v/vlib/rand/mt19937.v

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// Copyright (c) 2019-2020 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 rand
import math.bits
/*
C++ functions for MT19937, with initialization improved 2002/2/10.
Coded by Takuji Nishimura and Makoto Matsumoto.
This is a faster version by taking Shawn Cokus's optimization,
Matthe Bellew's simplification, Isaku Wada's real version.
Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The names of its contributors may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Any feedback is very welcome.
http://www.math.keio.ac.jp/matumoto/emt.html
email: matumoto@math.keio.ac.jp
*/
const (
nn = 312
mm = 156
matrix_a = 0xB5026F5AA96619E9
um = 0xFFFFFFFF80000000
lm = 0x7FFFFFFF
inv_f64_limit = 1.0 / 9007199254740992.0
)
// A generator that uses the Mersenne Twister algorithm with period 2^19937
pub struct MT19937RNG {
mut:
state []u64 = calculate_state(time_seed_array(2), mut []u64{len: nn})
mti int = nn
next_rnd u32 = 0
has_next bool = false
}
fn calculate_state(seed_data []u32, mut state []u64) []u64 {
lo := u64(seed_data[0])
hi := u64(seed_data[1])
state[0] = u64((hi << 32) | lo)
for j := 1; j < nn; j++ {
state[j] = u64(6364136223846793005) * (state[j - 1] ^ (state[j - 1] >> 62)) + u64(j)
}
return state
}
// seed() - Set the seed, needs only two u32s in little endian format as [lower, higher]
pub fn (mut rng MT19937RNG) seed(seed_data []u32) {
if seed_data.len != 2 {
eprintln('mt19937 needs only two 32bit integers as seed: [lower, higher]')
exit(1)
}
rng.state = calculate_state(seed_data, mut rng.state)
rng.mti = nn
rng.next_rnd = 0
rng.has_next = false
}
// rng.u32() - return a pseudorandom 32bit int in [0, 2**32)
[inline]
pub fn (mut rng MT19937RNG) u32() u32 {
if rng.has_next {
rng.has_next = false
return rng.next_rnd
}
ans := rng.u64()
rng.next_rnd = u32(ans >> 32)
rng.has_next = true
return u32(ans & 0xffffffff)
}
// rng.u64() - return a pseudorandom 64bit int in [0, 2**64)
[inline]
pub fn (mut rng MT19937RNG) u64() u64 {
mag01 := [u64(0), u64(matrix_a)]
mut x := u64(0)
mut i := int(0)
if rng.mti >= nn {
for i = 0; i < nn - mm; i++ {
x = (rng.state[i] & um) | (rng.state[i + 1] & lm)
rng.state[i] = rng.state[i + mm] ^ (x >> 1) ^ mag01[int(x & 1)]
}
for i < nn - 1 {
x = (rng.state[i] & um) | (rng.state[i + 1] & lm)
rng.state[i] = rng.state[i + (mm - nn)] ^ (x >> 1) ^ mag01[int(x & 1)]
i++
}
x = (rng.state[nn - 1] & um) | (rng.state[0] & lm)
rng.state[nn - 1] = rng.state[mm - 1] ^ (x >> 1) ^ mag01[int(x & 1)]
rng.mti = 0
}
x = rng.state[rng.mti]
rng.mti++
x ^= (x >> 29) & 0x5555555555555555
x ^= (x << 17) & 0x71D67FFFEDA60000
x ^= (x << 37) & 0xFFF7EEE000000000
x ^= (x >> 43)
return x
}
// rng.int() - return a 32-bit signed (possibly negative) int
[inline]
pub fn (mut rng MT19937RNG) int() int {
return int(rng.u32())
}
// rng.i64() - return a 64-bit signed (possibly negative) i64
[inline]
pub fn (mut rng MT19937RNG) i64() i64 {
return i64(rng.u64())
}
// rng.int31() - return a 31bit positive pseudorandom integer
[inline]
pub fn (mut rng MT19937RNG) int31() int {
return int(rng.u32() >> 1)
}
// rng.int63() - return a 63bit positive pseudorandom integer
