91 lines
1.9 KiB
C
91 lines
1.9 KiB
C
|
#include "tommath_private.h"
|
||
|
|
#ifdef BN_MP_TC_XOR_C
|
||
|
|
/* LibTomMath, multiple-precision integer library -- Tom St Denis
|
||
|
|
*
|
||
|
|
* LibTomMath is a library that provides multiple-precision
|
||
|
|
* integer arithmetic as well as number theoretic functionality.
|
||
|
|
*
|
||
|
|
* The library was designed directly after the MPI library by
|
||
|
|
* Michael Fromberger but has been written from scratch with
|
||
|
|
* additional optimizations in place.
|
||
|
|
*
|
||
|
|
* The library is free for all purposes without any express
|
||
|
|
* guarantee it works.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* two complement xor */
|
||
|
|
int mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c)
|
||
|
|
{
|
||
|
|
int res = MP_OKAY, bits;
|
||
|
|
int as = mp_isneg(a), bs = mp_isneg(b), s = 0;
|
||
|
|
mp_int *mx = 0, _mx, acpy, bcpy;
|
||
|
|
|
||
|
|
if (as || bs) {
|
||
|
|
bits = MAX(mp_count_bits(a), mp_count_bits(b));
|
||
|
|
res = mp_init_set_int(&_mx, 1);
|
||
|
|
if (res != MP_OKAY) {
|
||
|
|
goto end;
|
||
|
|
}
|
||
|
|
|
||
|
|
mx = &_mx;
|
||
|
|
res = mp_mul_2d(mx, bits + 1, mx);
|
||
|
|
if (res != MP_OKAY) {
|
||
|
|
goto end;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (as) {
|
||
|
|
res = mp_init(&acpy);
|
||
|
|
if (res != MP_OKAY) {
|
||
|
|
goto end;
|
||
|
|
}
|
||
|
|
|
||
|
|
res = mp_add(mx, a, &acpy);
|
||
|
|
if (res != MP_OKAY) {
|
||
|
|
mp_clear(&acpy);
|
||
|
|
goto end;
|
||
|
|
}
|
||
|
|
a = &acpy;
|
||
|
|
}
|
||
|
|
if (bs) {
|
||
|
|
res = mp_init(&bcpy);
|
||
|
|
if (res != MP_OKAY) {
|
||
|
|
goto end;
|
||
|
|
}
|
||
|
|
|
||
|
|
res = mp_add(mx, b, &bcpy);
|
||
|
|
if (res != MP_OKAY) {
|
||
|
|
mp_clear(&bcpy);
|
||
|
|
goto end;
|
||
|
|
}
|
||
|
|
b = &bcpy;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
res = mp_xor(a, b, c);
|
||
|
|
s = as ^ bs;
|
||
|
|
|
||
|
|
if (s && res == MP_OKAY) {
|
||
|
|
res = mp_sub(c, mx, c);
|
||
|
|
}
|
||
|
|
|
||
|
|
end:
|
||
|
|
if (a == &acpy) {
|
||
|
|
mp_clear(&acpy);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (b == &bcpy) {
|
||
|
|
mp_clear(&bcpy);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (mx == &_mx) {
|
||
|
|
mp_clear(mx);
|
||
|
|
}
|
||
|
|
|
||
|
|
return res;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* ref: $Format:%D$ */
|
||
|
|
/* git commit: $Format:%H$ */
|
||
|
|
/* commit time: $Format:%ai$ */
|