bn_mp_set_int.c 1.16 KB
Newer Older
1
#include "tommath_private.h"
2 3 4 5 6 7 8 9 10 11
#ifdef BN_MP_SET_INT_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.
 *
12
 * SPDX-License-Identifier: Unlicense
13 14 15
 */

/* set a 32-bit const */
16
int mp_set_int(mp_int *a, unsigned long b)
17
{
18 19 20
   int     x, res;

   mp_zero(a);
21

22 23 24 25 26 27
   /* set four bits at a time */
   for (x = 0; x < 8; x++) {
      /* shift the number up four bits */
      if ((res = mp_mul_2d(a, 4, a)) != MP_OKAY) {
         return res;
      }
28

29 30
      /* OR in the top four bits of the source */
      a->dp[0] |= (mp_digit)(b >> 28) & 15uL;
31

32 33
      /* shift the source up to the next four bits */
      b <<= 4;
34

35 36 37 38 39
      /* ensure that digits are not clamped off */
      a->used += 1;
   }
   mp_clamp(a);
   return MP_OKAY;
40 41 42
}
#endif

43 44 45
/* ref:         HEAD -> master, tag: v1.1.0 */
/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */