1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef EBMLUTIL_H_ 18 #define EBMLUTIL_H_ 19 20 #include <stdint.h> 21 22 namespace webm { 23 24 // Encode the id and/or size of an EBML element bytes by setting a leading length descriptor bit: 25 // 26 // 1xxxxxxx - 1-byte values 27 // 01xxxxxx xxxxxxxx - 28 // 001xxxxx xxxxxxxx xxxxxxxx - 29 // 0001xxxx xxxxxxxx xxxxxxxx xxxxxxxx - ... 30 // 00001xxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx - 31 // 000001xx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx - 32 // 0000001x xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx - 33 // 00000001 xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx - 8-byte values 34 // 35 // This function uses the least the number of bytes possible. 36 uint64_t encodeUnsigned(uint64_t u); 37 38 // Like above but pads the input value with leading zeros up to the specified width. The length 39 // descriptor is calculated based on width. 40 uint64_t encodeUnsigned(uint64_t u, int width); 41 42 // Serialize an EBML coded id or size in big-endian order. 43 int serializeCodedUnsigned(uint64_t u, uint8_t* bary); 44 45 // Calculate the length of an EBML coded id or size from its length descriptor. 46 int sizeOf(uint64_t u); 47 48 } 49 50 #endif /* EBMLUTIL_H_ */ 51
