Add 'plugins/USBPrinting/' from commit 'b28ca0881a'

git-subtree-dir: plugins/USBPrinting
git-subtree-mainline: 3823afd8cc
git-subtree-split: b28ca0881a

plugins/USBPrinting/avr_isp/intelHex.py

@@ -0,0 +1,46 @@
+"""
+Module to read intel hex files into binary data blobs.
+IntelHex files are commonly used to distribute firmware
+See: http://en.wikipedia.org/wiki/Intel_HEX
+This is a python 3 conversion of the code created by David Braam for the Cura project.
+"""
+import io
+
+def readHex(filename):
+    """
+    Read an verify an intel hex file. Return the data as an list of bytes.
+    """
+    data = []
+    extraAddr = 0
+    f = io.open(filename, "r")
+    for line in f:
+        line = line.strip()
+        if len(line) < 1:
+            continue
+        if line[0] != ':':
+            raise Exception("Hex file has a line not starting with ':'")
+        recLen = int(line[1:3], 16)
+        addr = int(line[3:7], 16) + extraAddr
+        recType = int(line[7:9], 16)
+        if len(line) != recLen * 2 + 11:
+            raise Exception("Error in hex file: " + line)
+        checkSum = 0
+        for i in range(0, recLen + 5):
+            checkSum += int(line[i*2+1:i*2+3], 16)
+        checkSum &= 0xFF
+        if checkSum != 0:
+            raise Exception("Checksum error in hex file: " + line)
+        
+        if recType == 0:#Data record
+            while len(data) < addr + recLen:
+                data.append(0)
+            for i in range(0, recLen):
+                data[addr + i] = int(line[i*2+9:i*2+11], 16)
+        elif recType == 1:	#End Of File record
+            pass
+        elif recType == 2:	#Extended Segment Address Record
+            extraAddr = int(line[9:13], 16) * 16
+        else:
+            print(recType, recLen, addr, checkSum, line)
+    f.close()
+    return data