROTLI_UNALIGNED_READ_FAST && BROTLI_IS_CONSTANT(n_bits) &&
      (n_bits <= 8)) {
    brotli_reg_t bit_pos = br->bit_pos_;
    if (bit_pos <= 8) {
      br->val_ = BrotliBitReaderLoadBits(br->val_,
          BROTLI_UNALIGNED_LOAD32LE(br->next_in), 24, bit_pos);
      br->bit_pos_ = bit_pos + 24;
      br->next_in += 3;
    }
  } else {
    brotli_reg_t bit_pos = br->bit_pos_;
    if (bit_pos <= 16) {
      br->val_ = BrotliBitReaderLoadBits(br->val_,
          (uint32_t)BROTLI_UNALIGNED_LOAD16LE(br->next_in), 16, bit_pos);
      br->bit_pos_ = bit_pos + 16;
      br->next_in += BROTLI_SHORT_FILL_BIT_WINDOW_READ;
    }
  }
#endif
}

/* Mostly like BrotliFillBitWindow, but guarantees only 16 bits and reads no
   more than BROTLI_SHORT_FILL_BIT_WINDOW_READ bytes of input. */
static BROTLI_INLINE void BrotliFillBitWindow16(BrotliBitReader* const br) {
  BrotliFillBitWindow(br, 17);
}

/* Tries to pull one byte of input to accumulator.
   Returns BROTLI_FALSE if there is no input available. */
static BROTLI_INLINE BROTLI_BOOL BrotliPullByte(BrotliBitReader* const br) {
  if (br->next_in == br->last_in) {
    return BROTLI_FALSE;
  }
  br->val_ = BrotliBitReaderLoadBits(br->val_,
      (brotli_reg_t)*br->next_in, 8, br->bit_pos_);
  br->bit_pos_ += 8;
  ++br->next_in;
  return BROTLI_TRUE;
}

/* Returns currently available bits.
   The number of valid bits could be calculated by BrotliGetAvailableBits. */
static BROTLI_INLINE brotli_reg_t BrotliGetBitsUnmasked(
    BrotliBitReader* const br) {
  return br->val_;
}

/* Like BrotliGetBits, but does not mask the result.
   The result contains at least 16 valid bits. */
static BROTLI_INLINE brotli_reg_t BrotliGet16BitsUnmasked(
    BrotliBitReader* const br) {
  BrotliFillBitWindow(br, 16);
  return (brotli_reg_t)BrotliGetBitsUnmasked(br);
}

/* Returns the specified number of bits from |br| without advancing bit
   position. */
static BROTLI_INLINE brotli_reg_t BrotliGetBits(
    BrotliBitReader* const br, brotli_reg_t n_bits) {
  BrotliFillBitWindow(br, n_bits);
  return BrotliGetBitsUnmasked(br) & BitMask(n_bits);
}

/* Tries to peek the specified amount of bits. Returns BROTLI_FALSE, if there
   is not enough input. */
static BROTLI_INLINE BROTLI_BOOL BrotliSafeGetBits(
    BrotliBitReader* const br, brotli_reg_t n_bits, brotli_reg_t* val) {
  while (BrotliGetAvailableBits(br) < n_bits) {
    if (!BrotliPullByte(br)) {
      return BROTLI_FALSE;
    }
  }
  *val = BrotliGetBitsUnmasked(br) & BitMask(n_bits);
  return BROTLI_TRUE;
}

/* Advances the bit pos by |n_bits|. */
static BROTLI_INLINE void BrotliDropBits(
    BrotliBitReader* const br, brotli_reg_t n_bits) {
  br->bit_pos_ -= n_bits;
  br->val_ >>= n_bits;
}

/* Make sure that there are no spectre bits in accumulator.
   This is important for the cases when some bytes are skipped
   (i.e. never placed into accumulator). */
static BROTLI_INLINE void BrotliBitReaderNormalize(BrotliBitReader* br) {
  /* Actually, it is enough to normalize when br->bit_pos_ == 0 */
  if (br->bit_pos_ < (sizeof(brotli_reg_t) << 3u)) {
    br->val_ &= (((brotli_reg_t)1) << br->bit_pos_) - 1;
  }
}

static BROTLI_INLINE void BrotliBitReaderUnload(BrotliBitReader* br) {
  brotli_reg_t unused_bytes = BrotliGetAvailableBits(br) >> 3;
  brotli_reg_t unused_bits = unused_bytes << 3;
  br->next_in =
      (unused_bytes == 0) ? br->next_in : (br->next_in - unused_bytes);
  br->bit_pos_ -= unused_bits;
  BrotliBitReaderNormalize(br);
}

/* Reads the specified number of bits from |br| and advances the bit pos.
   Precondition: accumulator MUST contain at least |n_bits|. */
static BROTLI_INLINE void BrotliTakeBits(BrotliBitReader* const br,
                                         brotli_reg_t n_bits,
                                         brotli_reg_t* val) {
  *val = BrotliGetBitsUnmasked(br) & BitMask(n_bits);
  BROTLI_LOG(("[BrotliTakeBits]  %d %d %d val: %6x\n",
              (int)BrotliBitReaderGetAvailIn(br), (int)br->bit_pos_,
              (int)n_bits, (int)*val));
  BrotliDropBits(br, n_bits);
}

/* Reads the specified number of bits from |br| and advances the bit pos.
   Assumes that there is enough input to perform BrotliFillBitWindow.
   Up to 24 bits are allowed to be requested from this method. */
static BROTLI_INLINE brotli_reg_t BrotliReadBits24(
    BrotliBitReader* const br, brotli_reg_t n_bits) {
  BROTLI_DCHECK(n_bits <= 24);
  if (BROTLI_64_BITS || (n_bits <= 16)) {
    brotli_reg_t val;
    BrotliFillBitWindow(br, n_bits);
    BrotliTakeBits(br, n_bits, &val);
    return val;
  } else {
    brotli_reg_t low_val;
    brotli_reg_t high_val;
    BrotliFillBitWindow(br, 16);
    BrotliTakeBits(br, 16, &low_val);
    BrotliFillBitWindow(br, 8);
    BrotliTakeBits(br, n_bits - 16, &high_val);
    return low_val | (high_val << 16);
  }
}

/* Same as BrotliReadBits24, but allows reading up to 32 bits. */
static BROTLI_INLINE brotli_reg_t BrotliReadBits32(
    BrotliBitReader* const br, brotli_reg_t n_bits) {
  BROTLI_DCHECK(n_bits <= 32);
  if (BROTLI_64_BITS || (n_bits <= 16)) {
    brotli_reg_t val;
    BrotliFillBitWindow(br, n_bits);
    BrotliTakeBits(br, n_bits, &val);
    return val;
  } else {
    brotli_reg_t low_val;
    brotli_reg_t high_val;
    BrotliFillBitWindow(br, 16);
    BrotliTakeBits(br, 16, &low_val);
    BrotliFillBitWindow(br, 16);
    BrotliTakeBits(br, n_bits - 16, &high_val);
    return low_val | (high_val << 16);
  }
}

/* Tries to read the specified amount of bits. Returns BROTLI_FALSE, if there
   is not enough input. |n_bits| MUST be positive.
   Up to 24 bits are allowed to be requested from this method. */
static BROTLI_INLINE BROTLI_BOOL BrotliSafeReadBits(
    BrotliBitReader* const br, brotli_reg_t n_bits, brotli_reg_t* val) {
  BROTLI_DCHECK(n_bits <= 24);
  while (BrotliGetAvailableBits(br) < n_bits) {
    if (!BrotliPullByte(br)) {
      return BROTLI_FALSE;
    }
  }
  BrotliTakeBits(br, n_bits, val);
  return BROTLI_TRUE;
}

/* Same as BrotliSafeReadBits, but allows reading up to 32 bits. */
static BROTLI_INLINE BROTLI_BOOL BrotliSafeReadBits32(
    BrotliBitReader* const br, brotli_reg_t n_bits, brotli_reg_t* val) {
  BROTLI_DCHECK(n_bits <= 32);
  if (BROTLI_64_BITS || (n_bits <= 24)) {
    while (BrotliGetAvailableBits(br) < n_bits) {
      if (!BrotliPullByte(br)) {
        return BROTLI_FALSE;
      }
    }
    BrotliTakeBits(br, n_bits, val);
    return BROTLI_TRUE;
  } else {
    return BrotliSafeReadBits32Slow(br, n_bits, val);
  }
}

/* Advances the bit reader position to the next byte boundary and verifies
   that any skipped bits are set to zero. */
static BROTLI_INLINE BROTLI_BOOL BrotliJumpToByteBoundary(BrotliBitReader* br) {
  brotli_reg_t pad_bits_count = BrotliGetAvailableBits(br) & 0x7;
  brotli_reg_t pad_bits = 0;
  if (pad_bits_count != 0) {
    BrotliTakeBits(br, pad_bits_count, &pad_bits);
  }
  BrotliBitReaderNormalize(br);
  return TO_BROTLI_BOOL(pad_bits == 0);
}

static BROTLI_INLINE void BrotliDropBytes(BrotliBitReader* br, size_t num) {
  /* Check detour is legal: accumulator must to be empty. */
  BROTLI_DCHECK(br->bit_pos_ == 0);
  BROTLI_DCHECK(br->val_ == 0);
  br->next_in += num;
}

/* Copies remaining input bytes stored in the bit reader to the output. Value
   |num| may not be larger than BrotliGetRemainingBytes. The bit reader must be
   warmed up again after this. */
static BROTLI_INLINE void BrotliCopyBytes(uint8_t* dest,
                                          BrotliBitReader* br, size_t num) {
  while (BrotliGetAvailableBits(br) >= 8 && num > 0) {
    *dest = (uint8_t)BrotliGetBitsUnmasked(br);
    BrotliDropBits(br, 8);
    ++dest;
    --num;
  }
  BrotliBitReaderNormalize(br);
  if (num > 0) {
    memcpy(dest, br->next_in, num);
    BrotliDropBytes(br, num);
  }
}

BROTLI_UNUSED_FUNCTION void BrotliBitReaderSuppressUnusedFunctions(void) {
  BROTLI_UNUSED(&BrotliBitReaderSuppressUnusedFunctions);

  BROTLI_UNUSED(&BrotliBitReaderGetAvailIn);
  BROTLI_UNUSED(&BrotliBitReaderLoadBits);
  BROTLI_UNUSED(&BrotliBitReaderRestoreState);
  BROTLI_UNUSED(&BrotliBitReaderSaveState);
  BROTLI_UNUSED(&BrotliBitReaderSetInput);
  BROTLI_UNUSED(&BrotliBitReaderUnload);
  BROTLI_UNUSED(&BrotliCheckInputAmount);
  BROTLI_UNUSED(&BrotliCopyBytes);
  BROTLI_UNUSED(&BrotliFillBitWindow16);
  BROTLI_UNUSED(&BrotliGet16BitsUnmasked);
  BROTLI_UNUSED(&BrotliGetBits);
  BROTLI_UNUSED(&BrotliGetRemainingBytes);
  BROTLI_UNUSED(&BrotliJumpToByteBoundary);
  BROTLI_UNUSED(&BrotliReadBits24);
  BROTLI_UNUSED(&BrotliReadBits32);
  BROTLI_UNUSED(&BrotliSafeGetBits);
  BROTLI_UNUSED(&BrotliSafeReadBits);
  BROTLI_UNUSED(&BrotliSafeReadBits32);
}

#if defined(__cplusplus) || defined(c_plusplus)
}  /* extern "C" */
#endif

#endif  /* BROTLI_DEC_BIT_READER_H_ */

Coverage Report

Created: 2026-01-25 07:18

Line	Count	Source
1		/* Copyright 2013 Google Inc. All Rights Reserved.
2
3		Distributed under MIT license.
4		See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5		*/
6
7		/* Bit reading helpers */
8
9		#ifndef BROTLI_DEC_BIT_READER_H_
10		#define BROTLI_DEC_BIT_READER_H_
11
12		#include "../common/constants.h"
13		#include "../common/platform.h"
14
15		#if defined(__cplusplus) \|\| defined(c_plusplus)
16		extern "C" {
17		#endif
18
19	0	#define BROTLI_SHORT_FILL_BIT_WINDOW_READ (sizeof(brotli_reg_t) >> 1)
20
21		/* 162 bits + 7 bytes */
22	0	#define BROTLI_FAST_INPUT_SLACK 28
23
24		BROTLI_INTERNAL extern const brotli_reg_t kBrotliBitMask[33];
25
26	0	static BROTLI_INLINE brotli_reg_t BitMask(brotli_reg_t n) {
27	0	if (BROTLI_IS_CONSTANT(n) \|\| BROTLI_HAS_UBFX) {
28	0	/* Masking with this expression turns to a single
29	0	"Unsigned Bit Field Extract" UBFX instruction on ARM. */
30	0	return ~(~((brotli_reg_t)0) << n);
31	0	} else {
32	0	return kBrotliBitMask[n];
33	0	}
34	0	}
35
36		typedef struct {
37		brotli_reg_t val_; /* pre-fetched bits */
38		brotli_reg_t bit_pos_; /* current bit-reading position in val_ */
39		const uint8_t* next_in; /* the byte we're reading from */
40		const uint8_t* guard_in; /* position from which "fast-path" is prohibited */
41		const uint8_t* last_in; /* == next_in + avail_in */
42		} BrotliBitReader;
43
44		typedef struct {
45		brotli_reg_t val_;
46		brotli_reg_t bit_pos_;
47		const uint8_t* next_in;
48		size_t avail_in;
49		} BrotliBitReaderState;
50
51		/* Initializes the BrotliBitReader fields. */
52		BROTLI_INTERNAL void BrotliInitBitReader(BrotliBitReader* br);
53
54		/* Ensures that accumulator is not empty.
55		May consume up to sizeof(brotli_reg_t) - 1 bytes of input.
56		Returns BROTLI_FALSE if data is required but there is no input available.
57		For !BROTLI_UNALIGNED_READ_FAST this function also prepares bit reader for
58		aligned reading. */
59		BROTLI_INTERNAL BROTLI_BOOL BrotliWarmupBitReader(BrotliBitReader* br);
60
61		/* Fallback for BrotliSafeReadBits32. Extracted as noninlined method to unburden
62		the main code-path. Never called for RFC brotli streams, required only for
63		"large-window" mode and other extensions. */
64		BROTLI_INTERNAL BROTLI_NOINLINE BROTLI_BOOL BrotliSafeReadBits32Slow(
65		BrotliBitReader* br, brotli_reg_t n_bits, brotli_reg_t* val);
66
67		static BROTLI_INLINE size_t
68	0	BrotliBitReaderGetAvailIn(BrotliBitReader* const br) {
69	0	return (size_t)(br->last_in - br->next_in);
70	0	} Unexecuted instantiation: decode.c:BrotliBitReaderGetAvailIn Unexecuted instantiation: state.c:BrotliBitReaderGetAvailIn Unexecuted instantiation: bit_reader.c:BrotliBitReaderGetAvailIn
71
72		static BROTLI_INLINE void BrotliBitReaderSaveState(
73	0	BrotliBitReader* const from, BrotliBitReaderState* to) {
74	0	to->val_ = from->val_;
75	0	to->bit_pos_ = from->bit_pos_;
76	0	to->next_in = from->next_in;
77	0	to->avail_in = BrotliBitReaderGetAvailIn(from);
78	0	} Unexecuted instantiation: decode.c:BrotliBitReaderSaveState Unexecuted instantiation: state.c:BrotliBitReaderSaveState Unexecuted instantiation: bit_reader.c:BrotliBitReaderSaveState
79
80		static BROTLI_INLINE void BrotliBitReaderSetInput(
81	0	BrotliBitReader* const br, const uint8_t* next_in, size_t avail_in) {
82	0	br->next_in = next_in;
83	0	br->last_in = (avail_in == 0) ? next_in : (next_in + avail_in);
84	0	if (avail_in + 1 > BROTLI_FAST_INPUT_SLACK) {
85	0	br->guard_in = next_in + (avail_in + 1 - BROTLI_FAST_INPUT_SLACK);
86	0	} else {
87	0	br->guard_in = next_in;
88	0	}
89	0	} Unexecuted instantiation: decode.c:BrotliBitReaderSetInput Unexecuted instantiation: state.c:BrotliBitReaderSetInput Unexecuted instantiation: bit_reader.c:BrotliBitReaderSetInput
90
91		static BROTLI_INLINE void BrotliBitReaderRestoreState(
92	0	BrotliBitReader* const to, BrotliBitReaderState* from) {
93	0	to->val_ = from->val_;
94	0	to->bit_pos_ = from->bit_pos_;
95	0	to->next_in = from->next_in;
