tommath/bn_mp_get_int.c

46 lines
1.2 KiB
C
Raw Normal View History

#include <tommath_private.h>
2004-10-29 18:07:18 -04:00
#ifdef BN_MP_GET_INT_C
2004-04-11 16:46:22 -04:00
/* 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.
*
* Tom St Denis, tstdenis82@gmail.com, http://libtom.org
2004-04-11 16:46:22 -04:00
*/
/* get the lower 32-bits of an mp_int */
2014-09-01 20:14:38 -04:00
unsigned long mp_get_int(mp_int * a)
2004-04-11 16:46:22 -04:00
{
int i;
mp_min_u32 res;
2004-04-11 16:46:22 -04:00
if (a->used == 0) {
return 0;
}
/* get number of digits of the lsb we have to read */
2017-08-28 15:40:10 -04:00
i = MIN(a->used, (int)(((sizeof(unsigned long) * CHAR_BIT) + DIGIT_BIT - 1) / DIGIT_BIT)) - 1;
2004-04-11 16:46:22 -04:00
/* get most significant digit of result */
2017-08-28 15:40:10 -04:00
res = DIGIT(a, i);
2014-09-01 20:14:38 -04:00
2004-04-11 16:46:22 -04:00
while (--i >= 0) {
2017-08-28 15:40:10 -04:00
res = (res << DIGIT_BIT) | DIGIT(a, i);
2004-04-11 16:46:22 -04:00
}
/* force result to 32-bits always so it is consistent on non 32-bit platforms */
return res & 0xFFFFFFFFUL;
}
2004-10-29 18:07:18 -04:00
#endif
2005-08-01 12:37:28 -04:00
2017-08-28 10:27:26 -04:00
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */