2021-02-12 01:07:32 +00:00
|
|
|
// Copyright (C) 2020 Matthew Waters <matthew@centricular.com>
|
|
|
|
//
|
2022-01-15 18:40:12 +00:00
|
|
|
// This Source Code Form is subject to the terms of the Mozilla Public License, v2.0.
|
|
|
|
// If a copy of the MPL was not distributed with this file, You can obtain one at
|
|
|
|
// <https://mozilla.org/MPL/2.0/>.
|
2021-02-12 01:07:32 +00:00
|
|
|
//
|
2022-01-15 18:40:12 +00:00
|
|
|
// SPDX-License-Identifier: MPL-2.0
|
2021-02-12 01:07:32 +00:00
|
|
|
|
|
|
|
use byteorder::{BigEndian, ByteOrder};
|
|
|
|
use std::fmt;
|
|
|
|
|
|
|
|
#[allow(clippy::enum_variant_names)]
|
|
|
|
#[derive(Debug, Clone, Copy)]
|
|
|
|
pub enum ParseErrorCode {
|
|
|
|
WrongLength,
|
|
|
|
WrongMagicSequence,
|
|
|
|
WrongLayout,
|
|
|
|
}
|
|
|
|
|
|
|
|
#[derive(Debug, Clone)]
|
|
|
|
pub struct ParseError {
|
|
|
|
pub code: ParseErrorCode,
|
|
|
|
pub byte: usize,
|
|
|
|
pub msg: String,
|
|
|
|
}
|
|
|
|
|
|
|
|
pub fn extract_cdp(mut data: &[u8]) -> Result<&[u8], ParseError> {
|
|
|
|
/* logic from ccconverter */
|
|
|
|
let data_len = data.len();
|
|
|
|
|
|
|
|
if data.len() < 11 {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongLength,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: format!(
|
|
|
|
"cdp packet too short {}. expected at least {}",
|
|
|
|
data.len(),
|
|
|
|
11
|
|
|
|
),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
|
|
|
|
if 0x9669 != BigEndian::read_u16(&data[..2]) {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongMagicSequence,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: String::from("cdp packet does not have initial magic bytes of 0x9669"),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
data = &data[2..];
|
|
|
|
|
|
|
|
if (data[0] as usize) != data_len {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongLength,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: format!(
|
|
|
|
"advertised cdp packet length {} does not match length of data {}",
|
|
|
|
data[0], data_len
|
|
|
|
),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
data = &data[1..];
|
|
|
|
|
|
|
|
/* skip framerate value */
|
|
|
|
data = &data[1..];
|
|
|
|
|
|
|
|
let flags = data[0];
|
|
|
|
data = &data[1..];
|
|
|
|
|
|
|
|
if flags & 0x40 == 0 {
|
|
|
|
/* no cc_data */
|
|
|
|
return Ok(&[]);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* skip sequence counter */
|
|
|
|
data = &data[2..];
|
|
|
|
|
|
|
|
/* timecode present? */
|
|
|
|
if flags & 0x80 == 0x80 {
|
|
|
|
if data.len() < 5 {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongLength,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: String::from(
|
|
|
|
"cdp packet signals a timecode but is not large enough to contain a timecode",
|
|
|
|
),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
data = &data[5..];
|
|
|
|
}
|
|
|
|
|
|
|
|
/* cc_data */
|
|
|
|
if data.len() < 2 {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongLength,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: String::from(
|
|
|
|
"cdp packet signals cc_data but is not large enough to contain cc_data",
|
|
|
|
),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
|
|
|
|
if data[0] != 0x72 {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongMagicSequence,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: String::from("ccp is missing start code 0x72"),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
data = &data[1..];
|
|
|
|
|
|
|
|
let cc_count = data[0];
|
|
|
|
data = &data[1..];
|
|
|
|
if cc_count & 0xe0 != 0xe0 {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongMagicSequence,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: format!("reserved bits are not 0xe0, found {:02x}", cc_count & 0xe0),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
let cc_count = cc_count & 0x1f;
|
|
|
|
let len = 3 * cc_count as usize;
|
|
|
|
|
|
|
|
if len > data.len() {
|
|
|
|
return Err(ParseError {
|
|
|
|
code: ParseErrorCode::WrongLength,
|
|
|
|
byte: data_len - data.len(),
|
|
|
|
msg: String::from("cc_data length extends past the end of the cdp packet"),
|
|
|
|
});
|
|
|
|
}
|
|
|
|
|
|
|
|
/* TODO: validate checksum */
|
|
|
|
|
|
|
|
Ok(&data[..len])
|
|
|
|
}
|
|
|
|
|
|
|
|
impl fmt::Display for ParseError {
|
|
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
|
|
write!(f, "{:?} at byte {}: {}", self.code, self.byte, self.msg)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
impl std::error::Error for ParseError {}
|