kc3-lang/libtommath/bn_mp_get_bit.c

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• Hash : 44ccca75
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  Date : 2018-05-04T00:01:45
  

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• bn_mp_get_bit.c

• #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;
     bit = (mp_digit)1 << ((mp_digit)b % DIGIT_BIT);
     isset = a->dp[limb] & bit;
     return (isset != 0) ? MP_YES : MP_NO;
  }
  
  #endif
  

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