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#!/usr/bin/env python
import struct, sys
"""
Each timestamp field is an eight-byte value, first storing the time the
file was loaded into the editor in DOS date/time format (see
http://msdn.microsoft.com/en-us/library/ms724247(VS.85).aspx for details
of this format), and then the length of time the file was loaded in the
editor, in units of 1/18.2 second. (apparently this is fairly standard
in DOS apps - I don't know)
A new timestamp is written whenever the file is reloaded, but it is
overwritten if the file is re-saved multiple times in the same editing
session.
Thanks to Saga Musix for finally figuring this crazy format out.
"""
for filename in sys.argv[1:]:
f = open(filename, 'rb')
if f.read(4) != 'IMPM'.encode('ascii'):
print("%s: not an IT file" % filename)
continue
f.seek(0x20)
ordnum, insnum, smpnum, patnum = struct.unpack('<4H', f.read(8))
f.seek(0x2e)
special, = struct.unpack('<H', f.read(2))
if not (special & 2):
print("%s: history flag not set (old IT version?)" % filename)
continue
para = []
if special & 1: # message exists
f.seek(0x36)
msglen, msgoff = struct.unpack('<HL', f.read(6))
if msglen:
para.append(msgoff)
f.seek(0xc0 + ordnum)
# we'll assume history is invalid if it ends after the first parapointer
para_count = insnum + smpnum + patnum
para.extend(struct.unpack('<%sL' % para_count, f.read(4 * para_count)))
hist, = struct.unpack('<H', f.read(2))
hist_start = f.tell()
hist_len = hist_start + 8 * hist
try:
para_min = min(filter(None, para))
except ValueError:
para_min = hist_len
# history entry count follows parapointers
if not hist:
print("%s: history missing (probably not saved with IT)" % filename)
continue
if para_min < hist_len:
print("%s: history data overlaps parapointers (malformed?)" % filename)
continue
histdata = f.read(8 * hist)
if len(histdata) != 8 * hist:
print("%s: history malformed (probably not saved by IT)" % filename)
continue
f.close()
print(filename)
totalticks = 0
def ticks2hms(ticks):
secs = ticks / 18.2
h, m, s = int(secs / 3600), int(secs / 60) % 60, int(secs) % 60
return ''.join([('%dh' % h if h else ''), ('%dm' % m if h or m else ''), ('%ds' % s)])
for n in range(hist):
fatdate, fattime, ticks = struct.unpack('<HHL', histdata[8 * n : 8 * n + 8])
day = fatdate & 31
month = (fatdate >> 5) & 15
year = (fatdate >> 9) + 1980
second = (fattime & 31) * 2
minute = (fattime >> 5) & 63
hour = fattime >> 11
print('\t%04d-%02d-%02d %02d:%02d:%02d %s' % (year, month, day, hour, minute, second, ticks2hms(ticks)))
totalticks += ticks
print("\t%13d ticks = %s" % (totalticks, ticks2hms(totalticks)))
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