67 lines
1.2 KiB
C
67 lines
1.2 KiB
C
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/* Better random number generator by Battler. */
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#include <assert.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <inttypes.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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#include "disc_random.h"
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dword preconst = 0x6ED9EBA1;
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static __inline__ uint32_t rotl32c (uint32_t x, uint32_t n)
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{
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assert (n<32);
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return (x<<n) | (x>>(-n&31));
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}
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static __inline__ uint32_t rotr32c (uint32_t x, uint32_t n)
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{
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assert (n<32);
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return (x>>n) | (x<<(-n&31));
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}
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#define ROTATE_LEFT rotl32c
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#define ROTATE_RIGHT rotr32c
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static __inline__ unsigned long long rdtsc(void)
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{
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unsigned hi, lo;
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__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
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return ( (unsigned long long)lo)|( ((unsigned long long)hi)<<32 );
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}
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static UINT4 RDTSC(void)
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{
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return (UINT4) (rdtsc());
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}
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static void disc_random_twist(uint32_t *val)
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{
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*val = ROTATE_LEFT(*val, rand() % 32);
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*val ^= 0x5A827999;
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*val = ROTATE_RIGHT(*val, rand() % 32);
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*val ^= 0x4ED32706;
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}
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uint8_t disc_random_generate()
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{
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uint16_t r = 0;
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r = (rand() ^ ROTATE_LEFT(preconst, rand() % 32)) % 256;
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disc_random_twist(&preconst);
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return (r & 0xff);
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}
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void disc_random_init()
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{
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dword seed = RDTSC();
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srand(seed);
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return;
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}
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