Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 200 insertions, 0 deletions

diff --git a/modules/brotli/common/constants.h b/modules/brotli/common/constants.h
new file mode 100644
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+++ b/modules/brotli/common/constants.h
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+/* Copyright 2016 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/**
+ * @file
+ * Common constants used in decoder and encoder API.
+ */
+
+#ifndef BROTLI_COMMON_CONSTANTS_H_
+#define BROTLI_COMMON_CONSTANTS_H_
+
+#include "./platform.h"
+#include <brotli/port.h>
+#include <brotli/types.h>
+
+/* Specification: 7.3. Encoding of the context map */
+#define BROTLI_CONTEXT_MAP_MAX_RLE 16
+
+/* Specification: 2. Compressed representation overview */
+#define BROTLI_MAX_NUMBER_OF_BLOCK_TYPES 256
+
+/* Specification: 3.3. Alphabet sizes: insert-and-copy length */
+#define BROTLI_NUM_LITERAL_SYMBOLS 256
+#define BROTLI_NUM_COMMAND_SYMBOLS 704
+#define BROTLI_NUM_BLOCK_LEN_SYMBOLS 26
+#define BROTLI_MAX_CONTEXT_MAP_SYMBOLS (BROTLI_MAX_NUMBER_OF_BLOCK_TYPES + \
+                                        BROTLI_CONTEXT_MAP_MAX_RLE)
+#define BROTLI_MAX_BLOCK_TYPE_SYMBOLS (BROTLI_MAX_NUMBER_OF_BLOCK_TYPES + 2)
+
+/* Specification: 3.5. Complex prefix codes */
+#define BROTLI_REPEAT_PREVIOUS_CODE_LENGTH 16
+#define BROTLI_REPEAT_ZERO_CODE_LENGTH 17
+#define BROTLI_CODE_LENGTH_CODES (BROTLI_REPEAT_ZERO_CODE_LENGTH + 1)
+/* "code length of 8 is repeated" */
+#define BROTLI_INITIAL_REPEATED_CODE_LENGTH 8
+
+/* "Large Window Brotli" */
+
+/**
+ * The theoretical maximum number of distance bits specified for large window
+ * brotli, for 64-bit encoders and decoders. Even when in practice 32-bit
+ * encoders and decoders only support up to 30 max distance bits, the value is
+ * set to 62 because it affects the large window brotli file format.
+ * Specifically, it affects the encoding of simple huffman tree for distances,
+ * see Specification RFC 7932 chapter 3.4.
+ */
+#define BROTLI_LARGE_MAX_DISTANCE_BITS 62U
+#define BROTLI_LARGE_MIN_WBITS 10
+/**
+ * The maximum supported large brotli window bits by the encoder and decoder.
+ * Large window brotli allows up to 62 bits, however the current encoder and
+ * decoder, designed for 32-bit integers, only support up to 30 bits maximum.
+ */
+#define BROTLI_LARGE_MAX_WBITS 30
+
+/* Specification: 4. Encoding of distances */
+#define BROTLI_NUM_DISTANCE_SHORT_CODES 16
+/**
+ * Maximal number of "postfix" bits.
+ *
+ * Number of "postfix" bits is stored as 2 bits in meta-block header.
+ */
+#define BROTLI_MAX_NPOSTFIX 3
+#define BROTLI_MAX_NDIRECT 120
+#define BROTLI_MAX_DISTANCE_BITS 24U
+#define BROTLI_DISTANCE_ALPHABET_SIZE(NPOSTFIX, NDIRECT, MAXNBITS) ( \
+    BROTLI_NUM_DISTANCE_SHORT_CODES + (NDIRECT) +                    \
+    ((MAXNBITS) << ((NPOSTFIX) + 1)))
+/* BROTLI_NUM_DISTANCE_SYMBOLS == 1128 */
+#define BROTLI_NUM_DISTANCE_SYMBOLS \
+    BROTLI_DISTANCE_ALPHABET_SIZE(  \
+        BROTLI_MAX_NDIRECT, BROTLI_MAX_NPOSTFIX, BROTLI_LARGE_MAX_DISTANCE_BITS)
+
+/* ((1 << 26) - 4) is the maximal distance that can be expressed in RFC 7932
+   brotli stream using NPOSTFIX = 0 and NDIRECT = 0. With other NPOSTFIX and
+   NDIRECT values distances up to ((1 << 29) + 88) could be expressed. */
+#define BROTLI_MAX_DISTANCE 0x3FFFFFC
+
+/* ((1 << 31) - 4) is the safe distance limit. Using this number as a limit
+   allows safe distance calculation without overflows, given the distance
+   alphabet size is limited to corresponding size
+   (see kLargeWindowDistanceCodeLimits). */
+#define BROTLI_MAX_ALLOWED_DISTANCE 0x7FFFFFFC
+
+
+/* Specification: 4. Encoding of Literal Insertion Lengths and Copy Lengths */
+#define BROTLI_NUM_INS_COPY_CODES 24
+
+/* 7.1. Context modes and context ID lookup for literals */
+/* "context IDs for literals are in the range of 0..63" */
+#define BROTLI_LITERAL_CONTEXT_BITS 6
+
+/* 7.2. Context ID for distances */
+#define BROTLI_DISTANCE_CONTEXT_BITS 2
+
+/* 9.1. Format of the Stream Header */
+/* Number of slack bytes for window size. Don't confuse
+   with BROTLI_NUM_DISTANCE_SHORT_CODES. */
+#define BROTLI_WINDOW_GAP 16
+#define BROTLI_MAX_BACKWARD_LIMIT(W) (((size_t)1 << (W)) - BROTLI_WINDOW_GAP)
+
+typedef struct BrotliDistanceCodeLimit {
+  uint32_t max_alphabet_size;
+  uint32_t max_distance;
+} BrotliDistanceCodeLimit;
+
+/* This function calculates maximal size of distance alphabet, such that the
+   distances greater than the given values can not be represented.
