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Serializable pseudo-random number generators and distributions.
/*
* Copyright (c) 2022-2023 See AUTHORS file.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package com.github.tommyettinger.random;
/**
* A random number generator that is optimized for performance on 32-bit machines and with Google Web Toolkit,
* Respite32Random is a 32-bit-native generator here that doesn't have any shorter subcycles (because it only has one
* cycle, of length 2 to the 96). It effectively shares this property with {@link Xoshiro128PlusPlusRandom}, except that
* Xoshiro128PlusPlusRandom doesn't permit the state to be all 0s, while Respite32Random isn't adversely affected by
* that condition. This generator has three {@code int} states and doesn't use any
* multiplication. It does use the count leading zeros instruction, which is {@link Integer#numberOfLeadingZeros(int)}
* on most platforms, or the JS function {@code Math.clz32()} on GWT. This only counts leading zeros for the purposes of
* its state transition (for stateB and stateC), and using it the way this does is what allows the period to be so high.
*
* This algorithm hasn't been tested with ReMort, but passes 64TB of PractRand testing with no anomalies. Numerically
* similar initial states tend to be correlated with each other, even in the long term. This property is shared with
* many other generators, such as {@link Xoshiro256StarStarRandom}, and the correlation isn't as severe as it is in
* {@link WhiskerRandom}. Of the 32-bit-native generators, {@link ChopRandom} and {@link Jsf32Random} do not have
* correlations I can find, but {@link Xoshiro128PlusPlusRandom} does have noticeable correlation between numerically
* similar initial states.
*
* This implements all optional methods in EnhancedRandom except {@link #skip(long)}.
*
* The name comes from how this was a short break from generators that use 64-bit math, and also because it sounds
* similar to "respect" -- RespectRandom is a closely-related generator that is still in development. Respite and its
* relatives use the Speck cipher's round function to reliably randomize multiple states.
*
* Respite32Random is not currently considered stable; I am pursuing alternative implementation options that keep the
* same period and state properties.
*/
public class Respite32Random extends EnhancedRandom {
/**
* The first state; may be any int.
*/
public int stateA;
/**
* The second state; may be any int.
*/
public int stateB;
/**
* The third state; may be any int.
*/
public int stateC;
/**
* Creates a new Respite32Random with a random state.
*/
public Respite32Random() {
this(EnhancedRandom.seedFromMath());
}
/**
* Creates a new Respite32Random with the given seed; all {@code long} values are permitted.
* The seed will be passed to {@link #setSeed(long)} to attempt to adequately distribute the seed randomly.
*
* @param seed any {@code long} value
*/
public Respite32Random(long seed) {
super(seed);
setSeed(seed);
}
/**
* Creates a new Respite32Random with the given three states. All {@code int} values are permitted.
*
* @param stateA any {@code int} value
* @param stateB any {@code int} value
* @param stateC any {@code int} value
*/
public Respite32Random(int stateA, int stateB, int stateC) {
super(stateA);
this.stateA = stateA;
this.stateB = stateB;
this.stateC = stateC;
}
@Override
public String getTag() {
return "Re3R";
}
/**
* This generator has 3 {@code int} states, so this returns 3.
*
* @return 3 (three)
*/
@Override
public int getStateCount () {
return 3;
}
/**
* Gets the state determined by {@code selection}, as-is. The value for selection should be
* between 0 and 2, inclusive; if it is any other value this gets state C as if 2 was given.
*
* @param selection used to select which state variable to get; generally 0, 1, or 2
* @return the value of the selected state, which is an int that will be promoted to long
*/
@Override
public long getSelectedState (int selection) {
switch (selection) {
case 0:
return stateA;
case 1:
return stateB;
default:
return stateC;
}
}
/**
* Sets one of the states, determined by {@code selection}, to the lower 32 bits of {@code value}, as-is.
* Selections 0, 1, and 2 refer to states A, B, and C, and if the selection is anything
* else, this treats it as 2 and sets stateC. This always casts {@code value} to an int before using it.
