| /* |
| * PCG Random Number Generation for C. |
| * |
| * Copyright 2014 Melissa O'Neill <oneill@pcg-random.org> |
| * |
| * 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. |
| * |
| * For additional information about the PCG random number generation scheme, |
| * including its license and other licensing options, visit |
| * |
| * http://www.pcg-random.org |
| */ |
| |
| #include "pcg_basic.h" |
| |
| void pcg32_srandom_r(pcg32_random_t* rng, uint64_t initial_state, uint64_t initseq) { |
| rng->state = 0U; |
| rng->inc = (initseq << 1u) | 1u; |
| pcg32_random_r(rng); |
| rng->state += initial_state; |
| pcg32_random_r(rng); |
| } |
| |
| uint32_t pcg32_random_r(pcg32_random_t* rng) { |
| uint64_t oldstate = rng->state; |
| rng->state = oldstate * 6364136223846793005ULL + rng->inc; |
| uint32_t xorshifted = (uint32_t)(((oldstate >> 18u) ^ oldstate) >> 27u); |
| uint32_t rot = (uint32_t)(oldstate >> 59u); |
| return (xorshifted >> rot) | (xorshifted << ((~rot + 1u) & 31)); /* was (xorshifted >> rot) | (xorshifted << ((-rot) & 31)) */ |
| } |