91 lines
2.0 KiB
C
91 lines
2.0 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.
|
|
*
|
|
* SPDX-License-Identifier: Unlicense
|
|
*/
|
|
|
|
/* two complement xor */
|
|
int mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c)
|
|
{
|
|
int res = MP_OKAY, bits, abits, bbits;
|
|
int sa = a->sign, sb = b->sign;
|
|
mp_int *mx = NULL, _mx, acpy, bcpy;
|
|
|
|
if ((sa == MP_NEG) || (sb == MP_NEG)) {
|
|
abits = mp_count_bits(a);
|
|
bbits = mp_count_bits(b);
|
|
bits = MAX(abits, bbits);
|
|
res = mp_init_set_int(&_mx, 1uL);
|
|
if (res != MP_OKAY) {
|
|
goto end;
|
|
}
|
|
|
|
mx = &_mx;
|
|
res = mp_mul_2d(mx, bits + 1, mx);
|
|
if (res != MP_OKAY) {
|
|
goto end;
|
|
}
|
|
|
|
if (sa == MP_NEG) {
|
|
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 (sb == MP_NEG) {
|
|
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);
|
|
|
|
if ((((sa == MP_NEG) && (sb != MP_NEG)) || ((sa != MP_NEG) && (sb == MP_NEG))) && (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: $Format:%ai$ */
|