diff options
author | Matt Johnston <matt@ucc.asn.au> | 2006-03-08 13:16:18 +0000 |
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committer | Matt Johnston <matt@ucc.asn.au> | 2006-03-08 13:16:18 +0000 |
commit | 1c5fda515f96c27d4e3b732d887f418453f1cb14 (patch) | |
tree | bf90196389a9618de48c5acb5ce1d056aa347ce0 /bn_mp_get_int.c |
Import of libtommath 0.35
From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c
--HG--
branch : libtommath-orig
extra : convert_revision : 2b4b13ac88b2a81e5c86ba868c92c6a452630e02
Diffstat (limited to 'bn_mp_get_int.c')
-rw-r--r-- | bn_mp_get_int.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/bn_mp_get_int.c b/bn_mp_get_int.c new file mode 100644 index 0000000..034467b --- /dev/null +++ b/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@iahu.ca, 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 |