73 lines
1.9 KiB
Rust
73 lines
1.9 KiB
Rust
pub struct Crc8 {
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table : [u8; 256]
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}
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impl Crc8 {
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pub fn create_msb(polynomial : u8) -> Crc8 {
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let msbit : u8 = 0x80;
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let mut t : u8 = msbit;
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let mut tmp : u8;
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let mut i : u32 = 1;
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let mut idx : u8;
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let mut table : [u8; 256] = [0; 256];
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while i < 256 {
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if t & msbit != 0 { tmp = polynomial; } else { tmp = 0; }
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t = (t << 1) ^ tmp;
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for j in 0..i {
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idx = (i+j) as u8;
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table[(idx) as usize] = table[j as usize] ^ t;
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}
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i *= 2;
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}
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return Crc8{ table : table};
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}
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pub fn create_lsb(polynomial :u8) -> Crc8 {
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let mut i :u32 = 0xff;
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let mut j :u32;
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let mut t :u8 = 1;
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let mut tmp :u8;
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let mut idx :u8;
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let mut table : [u8; 256] = [0; 256];
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while i != 0 {
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if t & 1 != 0 { tmp = polynomial; } else { tmp = 0; }
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t = (t >> 1) ^ tmp;
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j = 0;
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while j < 256 {
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idx = (i+j) as u8;
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table[idx as usize] = table[j as usize] ^ t;
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j += 2 * i;
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}
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i >>= 1;
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}
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return Crc8{ table : table };
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}
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/// Update CRC using previously calculated value and return new one.
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pub fn update(&self, buffer : &[u8], crc: u8) -> u8 {
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let mut crc_tmp = crc;
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for i in 0..buffer.len() {
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crc_tmp = self.table[((crc_tmp ^ buffer[i])) as usize];
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}
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return crc_tmp;
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}
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/// Calculate crc8 with default presets compatible with defaults of mp_binary
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/// package used in kotlin Divan interfaces (msb, polynomial=0xA7, this is
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/// bluetooth presets btw).
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pub fn calc(data: &[u8]) -> u8 {
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let crc = Crc8::create_msb(0xA7);
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crc.update(data, 0)
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}
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}
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#[test]
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fn test_crc8() {
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let a = [1,2,3,4,5];
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assert_eq!(134, Crc8::calc(&a));
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} |