*
* @param selection used to select which state variable to set; generally 0, 1, or 2
* @param value the exact value to use for the selected state, if valid
*/
@Override
public void setSelectedState (int selection, long value) {
switch (selection) {
case 0:
stateA = (int) value;
break;
case 1:
stateB = (int) value;
break;
default:
stateC = (int) value;
break;
}
}
/**
* This initializes all 3 states of the generator to random values based on the given seed.
* (2 to the 64) known-good initial generator states can be produced here.
*
* @param seed the initial seed; may be any long
*/
@Override
public void setSeed (long seed) {
int a = (int)seed, b = (int)(seed >>> 32), c = (int)(~seed >>> 16);
for (int i = 0; i < 5; i++) {
b = (b << 24 | b >>> 8) + a ^ ++c;
a = (a << 3 | a >>> 29) ^ b;
}
stateA = a;
for (int i = 0; i < 5; i++) {
b = (b << 24 | b >>> 8) + a ^ ++c;
a = (a << 3 | a >>> 29) ^ b;
}
stateB = a;
for (int i = 0; i < 5; i++) {
b = (b << 24 | b >>> 8) + a ^ ++c;
a = (a << 3 | a >>> 29) ^ b;
}
stateC = a;
}
public long getStateA () {
return stateA;
}
/**
* Sets the first part of the state by casting the parameter to an int.
*
* @param stateA can be any long, but will be cast to an int before use
*/
public void setStateA (long stateA) {
this.stateA = (int)stateA;
}
public long getStateB () {
return stateB;
}
/**
* Sets the second part of the state by casting the parameter to an int.
*
* @param stateB can be any long, but will be cast to an int before use
*/
public void setStateB (long stateB) {
this.stateB = (int)stateB;
}
public long getStateC () {
return stateC;
}
/**
* Sets the third part of the state by casting the parameter to an int.
*
* @param stateC can be any long, but will be cast to an int before use
*/
public void setStateC (long stateC) {
this.stateC = (int)stateC;
}
/**
* Sets the state completely to the given three state variables, casting each to an int.
* This is the same as calling {@link #setStateA(long)}, {@link #setStateB(long)},
* and {@link #setStateC(long)} as a group.
*
* @param stateA the first state; can be any long, but will be cast to an int before use
* @param stateB the second state; can be any long, but will be cast to an int before use
* @param stateC the third state; can be any long, but will be cast to an int before use
*/
@Override
public void setState (long stateA, long stateB, long stateC) {
this.stateA = (int)stateA;
this.stateB = (int)stateB;
this.stateC = (int)stateC;
}
@Override
public long nextLong () {
int a = (stateA += 0x91E10DA5);
int b = (stateB += 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(a));
int c = (stateC += 0x7FEB352D ^ Integer.numberOfLeadingZeros(a&b));
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
long h = a;
a = (stateA += 0x91E10DA5);
b = (stateB += 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(a));
c = (stateC += 0x7FEB352D ^ Integer.numberOfLeadingZeros(a&b));
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
return h << 32 | (a & 0xFFFFFFFFL);
}
@Override
public long previousLong () {
int a = stateA;
int b = stateB;
int c = stateC;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
long l = (a & 0xFFFFFFFFL);
a = stateA;
b = stateB;
stateA -= 0x91E10DA5;
stateB -= 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(a);
stateC -= 0x7FEB352D ^ Integer.numberOfLeadingZeros(a&b);
a = stateA;
b = stateB;
c = stateC;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
long h = a;
a = stateA;
b = stateB;
stateA -= 0x91E10DA5;
stateB -= 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(a);
stateC -= 0x7FEB352D ^ Integer.numberOfLeadingZeros(a&b);
return h << 32 | l;
}
@Override
public int next (int bits) {
int a = (stateA += 0x91E10DA5);
int b = (stateB += 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(a));
int c = (stateC += 0x7FEB352D ^ Integer.numberOfLeadingZeros(a&b));
