Mic, 2008

Website: http://jiggawatt.org/muzak/xpmck/
Contact: micol972@gmail.com


What you will need

	Some basic knowledge of MML. For syntax information in english, see these guides:

	http://www.nullsleep.com/treasure/mck_guide/
	http://www.geocities.co.jp/Playtown-Denei/9628/mck/mckc-e.txt (mirror)


	To build the SEGA Master System / Game Gear version of the player you need WLA-DX:

	http://www.villehelin.com/wla.html


	To build the SEGA Genesis version of the player you need the GNU binutils for M68000.
	You can find prebuilt binaries for Windows here.
	The Genesis Z80 driver source builds with WLA-DX, although it isn't necessary to rebuild
	it unless you want to make changes to it.


	To build the Gameboy / Gameboy Color version of the player you need WLA-DX:

	http://www.villehelin.com/wla.html


	To build the Commodore 64 version of the player you need WLA-DX:

	http://www.villehelin.com/wla.html


P(P)MCK commands supported in XPMCK

	&, ^, <, >, [], {}, D, l, o, q, t, v, v-, v+, @, @@, @EN, @EP, @MP, @q, @v


New commands added in XPMCK

	@ADSR, @CS, @FBM, @FT, @MOD, @WT, @XPCM, @pw, @te, @ve, $, !, AM, FB, k, M, MF, OP, pw, RING, RS, SSG


New commands by target

	Commodore 64
	@ADSR, @FT, @pw, $, !, k, pw, RING

	CPS-1
	@ADSR, @FBM, @MOD, $, !, AM, FB, k, M, MF, OP, RS

	Gameboy / Gameboy Color
	@CS, @WT, @te, @ve, $, !, k

	SEGA Genesis / Megadrive
	@ADSR, @FBM, @MOD, @XPCM, $, !, AM, FB, k, M, MF, OP, RS, SSG

	SEGA Game Gear
	@CS, $, !, k

	SEGA Master System
	@ADSR, $, !, AM, FB, k, M, MF, RS


Specifications and limitations by target

	Commodore 64
	CPS-1
	Gameboy / Gameboy Color
	SEGA Genesis / Megadrive
	SEGA Game Gear
	SEGA Master System


Commandline options

	-h 		Show help
	-v		Verbose mode
	-w		Treat warnings as errors
	-c64		Output data suitable for the Commodore 64
	-cps		Output data suitable for the CPS-1 (YM2151)
	-gbc		Output data suitable for the Gameboy / Gameboy Color
	-gen		Output data suitable for the SEGA Genesis
	-sgg		Output data suitable for the SEGA Game Gear
	-sms		Output data suitable for the SEGA Master System

	If no output filename is specified it will be given the name .asm by
	default (or .s when the target is -gen).

	If the output filename has a .vgm extension and the target is gen, sms or sgg the
	compiler will generate a .vgm file (uncompressed) instead of an .asm file.

	Examples:

		xpmc.exe -cps foo		; Compile the file foo.mml into foo.vgm (only vgm output is supported for CPS-1).

		xpmc.exe -sgg foo.mml bar.vgm	; Compile the file foo.mml into bar.vgm.

		xpmc.exe -gbc -v foo.mml	; Compile the file foo.mml into foo.asm, verbose mode.



Compiler directives

	These are the XPMCK-specific preprocessor commands available:

		#ELSE			Used together with IFDEF/IFNDEF.

		#ELSIFDEF		Used together with IFDEF/IFNDEF.

		#ENDIF			Used together with IFDEF/IFNDEF.

		#EN-REV num		If num==0 EN macros work similar to other
					MML implementations.
					If num==1 EN is not cumulative, meaning that
					instead of {| 3 4 -7} you write {| 3 7 0}.

		#ERROR "message"	Output an error message and abort compilation.

		#IFDEF, #IFNDEF		Conditional compilation depending on if a
					symbol is defined or not.

					Currently the only symbol defined is the selected
					target, so this check would be valid:

						#IFDEF SMS
							; blah
						#ELSIFDEF SGG
							; blah
						#ENDIF

					The boolean operators & (AND) and | (OR) can be
					used:

						#IFDEF SMS | SGG
							; blah
						#ENDIF

					Note that the boolean operators take opposite
					meanings when IFNDEF is used, i.e.:

						#IFNDEF SMS | SGG	; Means "If not defined SMS or not defined SGG"

		#INCLUDE "filename"	Include the contents of another MML file.

		#NTSC			Inform the compiler that you are going to play the
					song with an update frequency of ~60 Hz. Along with
					the tempo and the note lengths this is used to
					calculate how long each note should be played.

		#PAL			Specify a 50 Hz update frequency. Mutually exclusive
					to #NTSC. Some targets only support 60 Hz playback -
					for these targets this command is ignored.

