ccsds length field calculation

This commit is contained in:
Robin Müller 2022-06-17 01:45:08 +02:00
parent e417384863
commit 6598d3458f
No known key found for this signature in database
GPG Key ID: 71B58F8A3CDFA9AC
2 changed files with 65 additions and 16 deletions

View File

@ -10,6 +10,8 @@ pub enum PacketError {
ToBytesSliceTooSmall(usize),
/// The [zerocopy] library failed to write to bytes
ToBytesZeroCopyError,
/// CRC16 needs to be calculated first
CrcCalculationMissing,
}
#[derive(Serialize, Deserialize, Debug, PartialEq, Copy, Clone)]
@ -375,17 +377,9 @@ pub mod zc {
((self.version_packet_id.get() >> 13) as u8) & 0b111
}
fn packet_id_raw(&self) -> u16 {
self.version_packet_id.get() & (!VERSION_MASK)
}
fn packet_id(&self) -> PacketId {
PacketId::from(self.packet_id_raw())
}
fn psc_raw(&self) -> u16 {
self.psc.get()
}
fn psc(&self) -> PacketSequenceCtrl {
PacketSequenceCtrl::from(self.psc_raw())
}
@ -394,6 +388,14 @@ pub mod zc {
fn data_len(&self) -> u16 {
self.data_len.get()
}
fn packet_id_raw(&self) -> u16 {
self.version_packet_id.get() & (!VERSION_MASK)
}
fn psc_raw(&self) -> u16 {
self.psc.get()
}
}
impl CcsdsPrimaryHeader for SpHeader {

View File

@ -1,7 +1,10 @@
use std::mem::size_of;
type CrcType = u16;
/// PUS C secondary header length is fixed
pub const PUC_TC_SECONDARY_HEADER_LEN: usize = size_of::<zc::PusTcDataFieldHeader>();
pub const PUS_TC_MIN_LEN_WITHOUT_APP_DATA: usize =
size_of::<crate::zc::SpHeader>() + size_of::<zc::PusTcDataFieldHeader>();
size_of::<crate::zc::SpHeader>() + PUC_TC_SECONDARY_HEADER_LEN + size_of::<CrcType>();
pub mod zc {
use crate::ecss::{PusError, PusVersion};
@ -95,10 +98,47 @@ pub mod srd {
}
}
pub fn len(&self) -> usize {
let mut length = super::PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
if let Some(app_data) = self.app_data {
length += app_data.len();
}
length
}
/// Calculate the CCSDS space packet data length field and sets it
pub fn set_ccsds_data_len(&mut self) {
self.sph.data_len = self.len() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
}
pub fn calc_crc16(&mut self) {
let mut digest = CRC_CCITT_FALSE.digest();
let sph_zc = crate::zc::SpHeader::from(self.sph);
digest.update(sph_zc.as_bytes());
let pus_tc_header =
super::zc::PusTcDataFieldHeader::try_from(self.data_field_header).unwrap();
digest.update(pus_tc_header.as_bytes());
if let Some(app_data) = self.app_data {
digest.update(app_data);
}
self.crc16 = Some(digest.finalize())
}
/// This function updates two important internal fields: The CCSDS packet length in the
/// space packet header and the CRC16 field. This function should be called before
/// the TC packet is serialized
pub fn update_packet_fields(&mut self) {
self.set_ccsds_data_len();
self.calc_crc16();
}
pub fn copy_to_buf(
&mut self,
&self,
slice: &mut (impl AsMut<[u8]> + ?Sized),
) -> Result<usize, PacketError> {
if self.crc16.is_none() {
return Err(PacketError::CrcCalculationMissing);
}
let mut_slice = slice.as_mut();
let mut curr_idx = 0;
let sph_zc = crate::zc::SpHeader::from(self.sph);
@ -126,10 +166,16 @@ pub mod srd {
mut_slice[curr_idx..curr_idx + app_data.len()].copy_from_slice(app_data);
curr_idx += app_data.len();
}
mut_slice[curr_idx..curr_idx + 2]
.copy_from_slice(self.crc16.unwrap().to_ne_bytes().as_slice());
curr_idx += 2;
Ok(curr_idx)
}
pub fn append_to_vec(&mut self, vec: &mut Vec<u8>) -> Result<usize, PacketError> {
pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PacketError> {
if self.crc16.is_none() {
return Err(PacketError::CrcCalculationMissing);
}
let sph_zc = crate::zc::SpHeader::from(self.sph);
let mut appended_len = super::PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
if let Some(app_data) = self.app_data {
@ -143,6 +189,7 @@ pub mod srd {
if let Some(app_data) = self.app_data {
vec.extend_from_slice(app_data);
}
vec.extend_from_slice(self.crc16.unwrap().to_ne_bytes().as_slice());
Ok(appended_len)
}
}
@ -213,19 +260,19 @@ mod tests {
fn test_tc() {
let mut sph = SpHeader::tc(0x42, 12).unwrap();
let mut pus_tc = PusTc::new(&mut sph, 1, 1, None);
let out = to_stdvec(&pus_tc).unwrap();
println!("Vector {:#04x?} with length {}", out, out.len());
let _out = to_stdvec(&pus_tc).unwrap();
let mut test_buf = [0; 32];
pus_tc.update_packet_fields();
assert_eq!(pus_tc.len(), 13);
let size = pus_tc
.copy_to_buf(test_buf.as_mut_slice())
.expect("Error writing TC to buffer");
println!("Test buffer: {:?} with {size} written bytes", test_buf);
println!("Test buffer: {:02x?} with {size} written bytes", test_buf);
let mut test_vec = Vec::new();
let size = pus_tc
.append_to_vec(&mut test_vec)
.expect("Error writing TC to vector");
println!("Test Vector: {:?} with {size} written bytes", test_vec);
println!("Test Vector: {:02x?} with {size} written bytes", test_vec);
}
}