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#![no_std]
#![allow(dead_code)]
#[derive(Debug)]
pub enum Error {
BadChar,
BufferTooSmall,
}
pub fn half_byte_to_hex(i: u8) -> u8 {
let h = i & 0xF;
if h < 0xA {
b'0' + h
} else {
b'A' + (h - 0xA)
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn half_byte_to_hex_test() {
assert_eq!(half_byte_to_hex(0xF), b'F');
assert_eq!(half_byte_to_hex(0x0), b'0');
assert_eq!(half_byte_to_hex(0x9), b'9');
assert_eq!(half_byte_to_hex(0xA), b'A');
}
}
pub fn hex_to_half_byte(c: u8) -> Result<u8, Error> {
if c >= b'0' && c <= b'9' {
Ok(c - b'0')
} else if c >= b'A' && c <= b'F' {
Ok(c - b'A' + 0xA)
} else {
Err(Error::BadChar)
}
}
pub fn hex_byte_to_byte(h: u8, l: u8) -> Result<u8, Error> {
Ok(hex_to_half_byte(h)? << 4 | hex_to_half_byte(l)? & 0xF)
}
pub fn bytes_to_hex(i: &[u8], o: &mut [u8]) -> Result<(), Error> {
if i.len() * 2 > o.len() {
return Err(Error::BufferTooSmall);
}
for (i, o) in i.iter().zip(o.chunks_mut(2)) {
o[0] = half_byte_to_hex(i >> 4);
o[1] = half_byte_to_hex(i & 0xF);
}
Ok(())
}
pub fn hex_to_bytes(i: &[u8], o: &mut [u8]) -> Result<(), Error> {
if i.len() / 2 > o.len() {
return Err(Error::BufferTooSmall);
}
for (i, o) in i.chunks(2).zip(o.iter_mut()) {
*o = hex_byte_to_byte(i[0], i[1])?;
}
Ok(())
}