bn_s_mp_get_bit.c 521 B

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  1. #include "tommath_private.h"
  2. #ifdef BN_S_MP_GET_BIT_C
  3. /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  4. /* SPDX-License-Identifier: Unlicense */
  5. /* Get bit at position b and return MP_YES if the bit is 1, MP_NO if it is 0 */
  6. mp_bool s_mp_get_bit(const mp_int *a, unsigned int b)
  7. {
  8. mp_digit bit;
  9. int limb = (int)(b / MP_DIGIT_BIT);
  10. if (limb >= a->used) {
  11. return MP_NO;
  12. }
  13. bit = (mp_digit)1 << (b % MP_DIGIT_BIT);
  14. return ((a->dp[limb] & bit) != 0u) ? MP_YES : MP_NO;
  15. }
  16. #endif