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godotengine
GitHub Repository: godotengine/godot
 Path: blob/master/thirdparty/brotli/dec/prefix.c
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/* Copyright 2025 Google Inc. All Rights Reserved.

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   Distributed under MIT license.

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

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*/

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#include "prefix.h"

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#include "../common/platform.h"  /* IWYU pragma: keep */

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#include "../common/static_init.h"

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#if (BROTLI_STATIC_INIT != BROTLI_STATIC_INIT_NONE)

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

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#endif

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#if defined(__cplusplus) || defined(c_plusplus)

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extern "C" {

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#endif

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#if (BROTLI_STATIC_INIT == BROTLI_STATIC_INIT_NONE)

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/* Embed kCmdLut. */

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#include "prefix_inc.h"

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#else

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BROTLI_COLD BROTLI_BOOL BrotliDecoderInitCmdLut(CmdLutElement* items) {

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  static const uint8_t kInsertLengthExtraBits[24] = {

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      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x02, 0x02, 0x03, 0x03,

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      0x04, 0x04, 0x05, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0C, 0x0E, 0x18};

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  static const uint8_t kCopyLengthExtraBits[24] = {

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      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x02, 0x02,

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      0x03, 0x03, 0x04, 0x04, 0x05, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x18};

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  static const uint8_t kCellPos[11] = {0, 1, 0, 1, 8, 9, 2, 16, 10, 17, 18};

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  uint16_t insert_length_offsets[24];

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  uint16_t copy_length_offsets[24];

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  insert_length_offsets[0] = 0;

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  copy_length_offsets[0] = 2;

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  for (size_t i = 0; i < 23; ++i) {

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    insert_length_offsets[i + 1] =

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        insert_length_offsets[i] + (uint16_t)(1u << kInsertLengthExtraBits[i]);

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    copy_length_offsets[i + 1] =

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        copy_length_offsets[i] + (uint16_t)(1u << kCopyLengthExtraBits[i]);

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  }

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  for (size_t symbol = 0; symbol < BROTLI_NUM_COMMAND_SYMBOLS; ++symbol) {

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    CmdLutElement* item = items + symbol;

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    const size_t cell_idx = symbol >> 6;

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    const size_t cell_pos = kCellPos[cell_idx];

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    const size_t copy_code = ((cell_pos << 3) & 0x18) + (symbol & 0x7);

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    const uint16_t copy_len_offset = copy_length_offsets[copy_code];

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    const size_t insert_code = (cell_pos & 0x18) + ((symbol >> 3) & 0x7);

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    item->copy_len_extra_bits = kCopyLengthExtraBits[copy_code];

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    item->context = (copy_len_offset > 4) ? 3 : ((uint8_t)copy_len_offset - 2);

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    item->copy_len_offset = copy_len_offset;

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    item->distance_code = (cell_idx >= 2) ? -1 : 0;

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    item->insert_len_extra_bits = kInsertLengthExtraBits[insert_code];

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    item->insert_len_offset = insert_length_offsets[insert_code];

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  }

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  return BROTLI_TRUE;

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}

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BROTLI_MODEL("small")

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CmdLutElement kCmdLut[BROTLI_NUM_COMMAND_SYMBOLS];

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#endif  /* BROTLI_STATIC_INIT */

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#if defined(__cplusplus) || defined(c_plusplus)

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}  /* extern "C" */

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#endif

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