| #[cfg(feature = "std")] |
| use std::hash::Hasher; |
| #[cfg(not(feature = "std"))] |
| use core::hash::Hasher; |
| |
| pub use util::make_table_crc16 as make_table; |
| |
| include!(concat!(env!("OUT_DIR"), "/crc16_constants.rs")); |
| |
| pub struct Digest { |
| table: [u16; 256], |
| initial: u16, |
| value: u16 |
| } |
| |
| pub trait Hasher16 { |
| fn reset(&mut self); |
| fn write(&mut self, bytes: &[u8]); |
| fn sum16(&self) -> u16; |
| } |
| |
| pub fn update(mut value: u16, table: &[u16; 256], bytes: &[u8]) -> u16 { |
| value = !value; |
| for &i in bytes.iter() { |
| value = table[((value as u8) ^ i) as usize] ^ (value >> 8) |
| } |
| !value |
| } |
| |
| pub fn checksum_x25(bytes: &[u8]) -> u16 { |
| return update(0, &X25_TABLE, bytes); |
| } |
| |
| pub fn checksum_usb(bytes: &[u8]) -> u16 { |
| return update(0, &USB_TABLE, bytes); |
| } |
| |
| impl Digest { |
| pub fn new(poly: u16) -> Digest { |
| Digest { |
| table: make_table(poly), |
| initial: 0, |
| value: 0 |
| } |
| } |
| |
| pub fn new_with_initial(poly: u16, initial: u16) -> Digest { |
| Digest { |
| table: make_table(poly), |
| initial: initial, |
| value: initial |
| } |
| } |
| } |
| |
| impl Hasher16 for Digest { |
| fn reset(&mut self) { |
| self.value = self.initial; |
| } |
| fn write(&mut self, bytes: &[u8]) { |
| self.value = update(self.value, &self.table, bytes); |
| } |
| fn sum16(&self) -> u16 { |
| self.value |
| } |
| } |
| |
| /// Implementation of std::hash::Hasher so that types which #[derive(Hash)] can hash with Digest. |
| impl Hasher for Digest { |
| fn write(&mut self, bytes: &[u8]) { |
| Hasher16::write(self, bytes); |
| } |
| |
| fn finish(&self) -> u64 { |
| self.sum16() as u64 |
| } |
| } |