Created
May 10, 2022 16:21
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sfc32 random number generator, typescript
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// SFC32 random number generator, public domain code adapted | |
// from https://github.com/bryc/code/blob/master/jshash/PRNGs.md | |
function PRNG(seed: number): { | |
nextInt(): number; | |
nextFloat(): number; | |
getState(): number[]; | |
setState(state: number[]): void | |
} { | |
let a = 0, b = seed, c = 0, d = 1; | |
function sfc32() { | |
a |= 0; b |= 0; c |= 0; d |= 0; | |
var t = (a + b | 0) + d | 0; | |
d = d + 1 | 0; | |
a = b ^ b >>> 9; | |
b = c + (c << 3) | 0; | |
c = c << 21 | c >>> 11; | |
c = c + t | 0; | |
return t >>> 0; | |
}; | |
for (let i = 0; i < 12; i++) sfc32(); // scramble the seed | |
return { | |
nextInt: sfc32, | |
nextFloat() { return sfc32() / 4294967296; }, | |
getState() { return [a, b, c, d]; }, | |
setState(state: number[]) { [a, b, c, d] = state; }, | |
}; | |
} |
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