		#SONG num		Start a new song. This directive is used to put multiple songs
					in the same mml file. num has a valid range of 2-100.
					All songs share the same effect macros.

		#TUNE			Use an alternative frequency table on the SEGA Master
					System to lower the error percentage on higher octaves.

		#WARNING "message"	Output a warning. Aborts compilation if the -w switch has been used.

		#UNIFORM-VOLUME num	Specify a custom maximum volume for all channels.
					The volumes will be scaled to the valid range of
					the target machine.


Syntax

Comment
		Single line comments start with a ; (semi-colon).
		Multiline comments start with /* and end with */


Instrument / algorithm selection (All)
	@num
		Apart from selecting the duty cycle for channels that support it,
		@ also has another purpose in XPMCK. For FM channels it is used to
		select the instrument or algorithm for the channel.
		On the SEGA Master System (YM2413) the valid range depends on the
		channel's current output mode:

			M0 (melody):
				@0  = Custom
				@1  = Violin
				@2  = Guitar
				@3  = Piano
				@4  = Flute
				@5  = Clarinet
				@6  = Oboe
				@7  = Trumpet
				@8  = Organ
				@9  = Horn
				@10 = Synthesizer
				@11 = Harpsichord
				@12 = Vibraphone
				@13 = Synthesizer bass
				@14 = Acoustic bass
				@15 = Electric guitar

			M1 (rhythm):
				@0  = Bass drum
				@1  = Snare drum
				@2  = Hi-hat
				@3  = Top cymbal
				@4  = Tom-tom

		When in rhythm mode, each instrument has a global volume that is shared by
		all channels. This means that a channel modifying the volume for one of the
		rhythm instruments will affect all other channels that are using the same
		instrument.

		On the SEGA Genesis (YM2612) the valid range is 0-7 and selects a range
		of instrument sounds according to the following table:

			@0 = Distortion guitar, high hat chopper bass
			@1 = Harp, PSG-like sound
			@2 = Bass, electric guitar, brass, piano, woods
			@3 = Strings, folk guitar, chimes
			@4 = Flute, bells, chorus, bass drum, snare drum, tom-tom
			@5 = Brass, organ
			@6 = Xylophone, tom-tom, organ, vibraphone, snare drum, bass drum
			@7 = Pipe organ

		On the CPS-1 (YM2151) the valid range is 0-7 and selects a range
		of instrument sounds similar to the SEGA Genesis.

		The type of sound generated on the SEGA Genesis and CPS-1 also depends on
		the current feedback setting (see the FB command).

		On the Commodore 64 this command selects the waveform to use:

			@0 = Triangle
			@1 = Saw
			@2 = Square
			@3 = Noise

		One the SEGA Master System and SEGA Game Gear this command switches between
		white noise and periodic noise generation for channel D (0 = white, 1 = periodic).


ADSR envelope (C64, CPS-1, Genesis, Master System)
	@ADSRnum = { attack decay sustain release } or
	           { attack decay1 decay2 sustain release }
		Specify attack rate, decay rate, sustain level and release rate.

		On the SEGA Master System (YM2413) the four-parameter version
		is used and all values have a range of 0-15 (15 being the fastest
		rate / maximum level). Only the custom instrument (@0) uses the
		ADSR parameters, all other instruments have fixed ADSR envelopes.

		On the SEGA Genesis (YM2612) the five-parameter version is used
		and all values have a range of 0-31 (the LSB of sustain and release
		is ignored since they are stored as 4-bit values in the YM2612
		registers). decay1 is the initial fast decay rate, while decay2 is
		the secondary slower decay rate. This command is operator-specific.

		The CPS-1 (YM2151) uses the same type of ADSR envelopes as the SEGA
		Genesis.

		On the Commodore 64 the four-parameter version is used and all values
		have a range of 0-15 (15 being the fastest rate / maximum level).

		Example:

			#IFDEF GEN|CPS
				@ADSR1 = {28 29 4 25 10}
			#ELSIFDEF SMS
				@ADSR1 = {12 13 11 9}
			#ENDIF

			F v10 OP0 ADSR1 c4


Channel separation (pan) macro (GBC, Game Gear)
	@CSnum = { ... | ...}
		Pans the sound on targets that support it. Valid range is -63-63.
		-63 means full left, 0 means center and 63 means full right.

		The macro is applied to a channel with CSnum and disabled with CSOF.


FM feedback macro (CPS-1, Genesis)
	@FBMnum = { ... | ...}
		Specifies the amount of self-feedback for operator 1. This command
		is used in combination with the @ command on the SEGA Genesis and
		CPS-1 FM channels to select the type of sound generated.
		This is the macro version of FB, and allows for rapid changes of
		the feedback value.
		Valid range is 0-7.

