kc3-lang/libtommath/bn_mp_get_long.c

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• Hash : 6dc8ae5b
  Author :
  Date : 2019-03-26T11:30:21
  

  efficiency improvement in get/set routines

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• bn_mp_get_long.c

• #include "tommath_private.h"
  #ifdef BN_MP_GET_LONG_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.
   *
   * SPDX-License-Identifier: Unlicense
   */
  
  /* get the lower unsigned long of an mp_int, platform dependent */
  unsigned long mp_get_long(const mp_int *a)
  {
     int i;
     unsigned long res;
  
     if (IS_ZERO(a)) {
        return 0;
     }
  
     /* get number of digits of the lsb we have to read */
     i = MIN(a->used, ((((int)sizeof(unsigned long) * CHAR_BIT) + DIGIT_BIT - 1) / DIGIT_BIT)) - 1;
  
     /* get most significant digit of result */
     res = (unsigned long)a->dp[i];
  
  #if (ULONG_MAX != 0xFFFFFFFFUL) || (DIGIT_BIT < 32)
     while (--i >= 0) {
        res = (res << DIGIT_BIT) | (unsigned long)a->dp[i];
     }
  #endif
     return res;
  }
  #endif
  
  /* ref:         $Format:%D$ */
  /* git commit:  $Format:%H$ */
  /* commit time: $Format:%ai$ */
  

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