The memchr
crate provides heavily optimized routines for searching bytes.
Dual-licensed under MIT or the UNLICENSE.
The memchr
function is traditionally provided by libc, however, the performance of memchr
can vary significantly depending on the specific implementation of libc that is used. They can range from manually tuned Assembly implementations (like that found in GNU's libc) all the way to non-vectorized C implementations (like that found in MUSL).
To smooth out the differences between implementations of libc, at least on x86_64
for Rust 1.27+, this crate provides its own implementation of memchr
that should perform competitively with the one found in GNU's libc. The implementation is in pure Rust and has no dependency on a C compiler or an Assembler.
Additionally, GNU libc also provides an extension, memrchr
. This crate provides its own implementation of memrchr
as well, on top of memchr2
, memchr3
, memrchr2
and memrchr3
. The difference between memchr
and memchr2
is that that memchr2
permits finding all occurrences of two bytes instead of one. Similarly for memchr3
.
memchr links to the standard library by default, but you can disable the use_std
feature if you want to use it in a #![no_std]
crate:
[dependencies] memchr = { version = "2", default-features = false }
On x86 platforms, when the use_std
feature is disabled, the SSE2 implementation of memchr will be used in compilers that support it. When use_std
is enabled, the AVX implementation of memchr will be used if the CPU is determined to support it at runtime.