1[base64](https://crates.io/crates/base64) 2=== 3 4[](https://crates.io/crates/base64) [](https://docs.rs/base64) [](https://travis-ci.org/alicemaz/rust-base64) [](https://codecov.io/gh/alicemaz/rust-base64) 5 6<a href="https://www.jetbrains.com/?from=rust-base64"><img src="/icon_CLion.svg" height="40px"/></a> 7 8Made with CLion. Thanks to JetBrains for supporting open source! 9 10It's base64. What more could anyone want? 11 12Example 13--- 14 15```rust 16extern crate base64; 17 18use base64::{encode, decode}; 19 20fn main() { 21 let a = b"hello world"; 22 let b = "aGVsbG8gd29ybGQ="; 23 24 assert_eq!(encode(a), b); 25 assert_eq!(a, &decode(b).unwrap()[..]); 26} 27``` 28 29See the [docs](https://docs.rs/base64) for all the details. 30 31Rust version compatibility 32--- 33 34The minimum required Rust version is 1.27.2. 35 36Developing 37--- 38 39Benchmarks are in `benches/`. Running them requires nightly rust, but `rustup` makes it easy: 40 41``` 42rustup run nightly cargo bench 43``` 44 45Decoding is aided by some pre-calculated tables, which are generated by: 46 47``` 48cargo run --example make_tables > src/tables.rs.tmp && mv src/tables.rs.tmp src/tables.rs 49``` 50 51Profiling 52--- 53 54On Linux, you can use [perf](https://perf.wiki.kernel.org/index.php/Main_Page) for profiling. Then compile the benchmarks with `rustup nightly run cargo bench --no-run`. 55 56Run the benchmark binary with `perf` (shown here filtering to one particular benchmark, which will make the results easier to read). `perf` is only available to the root user on most systems as it fiddles with event counters in your CPU, so use `sudo`. We need to run the actual benchmark binary, hence the path into `target`. You can see the actual full path with `rustup run nightly cargo bench -v`; it will print out the commands it runs. If you use the exact path that `bench` outputs, make sure you get the one that's for the benchmarks, not the tests. You may also want to `cargo clean` so you have only one `benchmarks-` binary (they tend to accumulate). 57 58``` 59sudo perf record target/release/deps/benchmarks-* --bench decode_10mib_reuse 60``` 61 62Then analyze the results, again with perf: 63 64``` 65sudo perf annotate -l 66``` 67 68You'll see a bunch of interleaved rust source and assembly like this. The section with `lib.rs:327` is telling us that 4.02% of samples saw the `movzbl` aka bit shift as the active instruction. However, this percentage is not as exact as it seems due to a phenomenon called *skid*. Basically, a consequence of how fancy modern CPUs are is that this sort of instruction profiling is inherently inaccurate, especially in branch-heavy code. 69 70``` 71 lib.rs:322 0.70 : 10698: mov %rdi,%rax 72 2.82 : 1069b: shr $0x38,%rax 73 : if morsel == decode_tables::INVALID_VALUE { 74 : bad_byte_index = input_index; 75 : break; 76 : }; 77 : accum = (morsel as u64) << 58; 78 lib.rs:327 4.02 : 1069f: movzbl (%r9,%rax,1),%r15d 79 : // fast loop of 8 bytes at a time 80 : while input_index < length_of_full_chunks { 81 : let mut accum: u64; 82 : 83 : let input_chunk = BigEndian::read_u64(&input_bytes[input_index..(input_index + 8)]); 84 : morsel = decode_table[(input_chunk >> 56) as usize]; 85 lib.rs:322 3.68 : 106a4: cmp $0xff,%r15 86 : if morsel == decode_tables::INVALID_VALUE { 87 0.00 : 106ab: je 1090e <base64::decode_config_buf::hbf68a45fefa299c1+0x46e> 88``` 89 90 91Fuzzing 92--- 93 94This uses [cargo-fuzz](https://github.com/rust-fuzz/cargo-fuzz). See `fuzz/fuzzers` for the available fuzzing scripts. To run, use an invocation like these: 95 96``` 97cargo +nightly fuzz run roundtrip 98cargo +nightly fuzz run roundtrip_no_pad 99cargo +nightly fuzz run roundtrip_random_config -- -max_len=10240 100``` 101 102 103License 104--- 105 106This project is dual-licensed under MIT and Apache 2.0. 107
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