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v/vlib/rand/rand.v

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V

// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
[has_globals]
module rand
import math.bits
import rand.config
import rand.constants
import rand.wyrand
// PRNG is a common interface for all PRNGs that can be used seamlessly with the rand
// modules's API. It defines all the methods that a PRNG (in the vlib or custom made) must
// implement in order to ensure that _all_ functions can be used with the generator.
pub interface PRNG {
mut:
seed(seed_data []u32)
// TODO: Support buffering for bytes
// byte() byte
// bytes(bytes_needed int) ?[]byte
// u16() u16
u32() u32
u64() u64
free()
}
// byte returns a uniformly distributed pseudorandom 8-bit unsigned positive `byte`.
[inline]
pub fn (mut rng PRNG) byte() byte {
// TODO: Reimplement for all PRNGs efficiently
return byte(rng.u32() & 0xff)
}
// bytes returns a buffer of `bytes_needed` random bytes.
[inline]
pub fn (mut rng PRNG) bytes(bytes_needed int) ?[]byte {
// TODO: Reimplement for all PRNGs efficiently
if bytes_needed < 0 {
return error('can not read < 0 random bytes')
}
mut res := []byte{cap: bytes_needed}
mut remaining := bytes_needed
for remaining > 8 {
mut value := rng.u64()
for _ in 0 .. 8 {
res << byte(value & 0xff)
value >>= 8
}
remaining -= 8
}
for remaining > 4 {
mut value := rng.u32()
for _ in 0 .. 4 {
res << byte(value & 0xff)
value >>= 8
}
remaining -= 4
}
for remaining > 0 {
res << rng.byte()
remaining -= 1
}
return res
}
// u32n returns a uniformly distributed pseudorandom 32-bit signed positive `u32` in range `[0, max)`.
[inline]
pub fn (mut rng PRNG) u32n(max u32) ?u32 {
if max == 0 {
return error('max must be positive integer')
}
// Owing to the pigeon-hole principle, we can't simply do
// val := rng.u32() % max.
// It'll wreck the properties of the distribution unless
// max evenly divides 2^32. So we divide evenly to
// the closest power of two. Then we loop until we find
// an int in the required range
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 uniformly distributed pseudorandom 64-bit signed positive `u64` in range `[0, max)`.
[inline]
pub fn (mut rng PRNG) u64n(max u64) ?u64 {
if max == 0 {
return error('max must be positive integer')
}
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)
}
// u32_in_range returns a uniformly distributed pseudorandom 32-bit unsigned `u32` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) u32_in_range(min u32, max u32) ?u32 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.u32n(max - min) ?
}
// u64_in_range returns a uniformly distributed pseudorandom 64-bit unsigned `u64` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) u64_in_range(min u64, max u64) ?u64 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.u64n(max - min) ?
}
// int returns a (possibly negative) pseudorandom 32-bit `int`.
[inline]
pub fn (mut rng PRNG) int() int {
return int(rng.u32())
}
// i64 returns a (possibly negative) pseudorandom 64-bit `i64`.
[inline]
pub fn (mut rng PRNG) i64() i64 {
return i64(rng.u64())
}
// int31 returns a positive pseudorandom 31-bit `int`.
[inline]
pub fn (mut rng PRNG) 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 PRNG) 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 PRNG) intn(max int) ?int {
if max <= 0 {
return error('max has to be positive.')
}
return int(rng.u32n(u32(max)) ?)
}
// i64n returns a pseudorandom int that lies in `[0, max)`.
[inline]
pub fn (mut rng PRNG) i64n(max i64) ?i64 {
if max <= 0 {
return error('max has to be positive.')
}
return i64(rng.u64n(u64(max)) ?)
}
// int_in_range returns a pseudorandom `int` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) int_in_range(min int, max int) ?int {
if max <= min {
return error('max must be greater than min')
}
// 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 PRNG) i64_in_range(min i64, max i64) ?i64 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.i64n(max - min) ?
}
// f32 returns a pseudorandom `f32` value in range `[0, 1)`.
[inline]
pub fn (mut rng PRNG) 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 PRNG) 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 PRNG) f32n(max f32) ?f32 {
if max <= 0 {
return error('max has to be positive.')
}
return rng.f32() * max
}
// f64n returns a pseudorandom `f64` value in range `[0, max)`.
[inline]
pub fn (mut rng PRNG) f64n(max f64) ?f64 {
if max <= 0 {
return error('max has to be positive.')
}
return rng.f64() * max
}
// f32_in_range returns a pseudorandom `f32` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) f32_in_range(min f32, max f32) ?f32 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.f32n(max - min) ?
}
// i64_in_range returns a pseudorandom `i64` in range `[min, max)`.
[inline]
pub fn (mut rng PRNG) f64_in_range(min f64, max f64) ?f64 {
if max <= min {
return error('max must be greater than min')
}
return min + rng.f64n(max - min) ?
}
__global default_rng &PRNG
// new_default returns a new instance of the default RNG. If the seed is not provided, the current time will be used to seed the instance.
