fast-modulo

This crate needs nightly. (for feature(asm))

benchmark

OS: Ubuntu 18.04, CPU: AMD Ryzen 7 2700X, rustc 1.51.0-nightly (257becbfe 2020-12-27) ``` reference::mulmod_u64 time: [23.077 ns 23.102 ns 23.134 ns]
Found 4 outliers among 100 measurements (4.00%) 3 (3.00%) high mild 1 (1.00%) high severe

mulmod_u64 time: [10.223 ns 10.230 ns 10.236 ns]

reference::mod_u128u64 time: [36.684 ns 36.705 ns 36.727 ns]
Found 18 outliers among 100 measurements (18.00%) 16 (16.00%) high mild 2 (2.00%) high severe

mod_u128u64 time: [13.862 ns 13.869 ns 13.878 ns]

reference::powmod_u64 time: [2.2811 us 2.2840 us 2.2872 us]
Found 1 outliers among 100 measurements (1.00%) 1 (1.00%) high mild

powmod_u64 time: [916.39 ns 917.03 ns 917.77 ns]
Found 2 outliers among 100 measurements (2.00%) 2 (2.00%) high mild ```

Licence

AGPL-3.0-or-later