dfu-util Code

--- a/dfuse-pack.py
+++ b/dfuse-pack.py
@@ -14,8 +14,8 @@
 def consume(fmt,data,names):
   n = struct.calcsize(fmt)
   return named(struct.unpack(fmt,data[:n]),names),data[n:]
-def cstring(string):
-  return string.split('\0',1)[0]
+def cstring(bytestring):
+  return bytestring.partition(b'\0')[0]
 def compute_crc(data):
   return 0xFFFFFFFF & -zlib.crc32(data) -1
 
@@ -56,16 +56,16 @@
     print("PARSE ERROR")
 
 def build(file,targets,device=DEFAULT_DEVICE):
-  data = ''
+  data = b''
   for t,target in enumerate(targets):
-    tdata = ''
+    tdata = b''
     for image in target:
       tdata += struct.pack('<2I',image['address'],len(image['data']))+image['data']
-    tdata = struct.pack('<6sBI255s2I','Target',0,1,'ST...',len(tdata),len(target)) + tdata
+    tdata = struct.pack('<6sBI255s2I',b'Target',0,1,b'ST...',len(tdata),len(target)) + tdata
     data += tdata
-  data  = struct.pack('<5sBIB','DfuSe',1,len(data)+11,len(targets)) + data
+  data  = struct.pack('<5sBIB',b'DfuSe',1,len(data)+11,len(targets)) + data
   v,d=[int(x,0) & 0xFFFF for x in device.split(':',1)]
-  data += struct.pack('<4H3sB',0,d,v,0x011a,'UFD',16)
+  data += struct.pack('<4H3sB',0,d,v,0x011a,b'UFD',16)
   crc   = compute_crc(data)
   data += struct.pack('<I',crc)
   open(file,'wb').write(data)