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lrwn: Implement applayer v1 fragmentation encoding func.

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This commit is contained in:
Orne Brocaar 2025-01-10 10:41:14 +00:00
parent 87c498544d
commit 08c3ef00f9
1 changed files with 151 additions and 0 deletions
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151
lrwn/src/applayer/fragmentation/v1.rs
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@ -487,6 +487,65 @@ pub struct DataFragmentPayloadIndexAndN {
pub frag_index: u8,
}
// Encode the given slice of bytes to fragments including forward error correction.
// This is based on the proposed FEC code from the Fragmented Data Block Transport over
// LoRaWAN recommendation.
pub fn encode(payload: &[u8], fragment_size: usize, redundancy: usize) -> Result<Vec<Vec<u8>>> {
if payload.len() % fragment_size != 0 {
return Err(anyhow!("Payload size must be a multiple of fragment_size"));
}
// fragment the data into rows
let mut data_rows: Vec<Vec<u8>> = payload.chunks(fragment_size).map(|v| v.to_vec()).collect();
let w = data_rows.len();
for y in 0..redundancy {
let mut s = vec![0; fragment_size];
let a = matrix_line(y + 1, w);
for x in 0..w {
if a[x] == 1 {
for (m, s_val) in s.iter_mut().enumerate() {
*s_val ^= data_rows[x][m];
}
}
}
data_rows.push(s);
}
Ok(data_rows)
}
fn prbs23(x: usize) -> usize {
let b0 = x & 1;
let b1 = (x & 32) / 32;
(x / 2) + (b0 ^ b1) * (1 << 22)
}
fn is_power_2(num: usize) -> bool {
num != 0 && (num & (num - 1)) == 0
}
fn matrix_line(n: usize, m: usize) -> Vec<usize> {
let mut line = vec![0; m];
let mm = if is_power_2(m) { 1 } else { 0 };
let mut x = 1 + (1001 * n);
for _nb_coeff in 0..(m / 2) {
let mut r = 1 << 16;
while r >= m {
x = prbs23(x);
r = x % (m + mm);
}
line[r] = 1;
}
line
}
#[cfg(test)]
mod test {
use super::*;
@ -759,6 +818,98 @@ mod test {
run_tests_decode(&decode_tests);
}
#[test]
fn test_encode() {
struct EncodeTest {
name: String,
data: Vec<u8>,
fragment_size: usize,
redundancy: usize,
expected_fragments: Vec<Vec<u8>>,
expected_error: Option<String>,
}
let mut data = vec![0; 100];
for (i, v) in data.iter_mut().enumerate() {
*v = i as u8;
}
let tests = [
EncodeTest {
name: "invalid fragment size".into(),
data: vec![0; 5],
fragment_size: 10,
redundancy: 0,
expected_fragments: vec![],
expected_error: Some("Payload size must be a multiple of fragment_size".into()),
},
EncodeTest {
name: "fragment size 10, redundancy 10".into(),
data: data.clone(),
fragment_size: 10,
redundancy: 10,
expected_fragments: vec![
vec![0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9],
vec![0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10, 0x11, 0x12, 0x13],
vec![0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d],
vec![0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27],
vec![0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31],
vec![0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b],
vec![0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45],
vec![0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f],
vec![0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59],
vec![0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63],
vec![0x26, 0x26, 0x22, 0x22, 0x2e, 0x2e, 0x22, 0x22, 0x26, 0x26],
vec![0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x6a, 0x6b, 0x7c, 0x7d],
vec![0x5c, 0x5d, 0x6e, 0x6f, 0x10, 0x11, 0x2, 0x3, 0x4, 0x5],
vec![0x36, 0x36, 0x32, 0x32, 0x3e, 0x3e, 0x22, 0x22, 0x36, 0x36],
vec![0x3a, 0x3a, 0xe, 0xe, 0xa, 0xa, 0x6, 0x6, 0xa, 0xa],
vec![0xe, 0xe, 0x32, 0x32, 0x36, 0x36, 0x22, 0x22, 0x3e, 0x3e],
vec![0x2, 0x2, 0xe, 0xe, 0x72, 0x72, 0x76, 0x76, 0x62, 0x62],
vec![0x1e, 0x1e, 0x1a, 0x1a, 0x66, 0x66, 0x5a, 0x5a, 0x4e, 0x4e],
vec![0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x30, 0x31, 0x22, 0x23],
vec![0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x18, 0x19, 0xa, 0xb],
],
expected_error: None,
},
EncodeTest {
name: "fragment size 10, redundancy 5".into(),
data: data.clone(),
fragment_size: 10,
redundancy: 5,
expected_fragments: vec![
vec![0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9],
vec![0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10, 0x11, 0x12, 0x13],
vec![0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d],
vec![0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27],
vec![0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31],
vec![0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b],
vec![0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45],
vec![0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f],
vec![0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59],
vec![0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63],
vec![0x26, 0x26, 0x22, 0x22, 0x2e, 0x2e, 0x22, 0x22, 0x26, 0x26],
vec![0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x6a, 0x6b, 0x7c, 0x7d],
vec![0x5c, 0x5d, 0x6e, 0x6f, 0x10, 0x11, 0x2, 0x3, 0x4, 0x5],
vec![0x36, 0x36, 0x32, 0x32, 0x3e, 0x3e, 0x22, 0x22, 0x36, 0x36],
vec![0x3a, 0x3a, 0xe, 0xe, 0xa, 0xa, 0x6, 0x6, 0xa, 0xa],
],
expected_error: None,
},
];
for tst in &tests {
println!("> {}", tst.name);
let res = encode(&tst.data, tst.fragment_size, tst.redundancy);
if let Some(e) = &tst.expected_error {
assert_eq!(e, &res.err().unwrap().to_string());
} else {
assert_eq!(tst.expected_fragments, res.unwrap());
}
}
}
fn run_tests_encode(tests: &[CommandTest]) {
for tst in tests {
println!("> {}", tst.name);