Initial project import

tools/v/vlib/rand/mt19937/mt19937.v

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+// Copyright (c) 2019-2024 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 mt19937
+
+import rand.buffer
+import rand.seed
+
+/*
+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.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+   email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
+*/
+pub const seed_len = 2
+
+const nn = 312
+const mm = 156
+const matrix_a = 0xB5026F5AA96619E9
+const um = 0xFFFFFFFF80000000
+const lm = 0x7FFFFFFF
+const inv_f64_limit = 1.0 / 9007199254740992.0
+
+// MT19937RNG is generator that uses the Mersenne Twister algorithm with period 2^19937.
+// **NOTE**: The RNG is not seeded when instantiated so remember to seed it before use.
+pub struct MT19937RNG {
+	buffer.PRNGBuffer
+mut:
+	state []u64 = get_first_state(seed.time_seed_array(2))
+	mti   int   = nn
+}
+
+fn get_first_state(seed_data []u32) []u64 {
+	mut state := []u64{len: nn}
+	calculate_state(seed_data, mut state)
+	return state
+}
+
+// calculate_state returns a random state array calculated from the `seed_data`.
+@[ignore_overflow]
+fn calculate_state(seed_data []u32, mut state []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)
+	}
+}
+
+// seed sets the current random state based on `seed_data`.
+// seed expects `seed_data` to be only two `u32`s 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)
+	}
+	calculate_state(seed_data, mut rng.state)
+	rng.mti = nn
+	rng.bytes_left = 0
+	rng.buffer = 0
+}
+
+// byte returns a uniformly distributed pseudorandom 8-bit unsigned positive `byte`.
+@[inline]
+pub fn (mut rng MT19937RNG) u8() u8 {
+	if rng.bytes_left >= 1 {
+		rng.bytes_left -= 1
+		value := u8(rng.buffer)
+		rng.buffer >>= 8
+		return value
+	}
+	rng.buffer = rng.u64()
+	rng.bytes_left = 7
+	value := u8(rng.buffer)
+	rng.buffer >>= 8
+	return value
+}
+
+// u16 returns a pseudorandom 16bit int in range `[0, 2¹⁶)`.
+@[inline]
+pub fn (mut rng MT19937RNG) u16() u16 {
+	if rng.bytes_left >= 2 {
+		rng.bytes_left -= 2
+		value := u16(rng.buffer)
+		rng.buffer >>= 16
+		return value
+	}
+	ans := rng.u64()
+	rng.buffer = ans >> 16
+	rng.bytes_left = 6
+	return u16(ans)
+}
+
+// u32 returns a pseudorandom 32bit int in range `[0, 2³²)`.
+@[inline]
+pub fn (mut rng MT19937RNG) u32() u32 {
+	// Can we take a whole u32 out of the buffer?
+	if rng.bytes_left >= 4 {
+		rng.bytes_left -= 4
+		value := u32(rng.buffer)
+		rng.buffer >>= 32
+		return value
+	}
+	ans := rng.u64()
+	rng.buffer = ans >> 32
+	rng.bytes_left = 4
+	return u32(ans)
+}
+
+const mag01 = [u64(0), u64(matrix_a)]
+
+// u64 returns a pseudorandom 64bit int in range `[0, 2⁶⁴)`.
+@[direct_array_access; ignore_overflow; inline]
+pub fn (mut rng MT19937RNG) u64() u64 {
+	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
+}
+
+// block_size returns the number of bits that the RNG can produce in a single iteration.
+@[inline]
+pub fn (mut rng MT19937RNG) block_size() int {
+	return 64
+}
+
+// free should be called when the generator is no longer needed.
+@[unsafe]
+pub fn (mut rng MT19937RNG) free() {
+	unsafe { rng.state.free() }
+}

