crc_catalog/
lib.rs

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1#![no_std]
2
3#[rustfmt::skip]
4pub mod algorithm;
5pub mod poly;
6pub use algorithm::*;
7
8pub trait Width: Sized + 'static {}
9impl Width for u8 {}
10impl Width for u16 {}
11impl Width for u32 {}
12impl Width for u64 {}
13impl Width for u128 {}
14
15/// This struct describes a CRC algorithm using the fields specified by the [Catalogue of
16/// parametrised CRC algorithms](https://reveng.sourceforge.io/crc-catalogue/all.htm).
17pub struct Algorithm<W: Width> {
18    /// The number of bit cells in the linear feedback shift register; the degree of the generator
19    /// polynomial, minus one.
20    pub width: u8,
21    /// The generator polynomial that sets the feedback tap positions of the shift register. The
22    /// least significant bit corresponds to the inward end of the shift register, and is always
23    /// set. The highest-order term is omitted.
24    pub poly: W,
25    /// The settings of the bit cells at the start of each calculation, before reading the first
26    /// message bit. The least significant bit corresponds to the inward end of the shift register.
27    pub init: W,
28    /// If equal to `false`, specifies that the characters of the message are read bit-by-bit, most
29    /// significant bit (MSB) first; if equal to `true`, the characters are read bit-by-bit, least
30    /// significant bit (LSB) first. Each sampled message bit is then XORed with the bit being
31    /// simultaneously shifted out of the register at the most significant end, and the result is
32    /// passed to the feedback taps.
33    pub refin: bool,
34    /// If equal to `false`, specifies that the contents of the register after reading the last
35    /// message bit are unreflected before presentation; if equal to `true`, it specifies that they
36    /// are reflected, character-by-character, before presentation. For the purpose of this
37    /// definition, the reflection is performed by swapping the content of each cell with that of
38    /// the cell an equal distance from the opposite end of the register; the characters of the CRC
39    /// are then true images of parts of the reflected register, the character containing the
40    /// original MSB always appearing first.
41    pub refout: bool,
42    /// The XOR value applied to the contents of the register after the last message bit has been
43    /// read and after the optional reflection. It has the same endianness as the CRC such that its
44    /// true image appears in the characters of the CRC.
45    pub xorout: W,
46    /// The contents of the register after initialising, reading the UTF-8 string `"123456789"` (as
47    /// 8-bit characters), optionally reflecting, and applying the final XOR.
48    pub check: W,
49    /// The contents of the register after initialising, reading an error-free codeword and
50    /// optionally reflecting the register (if [`refout`](Algorithm::refout)=`true`), but not
51    /// applying the final XOR. This is mathematically equivalent to initialising the register with
52    /// the xorout parameter, reflecting it as described (if [`refout`](Algorithm::refout)=`true`),
53    /// reading as many zero bits as there are cells in the register, and reflecting the result (if
54    /// [`refin`](Algorithm::refin)=`true`). The residue of a crossed-endian model is calculated
55    /// assuming that the characters of the received CRC are specially reflected before submitting
56    /// the codeword.
57    pub residue: W,
58}
crc_catalog/lib.rs

crc_catalog/
lib.rs
