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-rw-r--r--vendor/adler-0.2.3/src/algo.rs146
-rw-r--r--vendor/adler-0.2.3/src/lib.rs215
2 files changed, 361 insertions, 0 deletions
diff --git a/vendor/adler-0.2.3/src/algo.rs b/vendor/adler-0.2.3/src/algo.rs
new file mode 100644
index 000000000..650cffa6c
--- /dev/null
+++ b/vendor/adler-0.2.3/src/algo.rs
@@ -0,0 +1,146 @@
+use crate::Adler32;
+use std::ops::{AddAssign, MulAssign, RemAssign};
+
+impl Adler32 {
+ pub(crate) fn compute(&mut self, bytes: &[u8]) {
+ // The basic algorithm is, for every byte:
+ // a = (a + byte) % MOD
+ // b = (b + a) % MOD
+ // where MOD = 65521.
+ //
+ // For efficiency, we can defer the `% MOD` operations as long as neither a nor b overflows:
+ // - Between calls to `write`, we ensure that a and b are always in range 0..MOD.
+ // - We use 32-bit arithmetic in this function.
+ // - Therefore, a and b must not increase by more than 2^32-MOD without performing a `% MOD`
+ // operation.
+ //
+ // According to Wikipedia, b is calculated as follows for non-incremental checksumming:
+ // b = n×D1 + (n−1)×D2 + (n−2)×D3 + ... + Dn + n*1 (mod 65521)
+ // Where n is the number of bytes and Di is the i-th Byte. We need to change this to account
+ // for the previous values of a and b, as well as treat every input Byte as being 255:
+ // b_inc = n×255 + (n-1)×255 + ... + 255 + n*65520
+ // Or in other words:
+ // b_inc = n*65520 + n(n+1)/2*255
+ // The max chunk size is thus the largest value of n so that b_inc <= 2^32-65521.
+ // 2^32-65521 = n*65520 + n(n+1)/2*255
+ // Plugging this into an equation solver since I can't math gives n = 5552.18..., so 5552.
+ //
+ // On top of the optimization outlined above, the algorithm can also be parallelized with a
+ // bit more work:
+ //
+ // Note that b is a linear combination of a vector of input bytes (D1, ..., Dn).
+ //
+ // If we fix some value k<N and rewrite indices 1, ..., N as
+ //
+ // 1_1, 1_2, ..., 1_k, 2_1, ..., 2_k, ..., (N/k)_k,
+ //
+ // then we can express a and b in terms of sums of smaller sequences kb and ka:
+ //
+ // ka(j) := D1_j + D2_j + ... + D(N/k)_j where j <= k
+ // kb(j) := (N/k)*D1_j + (N/k-1)*D2_j + ... + D(N/k)_j where j <= k
+ //
+ // a = ka(1) + ka(2) + ... + ka(k) + 1
+ // b = k*(kb(1) + kb(2) + ... + kb(k)) - 1*ka(2) - ... - (k-1)*ka(k) + N
+ //
+ // We use this insight to unroll the main loop and process k=4 bytes at a time.
+ // The resulting code is highly amenable to SIMD acceleration, although the immediate speedups
+ // stem from increased pipeline parallelism rather than auto-vectorization.
+ //
+ // This technique is described in-depth (here:)[https://software.intel.com/content/www/us/\
+ // en/develop/articles/fast-computation-of-fletcher-checksums.html]
+
+ const MOD: u32 = 65521;
+ const CHUNK_SIZE: usize = 5552 * 4;
+
+ let mut a = u32::from(self.a);
+ let mut b = u32::from(self.b);
+ let mut a_vec = U32X4([0; 4]);
+ let mut b_vec = a_vec;
+
+ let (bytes, remainder) = bytes.split_at(bytes.len() - bytes.len() % 4);
+
+ // iterate over 4 bytes at a time
+ let chunk_iter = bytes.chunks_exact(CHUNK_SIZE);
+ let remainder_chunk = chunk_iter.remainder();
+ for chunk in chunk_iter {
+ for byte_vec in chunk.chunks_exact(4) {
+ let val = U32X4::from(byte_vec);
+ a_vec += val;
+ b_vec += a_vec;
+ }
+ b += CHUNK_SIZE as u32 * a;
+ a_vec %= MOD;
+ b_vec %= MOD;
+ b %= MOD;
+ }
+ // special-case the final chunk because it may be shorter than the rest
+ for byte_vec in remainder_chunk.chunks_exact(4) {
+ let val = U32X4::from(byte_vec);
+ a_vec += val;
+ b_vec += a_vec;
+ }
+ b += remainder_chunk.len() as u32 * a;
+ a_vec %= MOD;
+ b_vec %= MOD;
+ b %= MOD;
+
+ // combine the sub-sum results into the main sum
+ b_vec *= 4;
+ b_vec.0[1] += MOD - a_vec.0[1];
