| // 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. |
| // |
| // Helper function for bit twiddling |
| |
| #ifndef WOFF2_PORT_H_ |
| #define WOFF2_PORT_H_ |
| |
| namespace woff2 { |
| |
| typedef unsigned int uint32; |
| |
| inline int Log2Floor(uint32 n) { |
| #if defined(__GNUC__) |
| return n == 0 ? -1 : 31 ^ __builtin_clz(n); |
| #else |
| if (n == 0) |
| return -1; |
| int log = 0; |
| uint32 value = n; |
| for (int i = 4; i >= 0; --i) { |
| int shift = (1 << i); |
| uint32 x = value >> shift; |
| if (x != 0) { |
| value = x; |
| log += shift; |
| } |
| } |
| assert(value == 1); |
| return log; |
| #endif |
| } |
| |
| } // namespace woff2 |
| #endif // WOFF2_PORT_H_ |