+
+   This limits are designed to support fast and safe 32-bit decoders.
+   "32-bit" means that signed integer values up to ((1 << 31) - 1) could be
+   safely expressed.
+
+   Brotli distance alphabet symbols do not represent consecutive distance
+   ranges. Each distance alphabet symbol (excluding direct distances and short
+   codes), represent interleaved (for NPOSTFIX > 0) range of distances.
+   A "group" of consecutive (1 << NPOSTFIX) symbols represent non-interleaved
+   range. Two consecutive groups require the same amount of "extra bits".
+
+   It is important that distance alphabet represents complete "groups".
+   To avoid complex logic on encoder side about interleaved ranges
+   it was decided to restrict both sides to complete distance code "groups".
+ */
+BROTLI_UNUSED_FUNCTION BrotliDistanceCodeLimit BrotliCalculateDistanceCodeLimit(
+    uint32_t max_distance, uint32_t npostfix, uint32_t ndirect) {
+  BrotliDistanceCodeLimit result;
+  /* Marking this function as unused, because not all files
+     including "constants.h" use it -> compiler warns about that. */
+  BROTLI_UNUSED(&BrotliCalculateDistanceCodeLimit);
+  if (max_distance <= ndirect) {
+    /* This case never happens / exists only for the sake of completeness. */
+    result.max_alphabet_size = max_distance + BROTLI_NUM_DISTANCE_SHORT_CODES;
+    result.max_distance = max_distance;
+    return result;
+  } else {
+    /* The first prohibited value. */
+    uint32_t forbidden_distance = max_distance + 1;
+    /* Subtract "directly" encoded region. */
+    uint32_t offset = forbidden_distance - ndirect - 1;
+    uint32_t ndistbits = 0;
+    uint32_t tmp;
+    uint32_t half;
+    uint32_t group;
+    /* Postfix for the last dcode in the group. */
+    uint32_t postfix = (1u << npostfix) - 1;
+    uint32_t extra;
+    uint32_t start;
+    /* Remove postfix and "head-start". */
+    offset = (offset >> npostfix) + 4;
+    /* Calculate the number of distance bits. */
+    tmp = offset / 2;
+    /* Poor-man's log2floor, to avoid extra dependencies. */
+    while (tmp != 0) {ndistbits++; tmp = tmp >> 1;}
+    /* One bit is covered with subrange addressing ("half"). */
+    ndistbits--;
+    /* Find subrange. */
+    half = (offset >> ndistbits) & 1;
+    /* Calculate the "group" part of dcode. */
+    group = ((ndistbits - 1) << 1) | half;
+    /* Calculated "group" covers the prohibited distance value. */
+    if (group == 0) {
+      /* This case is added for correctness; does not occur for limit > 128. */
+      result.max_alphabet_size = ndirect + BROTLI_NUM_DISTANCE_SHORT_CODES;
+      result.max_distance = ndirect;
+      return result;
+    }
+    /* Decrement "group", so it is the last permitted "group". */
+    group--;
+    /* After group was decremented, ndistbits and half must be recalculated. */
+    ndistbits = (group >> 1) + 1;
+    /* The last available distance in the subrange has all extra bits set. */
+    extra = (1u << ndistbits) - 1;
+    /* Calculate region start. NB: ndistbits >= 1. */
+    start = (1u << (ndistbits + 1)) - 4;
+    /* Move to subregion. */
+    start += (group & 1) << ndistbits;
+    /* Calculate the alphabet size. */
+    result.max_alphabet_size = ((group << npostfix) | postfix) + ndirect +
+        BROTLI_NUM_DISTANCE_SHORT_CODES + 1;
+    /* Calculate the maximal distance representable by alphabet. */
+    result.max_distance = ((start + extra) << npostfix) + postfix + ndirect + 1;
+    return result;
+  }
+}
+
+/* Represents the range of values belonging to a prefix code:
+   [offset, offset + 2^nbits) */
+typedef struct {
+  uint16_t offset;
+  uint8_t nbits;
+} BrotliPrefixCodeRange;
+
+/* "Soft-private", it is exported, but not "advertised" as API. */
+BROTLI_COMMON_API extern const BrotliPrefixCodeRange
+    _kBrotliPrefixCodeRanges[BROTLI_NUM_BLOCK_LEN_SYMBOLS];
+
+#endif  /* BROTLI_COMMON_CONSTANTS_H_ */