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genmidi: Split off GENMIDI code into separate file.

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Split out code for handling the GENMIDI format into a separate genmidi.py
file. Add routine to load the contents of a GENMIDI lump.
This commit is contained in:
Simon Howard 2012-01-04 01:20:38 +00:00
parent 85482928d5
commit 3b96d7f1de
3 changed files with 223 additions and 94 deletions
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96
lumps/genmidi/mkgenmidi
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@ -29,106 +29,14 @@
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
from instrument import NullInstrument
import struct
import genmidi
import sys
GENMIDI_HEADER = "#OPL_II#"
FLAG_FIXED_PITCH = 0x0001
FLAG_TWO_VOICE = 0x0004
KSL_MASK = 0xc0
VOLUME_MASK = 0x3f
# Order of fields in GENMIDI data structures.
GENMIDI_FIELDS = [
"m_am_vibrato_eg",
"m_attack_decay",
"m_sustain_release",
"m_waveform",
"m_ksl",
"m_volume",
"feedback_fm",
"c_am_vibrato_eg",
"c_attack_decay",
"c_sustain_release",
"c_waveform",
"c_ksl",
"c_volume",
"null",
"note_offset"
]
# Encode a single voice of an instrument to binary.
def encode_voice(data, offset):
result = dict(data)
result["m_ksl"] = data["m_ksl_volume"] & KSL_MASK
result["m_volume"] = data["m_ksl_volume"] & VOLUME_MASK
result["c_ksl"] = data["c_ksl_volume"] & KSL_MASK
result["c_volume"] = data["c_ksl_volume"] & VOLUME_MASK
result["null"] = 0
result["note_offset"] = offset
return struct.pack("<BBBBBBBBBBBBBBh",
*map(lambda key: result[key], GENMIDI_FIELDS))
# Encode an instrument to binary.
def encode_instrument(instrument):
flags = 0
instr1_data = encode_voice(instrument.voice1, instrument.offset1)
if instrument.voice2 is not None:
flags |= FLAG_TWO_VOICE
instr2_data = encode_voice(instrument.voice2,
instrument.offset2)
else:
instr2_data = encode_voice(NullInstrument.voice1, 0)
if instrument.fixed_note is not None:
flags |= FLAG_FIXED_PITCH
fixed_note = instrument.fixed_note
else:
fixed_note = 0
header = struct.pack("<hBB", flags, 128, fixed_note)
return header + instr1_data + instr2_data
def encode_instruments():
result = []
for instrument in INSTRUMENTS + PERCUSSION:
result.append(encode_instrument(instrument))
return b"".join(result)
def encode_instrument_names():
result = []
for instrument in INSTRUMENTS + PERCUSSION:
result.append(struct.pack("32s", instrument.voice1["name"]))
return b"".join(result)
def encode_genmidi():
header = struct.pack("%is" % len(GENMIDI_HEADER), GENMIDI_HEADER)
return header + encode_instruments() + encode_instrument_names()
if len(sys.argv) != 2:
print >> sys.stderr, "Usage: %s <filename>" % sys.argv[0]
sys.exit(-1)
from config import INSTRUMENTS, PERCUSSION
f = open(sys.argv[1], "w")
f.write(encode_genmidi())
f.close()
genmidi.write(sys.argv[1], INSTRUMENTS + PERCUSSION)