96	0	BrotliBitReaderSetInput(to, from->next_in, from->avail_in);
97	0	} Unexecuted instantiation: decode.c:BrotliBitReaderRestoreState Unexecuted instantiation: state.c:BrotliBitReaderRestoreState Unexecuted instantiation: bit_reader.c:BrotliBitReaderRestoreState
98
99		static BROTLI_INLINE brotli_reg_t BrotliGetAvailableBits(
100	0	const BrotliBitReader* br) {
101	0	return br->bit_pos_;
102	0	} Unexecuted instantiation: decode.c:BrotliGetAvailableBits Unexecuted instantiation: state.c:BrotliGetAvailableBits Unexecuted instantiation: bit_reader.c:BrotliGetAvailableBits
103
104		/* Returns amount of unread bytes the bit reader still has buffered from the
105		BrotliInput, including whole bytes in br->val_. Result is capped with
106		maximal ring-buffer size (larger number won't be utilized anyway). */
107	0	static BROTLI_INLINE size_t BrotliGetRemainingBytes(BrotliBitReader* br) {
108	0	static const size_t kCap = (size_t)1 << BROTLI_LARGE_MAX_WBITS;
109	0	size_t avail_in = BrotliBitReaderGetAvailIn(br);
110	0	if (avail_in > kCap) return kCap;
111	0	return avail_in + (BrotliGetAvailableBits(br) >> 3);
112	0	} Unexecuted instantiation: decode.c:BrotliGetRemainingBytes Unexecuted instantiation: state.c:BrotliGetRemainingBytes Unexecuted instantiation: bit_reader.c:BrotliGetRemainingBytes
113
114		/* Checks if there is at least \|num\| bytes left in the input ring-buffer
115		(excluding the bits remaining in br->val_). */
116		static BROTLI_INLINE BROTLI_BOOL BrotliCheckInputAmount(
117	0	BrotliBitReader* const br) {
118	0	return TO_BROTLI_BOOL(br->next_in < br->guard_in);
119	0	} Unexecuted instantiation: decode.c:BrotliCheckInputAmount Unexecuted instantiation: state.c:BrotliCheckInputAmount Unexecuted instantiation: bit_reader.c:BrotliCheckInputAmount
120
121		/* Load more bits into accumulator. */
122		static BROTLI_INLINE brotli_reg_t BrotliBitReaderLoadBits(brotli_reg_t val,
123		brotli_reg_t new_bits,
124		brotli_reg_t count,
125	0	brotli_reg_t offset) {
126	0	BROTLI_DCHECK(
127	0	!((val >> offset) & ~new_bits & ~(~((brotli_reg_t)0) << count)));
128	0	(void)count;
129	0	return val \| (new_bits << offset);
130	0	} Unexecuted instantiation: decode.c:BrotliBitReaderLoadBits Unexecuted instantiation: state.c:BrotliBitReaderLoadBits Unexecuted instantiation: bit_reader.c:BrotliBitReaderLoadBits
131
132		/* Guarantees that there are at least \|n_bits\| + 1 bits in accumulator.
133		Precondition: accumulator contains at least 1 bit.
134		\|n_bits\| should be in the range [1..24] for regular build. For portable
135		non-64-bit little-endian build only 16 bits are safe to request. */
136		static BROTLI_INLINE void BrotliFillBitWindow(
137	0	BrotliBitReader* const br, brotli_reg_t n_bits) {
138	0	#if (BROTLI_64_BITS)
139	0	if (BROTLI_UNALIGNED_READ_FAST && BROTLI_IS_CONSTANT(n_bits) &&
140	0	(n_bits <= 8)) {
141	0	brotli_reg_t bit_pos = br->bit_pos_;
142	0	if (bit_pos <= 8) {
143	0	br->val_ = BrotliBitReaderLoadBits(br->val_,
144	0	BROTLI_UNALIGNED_LOAD64LE(br->next_in), 56, bit_pos);
145	0	br->bit_pos_ = bit_pos + 56;
146	0	br->next_in += 7;
147	0	}
148	0	} else if (BROTLI_UNALIGNED_READ_FAST && BROTLI_IS_CONSTANT(n_bits) &&
149	0	(n_bits <= 16)) {
150	0	brotli_reg_t bit_pos = br->bit_pos_;
151	0	if (bit_pos <= 16) {
152	0	br->val_ = BrotliBitReaderLoadBits(br->val_,
153	0	BROTLI_UNALIGNED_LOAD64LE(br->next_in), 48, bit_pos);
154	0	br->bit_pos_ = bit_pos + 48;
155	0	br->next_in += 6;
156	0	}
157	0	} else {
158	0	brotli_reg_t bit_pos = br->bit_pos_;
159	0	if (bit_pos <= 32) {
160	0	br->val_ = BrotliBitReaderLoadBits(br->val_,
161	0	(uint64_t)BROTLI_UNALIGNED_LOAD32LE(br->next_in), 32, bit_pos);
162	0	br->bit_pos_ = bit_pos + 32;
163	0	br->next_in += BROTLI_SHORT_FILL_BIT_WINDOW_READ;
164	0	}
165	0	}
166		#else
167		if (BROTLI_UNALIGNED_READ_FAST && BROTLI_IS_CONSTANT(n_bits) &&
168		(n_bits <= 8)) {
169		brotli_reg_t bit_pos = br->bit_pos_;
170		if (bit_pos <= 8) {
171		br->val_ = BrotliBitReaderLoadBits(br->val_,
172		BROTLI_UNALIGNED_LOAD32LE(br->next_in), 24, bit_pos);
173		br->bit_pos_ = bit_pos + 24;
174		br->next_in += 3;
175		}
176		} else {
177		brotli_reg_t bit_pos = br->bit_pos_;
178		if (bit_pos <= 16) {
179		br->val_ = BrotliBitReaderLoadBits(br->val_,
180		(uint32_t)BROTLI_UNALIGNED_LOAD16LE(br->next_in), 16, bit_pos);
181		br->bit_pos_ = bit_pos + 16;
182		br->next_in += BROTLI_SHORT_FILL_BIT_WINDOW_READ;
183		}
184		}
185		#endif
186	0	} Unexecuted instantiation: decode.c:BrotliFillBitWindow Unexecuted instantiation: state.c:BrotliFillBitWindow Unexecuted instantiation: bit_reader.c:BrotliFillBitWindow
187
188		/* Mostly like BrotliFillBitWindow, but guarantees only 16 bits and reads no
189		more than BROTLI_SHORT_FILL_BIT_WINDOW_READ bytes of input. */
190	0	static BROTLI_INLINE void BrotliFillBitWindow16(BrotliBitReader* const br) {
191	0	BrotliFillBitWindow(br, 17);
192	0	} Unexecuted instantiation: decode.c:BrotliFillBitWindow16 Unexecuted instantiation: state.c:BrotliFillBitWindow16 Unexecuted instantiation: bit_reader.c:BrotliFillBitWindow16
193
194		/* Tries to pull one byte of input to accumulator.
195		Returns BROTLI_FALSE if there is no input available. */
196	0	static BROTLI_INLINE BROTLI_BOOL BrotliPullByte(BrotliBitReader* const br) {
197	0	if (br->next_in == br->last_in) {
198	0	return BROTLI_FALSE;
199	0	}
200	0	br->val_ = BrotliBitReaderLoadBits(br->val_,
201	0	(brotli_reg_t)*br->next_in, 8, br->bit_pos_);
202	0	br->bit_pos_ += 8;
203	0	++br->next_in;
204	0	return BROTLI_TRUE;
205	0	} Unexecuted instantiation: decode.c:BrotliPullByte Unexecuted instantiation: state.c:BrotliPullByte Unexecuted instantiation: bit_reader.c:BrotliPullByte
206
207		/* Returns currently available bits.
208		The number of valid bits could be calculated by BrotliGetAvailableBits. */
209		static BROTLI_INLINE brotli_reg_t BrotliGetBitsUnmasked(
210	0	BrotliBitReader* const br) {
211	0	return br->val_;
212	0	} Unexecuted instantiation: decode.c:BrotliGetBitsUnmasked Unexecuted instantiation: state.c:BrotliGetBitsUnmasked Unexecuted instantiation: bit_reader.c:BrotliGetBitsUnmasked
213
214		/* Like BrotliGetBits, but does not mask the result.
215		The result contains at least 16 valid bits. */
216		static BROTLI_INLINE brotli_reg_t BrotliGet16BitsUnmasked(
217	0	BrotliBitReader* const br) {
218	0	BrotliFillBitWindow(br, 16);
219	0	return (brotli_reg_t)BrotliGetBitsUnmasked(br);
220	0	} Unexecuted instantiation: decode.c:BrotliGet16BitsUnmasked Unexecuted instantiation: state.c:BrotliGet16BitsUnmasked Unexecuted instantiation: bit_reader.c:BrotliGet16BitsUnmasked
221
222		/* Returns the specified number of bits from \|br\| without advancing bit
223		position. */
224		static BROTLI_INLINE brotli_reg_t BrotliGetBits(
225	0	BrotliBitReader* const br, brotli_reg_t n_bits) {
226	0	BrotliFillBitWindow(br, n_bits);
227	0	return BrotliGetBitsUnmasked(br) & BitMask(n_bits);
228	0	} Unexecuted instantiation: decode.c:BrotliGetBits Unexecuted instantiation: state.c:BrotliGetBits Unexecuted instantiation: bit_reader.c:BrotliGetBits
229
230		/* Tries to peek the specified amount of bits. Returns BROTLI_FALSE, if there
231		is not enough input. */
232		static BROTLI_INLINE BROTLI_BOOL BrotliSafeGetBits(
233	0	BrotliBitReader* const br, brotli_reg_t n_bits, brotli_reg_t* val) {
234	0	while (BrotliGetAvailableBits(br) < n_bits) {
235	0	if (!BrotliPullByte(br)) {
236	0	return BROTLI_FALSE;
237	0	}
238	0	}
239	0	*val = BrotliGetBitsUnmasked(br) & BitMask(n_bits);
240	0	return BROTLI_TRUE;
241	0	} Unexecuted instantiation: decode.c:BrotliSafeGetBits Unexecuted instantiation: state.c:BrotliSafeGetBits Unexecuted instantiation: bit_reader.c:BrotliSafeGetBits
242
243		/* Advances the bit pos by \|n_bits\|. */
244		static BROTLI_INLINE void BrotliDropBits(
245	0	BrotliBitReader* const br, brotli_reg_t n_bits) {
246	0	br->bit_pos_ -= n_bits;
247	0	br->val_ >>= n_bits;
248	0	} Unexecuted instantiation: decode.c:BrotliDropBits Unexecuted instantiation: state.c:BrotliDropBits Unexecuted instantiation: bit_reader.c:BrotliDropBits
249
250		/* Make sure that there are no spectre bits in accumulator.
251		This is important for the cases when some bytes are skipped
252		(i.e. never placed into accumulator). */
