genmidi: Update to support Python 3 build.

Tweak the code used to build the GENMIDI Lump so that it properly
supports Python 3 for build. Tested use cases were:
 * Normal build
 * a2i-to-sbi script to convert AdTrack2 instruments to SBI format
 * dumpgenmidi script to dump the instruments from a GENMIDI lump.
 * Running genmidi.py, sbi_file.py, a2i_file.py standalone to print the
   contents of files in their respective formats.

lumps/genmidi/a2i_file.py

@@ -215,17 +215,19 @@ def decode_type_9(data):
 	# Decode instrument name
 
 	ps = decompressed_data[14:]
-	instr_data["name"], = struct.unpack("%ip" % len(ps), ps)
+	instr_name, = struct.unpack("%ip" % len(ps), ps)
+	instr_data["name"] = instr_name.decode("ascii")
 
 	return instr_data
 
 def read(filename):
-	f = open(filename)
-	data = f.read()
-	f.close()
+	with open(filename, "rb") as f:
+		data = f.read()
 
 	hdrstr, crc, filever = struct.unpack("<7sHB", data[0:10])
 
+	hdrstr = hdrstr.decode("ascii")
+
 	if hdrstr.lower() != HEADER_STRING.lower():
 		raise Exception("Wrong file header ID string")
 

lumps/genmidi/dumpgenmidi

@@ -68,7 +68,7 @@ def instr_to_str_def(filename, filename2, instr):
 	return "Instrument(%s)" % (", ".join(args))
 
 def print_instr_def(filename, filename2, instr):
-	print "\t%s," % instr_to_str_def(filename, filename2, instr)
+	print("\t%s," % instr_to_str_def(filename, filename2, instr))
 
 def dump_instrument(filename, filename2, instr):
 
@@ -82,7 +82,7 @@ def dump_instrument(filename, filename2, instr):
 		               instr.voice2)
 
 if len(sys.argv) != 2:
-	print >> sys.stderr, "Usage: %s <filename>" % sys.argv[0]
+	sys.stderr.write("Usage: %s <filename>\n" % sys.argv[0])
 	sys.exit(-1)
 
 instruments = genmidi.read(sys.argv[1])
@@ -90,7 +90,7 @@ instruments = genmidi.read(sys.argv[1])
 main_instrs = instruments[0:128]
 percussion = instruments[128:]
 
-print "INSTRUMENTS = ["
+print("INSTRUMENTS = [")
 
 for i in range(len(main_instrs)):
 	instr = main_instrs[i]
@@ -99,9 +99,9 @@ for i in range(len(main_instrs)):
 	dump_instrument(filename, filename2, instr)
 	print_instr_def(filename, filename2, instr)
 
-print "]"
-print
-print "PERCUSSION = ["
+print("]")
+print("")
+print("PERCUSSION = [")
 
 for i in range(len(percussion)):
 	instr = percussion[i]
@@ -110,5 +110,5 @@ for i in range(len(percussion)):
 	dump_instrument(filename, filename2, instr)
 	print_instr_def(filename, filename2, instr)
 
-print "]"
+print("]")
 

lumps/genmidi/genmidi.py

@@ -120,20 +120,19 @@ def encode_instrument_names(instruments):
 	result = []
 
 	for instrument in instruments:
-		result.append(struct.pack("32s", instrument.voice1["name"]))
+		instr_name = instrument.voice1["name"].encode("ascii")
+		result.append(struct.pack("32s", instr_name))
 
 	return b"".join(result)
 
 def write(filename, instruments):
-	header = struct.pack("%is" % len(GENMIDI_HEADER), GENMIDI_HEADER)
+	header = struct.pack("%is" % len(GENMIDI_HEADER),
+	                     GENMIDI_HEADER.encode("ascii"))
 
-	f = open(filename, 'w')
-
-	f.write(header)
-	f.write(encode_instruments(instruments))
-	f.write(encode_instrument_names(instruments))
-
-	f.close()
+	with open(filename, "wb") as f:
+		f.write(header)
+		f.write(encode_instruments(instruments))
+		f.write(encode_instrument_names(instruments))
 
 def decode_voice(data, name):
 
@@ -145,7 +144,7 @@ def decode_voice(data, name):
 
 	result["m_ksl_volume"] = result["m_ksl"] | result["m_volume"]
 	result["c_ksl_volume"] = result["c_ksl"] | result["c_volume"]
-	result["name"] = name.rstrip("\0")
+	result["name"] = name.decode("ascii").rstrip("\0")
 
 	return result
 
@@ -174,14 +173,13 @@ def decode_instrument(data, name):
 	                  note=fixed_note)
 
 def read(filename):
-	f = open(filename)
-	data = f.read()
-	f.close()
+	with open(filename, "rb") as f:
+		data = f.read()
 
 	# Check header:
 
 	header = data[0:len(GENMIDI_HEADER)]
-	if header != GENMIDI_HEADER:
+	if header.decode("ascii") != GENMIDI_HEADER:
 		raise Exception("Incorrect header for GENMIDI lump")
 
 	body = data[len(GENMIDI_HEADER):]

lumps/genmidi/midi.py

@@ -80,5 +80,5 @@ def def_for_note(note):
 	NOTES = [ "C", "Cs", "D", "Ds", "E", "F", "Fs",
 	          "G", "Gs", "A", "As", "B" ]
 
-	return "%s.%s" % (OCTAVES[note / 12], NOTES[note % 12])
+	return "%s.%s" % (OCTAVES[note // 12], NOTES[note % 12])
 

lumps/genmidi/sbi_file.py

@@ -53,17 +53,17 @@ FIELDS = [
 ]
 
 def read(filename):
-	f = open(filename)
-	data = f.read()
-	f.close()
+	with open(filename, "rb") as f:
+		data = f.read()
 
 	header, name = struct.unpack("4s32s", data[0:36])
+	header = header.decode("ascii")
 
 	if header != HEADER_VALUE:
 		raise Exception("Invalid header for SBI file!")
 
 	instr_data = data[36:]
-	result = { "name": name.rstrip("\0") }
+	result = { "name": name.decode("ascii").rstrip("\0") }
 
 	for i in range(len(FIELDS)):
 		result[FIELDS[i]], = struct.unpack("B", instr_data[i:i+1])
@@ -71,16 +71,14 @@ def read(filename):
 	return result
 
 def write(filename, data):
-	f = open(filename, 'w')
+	with open(filename, "wb") as f:
+		f.write(struct.pack("4s", HEADER_VALUE.encode("ascii")))
+		f.write(struct.pack("32s", data["name"].encode("ascii")))
 
-	f.write(struct.pack("4s32s", HEADER_VALUE, data["name"]))
-
-	for field in FIELDS:
-		f.write(struct.pack("B", data[field]))
-	for x in range(16 - len(FIELDS)):
-		f.write(struct.pack("B", 0))
-
-	f.close()
+		for field in FIELDS:
+			f.write(struct.pack("B", data[field]))
+		for x in range(16 - len(FIELDS)):
+			f.write(struct.pack("B", 0))
 
 if __name__ == "__main__":
 	for filename in sys.argv[1:]: