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fix hdlc ops

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This commit is contained in:
Will Greenberg
2023-12-07 18:49:39 -08:00
parent 76555fe68c
commit 10bafc3faa
1 changed files with 19 additions and 13 deletions
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32
src/hdlc.rs
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@@ -23,16 +23,23 @@ pub enum HdlcError {
pub fn hdlc_encapsulate(data: &[u8], crc: &Crc<u16>) -> Vec<u8> {
let mut result: Vec<u8> = vec![];
result.put_u16_le(crc.checksum(&data));
let escaped = data.iter()
.flat_map(|&b| match b {
// TODO: is this too expensive?
0x7e => vec![0x7d, 0x5e],
0x7d => vec![0x7d, 0x5d],
_ => vec![b],
});
result.extend(escaped);
for &b in data {
match b {
0x7e => result.extend([0x7d, 0x5e]),
0x7d => result.extend([0x7d, 0x5d]),
_ => result.push(b),
}
}
for b in crc.checksum(&data).to_le_bytes() {
match b {
0x7e => result.extend([0x7d, 0x5e]),
0x7d => result.extend([0x7d, 0x5d]),
_ => result.push(b),
}
}
result.push(0x7e);
result
}
@@ -43,14 +50,13 @@ pub fn hdlc_decapsulate(data: &[u8], crc: &Crc<u16>) -> Result<Vec<u8>, HdlcErro
return Err(HdlcError::TooShort);
}
let last_char = data[data.len() - 1]; // safe since len() >= 3
if last_char != 0x7e {
return Err(HdlcError::NoTrailingCharacter(last_char));
if data[data.len() - 1] != 0x7e {
return Err(HdlcError::NoTrailingCharacter(data[data.len() - 1]));
}
let mut unescaped = Vec::new();
let mut escaping = false;
for &b in data {
for &b in &data[..data.len() - 1] {
if escaping {
match b {
0x5e => unescaped.push(0x7e),