1 files changed, 65 insertions, 0 deletions
diff --git a/modules/woff2/src/woff2_common.cc b/modules/woff2/src/woff2_common.cc
new file mode 100644
index 000000000..9dc7cbd5c
--- /dev/null
+++ b/modules/woff2/src/woff2_common.cc
@@ -0,0 +1,65 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Helpers common across multiple parts of woff2
+
+#include <algorithm>
+
+#include "./woff2_common.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) {
+    uint32_t v;
+    memcpy(&v, buf + i, 4);
+#if (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__))
+    checksum += (((v & 0xFF) << 24) | ((v & 0xFF00) << 8) |
+      ((v & 0xFF0000) >> 8) | ((v & 0xFF000000) >> 24));
+#elif (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+    checksum += v;
+#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