1 files changed, 58 insertions, 0 deletions
diff --git a/modules/woff2/src/woff2_common.cc b/modules/woff2/src/woff2_common.cc
new file mode 100644
index 0000000000..fe0a3beda7
--- /dev/null
+++ b/modules/woff2/src/woff2_common.cc
@@ -0,0 +1,58 @@
+/* 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