libtommath/bn_s_mp_get_bit.c
Daniel Mendler a8239c2465
deprecate mp_get_bit
The return type of mp_get_bit was imprecise (either mp_err or mp_bool),
therefore this function is deprecated in favor of s_mp_get_bit for now.

If we need s_mp_get_bit to be public, we should add it under a different
name. However since mp_set_bit is not available, I don't think there any
downstream users (ab)using mp_int as bitsets.
2019-05-18 10:03:47 +02:00

22 lines
521 B
C

#include "tommath_private.h"
#ifdef BN_S_MP_GET_BIT_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* Get bit at position b and return MP_YES if the bit is 1, MP_NO if it is 0 */
mp_bool s_mp_get_bit(const mp_int *a, unsigned int b)
{
mp_digit bit;
int limb = (int)(b / MP_DIGIT_BIT);
if (limb >= a->used) {
return MP_NO;
}
bit = (mp_digit)1 << (b % MP_DIGIT_BIT);
return ((a->dp[limb] & bit) != 0u) ? MP_YES : MP_NO;
}
#endif