		Example:

			@FBM0 = { | 0 0 3 3 7 7}

			E v9 @2 FBM0 c1


Filter macro (C64)
	@FTnum = { type cutoff resonance }
		Specifies a filter macro for use on Commodore 64 channels.
		type selects the type of filter to use, and has a valid range of 0-3 (0 = low pass,
		1 = high pass, 2 = band pass, 3 = notch reject).
		cutoff specifies the cutoff frequency, and has a valid range of 0-2047 (which
		corresponds to a frequency range of about 30-12000 Hz).
		resonance specifies the filter resonance, and has a valid range of 0-15.

		Note that the filter parameters are shared between all channels, while filtering
		can be enabled/disabled individually per channel. Thus, applying a new filter on one
		channel will affect all other channels that have filtering enabled, while disabling
		filtering will not affect other channels.

		The macro is applied to a channel with FTnum and disabled with FTOF.

		Example:

			@FT0 = {0 400 2}	; Set a low pass filter.

			A @0 v10 FT0


Modulator (CPS-1, Genesis)
	@MODnum = { lfo ams fms } or
	          { lfo amd fmd ams fms waveform }
		Specifies a modulator to be used for modulating the amplitude and/or
		frequency of a channel.

		SEGA genesis:
		The 3-parameter form is used.
		lfo selects the frequency of the modulator LFO. Valid range is 0-7
		(7 beging the maximum frequency). Note that the LFO is shared for all channels,
		so issuing a MOD command on one channel will affect all other channels that
		are using a modulator.
		ams selects the amplitude modulation sensitivity. Valid range is 0-7
		(7 being the maximum sensitivity). Amplitude modulation also has to be separately
		enabled with the AM command. This can be done per operator.
		fms selects the frequency modulation sensitivity. Valid range is 0-3
		(3 being the maximum sensitivity).

		CPS-1:
		The 6-parameter form is used.
		lfo selects the frequency of the modulator LFO. Valid range is 0-255
		(255 beging the maximum frequency). Note that the LFO is shared for all channels,
		so issuing a MOD command on one channel will affect all other channels that
		are using a modulator.
		amd selects the amplitude modulation depth. Valid range is 0-127.
		fmd selects the frequency modulation depth. Valid range is 0-127.
		ams selects the amplitude modulation sensitivity. Valid range is 0-3
		(3 being the maximum sensitivity). Amplitude modulation also has to be separately
		enabled with the AM command. This can be done per operator.
		fms selects the frequency modulation sensitivity. Valid range is 0-7
		(7 being the maximum sensitivity).
		waveform selects the waveform of the modulator LFO. Valid range is 0-3
		(0 = saw, 1 = square, 2 = triangle, 3 = noise).

		This command is currently only supported for the FM channels on the SEGA Genesis,
		and on the CPS-1.

		The macro is applied to a channel with MODnum and disabled with MODOF.

		Example:

			@MOD0 = {4 2 2}

			E v100 MOD0 OP0 AM1 c1


Waveform definition (GBC)
	@WTnum = { sample sample sample ... } or
	         { "filename.wav" resample volume }
		Defines a waveform for playback on channels that supports it.
		In the first case the sequence should contain 32 unsigned samples in the
		range 0..MAX-VOLUME.
		In the second case the first value should be a string specifying a
		.wav file to convert. The resample parameter is the frequency to
		resample the .wav file to, and volume specifies the upper limit
		of the volume range the sample data will be scaled to.

		Example:

			@WT0 = {"kickdrum.wav" 8000 15}
			@WT1 = {0 0 0 15 0 0 0 15 0 0 0 15 0 0 0 15 0 0 0 15 0 0 0 15 0 0 0 15 0 0 0 15}

			C v3 WT1 c4


PCM definition (Genesis)
	@XPCMnum = { "filename.wav" resample }
		Defines a PCM sample for playback on channels that supports it.
		The resample parameter is the frequency to resample the .wav file to (or 0 if you
		don't want any resampling). The resampling done by XPMC is of quite poor quality, so
		you should consider resampling in a wave editor instead. The native playback rates
		in XPMCK are as follows:

			SEGA Genesis:	8820 Hz

		XPMC will automatically convert the samples to 8-bit mono if needed.

		Each sample is tied to a specific note, specified by num, starting from C in
		octave 0. So num=0 means a C in octave 0 is used to play the sample, 3 means
		D+ in octave 0, 12 means C in octave 1, etc. Usually one will skip all the numbers
		that correspond to sharps, simply because it's easier to type dddd than c+c+c+c+.

		Example:

			@XPCM0 = {"kickdrum.wav" 8000}

			J o0 M2 c4


Pulse width macro (C64)
	@pwnum = { ... | ... }
		Macro version of pw.

