const-hex
This crate provides a fast conversion of byte arrays to hexadecimal strings, both at compile time, and at run time.
It aims to be a drop-in replacement for the hex crate, as well as extending
the API with const-eval, a const-generics formatting buffer, similar
to itoa's, and more.
Version requirement: rustc 1.64+
Performance
This crate's performance is comparable with faster-hex, but the latter only
provides specialized implementations for x86/x86-64.
This crate is 10 to 50 times faster than hex in encoding and decoding, and
100+ times faster than libstd in formatting.
The following benchmarks were ran on an AMD Ryzen 9 7950X, compiled with
1.80.0-nightly (bdbbb6c6a 2024-05-26) on x86_64-unknown-linux-gnu.
You can run these benchmarks with cargo bench --features std on a nightly
compiler.
test check::const_hex::bench1_32b ... bench: 9.79 ns/iter (+/- 2.22)
test check::const_hex::bench2_256b ... bench: 20.22 ns/iter (+/- 6.41)
test check::const_hex::bench3_2k ... bench: 124.57 ns/iter (+/- 9.68)
test check::const_hex::bench4_16k ... bench: 927.53 ns/iter (+/- 81.94)
test check::const_hex::bench5_128k ... bench: 7,300.16 ns/iter (+/- 153.57)
test check::const_hex::bench6_1m ... bench: 59,886.62 ns/iter (+/- 1,312.15)
test check::faster_hex::bench1_32b ... bench: 2.93 ns/iter (+/- 0.20)
test check::faster_hex::bench2_256b ... bench: 15.54 ns/iter (+/- 0.77)
test check::faster_hex::bench3_2k ... bench: 121.17 ns/iter (+/- 0.70)
test check::faster_hex::bench4_16k ... bench: 945.17 ns/iter (+/- 12.48)
test check::faster_hex::bench5_128k ... bench: 7,632.07 ns/iter (+/- 172.68)
test check::faster_hex::bench6_1m ... bench: 61,427.03 ns/iter (+/- 732.21)
test check::naive::bench1_32b ... bench: 26.15 ns/iter (+/- 1.04)
test check::naive::bench2_256b ... bench: 225.69 ns/iter (+/- 9.02)
test check::naive::bench3_2k ... bench: 1,952.05 ns/iter (+/- 20.46)
test check::naive::bench4_16k ... bench: 20,329.63 ns/iter (+/- 455.31)
test check::naive::bench5_128k ... bench: 503,460.10 ns/iter (+/- 8,930.00)
test check::naive::bench6_1m ... bench: 4,252,331.00 ns/iter (+/- 191,519.79)
test decode::const_hex::bench1_32b ... bench: 19.49 ns/iter (+/- 0.82)
test decode::const_hex::bench2_256b ... bench: 41.47 ns/iter (+/- 1.45)
test decode::const_hex::bench3_2k ... bench: 236.69 ns/iter (+/- 2.75)
test decode::const_hex::bench4_16k ... bench: 1,682.25 ns/iter (+/- 18.07)
test decode::const_hex::bench5_128k ... bench: 13,096.94 ns/iter (+/- 138.05)
test decode::const_hex::bench6_1m ... bench: 105,360.67 ns/iter (+/- 2,771.85)
test decode::faster_hex::bench1_32b ... bench: 16.49 ns/iter (+/- 0.12)
test decode::faster_hex::bench2_256b ... bench: 54.92 ns/iter (+/- 1.74)
test decode::faster_hex::bench3_2k ... bench: 246.11 ns/iter (+/- 3.25)
test decode::faster_hex::bench4_16k ... bench: 1,839.88 ns/iter (+/- 22.36)
test decode::faster_hex::bench5_128k ... bench: 14,376.52 ns/iter (+/- 203.97)
