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 offers performance comparable to faster-hex on x86/x86-64
architectures but outperforms it on other platforms, as faster-hex is
only optimized 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
1.83.0-nightly (9ff5fc4ff 2024-10-03) 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: 3.07 ns/iter (+/- 0.62)
test check::const_hex::bench2_256b ... bench: 15.65 ns/iter (+/- 0.46)
test check::const_hex::bench3_2k ... bench: 120.12 ns/iter (+/- 4.08)
test check::const_hex::bench4_16k ... bench: 935.28 ns/iter (+/- 19.27)
test check::const_hex::bench5_128k ... bench: 7,442.57 ns/iter (+/- 4,921.92)
test check::const_hex::bench6_1m ... bench: 59,889.93 ns/iter (+/- 1,471.89)
test check::faster_hex::bench1_32b ... bench: 2.79 ns/iter (+/- 0.08)
test check::faster_hex::bench2_256b ... bench: 14.97 ns/iter (+/- 0.40)
test check::faster_hex::bench3_2k ... bench: 122.31 ns/iter (+/- 5.01)
test check::faster_hex::bench4_16k ... bench: 984.16 ns/iter (+/- 11.57)
test check::faster_hex::bench5_128k ... bench: 7,855.54 ns/iter (+/- 61.75)
test check::faster_hex::bench6_1m ... bench: 63,171.43 ns/iter (+/- 3,022.35)
test check::naive::bench1_32b ... bench: 17.05 ns/iter (+/- 2.25)
test check::naive::bench2_256b ... bench: 188.65 ns/iter (+/- 6.14)
test check::naive::bench3_2k ... bench: 2,050.15 ns/iter (+/- 313.23)
test check::naive::bench4_16k ... bench: 16,852.37 ns/iter (+/- 983.27)
test check::naive::bench5_128k ... bench: 521,793.20 ns/iter (+/- 18,279.50)
test check::naive::bench6_1m ... bench: 4,007,801.65 ns/iter (+/- 80,974.34)
test decode::const_hex::bench1_32b ... bench: 17.57 ns/iter (+/- 0.53)
test decode::const_hex::bench2_256b ... bench: 39.20 ns/iter (+/- 3.36)
test decode::const_hex::bench3_2k ... bench: 236.98 ns/iter (+/- 3.22)
test decode::const_hex::bench4_16k ... bench: 1,708.26 ns/iter (+/- 38.29)
test decode::const_hex::bench5_128k ... bench: 13,258.62 ns/iter (+/- 665.24)
test decode::const_hex::bench6_1m ... bench: 108,937.41 ns/iter (+/- 6,453.24)
test decode::faster_hex::bench1_32b ... bench: 17.25 ns/iter (+/- 0.14)
test decode::faster_hex::bench2_256b ... bench: 55.01 ns/iter (+/- 1.33)
test decode::faster_hex::bench3_2k ... bench: 253.37 ns/iter (+/- 6.11)
test decode::faster_hex::bench4_16k ... bench: 1,864.45 ns/iter (+/- 25.81)
test decode::faster_hex::bench5_128k ... bench: 14,664.17 ns/iter (+/- 268.45)
test decode::faster_hex::bench6_1m ... bench: 118,576.16 ns/iter (+/- 2,564.34)
test decode::hex::bench1_32b ... bench: 107.13 ns/iter (+/- 7.28)
test decode::hex::bench2_256b ... bench: 666.06 ns/iter (+/- 16.19)
test decode::hex::bench3_2k ... bench: 5,044.12 ns/iter (+/- 147.09)
test decode::hex::bench4_16k ... bench: 40,003.46 ns/iter (+/- 999.15)
test decode::hex::bench5_128k ... bench: 797,007.70 ns/iter (+/- 10,044.26)
test decode::hex::bench6_1m ... bench: 6,409,293.90 ns/iter (+/- 102,747.28)
test decode::rustc_hex::bench1_32b ... bench: 139.10 ns/iter (+/- 5.50)
test decode::rustc_hex::bench2_256b ... bench: 852.05 ns/iter (+/- 24.91)
