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author | RĂ©mi Verschelde <rverschelde@gmail.com> | 2020-10-30 15:00:44 +0100 |
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committer | GitHub <noreply@github.com> | 2020-10-30 15:00:44 +0100 |
commit | f98db723b91feb5ffc54460813be2c712e0b8ff8 (patch) | |
tree | 0f35f28b6a3f7cd2578cd8af320122a952030fe5 /thirdparty | |
parent | b1ed10da1b5452486cd745964672f8017404eaeb (diff) | |
parent | 31faa1f22626b8745ed4a1541497832b6f595df2 (diff) |
Merge pull request #43184 from Chaosus/fix_randi_range_biased
Fix biased output of randi_range
Diffstat (limited to 'thirdparty')
-rw-r--r-- | thirdparty/misc/pcg.cpp | 10 | ||||
-rw-r--r-- | thirdparty/misc/pcg.h | 1 |
2 files changed, 11 insertions, 0 deletions
diff --git a/thirdparty/misc/pcg.cpp b/thirdparty/misc/pcg.cpp index c421e16f89..5f4bf40460 100644 --- a/thirdparty/misc/pcg.cpp +++ b/thirdparty/misc/pcg.cpp @@ -23,3 +23,13 @@ void pcg32_srandom_r(pcg32_random_t* rng, uint64_t initstate, uint64_t initseq) rng->state += initstate; pcg32_random_r(rng); } + +// Source from https://github.com/imneme/pcg-c-basic/blob/master/pcg_basic.c +uint32_t pcg32_boundedrand_r(pcg32_random_t *rng, uint32_t bound) { + uint32_t threshold = -bound % bound; + for (;;) { + uint32_t r = pcg32_random_r(rng); + if (r >= threshold) + return r % bound; + } +} diff --git a/thirdparty/misc/pcg.h b/thirdparty/misc/pcg.h index 6f42b3b094..0faab73e64 100644 --- a/thirdparty/misc/pcg.h +++ b/thirdparty/misc/pcg.h @@ -11,5 +11,6 @@ typedef struct { uint64_t state; uint64_t inc; } pcg32_random_t; uint32_t pcg32_random_r(pcg32_random_t* rng); void pcg32_srandom_r(pcg32_random_t* rng, uint64_t initstate, uint64_t initseq); +uint32_t pcg32_boundedrand_r(pcg32_random_t* rng, uint32_t bound); #endif // RANDOM_H |