diff options
Diffstat (limited to 'v_windows/v/vlib/rand/splitmix64/splitmix64.v')
| -rw-r--r-- | v_windows/v/vlib/rand/splitmix64/splitmix64.v | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/v_windows/v/vlib/rand/splitmix64/splitmix64.v b/v_windows/v/vlib/rand/splitmix64/splitmix64.v new file mode 100644 index 0000000..d3cb9d1 --- /dev/null +++ b/v_windows/v/vlib/rand/splitmix64/splitmix64.v @@ -0,0 +1,225 @@ +// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved. +// Use of this source code is governed by an MIT license +// that can be found in the LICENSE file. +module splitmix64 + +import rand.seed +import rand.constants + +// SplitMix64RNG ported from http://xoshiro.di.unimi.it/splitmix64.c +pub struct SplitMix64RNG { +mut: + state u64 = seed.time_seed_64() + has_extra bool + extra u32 +} + +// seed sets the seed of the accepting SplitMix64RNG to the given data +// in little-endian format (i.e. lower 32 bits are in [0] and higher 32 bits in [1]). +pub fn (mut rng SplitMix64RNG) seed(seed_data []u32) { + if seed_data.len != 2 { + eprintln('SplitMix64RNG needs 2 32-bit unsigned integers as the seed.') + exit(1) + } + rng.state = seed_data[0] | (u64(seed_data[1]) << 32) + rng.has_extra = false +} + +// u32 updates the PRNG state and returns the next pseudorandom `u32`. +[inline] +pub fn (mut rng SplitMix64RNG) u32() u32 { + if rng.has_extra { + rng.has_extra = false + return rng.extra + } + full_value := rng.u64() + lower := u32(full_value & constants.lower_mask) + upper := u32(full_value >> 32) + rng.extra = upper + rng.has_extra = true + return lower +} + +// u64 updates the PRNG state and returns the next pseudorandom `u64`. +[inline] +pub fn (mut rng SplitMix64RNG) u64() u64 { + rng.state += (0x9e3779b97f4a7c15) + mut z := rng.state + z = (z ^ ((z >> u64(30)))) * (0xbf58476d1ce4e5b9) + z = (z ^ ((z >> u64(27)))) * (0x94d049bb133111eb) + return z ^ (z >> (31)) +} + +// u32n returns a pseudorandom `u32` less than `bound`. +[inline] +pub fn (mut rng SplitMix64RNG) u32n(bound u32) u32 { + // This function is kept similar to the u64 version + if bound == 0 { + eprintln('max must be non-zero') + exit(1) + } + threshold := -bound % bound + for { + r := rng.u32() + if r >= threshold { + return r % bound + } + } + return u32(0) +} + +// u64n returns a pseudorandom `u64` less than `bound`. +[inline] +pub fn (mut rng SplitMix64RNG) u64n(bound u64) u64 { + // See pcg32.v for explanation of comment. This algorithm + // existed before the refactoring. + if bound == 0 { + eprintln('max must be non-zero') + exit(1) + } + threshold := -bound % bound + for { + r := rng.u64() + if r >= threshold { + return r % bound + } + } + return u64(0) +} + +// u32n returns a pseudorandom `u32` value that is guaranteed to be in range `[min, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) u32_in_range(min u32, max u32) u32 { + if max <= min { + eprintln('max must be greater than min') + exit(1) + } + return min + rng.u32n(max - min) +} + +// u64n returns a pseudorandom `u64` value that is guaranteed to be in range `[min, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) u64_in_range(min u64, max u64) u64 { + if max <= min { + eprintln('max must be greater than min') + exit(1) + } + return min + rng.u64n(max - min) +} + +// int returns a pseudorandom 32-bit (possibly negative) `int`. +[inline] +pub fn (mut rng SplitMix64RNG) int() int { + return int(rng.u32()) +} + +// i64 returns a pseudorandom 64-bit (possibly negative) `i64`. +[inline] +pub fn (mut rng SplitMix64RNG) i64() i64 { + return i64(rng.u64()) +} + +// int31 returns a positive pseudorandom 31-bit `int`. +[inline] +pub fn (mut rng SplitMix64RNG) int31() int { + return int(rng.u32() & constants.u31_mask) // Set the 32nd bit to 0. +} + +// int63 returns a positive pseudorandom 63-bit `i64`. +[inline] +pub fn (mut rng SplitMix64RNG) int63() i64 { + return i64(rng.u64() & constants.u63_mask) // Set the 64th bit to 0. +} + +// intn returns a pseudorandom `int` in range `[0, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) intn(max int) int { + if max <= 0 { + eprintln('max has to be positive.') + exit(1) + } + return int(rng.u32n(u32(max))) +} + +// i64n returns a pseudorandom `i64` in range `[0, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) i64n(max i64) i64 { + if max <= 0 { + eprintln('max has to be positive.') + exit(1) + } + return i64(rng.u64n(u64(max))) +} + +// int_in_range returns a pseudorandom `int` in range `[min, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) int_in_range(min int, max int) int { + if max <= min { + eprintln('max must be greater than min') + exit(1) + } + // This supports negative ranges like [-10, -5) because the difference is positive + return min + rng.intn(max - min) +} + +// i64_in_range returns a pseudorandom `i64` in range `[min, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) i64_in_range(min i64, max i64) i64 { + if max <= min { + eprintln('max must be greater than min') + exit(1) + } + return min + rng.i64n(max - min) +} + +// f32 returns a pseudorandom `f32` value in range `[0, 1)`. +[inline] +pub fn (mut rng SplitMix64RNG) f32() f32 { + return f32(rng.u32()) / constants.max_u32_as_f32 +} + +// f64 returns a pseudorandom `f64` value in range `[0, 1)`. +[inline] +pub fn (mut rng SplitMix64RNG) f64() f64 { + return f64(rng.u64()) / constants.max_u64_as_f64 +} + +// f32n returns a pseudorandom `f32` value in range `[0, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) f32n(max f32) f32 { + if max <= 0 { + eprintln('max has to be positive.') + exit(1) + } + return rng.f32() * max +} + +// f64n returns a pseudorandom `f64` value in range `[0, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) f64n(max f64) f64 { + if max <= 0 { + eprintln('max has to be positive.') + exit(1) + } + return rng.f64() * max +} + +// f32_in_range returns a pseudorandom `f32` in range `[min, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) f32_in_range(min f32, max f32) f32 { + if max <= min { + eprintln('max must be greater than min') + exit(1) + } + return min + rng.f32n(max - min) +} + +// i64_in_range returns a pseudorandom `i64` in range `[min, max)`. +[inline] +pub fn (mut rng SplitMix64RNG) f64_in_range(min f64, max f64) f64 { + if max <= min { + eprintln('max must be greater than min') + exit(1) + } + return min + rng.f64n(max - min) +} |