test decode::rustc_hex::bench3_2k ... bench: 6,086.40 ns/iter (+/- 109.08)
test decode::rustc_hex::bench4_16k ... bench: 48,171.36 ns/iter (+/- 11,681.51)
test decode::rustc_hex::bench5_128k ... bench: 893,339.65 ns/iter (+/- 46,849.14)
test decode::rustc_hex::bench6_1m ... bench: 7,147,395.90 ns/iter (+/- 235,201.49)
test decode_to_slice::const_hex::bench1_32b ... bench: 5.17 ns/iter (+/- 0.25)
test decode_to_slice::const_hex::bench2_256b ... bench: 27.20 ns/iter (+/- 1.37)
test decode_to_slice::const_hex::bench3_2k ... bench: 213.70 ns/iter (+/- 3.63)
test decode_to_slice::const_hex::bench4_16k ... bench: 1,704.88 ns/iter (+/- 22.26)
test decode_to_slice::const_hex::bench5_128k ... bench: 13,310.03 ns/iter (+/- 78.15)
test decode_to_slice::const_hex::bench6_1m ... bench: 107,783.54 ns/iter (+/- 2,276.99)
test decode_to_slice::faster_hex::bench1_32b ... bench: 6.71 ns/iter (+/- 0.05)
test decode_to_slice::faster_hex::bench2_256b ... bench: 29.46 ns/iter (+/- 0.41)
test decode_to_slice::faster_hex::bench3_2k ... bench: 223.09 ns/iter (+/- 2.95)
test decode_to_slice::faster_hex::bench4_16k ... bench: 1,758.51 ns/iter (+/- 14.19)
test decode_to_slice::faster_hex::bench5_128k ... bench: 13,838.49 ns/iter (+/- 252.65)
test decode_to_slice::faster_hex::bench6_1m ... bench: 114,228.23 ns/iter (+/- 2,169.09)
test decode_to_slice::hex::bench1_32b ... bench: 38.06 ns/iter (+/- 2.13)
test decode_to_slice::hex::bench2_256b ... bench: 311.96 ns/iter (+/- 34.52)
test decode_to_slice::hex::bench3_2k ... bench: 2,659.48 ns/iter (+/- 470.05)
test decode_to_slice::hex::bench4_16k ... bench: 22,164.21 ns/iter (+/- 5,764.35)
test decode_to_slice::hex::bench5_128k ... bench: 628,509.50 ns/iter (+/- 14,196.11)
test decode_to_slice::hex::bench6_1m ... bench: 5,191,809.60 ns/iter (+/- 160,102.40)
test encode::const_hex::bench1_32b ... bench: 7.06 ns/iter (+/- 0.15)
test encode::const_hex::bench2_256b ... bench: 12.38 ns/iter (+/- 0.68)
test encode::const_hex::bench3_2k ... bench: 74.18 ns/iter (+/- 1.46)
test encode::const_hex::bench4_16k ... bench: 471.42 ns/iter (+/- 12.26)
test encode::const_hex::bench5_128k ... bench: 3,756.98 ns/iter (+/- 76.00)
test encode::const_hex::bench6_1m ... bench: 30,716.17 ns/iter (+/- 795.98)
test encode::faster_hex::bench1_32b ... bench: 17.42 ns/iter (+/- 0.28)
test encode::faster_hex::bench2_256b ... bench: 39.66 ns/iter (+/- 3.48)
test encode::faster_hex::bench3_2k ... bench: 98.34 ns/iter (+/- 2.60)
test encode::faster_hex::bench4_16k ... bench: 618.01 ns/iter (+/- 9.90)
test encode::faster_hex::bench5_128k ... bench: 4,874.14 ns/iter (+/- 44.36)
test encode::faster_hex::bench6_1m ... bench: 42,883.20 ns/iter (+/- 1,099.36)
test encode::hex::bench1_32b ... bench: 102.11 ns/iter (+/- 1.75)
test encode::hex::bench2_256b ... bench: 726.20 ns/iter (+/- 11.22)
test encode::hex::bench3_2k ... bench: 5,707.51 ns/iter (+/- 49.69)
test encode::hex::bench4_16k ... bench: 45,401.65 ns/iter (+/- 838.45)
test encode::hex::bench5_128k ... bench: 363,538.00 ns/iter (+/- 40,336.74)
