1 // SPDX-License-Identifier: Apache-2.0 2 // ---------------------------------------------------------------------------- 3 // Copyright 2011-2021 Arm Limited 4 // 5 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 6 // use this file except in compliance with the License. You may obtain a copy 7 // of the License at: 8 // 9 // http://www.apache.org/licenses/LICENSE-2.0 10 // 11 // Unless required by applicable law or agreed to in writing, software 12 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 13 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 14 // License for the specific language governing permissions and limitations 15 // under the License. 16 // ---------------------------------------------------------------------------- 17 18 #include "astcenc_mathlib.h" 19 20 /** 21 * @brief 64-bit rotate left. 22 * 23 * @param val The value to rotate. 24 * @param count The rotation, in bits. 25 */ rotl(uint64_t val,int count)26static inline uint64_t rotl(uint64_t val, int count) 27 { 28 return (val << count) | (val >> (64 - count)); 29 } 30 31 /* See header for documentation. */ rand_init(uint64_t state[2])32void astc::rand_init(uint64_t state[2]) 33 { 34 state[0] = 0xfaf9e171cea1ec6bULL; 35 state[1] = 0xf1b318cc06af5d71ULL; 36 } 37 38 /* See header for documentation. */ rand(uint64_t state[2])39uint64_t astc::rand(uint64_t state[2]) 40 { 41 uint64_t s0 = state[0]; 42 uint64_t s1 = state[1]; 43 uint64_t res = s0 + s1; 44 s1 ^= s0; 45 state[0] = rotl(s0, 24) ^ s1 ^ (s1 << 16); 46 state[1] = rotl(s1, 37); 47 return res; 48 } 49