test decode::faster_hex::bench6_1m ... bench: 116,345.50 ns/iter (+/- 1,377.06)
test decode::hex::bench1_32b ... bench: 101.38 ns/iter (+/- 3.41)
test decode::hex::bench2_256b ... bench: 655.85 ns/iter (+/- 17.69)
test decode::hex::bench3_2k ... bench: 4,830.90 ns/iter (+/- 73.58)
test decode::hex::bench4_16k ... bench: 37,976.46 ns/iter (+/- 443.65)
test decode::hex::bench5_128k ... bench: 734,983.30 ns/iter (+/- 4,297.49)
test decode::hex::bench6_1m ... bench: 5,901,860.30 ns/iter (+/- 22,806.40)
test decode_to_slice::const_hex::bench1_32b ... bench: 11.03 ns/iter (+/- 0.50)
test decode_to_slice::const_hex::bench2_256b ... bench: 28.93 ns/iter (+/- 1.38)
test decode_to_slice::const_hex::bench3_2k ... bench: 210.49 ns/iter (+/- 5.65)
test decode_to_slice::const_hex::bench4_16k ... bench: 1,670.55 ns/iter (+/- 17.87)
test decode_to_slice::const_hex::bench5_128k ... bench: 13,094.65 ns/iter (+/- 115.89)
test decode_to_slice::const_hex::bench6_1m ... bench: 105,036.12 ns/iter (+/- 1,722.56)
test decode_to_slice::faster_hex::bench1_32b ... bench: 6.26 ns/iter (+/- 0.10)
test decode_to_slice::faster_hex::bench2_256b ... bench: 28.73 ns/iter (+/- 0.55)
test decode_to_slice::faster_hex::bench3_2k ... bench: 213.70 ns/iter (+/- 2.83)
test decode_to_slice::faster_hex::bench4_16k ... bench: 1,718.21 ns/iter (+/- 23.97)
test decode_to_slice::faster_hex::bench5_128k ... bench: 13,530.96 ns/iter (+/- 97.41)
test decode_to_slice::faster_hex::bench6_1m ... bench: 107,708.79 ns/iter (+/- 1,425.58)
test decode_to_slice::hex::bench1_32b ... bench: 39.07 ns/iter (+/- 1.85)
test decode_to_slice::hex::bench2_256b ... bench: 311.73 ns/iter (+/- 10.92)
test decode_to_slice::hex::bench3_2k ... bench: 2,515.69 ns/iter (+/- 63.09)
test decode_to_slice::hex::bench4_16k ... bench: 20,899.92 ns/iter (+/- 442.95)
test decode_to_slice::hex::bench5_128k ... bench: 634,859.00 ns/iter (+/- 6,609.09)
test decode_to_slice::hex::bench6_1m ... bench: 5,338,354.20 ns/iter (+/- 51,493.30)
test encode::const_hex::bench1_32b ... bench: 6.92 ns/iter (+/- 0.11)
test encode::const_hex::bench2_256b ... bench: 11.41 ns/iter (+/- 0.14)
test encode::const_hex::bench3_2k ... bench: 73.59 ns/iter (+/- 1.52)
test encode::const_hex::bench4_16k ... bench: 461.00 ns/iter (+/- 5.17)
test encode::const_hex::bench5_128k ... bench: 3,527.28 ns/iter (+/- 46.86)
test encode::const_hex::bench6_1m ... bench: 29,402.78 ns/iter (+/- 1,032.91)
test encode::faster_hex::bench1_32b ... bench: 17.30 ns/iter (+/- 0.30)
test encode::faster_hex::bench2_256b ... bench: 39.07 ns/iter (+/- 0.73)
test encode::faster_hex::bench3_2k ... bench: 102.93 ns/iter (+/- 1.92)
test encode::faster_hex::bench4_16k ... bench: 651.65 ns/iter (+/- 1.55)
test encode::faster_hex::bench5_128k ... bench: 5,074.50 ns/iter (+/- 22.97)
test encode::faster_hex::bench6_1m ... bench: 46,227.11 ns/iter (+/- 945.52)