test encode::hex::bench6_1m ... bench: 3,048,496.30 ns/iter (+/- 223,992.59)
test encode::rustc_hex::bench1_32b ... bench: 54.28 ns/iter (+/- 2.53)
test encode::rustc_hex::bench2_256b ... bench: 321.72 ns/iter (+/- 22.16)
test encode::rustc_hex::bench3_2k ... bench: 2,474.80 ns/iter (+/- 204.16)
test encode::rustc_hex::bench4_16k ... bench: 19,710.76 ns/iter (+/- 647.22)
test encode::rustc_hex::bench5_128k ... bench: 158,282.15 ns/iter (+/- 2,594.36)
test encode::rustc_hex::bench6_1m ... bench: 1,267,268.20 ns/iter (+/- 18,166.59)
test encode_to_slice::const_hex::bench1_32b ... bench: 1.57 ns/iter (+/- 0.01)
test encode_to_slice::const_hex::bench2_256b ... bench: 6.81 ns/iter (+/- 1.47)
test encode_to_slice::const_hex::bench3_2k ... bench: 58.47 ns/iter (+/- 5.82)
test encode_to_slice::const_hex::bench4_16k ... bench: 503.93 ns/iter (+/- 5.83)
test encode_to_slice::const_hex::bench5_128k ... bench: 3,959.53 ns/iter (+/- 85.04)
test encode_to_slice::const_hex::bench6_1m ... bench: 32,631.90 ns/iter (+/- 1,135.39)
test encode_to_slice::faster_hex::bench1_32b ... bench: 4.37 ns/iter (+/- 0.13)
test encode_to_slice::faster_hex::bench2_256b ... bench: 8.13 ns/iter (+/- 0.14)
test encode_to_slice::faster_hex::bench3_2k ... bench: 52.45 ns/iter (+/- 1.09)
test encode_to_slice::faster_hex::bench4_16k ... bench: 474.66 ns/iter (+/- 8.71)
test encode_to_slice::faster_hex::bench5_128k ... bench: 3,545.60 ns/iter (+/- 75.68)
test encode_to_slice::faster_hex::bench6_1m ... bench: 29,818.05 ns/iter (+/- 1,475.47)
test encode_to_slice::hex::bench1_32b ... bench: 12.11 ns/iter (+/- 0.31)
test encode_to_slice::hex::bench2_256b ... bench: 120.39 ns/iter (+/- 1.18)
test encode_to_slice::hex::bench3_2k ... bench: 996.18 ns/iter (+/- 10.03)
test encode_to_slice::hex::bench4_16k ... bench: 8,130.43 ns/iter (+/- 137.96)
test encode_to_slice::hex::bench5_128k ... bench: 65,671.00 ns/iter (+/- 612.36)
test encode_to_slice::hex::bench6_1m ... bench: 518,929.65 ns/iter (+/- 2,202.04)
test format::const_hex::bench1_32b ... bench: 10.01 ns/iter (+/- 0.09)
test format::const_hex::bench2_256b ... bench: 26.68 ns/iter (+/- 0.49)
test format::const_hex::bench3_2k ... bench: 121.17 ns/iter (+/- 3.15)
test format::const_hex::bench4_16k ... bench: 1,125.29 ns/iter (+/- 9.99)
test format::const_hex::bench5_128k ... bench: 8,998.22 ns/iter (+/- 162.09)
test format::const_hex::bench6_1m ... bench: 78,056.40 ns/iter (+/- 1,584.60)
test format::std::bench1_32b ... bench: 373.63 ns/iter (+/- 3.41)
test format::std::bench2_256b ... bench: 2,885.37 ns/iter (+/- 43.81)
test format::std::bench3_2k ... bench: 23,561.13 ns/iter (+/- 2,439.06)
test format::std::bench4_16k ... bench: 192,680.53 ns/iter (+/- 20,613.31)
test format::std::bench5_128k ... bench: 1,552,147.50 ns/iter (+/- 32,175.10)
test format::std::bench6_1m ... bench: 12,348,138.40 ns/iter (+/- 291,827.38)
Acknowledgements
hexfor the initial encoding/decoding implementationsfaster-hexfor thex86/x86-64check and decode implementations- dtolnay/itoa for the initial crate/library API layout