/* * PCG Random Number Generation for C. * * Copyright 2014 Melissa O'Neill * * 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 */ /* * This code is derived from the canonical C++ PCG implementation, which * has many additional features and is preferable if you can use C++ in * your project. * * The contents of this file were mechanically derived from pcg_variants.h * (every inline function defined there gets an exern declaration here). */ #include "pcg_variants.h" /* Functions to advance the underlying LCG, one version for each size and * each style. These functions are considered semi-private. There is rarely * a good reason to call them directly. */ extern inline void pcg_oneseq_64_step_r(struct pcg_state_64* rng); extern inline void pcg_oneseq_64_advance_r(struct pcg_state_64* rng, uint64_t delta); extern inline void pcg_mcg_64_step_r(struct pcg_state_64* rng); extern inline void pcg_mcg_64_advance_r(struct pcg_state_64* rng, uint64_t delta); extern inline void pcg_unique_64_step_r(struct pcg_state_64* rng); extern inline void pcg_unique_64_advance_r(struct pcg_state_64* rng, uint64_t delta); extern inline void pcg_setseq_64_step_r(struct pcg_state_setseq_64* rng); extern inline void pcg_setseq_64_advance_r(struct pcg_state_setseq_64* rng, uint64_t delta); /* Functions to seed the RNG state, one version for each size and each * style. Unlike the step functions, regular users can and should call * these functions. */ extern inline void pcg_oneseq_64_srandom_r(struct pcg_state_64* rng, uint64_t initstate); extern inline void pcg_mcg_64_srandom_r(struct pcg_state_64* rng, uint64_t initstate); extern inline void pcg_unique_64_srandom_r(struct pcg_state_64* rng, uint64_t initstate); extern inline void pcg_setseq_64_srandom_r(struct pcg_state_setseq_64* rng, uint64_t initstate, uint64_t initseq); /* Now, finally we create each of the individual generators. We provide * a random_r function that provides a random number of the appropriate * type (using the full range of the type) and a boundedrand_r version * that provides * * Implementation notes for boundedrand_r: * * To avoid bias, we need to make the range of the RNG a multiple of * bound, which we do by dropping output less than a threshold. * Let's consider a 32-bit case... A naive scheme to calculate the * threshold would be to do * * uint32_t threshold = 0x100000000ull % bound; * * but 64-bit div/mod is slower than 32-bit div/mod (especially on * 32-bit platforms). In essence, we do * * uint32_t threshold = (0x100000000ull-bound) % bound; * * because this version will calculate the same modulus, but the LHS * value is less than 2^32. * * (Note that using modulo is only wise for good RNGs, poorer RNGs * such as raw LCGs do better using a technique based on division.) * Empricical tests show that division is preferable to modulus for * reducting the range of an RNG. It's faster, and sometimes it can * even be statistically prefereable. */ /* Generation functions for XSH RS */ extern inline uint32_t pcg_oneseq_64_xsh_rs_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_oneseq_64_xsh_rs_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); extern inline uint32_t pcg_unique_64_xsh_rs_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_unique_64_xsh_rs_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); extern inline uint32_t pcg_setseq_64_xsh_rs_32_random_r(struct pcg_state_setseq_64* rng); extern inline uint32_t pcg_setseq_64_xsh_rs_32_boundedrand_r(struct pcg_state_setseq_64* rng, uint32_t bound); extern inline uint32_t pcg_mcg_64_xsh_rs_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_mcg_64_xsh_rs_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); /* Generation functions for XSH RR */ extern inline uint32_t pcg_oneseq_64_xsh_rr_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_oneseq_64_xsh_rr_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); extern inline uint32_t pcg_unique_64_xsh_rr_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_unique_64_xsh_rr_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); extern inline uint32_t pcg_setseq_64_xsh_rr_32_random_r(struct pcg_state_setseq_64* rng); extern inline uint32_t pcg_setseq_64_xsh_rr_32_boundedrand_r(struct pcg_state_setseq_64* rng, uint32_t bound); extern inline uint32_t pcg_mcg_64_xsh_rr_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_mcg_64_xsh_rr_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); /* Generation functions for RXS M XS (no MCG versions because they * don't make sense when you want to use the entire state) */ extern inline uint64_t pcg_oneseq_64_rxs_m_xs_64_random_r(struct pcg_state_64* rng); extern inline uint64_t pcg_oneseq_64_rxs_m_xs_64_boundedrand_r(struct pcg_state_64* rng, uint64_t bound); extern inline uint64_t pcg_unique_64_rxs_m_xs_64_random_r(struct pcg_state_64* rng); extern inline uint64_t pcg_unique_64_rxs_m_xs_64_boundedrand_r(struct pcg_state_64* rng, uint64_t bound); extern inline uint64_t pcg_setseq_64_rxs_m_xs_64_random_r(struct pcg_state_setseq_64* rng); extern inline uint64_t pcg_setseq_64_rxs_m_xs_64_boundedrand_r(struct pcg_state_setseq_64* rng, uint64_t bound); /* Generation functions for XSL RR (only defined for "large" types) */ extern inline uint32_t pcg_oneseq_64_xsl_rr_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_oneseq_64_xsl_rr_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); extern inline uint32_t pcg_unique_64_xsl_rr_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_unique_64_xsl_rr_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); extern inline uint32_t pcg_setseq_64_xsl_rr_32_random_r(struct pcg_state_setseq_64* rng); extern inline uint32_t pcg_setseq_64_xsl_rr_32_boundedrand_r(struct pcg_state_setseq_64* rng, uint32_t bound); extern inline uint32_t pcg_mcg_64_xsl_rr_32_random_r(struct pcg_state_64* rng); extern inline uint32_t pcg_mcg_64_xsl_rr_32_boundedrand_r(struct pcg_state_64* rng, uint32_t bound); /* Generation functions for XSL RR RR (only defined for "large" types) */ extern inline uint64_t pcg_oneseq_64_xsl_rr_rr_64_random_r(struct pcg_state_64* rng); extern inline uint64_t pcg_oneseq_64_xsl_rr_rr_64_boundedrand_r(struct pcg_state_64* rng, uint64_t bound); extern inline uint64_t pcg_unique_64_xsl_rr_rr_64_random_r(struct pcg_state_64* rng); extern inline uint64_t pcg_unique_64_xsl_rr_rr_64_boundedrand_r(struct pcg_state_64* rng, uint64_t bound); extern inline uint64_t pcg_setseq_64_xsl_rr_rr_64_random_r(struct pcg_state_setseq_64* rng); extern inline uint64_t pcg_setseq_64_xsl_rr_rr_64_boundedrand_r(struct pcg_state_setseq_64* rng, uint64_t bound);