--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/brotli/c/dec/bit_reader.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,423 @@
+/* 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 <string.h>  /* memcpy */
+
+#include <brotli/types.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_ */