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/* Copyright 2013 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
/* Helpers common across multiple parts of woff2 */
#include <algorithm>
#include "./woff2_common.h"
#include "./port.h"
namespace woff2 {
uint32_t ComputeULongSum(const uint8_t* buf, size_t size) {
uint32_t checksum = 0;
size_t aligned_size = size & ~3;
for (size_t i = 0; i < aligned_size; i += 4) {
#if defined(WOFF_LITTLE_ENDIAN)
uint32_t v = *reinterpret_cast<const uint32_t*>(buf + i);
checksum += (((v & 0xFF) << 24) | ((v & 0xFF00) << 8) |
((v & 0xFF0000) >> 8) | ((v & 0xFF000000) >> 24));
#elif defined(WOFF_BIG_ENDIAN)
checksum += *reinterpret_cast<const uint32_t*>(buf + i);
#else
checksum += (buf[i] << 24) | (buf[i + 1] << 16) |
(buf[i + 2] << 8) | buf[i + 3];
#endif
}
// treat size not aligned on 4 as if it were padded to 4 with 0's
if (size != aligned_size) {
uint32_t v = 0;
for (size_t i = aligned_size; i < size; ++i) {
v |= buf[i] << (24 - 8 * (i & 3));
}
checksum += v;
}
return checksum;
}
size_t CollectionHeaderSize(uint32_t header_version, uint32_t num_fonts) {
size_t size = 0;
if (header_version == 0x00020000) {
size += 12; // ulDsig{Tag,Length,Offset}
}
if (header_version == 0x00010000 || header_version == 0x00020000) {
size += 12 // TTCTag, Version, numFonts
+ 4 * num_fonts; // OffsetTable[numFonts]
}
return size;
}
} // namespace woff2
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