+ b_vec.0[2] += (MOD - a_vec.0[2]) * 2;
+ b_vec.0[3] += (MOD - a_vec.0[3]) * 3;
+ for &av in a_vec.0.iter() {
+ a += av;
+ }
+ for &bv in b_vec.0.iter() {
+ b += bv;
+ }
+
+ // iterate over the remaining few bytes in serial
+ for &byte in remainder.iter() {
+ a += u32::from(byte);
+ b += a;
+ }
+
+ self.a = (a % MOD) as u16;
+ self.b = (b % MOD) as u16;
+ }
+}
+
+#[derive(Copy, Clone)]
+struct U32X4([u32; 4]);
+
+impl U32X4 {
+ fn from(bytes: &[u8]) -> Self {
+ U32X4([
+ u32::from(bytes[0]),
+ u32::from(bytes[1]),
+ u32::from(bytes[2]),
+ u32::from(bytes[3]),
+ ])
+ }
+}
+
+impl AddAssign<Self> for U32X4 {
+ fn add_assign(&mut self, other: Self) {
+ for (s, o) in self.0.iter_mut().zip(other.0.iter()) {
+ *s += o;
+ }
+ }
+}
+
+impl RemAssign<u32> for U32X4 {
+ fn rem_assign(&mut self, quotient: u32) {
+ for s in self.0.iter_mut() {
+ *s %= quotient;
+ }
+ }
+}
+
+impl MulAssign<u32> for U32X4 {
+ fn mul_assign(&mut self, rhs: u32) {
+ for s in self.0.iter_mut() {
+ *s *= rhs;
+ }
+ }
+}
diff --git a/vendor/adler-0.2.3/src/lib.rs b/vendor/adler-0.2.3/src/lib.rs
new file mode 100644
index 000000000..ac29ea23f
--- /dev/null
+++ b/vendor/adler-0.2.3/src/lib.rs
@@ -0,0 +1,215 @@
+//! Adler-32 checksum implementation.
+//!
+//! This implementation features:
+//!
+//! - Permissively licensed (0BSD) clean-room implementation.
+//! - Zero dependencies.
+//! - Decent performance (3-4 GB/s).
+//! - `#![no_std]` support (with `default-features = false`).
+
+#![doc(html_root_url = "https://docs.rs/adler/0.2.3")]
+// Deny a few warnings in doctests, since rustdoc `allow`s many warnings by default
+#![doc(test(attr(deny(unused_imports, unused_must_use))))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![warn(missing_debug_implementations)]
+#![forbid(unsafe_code)]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(not(feature = "std"))]
+extern crate core as std;
+
+mod algo;
+
+use std::hash::Hasher;
+
+#[cfg(feature = "std")]
+use std::io::{self, BufRead};
+
+/// Adler-32 checksum calculator.
+///
+/// An instance of this type is equivalent to an Adler-32 checksum: It can be created in the default
+/// state via [`new`] (or the provided `Default` impl), or from a precalculated checksum via
+/// [`from_checksum`], and the currently stored checksum can be fetched via [`checksum`].
+///
+/// This type also implements `Hasher`, which makes it easy to calculate Adler-32 checksums of any
+/// type that implements or derives `Hash`. This also allows using Adler-32 in a `HashMap`, although
+/// that is not recommended (while every checksum is a hash, they are not necessarily good at being
+/// one).
+///
+/// [`new`]: #method.new
+/// [`from_checksum`]: #method.from_checksum
+/// [`checksum`]: #method.checksum
+#[derive(Debug, Copy, Clone)]
+pub struct Adler32 {
+ a: u16,
+ b: u16,
+}
+
+impl Adler32 {
+ /// Creates a new Adler-32 instance with default state.
+ #[inline]
+ pub fn new() -> Self {
+ Self::default()
+ }
+
+ /// Creates an `Adler32` instance from a precomputed Adler-32 checksum.
+ ///
+ /// This allows resuming checksum calculation without having to keep the `Adler32` instance
+ /// around.
+ ///
+ /// # Example
+ ///
+ /// ```
+ /// # use adler::Adler32;
+ /// let parts = [
+ /// "rust",
+ /// "acean",
+ /// ];
+ /// let whole = adler::adler32_slice(b"rustacean");
+ ///
+ /// let mut sum = Adler32::new();
+ /// sum.write_slice(parts[0].as_bytes());
+ /// let partial = sum.checksum();
+ ///
+ /// // ...later
+ ///
+ /// let mut sum = Adler32::from_checksum(partial);
+ /// sum.write_slice(parts[1].as_bytes());
+ /// assert_eq!(sum.checksum(), whole);
+ /// ```
+ #[inline]
+ pub fn from_checksum(sum: u32) -> Self {
+ Adler32 {
+ a: sum as u16,
+ b: (sum >> 16) as u16,
+ }
+ }
+
+ /// Returns the calculated checksum at this point in time.
