97 lines
1.8 KiB
C
97 lines
1.8 KiB
C
/*
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* 86Box A hypervisor and IBM PC system emulator that specializes in
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* running old operating systems and software designed for IBM
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* PC systems and compatibles from 1981 through fairly recent
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* system designs based on the PCI bus.
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*
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* This file is part of the 86Box distribution.
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*
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* A better random number generation, used for floppy weak bits
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* and network MAC address generation.
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*
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*
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*
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* Author: Miran Grca, <mgrca8@gmail.com>
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* Copyright 2016-2018 Miran Grca.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <86box/random.h>
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#if !(defined(__i386__) || defined (__x86_64__))
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#include <time.h>
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#endif
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uint32_t 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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#if 0
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assert (n<32);
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#endif
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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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#if 0
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assert (n<32);
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#endif
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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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#if defined(__i386__) || defined (__x86_64__)
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unsigned hi, lo;
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#ifdef _MSC_VER
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__asm {
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rdtsc
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mov hi, edx ; EDX:EAX is already standard return!!
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mov lo, eax
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}
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#else
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__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
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#endif
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return ( (unsigned long long)lo)|( ((unsigned long long)hi)<<32 );
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#else
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return time(NULL);
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#endif
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}
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static uint32_t RDTSC(void)
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{
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return (uint32_t) (rdtsc());
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}
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static void 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 random_generate(void)
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{
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uint16_t r = 0;
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r = (RDTSC() ^ ROTATE_LEFT(preconst, rand() % 32)) % 256;
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random_twist(&preconst);
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return (r & 0xff);
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}
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void random_init(void)
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{
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uint32_t seed = RDTSC();
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srand(seed);
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return;
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}
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