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#include <stdint.h>
#include <string.h>
#include <stdio.h>
typedef uint8_t leg_t;
typedef uint16_t dleg_t;
#if 0
static void mp_sqr( leg_t *result, leg_t const * a, int legs )
{
while( legs-- ) {
leg_t *offs = result+2*legs+1;
leg_t fac = a[legs];
int leg = legs;
dleg_t acc = (dleg_t)*offs + (dleg_t)fac * fac;
*(offs--) = (leg_t)acc;
acc >>= 8*sizeof(leg_t);
while( leg-- )
{
dleg_t subresult = fac * a[leg];
int carry = !!(subresult & (1<<(8*sizeof(dleg_t)-1)));
subresult <<= 1;
acc += subresult + *offs;
*(offs--) = (leg_t)acc;
acc >>= 8*sizeof(leg_t);
acc += carry;
}
while( acc )
{
acc += *offs;
*(offs--) = (leg_t)acc;
acc >>= 8*sizeof(leg_t);
}
}
}
#else
static void mp_sqr( leg_t *result, leg_t const * a, int legs )
{
int i;
while( legs-- ) {
leg_t *offs = result+2*legs+1;
leg_t fac = a[legs];
int leg = legs,i;
dleg_t acc = (dleg_t)*offs + (dleg_t)fac * (dleg_t)fac;
*(offs--) = (leg_t)acc;
acc >>= 8*sizeof(leg_t);
while( leg-- )
{
dleg_t subresult = (dleg_t)fac * (dleg_t)a[leg];
int carry = 1 & ( subresult >> (16*sizeof(leg_t)-1));
subresult ^= carry << (16*sizeof(leg_t)-1);
acc += 2 * subresult + (dleg_t)*offs;
*(offs--) = (leg_t)acc;
acc >>= 8*sizeof(leg_t);
acc += (dleg_t)carry << 8*sizeof(leg_t);
printf( "%04X %04X %d\n", acc, subresult, carry );
}
for(i=0;i<6;++i)
printf( "%02X", result[i] );
putchar(10);
while( acc )
{
acc += (dleg_t)*offs;
*(offs--) = (leg_t)acc;
acc >>= 8*sizeof(leg_t);
}
}
for(i=0;i<6;++i)
printf( "%02X", result[i] );
putchar(10);
}
#endif
int main() {
leg_t a[3] = { 0xff, 0xff, 0xa1 };
leg_t r[6] = {0,0,0,0,0,0};
int i;
mp_sqr( r, a, 3 );
for(i=0;i<6;++i)
printf( "%02X", r[i] );
putchar(10);
}
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