--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/brotli/c/enc/block_splitter.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,217 @@
+/* Copyright 2013 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Block split point selection utilities. */
+
+#include "block_splitter.h"
+
+#include <string.h>  /* memcpy, memset */
+
+#include "../common/platform.h"
+#include "bit_cost.h"
+#include "cluster.h"
+#include "command.h"
+#include "fast_log.h"
+#include "histogram.h"
+#include "memory.h"
+#include "quality.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+static const size_t kMaxLiteralHistograms = 100;
+static const size_t kMaxCommandHistograms = 50;
+static const double kLiteralBlockSwitchCost = 28.1;
+static const double kCommandBlockSwitchCost = 13.5;
+static const double kDistanceBlockSwitchCost = 14.6;
+static const size_t kLiteralStrideLength = 70;
+static const size_t kCommandStrideLength = 40;
+static const size_t kDistanceStrideLength = 40;
+static const size_t kSymbolsPerLiteralHistogram = 544;
+static const size_t kSymbolsPerCommandHistogram = 530;
+static const size_t kSymbolsPerDistanceHistogram = 544;
+static const size_t kMinLengthForBlockSplitting = 128;
+static const size_t kIterMulForRefining = 2;
+static const size_t kMinItersForRefining = 100;
+
+static size_t CountLiterals(const Command* cmds, const size_t num_commands) {
+  /* Count how many we have. */
+  size_t total_length = 0;
+  size_t i;
+  for (i = 0; i < num_commands; ++i) {
+    total_length += cmds[i].insert_len_;
+  }
+  return total_length;
+}
+
+static void CopyLiteralsToByteArray(const Command* cmds,
+                                    const size_t num_commands,
+                                    const uint8_t* data,
+                                    const size_t offset,
+                                    const size_t mask,
+                                    uint8_t* literals) {
+  size_t pos = 0;
+  size_t from_pos = offset & mask;
+  size_t i;
+  for (i = 0; i < num_commands; ++i) {
+    size_t insert_len = cmds[i].insert_len_;
+    if (from_pos + insert_len > mask) {
+      size_t head_size = mask + 1 - from_pos;
+      memcpy(literals + pos, data + from_pos, head_size);
+      from_pos = 0;
+      pos += head_size;
+      insert_len -= head_size;
+    }
+    if (insert_len > 0) {
+      memcpy(literals + pos, data + from_pos, insert_len);
+      pos += insert_len;
+    }
+    from_pos = (from_pos + insert_len + CommandCopyLen(&cmds[i])) & mask;
+  }
+}
+
+static BROTLI_INLINE uint32_t MyRand(uint32_t* seed) {
+  /* Initial seed should be 7. In this case, loop length is (1 << 29). */
+  *seed *= 16807U;
+  return *seed;
+}
+
+static BROTLI_INLINE double BitCost(size_t count) {
+  return count == 0 ? -2.0 : FastLog2(count);
+}
+
+#define HISTOGRAMS_PER_BATCH 64
+#define CLUSTERS_PER_BATCH 16
+
+#define FN(X) X ## Literal
+#define DataType uint8_t
+/* NOLINTNEXTLINE(build/include) */
+#include "block_splitter_inc.h"
+#undef DataType
+#undef FN
+
+#define FN(X) X ## Command
+#define DataType uint16_t
+/* NOLINTNEXTLINE(build/include) */
+#include "block_splitter_inc.h"
+#undef FN
+
+#define FN(X) X ## Distance
+/* NOLINTNEXTLINE(build/include) */
+#include "block_splitter_inc.h"
+#undef DataType
+#undef FN
+
+void BrotliInitBlockSplit(BlockSplit* self) {
+  self->num_types = 0;
+  self->num_blocks = 0;
+  self->types = 0;
+  self->lengths = 0;
+  self->types_alloc_size = 0;
+  self->lengths_alloc_size = 0;
+}
+
+void BrotliDestroyBlockSplit(MemoryManager* m, BlockSplit* self) {
+  BROTLI_FREE(m, self->types);
+  BROTLI_FREE(m, self->lengths);
+}
+
+/* Extracts literals, command distance and prefix codes, then applies
+ * SplitByteVector to create partitioning. */
+void BrotliSplitBlock(MemoryManager* m,
+                      const Command* cmds,
+                      const size_t num_commands,
+                      const uint8_t* data,
+                      const size_t pos,
+                      const size_t mask,
+                      const BrotliEncoderParams* params,
+                      BlockSplit* literal_split,
+                      BlockSplit* insert_and_copy_split,
+                      BlockSplit* dist_split) {
+  {
+    size_t literals_count = CountLiterals(cmds, num_commands);
+    uint8_t* literals = BROTLI_ALLOC(m, uint8_t, literals_count);
+    if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(literals)) return;
+    /* Create a continuous array of literals. */
+    CopyLiteralsToByteArray(cmds, num_commands, data, pos, mask, literals);
+    /* Create the block split on the array of literals.
