kc3-lang/libtommath/mp_2expt.c

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• Hash : c7686f24
  Author :
  Date : 2022-10-02T12:58:53
  

  slightly edit, update and run typos.sh Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

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• mp_2expt.c

• #include "tommath_private.h"
  #ifdef 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    err;
  
     /* zero a as per default */
     mp_zero(a);
  
     /* grow a to accommodate the single bit */
     if ((err = mp_grow(a, (b / MP_DIGIT_BIT) + 1)) != MP_OKAY) {
        return err;
     }
  
     /* 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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