diff options
| -rw-r--r-- | docs/crandom_api.md | 42 | ||||
| -rw-r--r-- | examples/demos.c | 7 | ||||
| -rw-r--r-- | stc/crandom.h | 2 |
3 files changed, 24 insertions, 27 deletions
diff --git a/docs/crandom_api.md b/docs/crandom_api.md index df5c3497..69cc4789 100644 --- a/docs/crandom_api.md +++ b/docs/crandom_api.md @@ -7,14 +7,14 @@ and can generate bounded uniform and normal distributed random numbers. See [random](https://en.cppreference.com/w/cpp/header/random) for similar c++ functionality. **stc64** is a novel, extremely fast PRNG by Tyge Løvset, suited for parallel usage. It features a -Weyl-sequence as part of the state. It is faster than *sfc64*, *wyhash64*, *pcg64*, and *xoshiro256\*\** -on common platforms. It does not require fast multiplication or 128-bit integer operations. It has a -256 bit state, but updates only 192 bit per generated number. +Weyl-sequence as part of the state. In general testing, **stc64** is the fastest among *pcg64*, +*xoshiro256`**`*, *sfc64*, and *lehmer64*. On some platforms, *wyrand64* is faster, but it has only +128-bit state with no minimum period length guarantee. *stc64* does not require fast multiplication +or 128-bit integer operations. It has 256 bit state, but updates only 192 bit per generated number. -There is no *jump function*, but by incrementing the Weyl-increment by 2, it starts a new -unique 2^64 *minimum* length period. Note that for each Weyl-increment (state[3]), the period -length is about 2^126 with a high probability. For a single thread, a minimum period of 2^127 -is generated when the Weyl-increment is incremented by 2 every 2^64 output. +There is no *jump function*, but for each odd number Weyl-increment (state[3]), it starts a new +unique 2^64 *minimum* length period. For a single thread, a minimum period of 2^127 is generated +when the Weyl-increment is incremented by 2 every 2^64 output. **stc64** passes *PractRand*, tested up to 8TB output, Vigna's Hamming weight test, and simple correlation tests, i.e. *n* interleaved streams with only one-bit differences in initial state. @@ -41,27 +41,23 @@ All cstr definitions and prototypes may be included in your C source file by inc ## Methods ```c - void stc64_srandom(uint64_t seed); - uint64_t stc64_random(void); +void stc64_srandom(uint64_t seed); // seed global rng +uint64_t stc64_random(void); // range [0, 2^64 - 1] - 1) stc64_t stc64_init(uint64_t seed); - 2) stc64_t stc64_with_seq(uint64_t seed, uint64_t seq); +stc64_t stc64_init(uint64_t seed); +stc64_t stc64_with_seq(uint64_t seed, uint64_t seq); // init with stream - 3) uint64_t stc64_rand(stc64_t* rng); - 4) double stc64_randf(stc64_t* rng); +uint64_t stc64_rand(stc64_t* rng); // range [0, 2^64 - 1] +double stc64_randf(stc64_t* rng); // range [0.0, 1.0) - 5) stc64_uniform_t stc64_uniform_init(int64_t low, int64_t high); - 6) int64_t stc64_uniform(stc64_t* rng, stc64_uniform_t* dist); - 7) stc64_uniformf_t stc64_uniformf_init(double low, double high); - 8) double stc64_uniformf(stc64_t* rng, stc64_uniformf_t* dist); +stc64_uniform_t stc64_uniform_init(int64_t low, int64_t high); // uniform-distribution +int64_t stc64_uniform(stc64_t* rng, stc64_uniform_t* dist); // range [low, high] +stc64_uniformf_t stc64_uniformf_init(double lowf, double highf); +double stc64_uniformf(stc64_t* rng, stc64_uniformf_t* dist); // range [lowf, highf) - 9) stc64_normalf_t stc64_normalf_init(double mean, double stddev); -10) double stc64_normalf(stc64_t* rng, stc64_normalf_t* dist); +stc64_normalf_t stc64_normalf_init(double mean, double stddev); // normal-distribution +double stc64_normalf(stc64_t* rng, stc64_normalf_t* dist); ``` -`1-2)` PRNG 64-bit engine initializers. `3)` Integer generator, range \[0, 2^64). -`4)` Double RNG with range \[0, 1). `5-6)` Uniform integer RNG with range \[*low*, *high*]. -`7-8)` Uniform double RNG with range \[*low*, *high*). `9-10)` Normal-distributed double -RNG, around 68% of the values fall within the range [*mean* - *stddev*, *mean* + *stddev*]. ## Example ```c diff --git a/examples/demos.c b/examples/demos.c index 4eac761c..553d6d88 100644 --- a/examples/demos.c +++ b/examples/demos.c @@ -161,11 +161,12 @@ void mapdemo3() cmap_str_emplace(&table, "Map", "test");
cmap_str_emplace(&table, "Make", "my");
cmap_str_emplace(&table, "Sunny", "day");
- cmap_str_value_t *e = cmap_str_find(&table, "Make").ref;
+ cmap_str_iter_t it = cmap_str_find(&table, "Make");
c_foreach (i, cmap_str, table)
printf("entry: %s: %s\n", i.ref->first.str, i.ref->second.str);
- printf("size %zu: remove: Make: %s\n", cmap_str_size(table), e->second.str);
- cmap_str_erase(&table, "Make");
+ printf("size %zu: remove: Make: %s\n", cmap_str_size(table), it.ref->second.str);
+ //cmap_str_erase(&table, "Make");
+ cmap_str_erase_at(&table, it);
printf("size %zu\n", cmap_str_size(table));
c_foreach (i, cmap_str, table)
diff --git a/stc/crandom.h b/stc/crandom.h index bf256d17..3dd9fe72 100644 --- a/stc/crandom.h +++ b/stc/crandom.h @@ -66,7 +66,7 @@ static stc64_t stc64_global = {{0x26aa069ea2fb1a4d, 0x70c72c95cd592d04, 0x504f33 STC_INLINE void stc64_srandom(uint64_t seed) { stc64_global = stc64_init(seed); }
STC_INLINE uint64_t stc64_random(void) { return stc64_rand(&stc64_global); }
-/* Float64 random number in range [low, high). */
+/* Float64 random number in range [0.0, 1.0). */
STC_INLINE double stc64_randf(stc64_t* rng) {
union {uint64_t i; double f;} u = {0x3FF0000000000000ull | (stc64_rand(rng) >> 12)};
return u.f - 1.0;
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