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diff 3rdparty/libtommath/bn_mp_get_long.c @ 0:2cf249471370
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author | Takahiro SHIMIZU <anatofuz@cr.ie.u-ryukyu.ac.jp> |
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date | Tue, 08 May 2018 16:09:12 +0900 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/3rdparty/libtommath/bn_mp_get_long.c Tue May 08 16:09:12 2018 +0900 @@ -0,0 +1,41 @@ +#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. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tstdenis82@gmail.com, http://libtom.org + */ + +/* get the lower unsigned long of an mp_int, platform dependent */ +unsigned long mp_get_long(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); + +#if (ULONG_MAX != 0xffffffffuL) || (DIGIT_BIT < 32) + while (--i >= 0) { + res = (res << DIGIT_BIT) | DIGIT(a,i); + } +#endif + return res; +} +#endif