[inline]
pub fn (mut rng MT19937RNG) int63() i64 {
return i64(rng.u64() >> 1)
}
// rng.u32n(max) - return a 32bit u32 in [0, max)
[inline]
pub fn (mut rng MT19937RNG) 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)
}
// rng.u64n(max) - return a 64bit u64 in [0, max)
[inline]
pub fn (mut rng MT19937RNG) 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)
}
// rng.u32n(min, max) returns a pseudorandom u32 value that is guaranteed to be in [min, max)
[inline]
pub fn (mut rng MT19937RNG) u32_in_range(min, max u32) u32 {
if max <= min {
eprintln('max must be greater than min')
exit(1)
}
return min + rng.u32n(max - min)
}
// rng.u64n(min, max) returns a pseudorandom u64 value that is guaranteed to be in [min, max)
[inline]
pub fn (mut rng MT19937RNG) u64_in_range(min, max u64) u64 {
if max <= min {
eprintln('max must be greater than min')
exit(1)
}
return min + rng.u64n(max - min)
}
// rng.intn(max) - return a 32bit positive int in [0, max)
[inline]
pub fn (mut rng MT19937RNG) intn(max int) int {
if max <= 0 {
eprintln('max has to be positive.')
exit(1)
}
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return int(rng.u32n(u32(max)))
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}
// rng.i64n(max) - return a 64bit positive i64 in [0, max)
[inline]
pub fn (mut rng MT19937RNG) i64n(max i64) i64 {
if max <= 0 {
eprintln('max has to be positive.')
exit(1)
}
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return i64(rng.u64n(u64(max)))
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}
// rng.int_in_range(min, max) - return a 32bit positive int in [0, max)
[inline]
pub fn (mut rng MT19937RNG) int_in_range(min, max int) int {
if max <= min {
eprintln('max must be greater than min.')
exit(1)
}
return min + rng.intn(max - min)
}
// rng.i64_in_range(min, max) - return a 64bit positive i64 in [0, max)
[inline]
pub fn (mut rng MT19937RNG) i64_in_range(min, max i64) i64 {
if max <= min {
eprintln('max must be greater than min.')
exit(1)
}
return min + rng.i64n(max - min)
}
// rng.f32() - return a 32bit real in [0, 1)
[inline]
pub fn (mut rng MT19937RNG) f32() f32 {
return f32(rng.f64())
}
// rng.f64() - return 64bit real in [0, 1)
[inline]
pub fn (mut rng MT19937RNG) f64() f64 {
return f64(rng.u64() >> 11) * inv_f64_limit
}
// rng.f32n(max) - return 64bit real in [0, max)
[inline]
pub fn (mut rng MT19937RNG) f32n(max f32) f32 {
if max <= 0 {
eprintln('max has to be positive.')
exit(1)
}
return rng.f32() * max
}
// rng.f64n(max) - return 64bit real in [0, max)
[inline]
pub fn (mut rng MT19937RNG) f64n(max f64) f64 {
if max <= 0 {
eprintln('max has to be positive.')
exit(1)
}
return rng.f64() * max
}
// rng.f32_in_range(min, max) returns a pseudorandom f32 that lies in [min, max)
[inline]
pub fn (mut rng MT19937RNG) f32_in_range(min, max f32) f32 {
if max <= min {
eprintln('max must be greater than min')
exit(1)
}
return min + rng.f32n(max - min)
}
// rng.i64_in_range(min, max) returns a pseudorandom i64 that lies in [min, max)
[inline]
pub fn (mut rng MT19937RNG) f64_in_range(min, max f64) f64 {
if max <= min {
eprintln('max must be greater than min')
exit(1)
}
return min + rng.f64n(max - min)
}