# HG changeset patch
# User Daniel O'Connor <darius@dons.net.au>
# Date 1242192729 -34200
# Node ID e2089824735a4f42bf6325639453f484a7e2f1d9
# Parent  a43a47dfc9025955f57e0f3a41a9c4577d0c170c
Make the read support work properly & check what the device gives us.

- Comment out debugging.
- Stringify result.
- Handle >1 packet reads (theoretically).
- Validate returned packet.

diff -r a43a47dfc902 -r e2089824735a usb488.py
--- a/usb488.py	Wed May 13 14:44:40 2009 +0930
+++ b/usb488.py	Wed May 13 15:02:09 2009 +0930
@@ -167,7 +167,11 @@
 
     def write(self, data):
         """Send data (string) to the scope"""
+
         orddata = map(ord, data)
+        # The device needs a \n at the end, enfore this
+        if orddata[-1] != '\n':
+            orddata += [ord('\n')]
         datalen = len(orddata)
 
         # Build the packet
@@ -190,7 +194,7 @@
             chunk = pkt[0:self.maxPacket]
             pkt = pkt[self.maxPacket:]
 
-            print "Sending %s bytes of data: %s" % (len(chunk), chunk)
+            #print "Sending %s bytes of data: %s" % (len(chunk), chunk)
             wrote = self.handle.bulkWrite(self.bulkoutep, chunk)
             if wrote != len(chunk):
                 raise "Short write, got %d, expected %d" % (wrote, len(chunk))
@@ -198,25 +202,56 @@
     def read(self):
         """Read data from the device"""
 
+        # Maximum we accept at once
+        # Was 2^31 - 1 but that seems to make things take too long to
+        # read (perhaps libusb tries to malloc it..)
+        datalen = 10240
+        data = []
+        
+        while True:
+            # Ask the device to send us something
+            pkt = [ REQUEST_DEV_DEP_MSG_IN, self.tag, ~self.tag & 0xff, 0x00,
+                    datalen & 0xff, datalen >> 8 & 0xff, datalen >> 16 & 0xff,
+                    datalen >> 24 & 0xff, 0, 0, 0, 0]
 
-        datalen = 1024
-        # Ask the device to send us something
-        pkt = [ REQUEST_DEV_DEP_MSG_IN, self.tag, ~self.tag & 0xff, 0x00,
-                datalen & 0xff, datalen >> 8 & 0xff, datalen >> 16 & 0xff,
-                datalen >> 24 & 0xff, 0, 0, 0, 0]
+            # Expected tag
+            exptag = self.tag
+            
+            # Bump tag
+            self.incrtag()
 
-        # Bump tag
-        self.incrtag()
+            # Send it
+            #print "Sending " + str(pkt)
+            wrote = self.handle.bulkWrite(self.bulkoutep, pkt)
+            if wrote != len(pkt):
+                print "Short write, got %d, expected %d" % (wrote, len(pkt))
 
-        # Send it
-        wrote = self.handle.bulkWrite(self.bulkoutep, pkt)
-        if wrote != len(pkt):
-            print "Short write, got %d, expected %d" % (wrote, len(pkt))
+            #print "Reading.."
+            read = self.handle.bulkRead(self.bulkinep, datalen)
+            #print "Read %s bytes: %s" % (len(read), str(read))
+
+            if read[0] != DEV_DEP_MSG_IN:
+                raise "Unexpected Msg ID, got %s expected %d" % (read[0], DEV_DEP_MSG_IN)
+            if read[1] != exptag:
+                raise "Unexpected tag, got %d expected %d" % (read[1], exptag)
+            if read[2] != ~exptag & 0xff:
+                raise "Unexpected tag inverse, got %d expected %d" % (read[1], ~exptag & 0xff)
 
-        read = self.handle.bulkRead(self.bulkinep, datalen)
-        print "Read %s bytes: %s" % (len(read), str(read))
-        return read
-        
+            actualdata = read[4] | read[5] << 8 | read[6] << 16 | read[7] << 24
+            #print "Computed datalen is %d" % (actualdata)
+            data += read[12:12 + actualdata]
+            if read[8] & 0x01:
+                #print "Breaking out due to EOM"
+                break
+
+        # Stringify result for easier consumption
+        result = reduce(lambda x, y: x+y, map(chr, data))
+        # Trim off \n if present
+        if result[-1] == '\n':
+            result = result[0:-1]
+
+        return result
+    
 def find488():
     """Search for a USB488 device, returns a handle, iface, dev tuple for it"""