1437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// Copyright 2013 Google Inc. All Rights Reserved. 2437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// 3437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// Licensed under the Apache License, Version 2.0 (the "License"); 4437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// you may not use this file except in compliance with the License. 5437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// You may obtain a copy of the License at 6437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// 7437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// http://www.apache.org/licenses/LICENSE-2.0 8437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// 9437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// Unless required by applicable law or agreed to in writing, software 10437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// distributed under the License is distributed on an "AS IS" BASIS, 11437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// See the License for the specific language governing permissions and 13437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// limitations under the License. 14437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// 15437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter// Helper function for bit twiddling 16437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter 17494c85cebbaaa0db345df69ffa1b639aa4652022Zoltan Szabadka#ifndef WOFF2_PORT_H_ 18494c85cebbaaa0db345df69ffa1b639aa4652022Zoltan Szabadka#define WOFF2_PORT_H_ 19437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter 20437bbad37074e472b66d427814275de84ca77f19Roderick Sheeternamespace woff2 { 21437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter 22437bbad37074e472b66d427814275de84ca77f19Roderick Sheetertypedef unsigned int uint32; 23437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter 24437bbad37074e472b66d427814275de84ca77f19Roderick Sheeterinline int Log2Floor(uint32 n) { 25437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter#if defined(__GNUC__) 26437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter return n == 0 ? -1 : 31 ^ __builtin_clz(n); 27437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter#else 28437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter if (n == 0) 29437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter return -1; 30437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter int log = 0; 31437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter uint32 value = n; 32437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter for (int i = 4; i >= 0; --i) { 33437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter int shift = (1 << i); 34437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter uint32 x = value >> shift; 35437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter if (x != 0) { 36437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter value = x; 37437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter log += shift; 38437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter } 39437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter } 40437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter assert(value == 1); 41437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter return log; 42437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter#endif 43437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter} 44437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter 45437bbad37074e472b66d427814275de84ca77f19Roderick Sheeter} // namespace woff2 46494c85cebbaaa0db345df69ffa1b639aa4652022Zoltan Szabadka#endif // WOFF2_PORT_H_ 47