woff2_common.cc (1547B)
1 /* Copyright 2013 Google Inc. All Rights Reserved. 2 3 Distributed under MIT license. 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT 5 */ 6 7 /* Helpers common across multiple parts of woff2 */ 8 9 #include <algorithm> 10 11 #include "./woff2_common.h" 12 13 #include "./port.h" 14 15 namespace woff2 { 16 17 18 uint32_t ComputeULongSum(const uint8_t* buf, size_t size) { 19 uint32_t checksum = 0; 20 size_t aligned_size = size & ~3; 21 for (size_t i = 0; i < aligned_size; i += 4) { 22 #if defined(WOFF_LITTLE_ENDIAN) 23 uint32_t v = *reinterpret_cast<const uint32_t*>(buf + i); 24 checksum += (((v & 0xFF) << 24) | ((v & 0xFF00) << 8) | 25 ((v & 0xFF0000) >> 8) | ((v & 0xFF000000) >> 24)); 26 #elif defined(WOFF_BIG_ENDIAN) 27 checksum += *reinterpret_cast<const uint32_t*>(buf + i); 28 #else 29 checksum += (buf[i] << 24) | (buf[i + 1] << 16) | 30 (buf[i + 2] << 8) | buf[i + 3]; 31 #endif 32 } 33 34 // treat size not aligned on 4 as if it were padded to 4 with 0's 35 if (size != aligned_size) { 36 uint32_t v = 0; 37 for (size_t i = aligned_size; i < size; ++i) { 38 v |= buf[i] << (24 - 8 * (i & 3)); 39 } 40 checksum += v; 41 } 42 43 return checksum; 44 } 45 46 size_t CollectionHeaderSize(uint32_t header_version, uint32_t num_fonts) { 47 size_t size = 0; 48 if (header_version == 0x00020000) { 49 size += 12; // ulDsig{Tag,Length,Offset} 50 } 51 if (header_version == 0x00010000 || header_version == 0x00020000) { 52 size += 12 // TTCTag, Version, numFonts 53 + 4 * num_fonts; // OffsetTable[numFonts] 54 } 55 return size; 56 } 57 58 } // namespace woff2