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