60 lines
1.0 KiB
C
60 lines
1.0 KiB
C
// random.c
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// !!!!YOU WERE HERE!!!!!//
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// MAKE A DOOM STYLE SHUFFLED RANDOMIZER, FOR JUST 8 BITS
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//
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// original uses unsigned long, tcc says that it's 4 bytes
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// public domain impl from:
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// http://lomont.org/papers/2008/Lomont_PRNG_2008.pdf
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u32 well_512() {
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// TODO: Make this more random / make sure it's correct ?
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/* new Uint32Array([2 << 30]).map(x => Math.random() * x).join(",\n") */
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static u32 state[16] = {
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1096601398, 347948986, 707021053, 1924450882,
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1184298871, 1860618357, 1301703596, 86165936,
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160838326, 1276044826, 98793404, 1014941842,
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1604941344,1520346171, 726203645, 1872316350,
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};
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static u32 index = 0;
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u32 a, b, c, d;
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a = state[index];
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c = state[(index + 13) & 15];
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b = a ^ c ^ (a << 16) ^ (c << 15);
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c = state[(index + 9) & 15];
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c ^= (c >> 11);
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a = state[index] = b ^ c;
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d = a ^ ((a << 5) & 0xda442d24UL);
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index = (index + 15) & 15;
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a = state[index];
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state[index] = a ^ b ^ d ^ (a << 2) ^ (b << 18) ^ (c << 28);
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return state[index];
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}
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u8 rnd_u8() {
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return well_512() & 0xff;
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}
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