test encode::hex::bench1_32b ... bench: 100.46 ns/iter (+/- 0.93)
test encode::hex::bench2_256b ... bench: 717.75 ns/iter (+/- 5.91)
test encode::hex::bench3_2k ... bench: 5,660.67 ns/iter (+/- 246.73)
test encode::hex::bench4_16k ... bench: 44,981.79 ns/iter (+/- 340.51)
test encode::hex::bench5_128k ... bench: 359,401.72 ns/iter (+/- 1,689.97)
test encode::hex::bench6_1m ... bench: 2,966,947.20 ns/iter (+/- 165,738.51)
test encode_to_slice::const_hex::bench1_32b ... bench: 1.55 ns/iter (+/- 0.04)
test encode_to_slice::const_hex::bench2_256b ... bench: 6.73 ns/iter (+/- 0.08)
test encode_to_slice::const_hex::bench3_2k ... bench: 54.23 ns/iter (+/- 2.06)
test encode_to_slice::const_hex::bench4_16k ... bench: 471.90 ns/iter (+/- 21.13)
test encode_to_slice::const_hex::bench5_128k ... bench: 3,730.44 ns/iter (+/- 113.80)
test encode_to_slice::const_hex::bench6_1m ... bench: 29,247.93 ns/iter (+/- 926.38)
test encode_to_slice::faster_hex::bench1_32b ... bench: 3.95 ns/iter (+/- 0.26)
test encode_to_slice::faster_hex::bench2_256b ... bench: 7.49 ns/iter (+/- 0.47)
test encode_to_slice::faster_hex::bench3_2k ... bench: 48.56 ns/iter (+/- 1.95)
test encode_to_slice::faster_hex::bench4_16k ... bench: 424.65 ns/iter (+/- 11.39)
test encode_to_slice::faster_hex::bench5_128k ... bench: 3,317.47 ns/iter (+/- 103.44)
test encode_to_slice::faster_hex::bench6_1m ... bench: 26,079.18 ns/iter (+/- 889.52)
test encode_to_slice::hex::bench1_32b ... bench: 11.99 ns/iter (+/- 0.30)
test encode_to_slice::hex::bench2_256b ... bench: 119.07 ns/iter (+/- 2.85)
test encode_to_slice::hex::bench3_2k ... bench: 999.68 ns/iter (+/- 26.35)
test encode_to_slice::hex::bench4_16k ... bench: 8,049.82 ns/iter (+/- 105.51)
test encode_to_slice::hex::bench5_128k ... bench: 65,186.25 ns/iter (+/- 758.98)
test encode_to_slice::hex::bench6_1m ... bench: 511,447.00 ns/iter (+/- 4,866.41)
test format::const_hex::bench1_32b ... bench: 9.84 ns/iter (+/- 0.21)
test format::const_hex::bench2_256b ... bench: 17.90 ns/iter (+/- 0.55)
test format::const_hex::bench3_2k ... bench: 119.47 ns/iter (+/- 3.87)
test format::const_hex::bench4_16k ... bench: 1,161.94 ns/iter (+/- 20.11)
test format::const_hex::bench5_128k ... bench: 9,580.23 ns/iter (+/- 188.10)
test format::const_hex::bench6_1m ... bench: 84,316.47 ns/iter (+/- 1,407.10)
test format::std::bench1_32b ... bench: 371.37 ns/iter (+/- 3.63)
test format::std::bench2_256b ... bench: 2,987.01 ns/iter (+/- 41.26)
test format::std::bench3_2k ... bench: 23,989.24 ns/iter (+/- 373.84)
test format::std::bench4_16k ... bench: 192,881.92 ns/iter (+/- 9,266.64)
test format::std::bench5_128k ... bench: 1,554,062.80 ns/iter (+/- 10,998.30)
test format::std::bench6_1m ... bench: 12,378,548.00 ns/iter (+/- 247,626.30)
Acknowledgements
hexfor the initial encoding/decoding implementationsfaster-hexfor thex86/x86-64check and decode implementations- dtolnay/itoa for the initial crate/library API layout