[manualfree]
pub fn new_default(config config.PRNGConfigStruct) &PRNG {
mut rng := &wyrand.WyRandRNG{}
rng.seed(config.seed_)
unsafe { config.seed_.free() }
return &PRNG(rng)
}
// get_current_rng returns the PRNG instance currently in use. If it is not changed, it will be an instance of wyrand.WyRandRNG.
pub fn get_current_rng() &PRNG {
return default_rng
}
// set_rng changes the default RNG from wyrand.WyRandRNG (or whatever the last RNG was) to the one
// provided by the user. Note that this new RNG must be seeded manually with a constant seed or the
// `seed.time_seed_array()` method. Also, it is recommended to store the old RNG in a variable and
// should be restored if work with the custom RNG is complete. It is not necessary to restore if the
// program terminates soon afterwards.
pub fn set_rng(rng &PRNG) {
default_rng = unsafe { rng }
}
// seed sets the given array of `u32` values as the seed for the `default_rng`. The default_rng is
// an instance of WyRandRNG which takes 2 u32 values. When using a custom RNG, make sure to use
// the correct number of u32s.
pub fn seed(seed []u32) {
default_rng.seed(seed)
}
// u32 returns a uniformly distributed `u32` in range `[0, 2³²)`.
pub fn u32() u32 {
return default_rng.u32()
}
// u64 returns a uniformly distributed `u64` in range `[0, 2⁶⁴)`.
pub fn u64() u64 {
return default_rng.u64()
}
// u32n returns a uniformly distributed pseudorandom 32-bit signed positive `u32` in range `[0, max)`.
pub fn u32n(max u32) ?u32 {
return default_rng.u32n(max)
}
// u64n returns a uniformly distributed pseudorandom 64-bit signed positive `u64` in range `[0, max)`.
pub fn u64n(max u64) ?u64 {
return default_rng.u64n(max)
}
// u32_in_range returns a uniformly distributed pseudorandom 32-bit unsigned `u32` in range `[min, max)`.
pub fn u32_in_range(min u32, max u32) ?u32 {
return default_rng.u32_in_range(min, max)
}
// u64_in_range returns a uniformly distributed pseudorandom 64-bit unsigned `u64` in range `[min, max)`.
pub fn u64_in_range(min u64, max u64) ?u64 {
return default_rng.u64_in_range(min, max)
}
// int returns a uniformly distributed pseudorandom 32-bit signed (possibly negative) `int`.
pub fn int() int {
return default_rng.int()
}
// intn returns a uniformly distributed pseudorandom 32-bit signed positive `int` in range `[0, max)`.
pub fn intn(max int) ?int {
return default_rng.intn(max)
}
// byte returns a uniformly distributed pseudorandom 8-bit unsigned positive `byte`.
pub fn byte() byte {
return default_rng.byte()
}
// int_in_range returns a uniformly distributed pseudorandom 32-bit signed int in range `[min, max)`.
// Both `min` and `max` can be negative, but we must have `min < max`.
pub fn int_in_range(min int, max int) ?int {
return default_rng.int_in_range(min, max)
}
// int31 returns a uniformly distributed pseudorandom 31-bit signed positive `int`.
pub fn int31() int {
return default_rng.int31()
}
// i64 returns a uniformly distributed pseudorandom 64-bit signed (possibly negative) `i64`.
pub fn i64() i64 {
return default_rng.i64()
}
// i64n returns a uniformly distributed pseudorandom 64-bit signed positive `i64` in range `[0, max)`.
pub fn i64n(max i64) ?i64 {
return default_rng.i64n(max)
}
// i64_in_range returns a uniformly distributed pseudorandom 64-bit signed `i64` in range `[min, max)`.
pub fn i64_in_range(min i64, max i64) ?i64 {
return default_rng.i64_in_range(min, max)
}
// int63 returns a uniformly distributed pseudorandom 63-bit signed positive `i64`.
pub fn int63() i64 {
return default_rng.int63()
}
// f32 returns a uniformly distributed 32-bit floating point in range `[0, 1)`.
pub fn f32() f32 {
return default_rng.f32()
}
// f64 returns a uniformly distributed 64-bit floating point in range `[0, 1)`.
pub fn f64() f64 {
return default_rng.f64()
}
// f32n returns a uniformly distributed 32-bit floating point in range `[0, max)`.
pub fn f32n(max f32) ?f32 {
return default_rng.f32n(max)
}
// f64n returns a uniformly distributed 64-bit floating point in range `[0, max)`.
pub fn f64n(max f64) ?f64 {
return default_rng.f64n(max)
}
// f32_in_range returns a uniformly distributed 32-bit floating point in range `[min, max)`.
pub fn f32_in_range(min f32, max f32) ?f32 {
return default_rng.f32_in_range(min, max)
}
// f64_in_range returns a uniformly distributed 64-bit floating point in range `[min, max)`.
pub fn f64_in_range(min f64, max f64) ?f64 {
return default_rng.f64_in_range(min, max)
}
// bytes returns a buffer of `bytes_needed` random bytes
pub fn bytes(bytes_needed int) ?[]byte {
return default_rng.bytes(bytes_needed)
}
const (
english_letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
hex_chars = 'abcdef0123456789'
ascii_chars = '!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\^_`abcdefghijklmnopqrstuvwxyz{|}~'
)