tommath/bn_mp_to_unsigned_bin.c
2010-07-15 17:25:17 +02:00

44 lines
1.1 KiB
C

/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is library that provides for multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library is 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.
*
* Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
*/
#include <tommath.h>
/* store in unsigned [big endian] format */
int
mp_to_unsigned_bin (mp_int * a, unsigned char *b)
{
int x, res;
mp_int t;
if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
return res;
}
x = 0;
while (mp_iszero (&t) == 0) {
if (DIGIT_BIT != 7) {
b[x++] = (unsigned char) (t.dp[0] & 255);
} else {
b[x++] = (unsigned char) (t.dp[0] | ((t.dp[1] & 0x01) << 7));
}
if ((res = mp_div_2d (&t, 8, &t, NULL)) != MP_OKAY) {
mp_clear (&t);
return res;
}
}
bn_reverse (b, x);
mp_clear (&t);
return MP_OKAY;
}