253	0	static BROTLI_INLINE void BrotliBitReaderNormalize(BrotliBitReader* br) {
254		/* Actually, it is enough to normalize when br->bit_pos_ == 0 */
255	0	if (br->bit_pos_ < (sizeof(brotli_reg_t) << 3u)) {
256	0	br->val_ &= (((brotli_reg_t)1) << br->bit_pos_) - 1;
257	0	}
258	0	} Unexecuted instantiation: decode.c:BrotliBitReaderNormalize Unexecuted instantiation: state.c:BrotliBitReaderNormalize Unexecuted instantiation: bit_reader.c:BrotliBitReaderNormalize
259
260	0	static BROTLI_INLINE void BrotliBitReaderUnload(BrotliBitReader* br) {
261	0	brotli_reg_t unused_bytes = BrotliGetAvailableBits(br) >> 3;
262	0	brotli_reg_t unused_bits = unused_bytes << 3;
263	0	br->next_in =
264	0	(unused_bytes == 0) ? br->next_in : (br->next_in - unused_bytes);
265	0	br->bit_pos_ -= unused_bits;
266	0	BrotliBitReaderNormalize(br);
267	0	} Unexecuted instantiation: decode.c:BrotliBitReaderUnload Unexecuted instantiation: state.c:BrotliBitReaderUnload Unexecuted instantiation: bit_reader.c:BrotliBitReaderUnload
268
269		/* Reads the specified number of bits from \|br\| and advances the bit pos.
270		Precondition: accumulator MUST contain at least \|n_bits\|. */
271		static BROTLI_INLINE void BrotliTakeBits(BrotliBitReader* const br,
272		brotli_reg_t n_bits,
273	0	brotli_reg_t* val) {
274	0	*val = BrotliGetBitsUnmasked(br) & BitMask(n_bits);
275	0	BROTLI_LOG(("[BrotliTakeBits] %d %d %d val: %6x\n",
276	0	(int)BrotliBitReaderGetAvailIn(br), (int)br->bit_pos_,
277	0	(int)n_bits, (int)*val));
278	0	BrotliDropBits(br, n_bits);
279	0	} Unexecuted instantiation: decode.c:BrotliTakeBits Unexecuted instantiation: state.c:BrotliTakeBits Unexecuted instantiation: bit_reader.c:BrotliTakeBits
280
281		/* Reads the specified number of bits from \|br\| and advances the bit pos.
282		Assumes that there is enough input to perform BrotliFillBitWindow.
283		Up to 24 bits are allowed to be requested from this method. */
284		static BROTLI_INLINE brotli_reg_t BrotliReadBits24(
285	0	BrotliBitReader* const br, brotli_reg_t n_bits) {
286	0	BROTLI_DCHECK(n_bits <= 24);
287	0	if (BROTLI_64_BITS \|\| (n_bits <= 16)) {
288	0	brotli_reg_t val;
289	0	BrotliFillBitWindow(br, n_bits);
290	0	BrotliTakeBits(br, n_bits, &val);
291	0	return val;
292	0	} else {
293	0	brotli_reg_t low_val;
294	0	brotli_reg_t high_val;
295	0	BrotliFillBitWindow(br, 16);
296	0	BrotliTakeBits(br, 16, &low_val);
297	0	BrotliFillBitWindow(br, 8);
298	0	BrotliTakeBits(br, n_bits - 16, &high_val);
299	0	return low_val \| (high_val << 16);
300	0	}
301	0	} Unexecuted instantiation: decode.c:BrotliReadBits24 Unexecuted instantiation: state.c:BrotliReadBits24 Unexecuted instantiation: bit_reader.c:BrotliReadBits24
302
303		/* Same as BrotliReadBits24, but allows reading up to 32 bits. */
304		static BROTLI_INLINE brotli_reg_t BrotliReadBits32(
305	0	BrotliBitReader* const br, brotli_reg_t n_bits) {
306	0	BROTLI_DCHECK(n_bits <= 32);
307	0	if (BROTLI_64_BITS \|\| (n_bits <= 16)) {
308	0	brotli_reg_t val;
309	0	BrotliFillBitWindow(br, n_bits);
310	0	BrotliTakeBits(br, n_bits, &val);
311	0	return val;
312	0	} else {
313	0	brotli_reg_t low_val;
314	0	brotli_reg_t high_val;
315	0	BrotliFillBitWindow(br, 16);
316	0	BrotliTakeBits(br, 16, &low_val);
317	0	BrotliFillBitWindow(br, 16);
318	0	BrotliTakeBits(br, n_bits - 16, &high_val);
319	0	return low_val \| (high_val << 16);
320	0	}
321	0	} Unexecuted instantiation: decode.c:BrotliReadBits32 Unexecuted instantiation: state.c:BrotliReadBits32 Unexecuted instantiation: bit_reader.c:BrotliReadBits32
322
323		/* Tries to read the specified amount of bits. Returns BROTLI_FALSE, if there
324		is not enough input. \|n_bits\| MUST be positive.
325		Up to 24 bits are allowed to be requested from this method. */
326		static BROTLI_INLINE BROTLI_BOOL BrotliSafeReadBits(
327	0	BrotliBitReader* const br, brotli_reg_t n_bits, brotli_reg_t* val) {
328	0	BROTLI_DCHECK(n_bits <= 24);
329	0	while (BrotliGetAvailableBits(br) < n_bits) {
330	0	if (!BrotliPullByte(br)) {
331	0	return BROTLI_FALSE;
332	0	}
333	0	}
334	0	BrotliTakeBits(br, n_bits, val);
335	0	return BROTLI_TRUE;
