Runka

usbserial/src/main/java/com/felhr/usbserial/FTDISerialDevice.java

@@ -2,12 +2,14 @@ package com.felhr.usbserial;
 
 import java.util.Arrays;
 
+import android.annotation.SuppressLint;
 import android.hardware.usb.UsbConstants;
 import android.hardware.usb.UsbDevice;
 import android.hardware.usb.UsbDeviceConnection;
 import android.hardware.usb.UsbEndpoint;
 import android.hardware.usb.UsbInterface;
 import android.hardware.usb.UsbRequest;
+import android.os.Build;
 import android.util.Log;
 
 import com.felhr.utils.SafeUsbRequest;
@@ -626,6 +628,10 @@ public class FTDISerialDevice extends UsbSerialDevice
             return 0;
         }
 
+        if (mr1Version) {
+            return readSyncJelly(buffer, timeout, stopTime);
+        }
+
         int n = buffer.length / 62;
         if(buffer.length % 62 != 0)
         {
@@ -666,4 +672,40 @@ public class FTDISerialDevice extends UsbSerialDevice
 
         return readen;
     }
+
+    private static final byte[] skip = new byte[2];
+
+    /**
+     * This method avoids creation of garbage by reusing the same
+     * array instance for skipping header bytes and running
+     * {@link UsbDeviceConnection#bulkTransfer(UsbEndpoint, byte[], int, int, int)}
+     * directly.
+     */
+    @SuppressLint("NewApi")
+    private int readSyncJelly(byte[] buffer, int timeout, long stopTime) {
+        int read = 0;
+        do
+        {
+            int timeLeft = 0;
+            if(timeout > 0)
+            {
+                timeLeft = (int) (stopTime - System.currentTimeMillis());
+                if (timeLeft <= 0)
+                {
+                    break;
+                }
+            }
+
+
+            int numberBytes = connection.bulkTransfer(inEndpoint, skip, skip.length, timeLeft);
+
+            if(numberBytes > 2) // Data received
+            {
+                numberBytes = connection.bulkTransfer(inEndpoint, buffer, read, 62, timeLeft);
+                read += numberBytes;
+            }
+        } while(read <= 0);
+
+        return read;
+    }
 }

usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java

@@ -22,7 +22,9 @@ public abstract class UsbSerialDevice implements UsbSerialInterface
 
     protected static final String COM_PORT = "COM ";
 
-    private static final boolean mr1Version;
+    // Android version < 4.3 It is not going to be asynchronous read operations
+    static final boolean mr1Version =
+            android.os.Build.VERSION.SDK_INT > android.os.Build.VERSION_CODES.JELLY_BEAN_MR1;
     protected final UsbDevice device;
     protected final UsbDeviceConnection connection;
 
@@ -47,15 +49,6 @@ public abstract class UsbSerialDevice implements UsbSerialInterface
     private String portName = "";
     protected boolean isOpen;
 
-    // Get Android version if version < 4.3 It is not going to be asynchronous read operations
-    static
-    {
-        if(android.os.Build.VERSION.SDK_INT > android.os.Build.VERSION_CODES.JELLY_BEAN_MR1)
-            mr1Version = true;
-        else
-            mr1Version = false;
-    }
-
     public UsbSerialDevice(UsbDevice device, UsbDeviceConnection connection)
     {
         this.device = device;
@@ -455,14 +448,13 @@ public abstract class UsbSerialDevice implements UsbSerialInterface
 
     protected void setThreadsParams(UsbRequest request, UsbEndpoint endpoint)
     {
+        writeThread.setUsbEndpoint(endpoint);
         if(mr1Version)
         {
             workerThread.setUsbRequest(request);
-            writeThread.setUsbEndpoint(endpoint);
         }else
         {
             readThread.setUsbEndpoint(request.getEndpoint());
-            writeThread.setUsbEndpoint(endpoint);
         }
     }