view libtommath/bn_mp_get_int.c @ 367:c046b66b76cd channel-fix

propagate from branch 'au.asn.ucc.matt.dropbear' (head 31dcd7a22983ef19d6c63248e415e71d292dd0ec) to branch 'au.asn.ucc.matt.dropbear.channel-fix' (head 7559a8cc4f6abe2338636f2aced3a395a79c172c)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 12 Oct 2006 03:01:10 +0000
parents eed26cff980b
children 5ff8218bcee9
line wrap: on
line source

#include <tommath.h>
#ifdef BN_MP_GET_INT_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.
 *
 * Tom St Denis, [email protected], http://math.libtomcrypt.org
 */

/* get the lower 32-bits of an mp_int */
unsigned long mp_get_int(mp_int * a) 
{
  int i;
  unsigned long res;

  if (a->used == 0) {
     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 = DIGIT(a,i);
   
  while (--i >= 0) {
    res = (res << DIGIT_BIT) | DIGIT(a,i);
  }

  /* force result to 32-bits always so it is consistent on non 32-bit platforms */
  return res & 0xFFFFFFFFUL;
}
#endif