+ #[inline]
+ pub fn checksum(&self) -> u32 {
+ (u32::from(self.b) << 16) | u32::from(self.a)
+ }
+
+ /// Adds `bytes` to the checksum calculation.
+ ///
+ /// If efficiency matters, this should be called with Byte slices that contain at least a few
+ /// thousand Bytes.
+ pub fn write_slice(&mut self, bytes: &[u8]) {
+ self.compute(bytes);
+ }
+}
+
+impl Default for Adler32 {
+ #[inline]
+ fn default() -> Self {
+ Adler32 { a: 1, b: 0 }
+ }
+}
+
+impl Hasher for Adler32 {
+ #[inline]
+ fn finish(&self) -> u64 {
+ u64::from(self.checksum())
+ }
+
+ fn write(&mut self, bytes: &[u8]) {
+ self.write_slice(bytes);
+ }
+}
+
+/// Calculates the Adler-32 checksum of a byte slice.
+pub fn adler32_slice(data: &[u8]) -> u32 {
+ let mut h = Adler32::new();
+ h.write_slice(data);
+ h.checksum()
+}
+
+/// Calculates the Adler-32 checksum of a `BufRead`'s contents.
+///
+/// The passed `BufRead` implementor will be read until it reaches EOF.
+///
+/// If you only have a `Read` implementor, wrap it in `std::io::BufReader`.
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+pub fn adler32_reader<R: BufRead>(reader: &mut R) -> io::Result<u32> {
+ let mut h = Adler32::new();
+ loop {
+ let len = {
+ let buf = reader.fill_buf()?;
+ if buf.is_empty() {
+ return Ok(h.checksum());
+ }
+
+ h.write_slice(buf);
+ buf.len()
+ };
+ reader.consume(len);
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use std::io::BufReader;
+
+ #[test]
+ fn zeroes() {
+ assert_eq!(adler32_slice(&[]), 1);
+ assert_eq!(adler32_slice(&[0]), 1 | 1 << 16);
+ assert_eq!(adler32_slice(&[0, 0]), 1 | 2 << 16);
+ assert_eq!(adler32_slice(&[0; 100]), 0x00640001);
+ assert_eq!(adler32_slice(&[0; 1024]), 0x04000001);
+ assert_eq!(adler32_slice(&[0; 1024 * 1024]), 0x00f00001);
+ }
+
+ #[test]
+ fn ones() {
+ assert_eq!(adler32_slice(&[0xff; 1024]), 0x79a6fc2e);
+ assert_eq!(adler32_slice(&[0xff; 1024 * 1024]), 0x8e88ef11);
+ }
+
+ #[test]
+ fn mixed() {
+ assert_eq!(adler32_slice(&[1]), 2 | 2 << 16);
+ assert_eq!(adler32_slice(&[40]), 41 | 41 << 16);
+
+ assert_eq!(adler32_slice(&[0xA5; 1024 * 1024]), 0xd5009ab1);
+ }
+
+ /// Example calculation from https://en.wikipedia.org/wiki/Adler-32.
+ #[test]
+ fn wiki() {
+ assert_eq!(adler32_slice(b"Wikipedia"), 0x11E60398);
+ }
+
+ #[test]
+ fn resume() {
+ let mut adler = Adler32::new();
+ adler.write_slice(&[0xff; 1024]);
+ let partial = adler.checksum();
+ assert_eq!(partial, 0x79a6fc2e); // from above
+ adler.write_slice(&[0xff; 1024 * 1024 - 1024]);
+ assert_eq!(adler.checksum(), 0x8e88ef11); // from above
+
+ // Make sure that we can resume computing from the partial checksum via `from_checksum`.
+ let mut adler = Adler32::from_checksum(partial);
+ adler.write_slice(&[0xff; 1024 * 1024 - 1024]);
+ assert_eq!(adler.checksum(), 0x8e88ef11); // from above
+ }
+
+ #[test]
+ fn bufread() {
+ fn test(data: &[u8], checksum: u32) {
+ // `BufReader` uses an 8 KB buffer, so this will test buffer refilling.
+ let mut buf = BufReader::new(data);
+ let real_sum = adler32_reader(&mut buf).unwrap();
+ assert_eq!(checksum, real_sum);
+ }
+
+ test(&[], 1);
+ test(&[0; 1024], 0x04000001);
+ test(&[0; 1024 * 1024], 0x00f00001);
+ test(&[0xA5; 1024 * 1024], 0xd5009ab1);
+ }
+}
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