A reasonable xor+shift random (similar to Marsaglia's, but only 64bit
instead of 128 bits), using the pentium's rdtsc-instrunction to add
additional "entropy" (i used gnu's inline assembler) :::
#define rdtscll(val) \
__asm__ __volatile__("rdtsc" : "=A" (val))
typedef unsigned long long BIGTHING;
BIGTHING rdtsc_rand(void);
/******************************************************/
BIGTHING rdtsc_rand(void)
{
static BIGTHING val=0x0000000011111111ULL;
BIGTHING new;
rdtscll(new);
val ^= (val >> 15) ^ (val << 14) ^ 9 ^ new;
return val;
}
/******************************************************/
The extra ^9 at the end can be omitted if the "new" is nonzero.
(is only meant to avoid the "val" becoming all-zeros. And shifting zeros won't
change the value ;-)
HTH,
AvK
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