Mercurial > dropbear
diff libtommath/bn_mp_reduce_is_2k_l.c @ 330:5488db2e9e4e
merge of 332f709a4cb39cde4cedab7c3be89e05f3023067
and ca4ca78b82c5d430c69ce01bf794e8886ce81431
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Sat, 10 Jun 2006 16:39:40 +0000 |
parents | eed26cff980b |
children | 5ff8218bcee9 |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libtommath/bn_mp_reduce_is_2k_l.c Sat Jun 10 16:39:40 2006 +0000 @@ -0,0 +1,40 @@ +#include <tommath.h> +#ifdef BN_MP_REDUCE_IS_2K_L_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 + */ + +/* determines if reduce_2k_l can be used */ +int mp_reduce_is_2k_l(mp_int *a) +{ + int ix, iy; + + if (a->used == 0) { + return MP_NO; + } else if (a->used == 1) { + return MP_YES; + } else if (a->used > 1) { + /* if more than half of the digits are -1 we're sold */ + for (iy = ix = 0; ix < a->used; ix++) { + if (a->dp[ix] == MP_MASK) { + ++iy; + } + } + return (iy >= (a->used/2)) ? MP_YES : MP_NO; + + } + return MP_NO; +} + +#endif