+     * Literal histograms can have alphabet size up to 256.
+     * Though, to accomodate context modeling, less than half of maximum size
+     * is allowed. */
+    SplitByteVectorLiteral(
+        m, literals, literals_count,
+        kSymbolsPerLiteralHistogram, kMaxLiteralHistograms,
+        kLiteralStrideLength, kLiteralBlockSwitchCost, params,
+        literal_split);
+    if (BROTLI_IS_OOM(m)) return;
+    BROTLI_FREE(m, literals);
+    /* NB: this might be a good place for injecting extra splitting without
+     *     increasing encoder complexity; however, output parition would be less
+     *     optimal than one produced with forced splitting inside
+     *     SplitByteVector (FindBlocks / ClusterBlocks). */
+  }
+
+  {
+    /* Compute prefix codes for commands. */
+    uint16_t* insert_and_copy_codes = BROTLI_ALLOC(m, uint16_t, num_commands);
+    size_t i;
+    if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(insert_and_copy_codes)) return;
+    for (i = 0; i < num_commands; ++i) {
+      insert_and_copy_codes[i] = cmds[i].cmd_prefix_;
+    }
+    /* Create the block split on the array of command prefixes. */
+    SplitByteVectorCommand(
+        m, insert_and_copy_codes, num_commands,
+        kSymbolsPerCommandHistogram, kMaxCommandHistograms,
+        kCommandStrideLength, kCommandBlockSwitchCost, params,
+        insert_and_copy_split);
+    if (BROTLI_IS_OOM(m)) return;
+    /* TODO(eustas): reuse for distances? */
+    BROTLI_FREE(m, insert_and_copy_codes);
+  }
+
+  {
+    /* Create a continuous array of distance prefixes. */
+    uint16_t* distance_prefixes = BROTLI_ALLOC(m, uint16_t, num_commands);
+    size_t j = 0;
+    size_t i;
+    if (BROTLI_IS_OOM(m) || BROTLI_IS_NULL(distance_prefixes)) return;
+    for (i = 0; i < num_commands; ++i) {
+      const Command* cmd = &cmds[i];
+      if (CommandCopyLen(cmd) && cmd->cmd_prefix_ >= 128) {
+        distance_prefixes[j++] = cmd->dist_prefix_ & 0x3FF;
+      }
+    }
+    /* Create the block split on the array of distance prefixes. */
+    SplitByteVectorDistance(
+        m, distance_prefixes, j,
+        kSymbolsPerDistanceHistogram, kMaxCommandHistograms,
+        kDistanceStrideLength, kDistanceBlockSwitchCost, params,
+        dist_split);
+    if (BROTLI_IS_OOM(m)) return;
+    BROTLI_FREE(m, distance_prefixes);
+  }
+}
+
+#if defined(BROTLI_TEST)
+size_t CountLiteralsForTest(const Command*, const size_t);
+size_t CountLiteralsForTest(const Command* cmds, const size_t num_commands) {
+  return CountLiterals(cmds, num_commands);
+}
+
+void CopyLiteralsToByteArrayForTest(const Command*,
+    const size_t, const uint8_t*, const size_t, const size_t, uint8_t*);
+void CopyLiteralsToByteArrayForTest(const Command* cmds,
+    const size_t num_commands, const uint8_t* data, const size_t offset,
+    const size_t mask, uint8_t* literals) {
+  CopyLiteralsToByteArray(cmds, num_commands, data, offset, mask, literals);
+}
+#endif
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}  /* extern "C" */
+#endif