From dc24ce4cf9f9d79220929f5bb665eba11b2db214 Mon Sep 17 00:00:00 2001
From: Willem Melching <willem.melching@gmail.com>
Date: Tue, 19 Mar 2024 12:51:12 +0100
Subject: [PATCH] [ISO-TP] wait for flow control every block_size frames (#42)

---
 src/isotp/mod.rs     | 18 +++++++++++++-----
 tests/isotp_tests.rs | 19 +++++++++++--------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/isotp/mod.rs b/src/isotp/mod.rs
index 57ceaf0..e63901b 100644
--- a/src/isotp/mod.rs
+++ b/src/isotp/mod.rs
@@ -184,7 +184,7 @@ impl<'a> IsoTPAdapter<'a> {
 
         self.send_first_frame(data).await;
         let frame = stream.next().await.unwrap()?;
-        let fc_config = self.receive_flow_control(&frame)?;
+        let mut fc_config = self.receive_flow_control(&frame)?;
 
         debug!("RX FC, data {}", hex::encode(&frame.data));
 
@@ -199,11 +199,19 @@ impl<'a> IsoTPAdapter<'a> {
         while let Some((idx, chunk)) = it.next() {
             self.send_consecutive_frame(chunk, idx).await;
 
-            // Sleep for separation time between frames
-            let last = it.peek().is_none();
-            if !last {
-                tokio::time::sleep(st_min).await;
+            // Wait for flow control every `block_size` frames, except for the first frame
+            if fc_config.block_size != 0 && idx > 0 && idx % fc_config.block_size as usize == 0 {
+                // Wait for next flow control
+                let frame = stream.next().await.unwrap()?;
+                fc_config = self.receive_flow_control(&frame)?;
+            } else {
+                // Sleep for separation time between frames
+                let last = it.peek().is_none();
+                if !last {
+                    tokio::time::sleep(st_min).await;
+                }
             }
+
         }
 
         Ok(())
diff --git a/tests/isotp_tests.rs b/tests/isotp_tests.rs
index 61612b5..f2e7b7f 100644
--- a/tests/isotp_tests.rs
+++ b/tests/isotp_tests.rs
@@ -118,12 +118,15 @@ async fn isotp_test_stmin() {
 #[tokio::test]
 #[serial_test::serial]
 async fn isotp_test_bs() {
-    let config = VECUConfig {
-        bs: 4,
-        ..Default::default()
-    };
-
-    // TODO: can we ensure that we actually wait for the
-    // flow control between blocks?
-    isotp_test_echo(64, config).await;
+    for bs in 1..=8 {
+        let config = VECUConfig {
+            bs,
+            ..Default::default()
+        };
+        isotp_test_echo(64, config).await;
+
+        // TODO: can we ensure that we actually wait for the
+        // flow control between blocks?
+        isotp_test_echo(64, config).await;
+    }
 }