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#![no_std]
#[cfg(not(feature = "no-stdlib"))]
#[macro_use]
extern crate std;
extern crate byteorder;
#[cfg(test)]
extern crate rand;
#[cfg(target_feature = "sse4.2")]
mod crc32c_hw;
#[cfg(target_feature = "sse4.2")]
mod crc32c_hw_consts;
#[cfg(target_feature = "sse4.2")]
use crc32c_hw::crc32c_update;
#[cfg(any(test, not(target_feature = "sse4.2")))]
mod crc32c_sw;
#[cfg(any(test, not(target_feature = "sse4.2")))]
mod crc32c_sw_consts;
#[cfg(not(target_feature = "sse4.2"))]
use crc32c_sw::crc32c_update;
#[cfg(not(feature = "no-stdlib"))]
pub use stdlib_implementation::*;
#[cfg(not(feature = "no-stdlib"))]
mod stdlib_implementation {
use super::*;
use std::hash::Hasher;
#[derive(Debug, Default, Copy, Clone, PartialEq, Eq)]
pub struct Digest(u32);
impl Digest {
pub fn new(crc: u32) -> Digest {
Digest(crc)
}
}
impl Hasher for Digest {
#[inline]
fn write(&mut self, buf: &[u8]) {
self.0 = crc32c_update(self.0, buf);
}
#[inline]
fn finish(&self) -> u64 {
u64::from(self.0)
}
}
}
pub fn compute<T>(buf: T) -> u32
where
T: AsRef<[u8]>,
{
crc32c_update(0, buf)
}
pub fn update<T>(crc: u32, buf: T) -> u32
where
T: AsRef<[u8]>,
{
crc32c_update(crc, buf)
}
#[cfg(all(test, not(feature = "no-stdlib"), target_feature = "sse4.2"))]
mod tests {
use super::crc32c_hw;
use super::crc32c_sw;
use rand::{thread_rng, Rng, RngCore};
macro_rules! compare_test {
(iterations = $iterations:expr,min = $min:expr,max = $max:expr) => {{
let mut rng = thread_rng();
for _ in 0..$iterations {
let mut buf = vec![0u8; rng.gen_range($min, $max)];
rng.fill_bytes(&mut buf);
let crc = rng.gen();
let crc_hw = crc32c_hw::crc32c_update(crc, &buf);
let crc_sw = crc32c_sw::crc32c_update(crc, &buf);
assert_eq!(crc_hw, crc_sw);
}
}};
}
#[test]
fn compare_hw_and_sw() {
compare_test!(iterations = 1000, min = 0, max = 430);
compare_test!(iterations = 2000, min = 0, max = 3900);
compare_test!(iterations = 3000, min = 0, max = 65000);
}
}