libtommath/bn_mp_get_long_long.c
2019-04-07 17:26:31 +02:00

30 lines
764 B
C

#include "tommath_private.h"
#ifdef BN_MP_GET_LONG_LONG_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* get the lower unsigned long long of an mp_int, platform dependent */
unsigned long long mp_get_long_long(const mp_int *a)
{
int i;
unsigned long long res;
if (IS_ZERO(a)) {
return 0;
}
/* get number of digits of the lsb we have to read */
i = MIN(a->used, (((CHAR_BIT * (int)sizeof(unsigned long long)) + DIGIT_BIT - 1) / DIGIT_BIT)) - 1;
/* get most significant digit of result */
res = (unsigned long long)a->dp[i];
#if DIGIT_BIT < 64
while (--i >= 0) {
res = (res << DIGIT_BIT) | (unsigned long long)a->dp[i];
}
#endif
return res;
}
#endif