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
return a >>> (32 - bits);
}
@Override
public int nextInt () {
int a = (stateA += 0x91E10DA5);
int b = (stateB += 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(a));
int c = (stateC += 0x7FEB352D ^ Integer.numberOfLeadingZeros(a&b));
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
return a;
}
@Override
public int previousInt() {
int a = stateA;
int b = stateB;
int c = stateC;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = (b << 24 | b >>> 8) + a ^ c;
a = (a << 3 | a >>> 29) ^ b;
b = stateA;
c = stateB;
stateA -= 0x91E10DA5;
stateB -= 0x6C8E9CF5 ^ Integer.numberOfLeadingZeros(b);
stateC -= 0x7FEB352D ^ Integer.numberOfLeadingZeros(b&c);
return a;
}
@Override
public int nextInt (int bound) {
return (int)(bound * (nextInt() & 0xFFFFFFFFL) >> 32) & ~(bound >> 31);
}
@Override
public int nextSignedInt (int outerBound) {
outerBound = (int)(outerBound * (nextInt() & 0xFFFFFFFFL) >> 32);
return outerBound + (outerBound >>> 31);
}
@Override
public void nextBytes (byte[] bytes) {
for (int i = 0; i < bytes.length; ) {for (int r = nextInt(), n = Math.min(bytes.length - i, 4); n-- > 0; r >>>= 8) {bytes[i++] = (byte)r;}}
}
@Override
public long nextLong (long inner, long outer) {
final long rand = nextLong();
if (inner >= outer)
return inner;
final long randLow = rand & 0xFFFFFFFFL;
final long randHigh = rand >>> 32;
final long bound = outer - inner;
final long boundLow = bound & 0xFFFFFFFFL;
final long boundHigh = (bound >>> 32);
return inner + (randHigh * boundLow >>> 32) + (randLow * boundHigh >>> 32) + randHigh * boundHigh;
}
@Override
public long nextSignedLong (long inner, long outer) {
if (outer < inner) {
long t = outer;
outer = inner + 1L;
inner = t + 1L;
}
final long bound = outer - inner;
final long rand = nextLong();
final long randLow = rand & 0xFFFFFFFFL;
final long randHigh = rand >>> 32;
final long boundLow = bound & 0xFFFFFFFFL;
final long boundHigh = (bound >>> 32);
return inner + (randHigh * boundLow >>> 32) + (randLow * boundHigh >>> 32) + randHigh * boundHigh;
}
@Override
public boolean nextBoolean () {
return nextInt() < 0;
}
@Override
public float nextFloat () {
return (nextInt() >>> 8) * 0x1p-24f;
}
@Override
public float nextInclusiveFloat () {
return (0x1000001L * (nextInt() & 0xFFFFFFFFL) >> 32) * 0x1p-24f;
}
@Override
public Respite32Random copy () {
return new Respite32Random(stateA, stateB, stateC);
}
@Override
public boolean equals (Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
Respite32Random that = (Respite32Random)o;
return stateA == that.stateA && stateB == that.stateB && stateC == that.stateC;
}
public String toString () {
return "Respite32Random{" + "stateA=" + (stateA) + ", stateB=" + (stateB) + ", stateC=" + (stateC) + "}";
}
// public static void main(String[] args) {
// Respite32Random random = new Respite32Random(1L);
// long n0 = random.nextLong();
// long n1 = random.nextLong();
// long n2 = random.nextLong();
// long n3 = random.nextLong();
// long n4 = random.nextLong();
// long n5 = random.nextLong();
// long p5 = random.previousLong();
// long p4 = random.previousLong();
// long p3 = random.previousLong();
// long p2 = random.previousLong();
// long p1 = random.previousLong();
// long p0 = random.previousLong();
// System.out.println(n0 == p0);
// System.out.println(n1 == p1);
// System.out.println(n2 == p2);
// System.out.println(n3 == p3);
// System.out.println(n4 == p4);
// System.out.println(n5 == p5);
// System.out.printf("0x%016XL vs. 0x%016XL\n", n0, p0);
// System.out.printf("0x%016XL vs. 0x%016XL\n", n1, p1);
// System.out.printf("0x%016XL vs. 0x%016XL\n", n2, p2);
// System.out.printf("0x%016XL vs. 0x%016XL\n", n3, p3);
// System.out.printf("0x%016XL vs. 0x%016XL\n", n4, p4);
// System.out.printf("0x%016XL vs. 0x%016XL\n", n5, p5);
// }
}