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use crate::{
navigation::{Ephemeris, NavKey},
prelude::{Constellation, Rinex},
};
use std::io::{Error, ErrorKind};
pub struct Streamer<'a> {
/// Pending bytes
pending_size: usize,
/// Pending frame
buffer: [u8; 1024],
/// Iterator
ephemeris_iter: Box<dyn Iterator<Item = (&'a NavKey, &'a Ephemeris)> + 'a>,
}
impl<'a> Streamer<'a> {
pub fn new(rinex: &'a Rinex) -> Self {
Self {
pending_size: 0,
buffer: [0; 1024],
ephemeris_iter: rinex.nav_ephemeris_frames_iter(),
}
}
}
impl<'a> std::io::Read for Streamer<'a> {
fn read(&mut self, buffer: &mut [u8]) -> std::io::Result<usize> {
let mut size = 0;
let mut size_avail = buffer.len();
if self.pending_size > 0 {
if size_avail < self.pending_size {
return Err(Error::new(ErrorKind::StorageFull, "would not fit"));
} else {
size += self.pending_size;
size_avail -= self.pending_size;
buffer[..self.pending_size].copy_from_slice(&self.buffer[..self.pending_size]);
self.pending_size = 0;
}
}
loop {
match self.ephemeris_iter.next() {
Some((key, ephemeris)) => match key.sv.constellation {
Constellation::GPS => {
if let Some(bytes) = ephemeris.to_ubx_mga_gps_qzss(key.epoch, key.sv) {
let new_len = bytes.len();
if size_avail > new_len {
buffer[size..size + new_len].copy_from_slice(&bytes);
size += new_len;
size_avail -= new_len;
} else {
self.pending_size = new_len;
self.buffer[..new_len].copy_from_slice(&bytes);
return Ok(size);
}
}
},
Constellation::QZSS => {
if let Some(bytes) = ephemeris.to_ubx_mga_gps_qzss(key.epoch, key.sv) {
let new_len = bytes.len();
if size_avail > new_len {
buffer[size..size + new_len].copy_from_slice(&bytes);
size += new_len;
size_avail -= new_len;
} else {
self.pending_size = new_len;
self.buffer[..new_len].copy_from_slice(&bytes);
return Ok(size);
}
}
},
Constellation::BeiDou => {
if let Some(bytes) = ephemeris.to_ubx_mga_bds(key.epoch, key.sv) {
let new_len = bytes.len();
if size_avail > new_len {
buffer[size..size + new_len].copy_from_slice(&bytes);
size += new_len;
size_avail -= new_len;
} else {
self.pending_size = new_len;
self.buffer[..new_len].copy_from_slice(&bytes);
return Ok(size);
}
}
},
Constellation::Glonass => {
if let Some(bytes) = ephemeris.to_ubx_mga_glo(key.sv) {
let new_len = bytes.len();
if size_avail > new_len {
buffer[size..size + new_len].copy_from_slice(&bytes);
size += new_len;
size_avail -= new_len;
} else {
self.pending_size = new_len;
self.buffer[..new_len].copy_from_slice(&bytes);
return Ok(size);
}
}
},
_ => {
// frame not supported
},
},
None => {
return Ok(size);
},
}
}
}
}