From: Thomas Karpiniec <tom.karpiniec@outlook.com>
Date: Fri, 17 Jan 2025 10:24:39 +0000 (+1100)
Subject: Fix packet encoding
X-Git-Url: https://code.octet-stream.net/m17rt/commitdiff_plain/2798b7a8f62b73aa2a88d4b34e861debd6462015?ds=sidebyside

Fix packet encoding
---

diff --git a/m17core/src/decode.rs b/m17core/src/decode.rs
index 115ff63..6c8e02b 100755
--- a/m17core/src/decode.rs
+++ b/m17core/src/decode.rs
@@ -144,8 +144,8 @@ pub(crate) fn parse_packet(frame: &[f32] /* length 192 */) -> Option<PacketFrame
     };
     // TODO: the spec is inconsistent about which bit in packet[25] is EOF
     // https://github.com/M17-Project/M17_spec/issues/147
-    let final_frame = (packet[25] & 0x04) > 0;
-    let number = packet[25] >> 3;
+    let final_frame = (packet[25] & 0x80) > 0;
+    let number = (packet[25] >> 2) & 0x1f;
     let counter = if final_frame {
         PacketFrameCounter::FinalFrame {
             payload_len: number as usize,
diff --git a/m17core/src/encode.rs b/m17core/src/encode.rs
index 4fc7429..5e0951e 100644
--- a/m17core/src/encode.rs
+++ b/m17core/src/encode.rs
@@ -31,11 +31,11 @@ pub(crate) fn encode_packet(frame: &PacketFrame) -> [f32; 192] {
     match frame.counter {
         PacketFrameCounter::Frame { index } => {
             type1[0..25].copy_from_slice(&frame.payload);
-            type1[25] = (index as u8) << 3;
+            type1[25] = (index as u8) << 2;
         }
         PacketFrameCounter::FinalFrame { payload_len } => {
             type1[0..payload_len].copy_from_slice(&frame.payload[0..payload_len]);
-            type1[25] = ((payload_len as u8) << 3) | 0x04;
+            type1[25] = ((payload_len as u8) << 2) | 0x80;
         }
     }
     let type3 = fec::encode(&type1, 206, p_3);