#include "tommath_private.h"
#ifdef BN_MP_GET_BIT_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.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
/* Checks the bit at position b and returns MP_YES
if the bit is 1, MP_NO if it is 0 and MP_VAL
in case of error */
int mp_get_bit(const mp_int *a, int b)
{
int limb;
mp_digit bit, isset;
if (b < 0) {
return MP_VAL;
}
limb = b / DIGIT_BIT;
/*
* Zero is a special value with the member "used" set to zero.
* Needs to be tested before the check for the upper boundary
* otherwise (limb >= a->used) would be true for a = 0
*/
if (mp_iszero(a) != MP_NO) {
return MP_NO;
}
if (limb >= a->used) {
return MP_VAL;
}
bit = (mp_digit)(1) << (b % DIGIT_BIT);
isset = a->dp[limb] & bit;
return (isset != 0u) ? MP_YES : MP_NO;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
