| // SPDX-License-Identifier: Apache-2.0 | |
| // ---------------------------------------------------------------------------- | |
| // Copyright 2011-2021 Arm Limited | |
| // | |
| // 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. | |
| // ---------------------------------------------------------------------------- | |
| /** | |
| * @brief 64-bit rotate left. | |
| * | |
| * @param val The value to rotate. | |
| * @param count The rotation, in bits. | |
| */ | |
| static inline uint64_t rotl(uint64_t val, int count) | |
| { | |
| return (val << count) | (val >> (64 - count)); | |
| } | |
| /* See header for documentation. */ | |
| void astc::rand_init(uint64_t state[2]) | |
| { | |
| state[0] = 0xfaf9e171cea1ec6bULL; | |
| state[1] = 0xf1b318cc06af5d71ULL; | |
| } | |
| /* See header for documentation. */ | |
| uint64_t astc::rand(uint64_t state[2]) | |
| { | |
| uint64_t s0 = state[0]; | |
| uint64_t s1 = state[1]; | |
| uint64_t res = s0 + s1; | |
| s1 ^= s0; | |
| state[0] = rotl(s0, 24) ^ s1 ^ (s1 << 16); | |
| state[1] = rotl(s1, 37); | |
| return res; | |
| } | |