tommath/etc/tune.c

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/* Tune the Karatsuba parameters
*
* Tom St Denis, tstdenis82@gmail.com
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*/
#include <tommath.h>
#include <stdint.h>
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/* how many times todo each size mult. Depends on your computer. For slow computers
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* this can be low like 5 or 10. For fast [re: Athlon] should be 25 - 50 or so
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*/
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#define TIMES (1UL<<14UL)
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#ifndef X86_TIMER
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/* RDTSC from Scott Duplichan */
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static uint64_t TIMFUNC(void)
{
# if defined __GNUC__
# if defined(__i386__) || defined(__x86_64__)
/* version from http://www.mcs.anl.gov/~kazutomo/rdtsc.html
* the old code always got a warning issued by gcc, clang did not complain...
*/
unsigned hi, lo;
__asm__ __volatile__("rdtsc" : "=a"(lo), "=d"(hi));
return ((uint64_t)lo)|(((uint64_t)hi)<<32);
# else /* gcc-IA64 version */
unsigned long result;
__asm__ __volatile__("mov %0=ar.itc" : "=r"(result) :: "memory");
while (__builtin_expect((int) result == -1, 0))
__asm__ __volatile__("mov %0=ar.itc" : "=r"(result) :: "memory");
return result;
# endif
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// Microsoft and Intel Windows compilers
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# elif defined _M_IX86
__asm rdtsc
# elif defined _M_AMD64
return __rdtsc();
# elif defined _M_IA64
# if defined __INTEL_COMPILER
# include <ia64intrin.h>
# endif
return __getReg(3116);
# else
# error need rdtsc function for this build
# endif
}
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/* *INDENT-OFF* */
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/* generic ISO C timer */
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static uint64_t LBL_T;
static void t_start(void) { LBL_T = TIMFUNC(); }
static uint64_t t_read(void) { return TIMFUNC() - LBL_T; }
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/* *INDENT-ON* */
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#else
extern void t_start(void);
extern uint64_t t_read(void);
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#endif
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static uint64_t time_mult(int size, int s)
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{
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unsigned long x;
mp_int a, b, c;
uint64_t t1;
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mp_init(&a);
mp_init(&b);
mp_init(&c);
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mp_rand(&a, size);
mp_rand(&b, size);
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if (s == 1) {
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KARATSUBA_MUL_CUTOFF = size;
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} else {
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KARATSUBA_MUL_CUTOFF = 100000;
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}
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t_start();
for (x = 0; x < TIMES; x++) {
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mp_mul(&a,&b,&c);
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}
t1 = t_read();
mp_clear(&a);
mp_clear(&b);
mp_clear(&c);
return t1;
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}
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static uint64_t time_sqr(int size, int s)
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{
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unsigned long x;
mp_int a, b;
uint64_t t1;
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mp_init(&a);
mp_init(&b);
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mp_rand(&a, size);
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if (s == 1) {
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KARATSUBA_SQR_CUTOFF = size;
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} else {
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KARATSUBA_SQR_CUTOFF = 100000;
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}
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t_start();
for (x = 0; x < TIMES; x++) {
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mp_sqr(&a,&b);
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}
t1 = t_read();
mp_clear(&a);
mp_clear(&b);
return t1;
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}
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int main(void)
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{
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uint64_t t1, t2;
int x, y;
for (x = 8; ; x += 2) {
t1 = time_mult(x, 0);
t2 = time_mult(x, 1);
printf("%d: %9llu %9llu, %9llu\n", x, t1, t2, t2 - t1);
if (t2 < t1) break;
}
y = x;
for (x = 8; ; x += 2) {
t1 = time_sqr(x, 0);
t2 = time_sqr(x, 1);
printf("%d: %9llu %9llu, %9llu\n", x, t1, t2, t2 - t1);
if (t2 < t1) break;
}
printf("KARATSUBA_MUL_CUTOFF = %d\n", y);
printf("KARATSUBA_SQR_CUTOFF = %d\n", x);
return 0;
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}
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/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */