kc3-lang/libtommath/bn_mp_2expt.c

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• Hash : 4534056c
  Author :
  Date : 2019-05-13T00:22:18
  

  use enums mp_err, mp_ord, mp_bool, mp_sign * MP_USE_ENUMS enables enums * Wc++-compat catches some implicit conversions if MP_USE_ENUMS is defined * 100% backwards compatible API/ABI if MP_USE_ENUMS is not defined

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• bn_mp_2expt.c

• #include "tommath_private.h"
  #ifdef BN_MP_2EXPT_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* computes a = 2**b
   *
   * Simple algorithm which zeroes the int, grows it then just sets one bit
   * as required.
   */
  mp_err mp_2expt(mp_int *a, int b)
  {
     mp_err    res;
  
     /* zero a as per default */
     mp_zero(a);
  
     /* grow a to accomodate the single bit */
     if ((res = mp_grow(a, (b / MP_DIGIT_BIT) + 1)) != MP_OKAY) {
        return res;
     }
  
     /* set the used count of where the bit will go */
     a->used = (b / MP_DIGIT_BIT) + 1;
  
     /* put the single bit in its place */
     a->dp[b / MP_DIGIT_BIT] = (mp_digit)1 << (mp_digit)(b % MP_DIGIT_BIT);
  
     return MP_OKAY;
  }
  #endif
  

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