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58 lines
1.5 KiB
C++
58 lines
1.5 KiB
C++
/* Copyright 2013 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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/* Helpers common across multiple parts of woff2 */
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#include <algorithm>
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#include "./woff2_common.h"
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#include "./port.h"
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namespace woff2 {
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uint32_t ComputeULongSum(const uint8_t* buf, size_t size) {
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uint32_t checksum = 0;
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size_t aligned_size = size & ~3;
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for (size_t i = 0; i < aligned_size; i += 4) {
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#if defined(WOFF_LITTLE_ENDIAN)
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uint32_t v = *reinterpret_cast<const uint32_t*>(buf + i);
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checksum += (((v & 0xFF) << 24) | ((v & 0xFF00) << 8) |
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((v & 0xFF0000) >> 8) | ((v & 0xFF000000) >> 24));
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#elif defined(WOFF_BIG_ENDIAN)
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checksum += *reinterpret_cast<const uint32_t*>(buf + i);
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#else
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checksum += (buf[i] << 24) | (buf[i + 1] << 16) |
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(buf[i + 2] << 8) | buf[i + 3];
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#endif
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}
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// treat size not aligned on 4 as if it were padded to 4 with 0's
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if (size != aligned_size) {
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uint32_t v = 0;
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for (size_t i = aligned_size; i < size; ++i) {
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v |= buf[i] << (24 - 8 * (i & 3));
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}
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checksum += v;
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}
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return checksum;
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}
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size_t CollectionHeaderSize(uint32_t header_version, uint32_t num_fonts) {
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size_t size = 0;
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if (header_version == 0x00020000) {
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size += 12; // ulDsig{Tag,Length,Offset}
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}
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if (header_version == 0x00010000 || header_version == 0x00020000) {
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size += 12 // TTCTag, Version, numFonts
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+ 4 * num_fonts; // OffsetTable[numFonts]
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}
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return size;
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}
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} // namespace woff2
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