1 /* 2 * Copyright (C) 2025 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 #include <stdint.h> 18 #include <stdio.h> 19 #include <unistd.h> // For usleep function 20 21 typedef uint32_t UInt32; 22 typedef uint16_t UInt16; 23 cond_branch_example_function(uint16_t * prob,uint8_t * buf)24void cond_branch_example_function(uint16_t* prob, uint8_t* buf) { 25 UInt32 range = 0xFFFFFFFF; 26 UInt32 code = 0; 27 UInt32 bound; 28 UInt16 ttt; 29 UInt32 symbol = 0; 30 31 do { 32 ttt = *(prob + symbol); 33 if (range < ((UInt32)1 << 24)) { 34 range <<= 8; 35 code = (code << 8) | (*buf++); 36 } 37 bound = (range >> 11) * ttt; 38 if (code < bound) { // <== This is mispredicted branch (conditional branch) 39 range = bound; 40 *(prob + symbol) = (UInt16)(ttt + (((1 << 11) - ttt) >> 5)); 41 symbol = (symbol + symbol); 42 } else { 43 range -= bound; 44 code -= bound; 45 *(prob + symbol) = (UInt16)(ttt - (ttt >> 5)); 46 symbol = (symbol + symbol) + 1; 47 } 48 } while (symbol < 0x100); // conditional branch 49 } 50 main()51int main() { 52 uint16_t prob[256] = {0}; 53 uint8_t buf[256] = {0}; 54 55 usleep(15000000); 56 57 // Call the conditional branch example function 58 cond_branch_example_function(prob, buf); 59 60 return 0; 61 } 62