mirror of
https://github.com/DragonOS-Community/DragonOS.git
synced 2025-06-17 12:47:19 +00:00
86 lines
2.8 KiB
Rust
86 lines
2.8 KiB
Rust
//! * Normal 64-bit CRC calculation.
|
|
//!
|
|
//! Taken from Linux Kernel 6.1.9
|
|
//!
|
|
//! This is a basic crc64 implementation following ECMA-182 specification,
|
|
//! which can be found from,
|
|
//! https://www.ecma-international.org/publications/standards/Ecma-182.htm
|
|
//!
|
|
//! Dr. Ross N. Williams has a great document to introduce the idea of CRC
|
|
//! algorithm, here the CRC64 code is also inspired by the table-driven
|
|
//! algorithm and detail example from this paper. This paper can be found
|
|
//! from,
|
|
//! http://www.ross.net/crc/download/crc_v3.txt
|
|
//!
|
|
//! crc64table[256] is the lookup table of a table-driven 64-bit CRC
|
|
//! calculation, which is generated by gen_crc64table.c in kernel build
|
|
//! time. The polynomial of crc64 arithmetic is from ECMA-182 specification
|
|
//! as well, which is defined as,
|
|
//!
|
|
//! x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
|
|
//! x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
|
|
//! x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
|
|
//! x^7 + x^4 + x + 1
|
|
//!
|
|
//! crc64rocksoft[256] table is from the Rocksoft specification polynomial
|
|
//! defined as,
|
|
//!
|
|
//! x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 +
|
|
//! x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 +
|
|
//! x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x^9 + x^6 + x^4 + x^3 + 1
|
|
|
|
use crate::tables::crc64::{CRC64_ROCKSOFT_TABLE, CRC64_TABLE};
|
|
|
|
/// crc64_be - Calculate bitwise big-endian ECMA-182 CRC64
|
|
///
|
|
/// ## 参数
|
|
///
|
|
/// - `crc`: seed value for computation. 0 or (u64)~0 for a new CRC calculation,
|
|
/// or the previous crc64 value if computing incrementally.
|
|
/// - `buf`: pointer to buffer over which CRC64 is run
|
|
pub fn crc64_be(mut crc: u64, buf: &[u8]) -> u64 {
|
|
for &byte in buf {
|
|
let t = ((crc >> 56) ^ (byte as u64)) & 0xff;
|
|
crc = CRC64_TABLE[t as usize] ^ (crc << 8);
|
|
}
|
|
crc
|
|
}
|
|
|
|
///
|
|
/// crc64_rocksoft_generic - Calculate bitwise Rocksoft CRC64
|
|
///
|
|
/// ## 参数
|
|
///
|
|
/// - `crc`: seed value for computation. 0 for a new CRC calculation, or the
|
|
/// previous crc64 value if computing incrementally.
|
|
/// - `buf`: pointer to buffer over which CRC64 is run
|
|
pub fn crc64_rocksoft_generic(mut crc: u64, buf: &[u8]) -> u64 {
|
|
crc = !crc;
|
|
|
|
for &byte in buf {
|
|
crc = (crc >> 8) ^ CRC64_ROCKSOFT_TABLE[(((crc & 0xff) as u8) ^ (byte)) as usize];
|
|
}
|
|
|
|
return !crc;
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
#[test]
|
|
fn crc64_be_single() {
|
|
let mut buf = [0u8; 1];
|
|
buf[0] = 0xaa;
|
|
let crc = crc64_be(0, &buf);
|
|
assert_eq!(crc, 0x2d071b6213a0cb8b);
|
|
}
|
|
|
|
#[test]
|
|
fn crc64_be_multibytes() {
|
|
let buf = b"0123456789";
|
|
let crc = crc64_be(0, buf);
|
|
assert_eq!(crc, 0x2a71ab4164c3bbe8);
|
|
}
|
|
}
|