Module lexical_core::atoi

Expand description

Fast lexical string-to-integer conversion routines.

These routines are wrapping, and therefore can accept any buffer for any size type, but will wrap to the desired value if overflow occurs.

The following benchmarks were run on an “Intel(R) Core(TM) i7-6560U CPU @ 2.20GHz” CPU, on Fedora 28, Linux kernel version 4.18.16-200 (x86-64), using the lexical formatter or x.parse(), avoiding any inefficiencies in Rust string parsing. The code was compiled with LTO and at an optimization level of 3.

The benchmarks with std were compiled using “rustc 1.29.2 (17a9dc751 2018-10-05”, and the no_std benchmarks were compiled using “rustc 1.31.0-nightly (46880f41b 2018-10-15)”.

The benchmark code may be found benches/atoi.rs.

Benchmarks

Type	lexical (ns/iter)	parse (ns/iter)	Relative Increase
u8	62,790	67,926	1.08x
u16	58,896	76,602	1.30x
u32	103,962	139,434	1.34x
u64	192,792	265,931	1.38x
i8	89,828	109,099	1.21x
i16	111,592	140,172	1.26x
i32	155,172	189,377	1.22x
i64	197,747	283,541	1.43x

Raw Benchmarks

test i8_lexical  ... bench:      89,828 ns/iter (+/- 9,172)
test i8_parse    ... bench:     109,099 ns/iter (+/- 2,711)
test i16_lexical ... bench:     111,592 ns/iter (+/- 3,862)
test i16_parse   ... bench:     140,172 ns/iter (+/- 7,194)
test i32_lexical ... bench:     155,172 ns/iter (+/- 5,248)
test i32_parse   ... bench:     189,377 ns/iter (+/- 10,131)
test i64_lexical ... bench:     197,747 ns/iter (+/- 18,041)
test i64_parse   ... bench:     283,541 ns/iter (+/- 14,240)
test u8_lexical  ... bench:      62,790 ns/iter (+/- 3,146)
test u8_parse    ... bench:      67,926 ns/iter (+/- 3,767)
test u16_lexical ... bench:      58,896 ns/iter (+/- 3,238)
test u16_parse   ... bench:      76,602 ns/iter (+/- 3,771)
test u32_lexical ... bench:     103,962 ns/iter (+/- 4,870)
test u32_parse   ... bench:     139,434 ns/iter (+/- 3,944)
test u64_lexical ... bench:     192,792 ns/iter (+/- 9,147)
test u64_parse   ... bench:     265,931 ns/iter (+/- 8,308)

Raw Benchmarks (no_std)

test i8_lexical  ... bench:      94,142 ns/iter (+/- 5,252)
test i8_parse    ... bench:     107,092 ns/iter (+/- 4,121)
test i16_lexical ... bench:     113,284 ns/iter (+/- 17,479)
test i16_parse   ... bench:     141,393 ns/iter (+/- 5,804)
test i32_lexical ... bench:     155,704 ns/iter (+/- 5,590)
test i32_parse   ... bench:     191,977 ns/iter (+/- 8,241)
test i64_lexical ... bench:     197,485 ns/iter (+/- 11,415)
test i64_parse   ... bench:     298,771 ns/iter (+/- 13,941)
test u8_lexical  ... bench:      61,893 ns/iter (+/- 1,171)
test u8_parse    ... bench:      73,681 ns/iter (+/- 7,508)
test u16_lexical ... bench:      60,014 ns/iter (+/- 2,605)
test u16_parse   ... bench:      78,667 ns/iter (+/- 2,899)
test u32_lexical ... bench:     102,840 ns/iter (+/- 2,770)
test u32_parse   ... bench:     140,070 ns/iter (+/- 3,443)
test u64_lexical ... bench:     191,493 ns/iter (+/- 2,648)
test u64_parse   ... bench:     279,269 ns/iter (+/- 12,914)