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author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
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committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
tree | 2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/vlib/rand/wyrand/wyrand.v | |
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Diffstat (limited to 'v_windows/v/vlib/rand/wyrand/wyrand.v')
-rw-r--r-- | v_windows/v/vlib/rand/wyrand/wyrand.v | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/v_windows/v/vlib/rand/wyrand/wyrand.v b/v_windows/v/vlib/rand/wyrand/wyrand.v new file mode 100644 index 0000000..22b71af --- /dev/null +++ b/v_windows/v/vlib/rand/wyrand/wyrand.v @@ -0,0 +1,252 @@ +// 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 wyrand + +import math.bits +import rand.seed +import rand.constants +import hash + +// Redefinition of some constants that we will need for pseudorandom number generation. +const ( + wyp0 = u64(0xa0761d6478bd642f) + wyp1 = u64(0xe7037ed1a0b428db) +) + +// WyRandRNG is a RNG based on the WyHash hashing algorithm. +pub struct WyRandRNG { +mut: + state u64 = seed.time_seed_64() + has_extra bool + extra u32 +} + +// seed sets the seed, needs only two `u32`s in little-endian format as [lower, higher]. +pub fn (mut rng WyRandRNG) seed(seed_data []u32) { + if seed_data.len != 2 { + eprintln('WyRandRNG 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 WyRandRNG) 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 WyRandRNG) u64() u64 { + unsafe { + mut seed1 := rng.state + seed1 += wyrand.wyp0 + rng.state = seed1 + return hash.wymum(seed1 ^ wyrand.wyp1, seed1) + } + return 0 +} + +// u32n returns a pseudorandom `u32` less than `max`. +[inline] +pub fn (mut rng WyRandRNG) u32n(max u32) u32 { + if max == 0 { + eprintln('max must be positive integer') + exit(1) + } + // Check SysRNG in system_rng.c.v for explanation + bit_len := bits.len_32(max) + if bit_len == 32 { + for { + value := rng.u32() + if value < max { + return value + } + } + } else { + mask := (u32(1) << (bit_len + 1)) - 1 + for { + value := rng.u32() & mask + if value < max { + return value + } + } + } + return u32(0) +} + +// u64n returns a pseudorandom `u64` less than `max`. +[inline] +pub fn (mut rng WyRandRNG) u64n(max u64) u64 { + if max == 0 { + eprintln('max must be positive integer') + exit(1) + } + bit_len := bits.len_64(max) + if bit_len == 64 { + for { + value := rng.u64() + if value < max { + return value + } + } + } else { + mask := (u64(1) << (bit_len + 1)) - 1 + for { + value := rng.u64() & mask + if value < max { + return value + } + } + } + return u64(0) +} + +// u32n returns a pseudorandom `u32` value that is guaranteed to be in range `[min, max)`. +[inline] +pub fn (mut rng WyRandRNG) 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 WyRandRNG) 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 (possibly negative) pseudorandom 32-bit `int`. +[inline] +pub fn (mut rng WyRandRNG) int() int { + return int(rng.u32()) +} + +// i64 returns a (possibly negative) pseudorandom 64-bit `i64`. +[inline] +pub fn (mut rng WyRandRNG) i64() i64 { + return i64(rng.u64()) +} + +// int31 returns a positive pseudorandom 31-bit `int`. +[inline] +pub fn (mut rng WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 int that lies in `[0, max)`. +[inline] +pub fn (mut rng WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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 WyRandRNG) 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) +} |