diff options
Diffstat (limited to 'third_party/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_is_2k.c')
-rw-r--r-- | third_party/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_is_2k.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_is_2k.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_is_2k.c new file mode 100644 index 0000000..a9f4f9f --- /dev/null +++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_reduce_is_2k.c @@ -0,0 +1,38 @@ +#include "tommath_private.h" +#ifdef BN_MP_REDUCE_IS_2K_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +/* determines if mp_reduce_2k can be used */ +mp_bool mp_reduce_is_2k(const mp_int *a) +{ + int ix, iy, iw; + mp_digit iz; + + if (a->used == 0) { + return MP_NO; + } else if (a->used == 1) { + return MP_YES; + } else if (a->used > 1) { + iy = mp_count_bits(a); + iz = 1; + iw = 1; + + /* Test every bit from the second digit up, must be 1 */ + for (ix = MP_DIGIT_BIT; ix < iy; ix++) { + if ((a->dp[iw] & iz) == 0u) { + return MP_NO; + } + iz <<= 1; + if (iz > MP_DIGIT_MAX) { + ++iw; + iz = 1; + } + } + return MP_YES; + } else { + return MP_YES; + } +} + +#endif |