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############################################################################
#
# File: midisig.icn
#
# Subject: Program to show signature of a MIDI file
#
# Author: Ralph E. Griswold
#
# Date: August 17, 1998
#
############################################################################
#
# This file is in the public domain.
#
############################################################################
#
# This program displays the signature of a MIDI file.
#
############################################################################
#
# Links: bincvt, convert
#
############################################################################
link bincvt
link convert
procedure main()
local rest, track, tracks, width, track_segs, seg, byte, bytes, code
local meta_event, event, command, channel
event := table()
event["8"] := "note off"
event["9"] := "note on"
event["a"] := "key after-touch"
event["b"] := "control change"
event["c"] := "program change"
event["d"] := "channel after-touch"
event["e"] := "pitch wheel change"
event["f"] := "SysEx event"
meta_event := table()
meta_event["\x00"] := "track sequence number"
meta_event["\x01"] := "text"
meta_event["\x02"] := "copyright"
meta_event["\x03"] := "sequence or track name"
meta_event["\x04"] := "track instrument name"
meta_event["\x05"] := "lyric"
meta_event["\x06"] := "marker"
meta_event["\x07"] := "cue point"
meta_event["\x20"] := "channel marker"
meta_event["\x2f"] := "end of track"
meta_event["\x51"] := "tempo"
meta_event["\x54"] := "SMPTE offset"
meta_event["\x58"] := "time signature"
meta_event["\x59"] := "key signature"
meta_event["\x07"] := "sequencer-specific information"
track_segs := []
reads(, 100000) ? {
="MThd" | stop("*** invalid header")
(unsigned(move(4)) = 6) | stop("*** invalid size")
write(
case unsigned(move(2)) of {
0 : "single track"
1 : "multi-track, synchronous"
2 : "multi-track, asynchronous"
default : stop("*** invalid track information")
} | stop("*** invalid track information")
)
write(tracks := unsigned(move(2)), " tracks") |
stop("*** invalid track number information")
write(unsigned(move(2)), " delta-ticks per quarter note") |
stop("*** invalid delta-tick information")
width := *tracks + 1
every track := 1 to tracks do {
="MTrk" | {
write(&errout, "*** short file")
break
}
rest := unsigned(move(4))
put(track_segs, move(rest))
}
}
track := 0
while seg := get(track_segs) do {
write()
track +:= 1
write("track", right(track, width), ": ", *seg, " bytes")
seg ? {
write("delta-time: ", get_time()) | stop("*** invalid delta-time")
byte := move(1)
if byte == "\xff" then {
write(
"meta-event: ",
\meta_event[code := move(1)] |
("unknown code " || image(code))
)
bytes := unsigned(move(1))
if 1 <= unsigned(code) <= 7 then write(" ", move(bytes))
}
else { # event
byte := exbase10(ord(byte), 16)
write(
"event: ",
\event[byte[1]] | ("unknown command " || image(byte[1])),
", channel ",
byte[2]
)
}
next # THE NEXT THING TO DO IS GET DATA BYTES
} # AND LOOP
}
end
# Decode delta-time.
procedure get_time()
local delta, byte
delta := ""
while byte := move(1) do {
if ord(byte) >= 128 then delta ||:= char(ord(byte) - 128)
else {
delta ||:= byte
return unsigned(delta)
}
}
fail # short data
end
|
