Populate initial packet length in ISOCH OUT URB

daynix#66 According to interface definition, the UsbDk shall return actual length on transfer completion. For isoch OUT transfers the controller does not return it on respective URB field on Win10 and the updated WDK documentation states this field is not used for ISOCH OUT transfers. Current commit populates the initial packet length in the URB, making the result consistent on both Win7 and Win10. Signed-off-by: Yuri Benditovich <[email protected]>
MaiSawAung · Jan 29, 2019 · 46c80ba · 46c80ba
1 parent 9ebf772
commit 46c80ba
Showing 1 changed file with 11 additions and 0 deletions.
diff --git a/UsbDk/Urb.cpp b/UsbDk/Urb.cpp
@@ -71,5 +71,16 @@ NTSTATUS CIsochronousUrb::Create(Direction TransferDirection, PVOID TransferBuff
 
     m_Urb->UrbIsochronousTransfer.TransferBuffer = TransferBuffer;
     m_Urb->UrbIsochronousTransfer.NumberOfPackets = static_cast<ULONG>(NumberOfPackets);
+
+    if (TransferDirection == URB_DIRECTION_OUT)
+    {
+        // initialize Length with initial packet length
+        // USB controller driver may override it (Win7)
+        for (size_t i = 0; i < NumberOfPackets; i++)
+        {
+            m_Urb->UrbIsochronousTransfer.IsoPacket[i].Length = static_cast<ULONG>(PacketSizes[i]);
+        }
+    }
+
     return FillOffsetsArray(NumberOfPackets, PacketSizes, TransferBufferSize);
 }