336	0	} Unexecuted instantiation: decode.c:BrotliSafeReadBits Unexecuted instantiation: state.c:BrotliSafeReadBits Unexecuted instantiation: bit_reader.c:BrotliSafeReadBits
337
338		/* Same as BrotliSafeReadBits, but allows reading up to 32 bits. */
339		static BROTLI_INLINE BROTLI_BOOL BrotliSafeReadBits32(
340	0	BrotliBitReader* const br, brotli_reg_t n_bits, brotli_reg_t* val) {
341	0	BROTLI_DCHECK(n_bits <= 32);
342	0	if (BROTLI_64_BITS \|\| (n_bits <= 24)) {
343	0	while (BrotliGetAvailableBits(br) < n_bits) {
344	0	if (!BrotliPullByte(br)) {
345	0	return BROTLI_FALSE;
346	0	}
347	0	}
348	0	BrotliTakeBits(br, n_bits, val);
349	0	return BROTLI_TRUE;
350	0	} else {
351	0	return BrotliSafeReadBits32Slow(br, n_bits, val);
352	0	}
353	0	} Unexecuted instantiation: decode.c:BrotliSafeReadBits32 Unexecuted instantiation: state.c:BrotliSafeReadBits32 Unexecuted instantiation: bit_reader.c:BrotliSafeReadBits32
354
355		/* Advances the bit reader position to the next byte boundary and verifies
356		that any skipped bits are set to zero. */
357	0	static BROTLI_INLINE BROTLI_BOOL BrotliJumpToByteBoundary(BrotliBitReader* br) {
358	0	brotli_reg_t pad_bits_count = BrotliGetAvailableBits(br) & 0x7;
359	0	brotli_reg_t pad_bits = 0;
360	0	if (pad_bits_count != 0) {
361	0	BrotliTakeBits(br, pad_bits_count, &pad_bits);
362	0	}
363	0	BrotliBitReaderNormalize(br);
364	0	return TO_BROTLI_BOOL(pad_bits == 0);
365	0	} Unexecuted instantiation: decode.c:BrotliJumpToByteBoundary Unexecuted instantiation: state.c:BrotliJumpToByteBoundary Unexecuted instantiation: bit_reader.c:BrotliJumpToByteBoundary
366
367	0	static BROTLI_INLINE void BrotliDropBytes(BrotliBitReader* br, size_t num) {
368		/* Check detour is legal: accumulator must to be empty. */
369	0	BROTLI_DCHECK(br->bit_pos_ == 0);
370	0	BROTLI_DCHECK(br->val_ == 0);
371	0	br->next_in += num;
372	0	} Unexecuted instantiation: decode.c:BrotliDropBytes Unexecuted instantiation: state.c:BrotliDropBytes Unexecuted instantiation: bit_reader.c:BrotliDropBytes
373
374		/* Copies remaining input bytes stored in the bit reader to the output. Value
375		\|num\| may not be larger than BrotliGetRemainingBytes. The bit reader must be
376		warmed up again after this. */
377		static BROTLI_INLINE void BrotliCopyBytes(uint8_t* dest,
378	0	BrotliBitReader* br, size_t num) {
379	0	while (BrotliGetAvailableBits(br) >= 8 && num > 0) {
380	0	*dest = (uint8_t)BrotliGetBitsUnmasked(br);
381	0	BrotliDropBits(br, 8);
382	0	++dest;
383	0	--num;
384	0	}
385	0	BrotliBitReaderNormalize(br);
386	0	if (num > 0) {
387	0	memcpy(dest, br->next_in, num);
388	0	BrotliDropBytes(br, num);
389	0	}
390	0	} Unexecuted instantiation: decode.c:BrotliCopyBytes Unexecuted instantiation: state.c:BrotliCopyBytes Unexecuted instantiation: bit_reader.c:BrotliCopyBytes
391
392	0	BROTLI_UNUSED_FUNCTION void BrotliBitReaderSuppressUnusedFunctions(void) {
393	0	BROTLI_UNUSED(&BrotliBitReaderSuppressUnusedFunctions);
394	0
395	0	BROTLI_UNUSED(&BrotliBitReaderGetAvailIn);
396	0	BROTLI_UNUSED(&BrotliBitReaderLoadBits);
397	0	BROTLI_UNUSED(&BrotliBitReaderRestoreState);
398	0	BROTLI_UNUSED(&BrotliBitReaderSaveState);
399	0	BROTLI_UNUSED(&BrotliBitReaderSetInput);
400	0	BROTLI_UNUSED(&BrotliBitReaderUnload);
401	0	BROTLI_UNUSED(&BrotliCheckInputAmount);
402	0	BROTLI_UNUSED(&BrotliCopyBytes);
403	0	BROTLI_UNUSED(&BrotliFillBitWindow16);
404	0	BROTLI_UNUSED(&BrotliGet16BitsUnmasked);
405	0	BROTLI_UNUSED(&BrotliGetBits);
406	0	BROTLI_UNUSED(&BrotliGetRemainingBytes);
407	0	BROTLI_UNUSED(&BrotliJumpToByteBoundary);
408	0	BROTLI_UNUSED(&BrotliReadBits24);
409	0	BROTLI_UNUSED(&BrotliReadBits32);
410	0	BROTLI_UNUSED(&BrotliSafeGetBits);
411	0	BROTLI_UNUSED(&BrotliSafeReadBits);
412	0	BROTLI_UNUSED(&BrotliSafeReadBits32);
413	0	} Unexecuted instantiation: decode.c:BrotliBitReaderSuppressUnusedFunctions Unexecuted instantiation: state.c:BrotliBitReaderSuppressUnusedFunctions Unexecuted instantiation: bit_reader.c:BrotliBitReaderSuppressUnusedFunctions
414
415		#if defined(__cplusplus) \|\| defined(c_plusplus)
416		} /* extern "C" */
417		#endif
418
419		#endif /* BROTLI_DEC_BIT_READER_H_ */