tools/v/vlib/rand/mt19937/mt19937_test.v

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+import math
+import rand
+import rand.mt19937
+import rand.seed
+
+const range_limit = 40
+const value_count = 1000
+const seeds = [[u32(0xcafebabe), u32(0xdeadbeef)], [u32(0xc0de), u32(0xfeed)]]
+
+const sample_size = 1000
+const stats_epsilon = 0.05
+const inv_sqrt_12 = 1.0 / math.sqrt(12)
+
+fn mt19937_basic_test() {
+	mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+	rng.seed([u32(0xdeadbeef)])
+	target := [u32(956529277), 3842322136, 3319553134, 1843186657, 2704993644, 595827513, 938518626,
+		1676224337, 3221315650, 1819026461]
+	for i := 0; i < 10; i++ {
+		assert target[i] == rng.u32()
+	}
+}
+
+fn gen_randoms(seed_data []u32, bound int) []u64 {
+	bound_u64 := u64(bound)
+	mut randoms := []u64{len: (20)}
+	mut rnd := &rand.PRNG(&mt19937.MT19937RNG{})
+	rnd.seed(seed_data)
+	for i in 0 .. 20 {
+		randoms[i] = rnd.u64n(bound_u64) or { panic("Couldn't obtain random u64") }
+	}
+	return randoms
+}
+
+fn test_mt19937_reproducibility() {
+	seed_data := seed.time_seed_array(2)
+	randoms1 := gen_randoms(seed_data, 1000)
+	randoms2 := gen_randoms(seed_data, 1000)
+	assert randoms1.len == randoms2.len
+	len := randoms1.len
+	for i in 0 .. len {
+		assert randoms1[i] == randoms2[i]
+	}
+}
+
+fn test_mt19937_variability() {
+	// If this test fails and if it is certainly not the implementation
+	// at fault, try changing the seed values. Repeated values are
+	// improbable but not impossible.
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		mut values := []u64{cap: value_count}
+		for i in 0 .. value_count {
+			value := rng.u64()
+			assert value !in values
+			assert values.len == i
+			values << value
+		}
+	}
+}
+
+fn check_uniformity_u64(mut rng rand.PRNG, range u64) {
+	range_f64 := f64(range)
+	expected_mean := range_f64 / 2.0
+	mut variance := 0.0
+	for _ in 0 .. sample_size {
+		diff := f64(rng.u64n(range) or { panic("Couldn't obtain random u64") }) - expected_mean
+		variance += diff * diff
+	}
+	variance /= sample_size - 1
+	sigma := math.sqrt(variance)
+	expected_sigma := range_f64 * inv_sqrt_12
+	error := (sigma - expected_sigma) / expected_sigma
+	assert math.abs(error) < stats_epsilon
+}
+
+fn test_mt19937_uniformity_u64() {
+	ranges := [14019545, 80240, 130]
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for range in ranges {
+			check_uniformity_u64(mut rng, u64(range))
+		}
+	}
+}
+
+fn check_uniformity_f64(mut rng rand.PRNG) {
+	expected_mean := 0.5
+	mut variance := 0.0
+	for _ in 0 .. sample_size {
+		diff := rng.f64() - expected_mean
+		variance += diff * diff
+	}
+	variance /= sample_size - 1
+	sigma := math.sqrt(variance)
+	expected_sigma := inv_sqrt_12
+	error := (sigma - expected_sigma) / expected_sigma
+	assert math.abs(error) < stats_epsilon
+}
+
+fn test_mt19937_uniformity_f64() {
+	// The f64 version
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		check_uniformity_f64(mut rng)
+	}
+}
+
+fn test_mt19937_u32n() {
+	max := u32(16384)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u32n(max) or { panic("Couldn't obtain random u32") }
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_u64n() {
+	max := u64(379091181005)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u64n(max) or { panic("Couldn't obtain random u64") }
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_u32_in_range() {
+	max := u32(484468466)
+	min := u32(316846)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u32_in_range(min, max) or { panic("Couldn't obtain random u32 in range.") }
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_u64_in_range() {
+	max := u64(216468454685163)
+	min := u64(6848646868)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u64_in_range(min, max) or { panic("Couldn't obtain random u64 in range.") }
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_int31() {
+	max_u31 := int(0x7FFFFFFF)
+	sign_mask := int(u32(0x80000000))
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.int31()
+			assert value >= 0
+			assert value <= max_u31
+			// This statement ensures that the sign bit is zero
+			assert (value & sign_mask) == 0
+		}
+	}
+}
+
+fn test_mt19937_int63() {
+	max_u63 := i64(0x7FFFFFFFFFFFFFFF)
+	sign_mask := i64(u64(0x8000000000000000))
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.int63()
+			assert value >= 0
+			assert value <= max_u63
+			assert (value & sign_mask) == 0
+		}
+	}
+}
+
+fn test_mt19937_intn() {
+	max := 2525642
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.intn(max) or { panic("Couldn't obtain random int") }
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_i64n() {
+	max := i64(3246727724653636)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.i64n(max) or { panic("Couldn't obtain random i64") }
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_int_in_range() {
+	min := -4252
+	max := 1034
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.int_in_range(min, max) or { panic("Couldn't obtain random int in range.") }
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_i64_in_range() {
+	min := i64(-24095)
+	max := i64(324058)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.i64_in_range(min, max) or { panic("Couldn't obtain random i64 in range.") }
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f32() {
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f32()
+			assert value >= 0.0
+			assert value < 1.0
+		}
+	}
+}
+
+fn test_mt19937_f64() {
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f64()
+			assert value >= 0.0
+			assert value < 1.0
+		}
+	}
+}
+
+fn test_mt19937_f32n() {
+	max := f32(357.0)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f32n(max) or { panic("Couldn't obtain random f32") }
+			assert value >= 0.0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f64n() {
+	max := 1.52e6
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f64n(max) or { panic("Couldn't obtain random f64") }
+			assert value >= 0.0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f32_in_range() {
+	min := f32(-24.0)
+	max := f32(125.0)
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f32_in_range(min, max) or { panic("Couldn't obtain random f32 in range.") }
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f64_in_range() {
+	min := -548.7
+	max := 5015.2
+	for seed in seeds {
+		mut rng := &rand.PRNG(&mt19937.MT19937RNG{})
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f64_in_range(min, max) or { panic("Couldn't obtain random f64 in range.") }
+			assert value >= min
+			assert value < max
+		}
+	}
+}