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author | Valentin Popov <valentin@popov.link> | 2024-01-08 00:21:28 +0300 |
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committer | Valentin Popov <valentin@popov.link> | 2024-01-08 00:21:28 +0300 |
commit | 1b6a04ca5504955c571d1c97504fb45ea0befee4 (patch) | |
tree | 7579f518b23313e8a9748a88ab6173d5e030b227 /vendor/simd-adler32/src/imp/scalar.rs | |
parent | 5ecd8cf2cba827454317368b68571df0d13d7842 (diff) | |
download | fparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.tar.xz fparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.zip |
Initial vendor packages
Signed-off-by: Valentin Popov <valentin@popov.link>
Diffstat (limited to 'vendor/simd-adler32/src/imp/scalar.rs')
-rw-r--r-- | vendor/simd-adler32/src/imp/scalar.rs | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/vendor/simd-adler32/src/imp/scalar.rs b/vendor/simd-adler32/src/imp/scalar.rs new file mode 100644 index 0000000..558813e --- /dev/null +++ b/vendor/simd-adler32/src/imp/scalar.rs @@ -0,0 +1,69 @@ +const MOD: u32 = 65521; +const NMAX: usize = 5552; + +pub fn update(a: u16, b: u16, data: &[u8]) -> (u16, u16) { + let mut a = a as u32; + let mut b = b as u32; + + let chunks = data.chunks_exact(NMAX); + let remainder = chunks.remainder(); + + for chunk in chunks { + for byte in chunk { + a = a.wrapping_add(*byte as _); + b = b.wrapping_add(a); + } + + a %= MOD; + b %= MOD; + } + + for byte in remainder { + a = a.wrapping_add(*byte as _); + b = b.wrapping_add(a); + } + + a %= MOD; + b %= MOD; + + (a as u16, b as u16) +} + +#[cfg(test)] +mod tests { + #[test] + fn zeroes() { + assert_eq!(adler32(&[]), 1); + assert_eq!(adler32(&[0]), 1 | 1 << 16); + assert_eq!(adler32(&[0, 0]), 1 | 2 << 16); + assert_eq!(adler32(&[0; 100]), 0x00640001); + assert_eq!(adler32(&[0; 1024]), 0x04000001); + assert_eq!(adler32(&[0; 1024 * 1024]), 0x00f00001); + } + + #[test] + fn ones() { + assert_eq!(adler32(&[0xff; 1024]), 0x79a6fc2e); + assert_eq!(adler32(&[0xff; 1024 * 1024]), 0x8e88ef11); + } + + #[test] + fn mixed() { + assert_eq!(adler32(&[1]), 2 | 2 << 16); + assert_eq!(adler32(&[40]), 41 | 41 << 16); + + assert_eq!(adler32(&[0xA5; 1024 * 1024]), 0xd5009ab1); + } + + /// Example calculation from https://en.wikipedia.org/wiki/Adler-32. + #[test] + fn wiki() { + assert_eq!(adler32(b"Wikipedia"), 0x11E60398); + } + + fn adler32(data: &[u8]) -> u32 { + let (a, b) = super::update(1, 0, data); + + u32::from(b) << 16 | u32::from(a) + } +} |