diff options
Diffstat (limited to 'libtommath/bn_mp_get_int.c')
| -rw-r--r-- | libtommath/bn_mp_get_int.c | 41 | 
1 files changed, 41 insertions, 0 deletions
| diff --git a/libtommath/bn_mp_get_int.c b/libtommath/bn_mp_get_int.c new file mode 100644 index 0000000..762cb23 --- /dev/null +++ b/libtommath/bn_mp_get_int.c @@ -0,0 +1,41 @@ +#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, tomstdenis@gmail.com, http://math.libtomcrypt.com + */ + +/* 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 | 
