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#[derive(Debug)]
pub enum Error {
NeedMoreData,
InvalidVarInt,
}
impl core::fmt::Display for Error {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
match self {
Error::NeedMoreData => f.write_str("NeedMoreData"),
Error::InvalidVarInt => f.write_str("InvalidVarInt"),
}
}
}
impl core::error::Error for Error {}
pub fn encode(mut v: u32) -> ([u8; 4], usize) {
let mut encoded = [0u8; 4];
let mut count = 0;
loop {
let mut byte = (v % 128) as u8;
v /= 128;
if v > 0 {
byte |= 0x80; // Set continuation bit
}
encoded[count] = byte;
count += 1;
if v == 0 {
break;
}
}
(encoded, count)
}
pub fn decode(buf: &[u8]) -> Result<(u32, usize), Error> {
let mut value = 0u32;
let v = buf.first().ok_or(Error::NeedMoreData)?;
value |= (v & 0x7F) as u32;
if v & 0x80 == 0 {
return Ok((value, 1));
}
let v = buf.get(1).ok_or(Error::NeedMoreData)?;
value |= ((v & 0x7F) as u32) << 7;
if v & 0x80 == 0 {
return Ok((value, 2));
}
let v = buf.get(2).ok_or(Error::NeedMoreData)?;
value |= ((v & 0x7F) as u32) << 14;
if v & 0x80 == 0 {
return Ok((value, 3));
}
let v = buf.get(3).ok_or(Error::NeedMoreData)?;
value |= ((v & 0x7F) as u32) << 21;
if v & 0x80 != 0 {
return Err(Error::InvalidVarInt);
}
Ok((value, 4))
}
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