		Example:

			@pw0 = {1 2 3}
			@pw1 = {2 2 | 0 0 1 1}

			A @pw0 c1 pw9 d1	; pw and @pw override eachother


Tone envelope (GBC)
	@tenum
		Specifies the current tone envelope (frequency sweep).
		Valid range of num is -7-7. Positive numbers make the frequency
		gradually increase, negative numbers make the frequency gradually
		decrease, and zero disables the effect.
		This command is currently only supported when the target is Gameboy /
		Gameboy Color.

		Example:

			A @te2 c1


Volume envelope (GBC)
	@venum
		Specifies the current volume envelope.
		Valid range of num is -7-7. Positive numbers make the volume
		gradually increase, negative numbers make the volume gradually
		decrease, and zero disables the effect.
		This command is currently only supported when the target is Gameboy /
		Gameboy Color.

		Example:

			A @ve-5 c1


Volume set (All)
	@vnum / vnum
		For the SEGA Genesis FM channels (channels E..J) and for the CPS-1, this
		command is operator specific, meaning that you can set the volume
		individually per operator. To set the volume for all operators at once,
		put an OP0 command before the volume command(s).

		On the Commodore 64 there is only one global volume that affects all
		channels. To get different loudness levels for different channels
		you can use ADSR envelopes and/or filters.

		Example:

			E OP0 v100
			F OP1 v105 OP2 v95 OP3 v80 OP4 v100


General macro (All)
	$id { ... } 
		Define/use a general macro. These can be used to save typing if a
		lot of smilar patterns are used in a song. Parameters are dereferenced
		with %num% (%1% being the first parameter).

		Example:

			$1 { [%1%]4 %2%.. }

			A $1(c, a)

		The macro invokation on channel A will expand to [c]4 a..


Callback (All)
	!id(frequency)
		Call a function on the host CPU. E.g. if playing a song on the
		SEGA Master System this command would call a function in your
		Z80 code. This can be used to synchronize the visual output
   		of your program with the music.
		The frequency parameter specifies how often the function should be
		called. The available values are:

		0			Never (disable the callback).

		1			Once (called during the next update).

		EVERY-NOTE		Called for every new note that is
					played on the channel(s).

		Example:

			AD !foo(EVERY-NOTE)
			A l16 cdef
			D l32 [g]8

		Here the function foo will be called each time a new note is
		played on channel A or D.


Amplitude modulation enable (CPS-1, Genesis, Master System)
	AMnum
		Used for the FM channels on the SEGA Genesis (channels E..J), and on the CPS-1.
		Enable/disable amplitude modulation for the currenly selected operator(s).
		Valid range of num is 0-1 (0=OFF, 1=ON).
		This command is used in conjunction with MOD.


Detune (All)
	Dnum
		For most targets this command works as usual (num specifies number of semitones
		to detune by).
		For the FM channels on the SEGA Genesis (channels E..J) the detune
		command has a more limited range of -3-3. The reason for this is that
		the value is written to the DT1 bits of the selected operator(s).
		Detuning for these channels is also controlled by the MF command.
		On the CPS-1 this command works as on the SEGA Genesis.


FM feedback (CPS-1, Genesis, Master System)
	FBnum
		Specifies the amount of self-feedback for operator 1. This command
		is used in combination with the @ command on the SEGA Genesis FM
		channels and on the CPS-1 to select the type of sound generated.
		Valid range is 0-7.

		Example:

			E v9 @2 FB6 c1


Set note length (alternative version) (All)
	knum
		Specifies the length of subsequent notes as num 32nd notes.
		Valid range is 1-256.

		Example:

			A k7 cdef  ; This is the same as A c8..d8..e8..f8..


Set note length (All)
	lnum
		Specifies the length of subsequent notes as 1/num (e.g with num=1 you get whole notes, with num=2 you get half notes, etc.)
		Valid range of num is 1, 2, 3, 4, 6, 8, 12, 16, 24, 32.

		Example:

			A l8 cd l12 ef
			B c8d8 e12f12


Output mode (CPS-1, Genesis, Master System)
	Mnum
		Specifies the output mode for channels that support more than one
		output mode.
		For the SEGA Master System this command is used for FM channels G..J
		to select melody or rhythm mode (M0 = melody (default), M1 = rhythm).
		Note that switching mode on any of these three channels affects all of
		them.

		For channel J on the SEGA Genesis this command is used to switch
		between FM and XPCM mode (M0 = FM, M2 = XPCM).

		For channel H on the CPS-1 this command is used to switch between melody
		and noise mode (M0 = melody, M1 = noise).

		Example:

			E v8 M0 @7 c1
			F v9 M1 @0 [d32r32]16


FM detuning multiplier (CPS-1, Genesis, Master System)
	MFnum
		Specifies the amount of detuning together with the D command for the FM
		channels on the SEGA Genesis and on the CPS-1.
		Valid range is 0-15.
		This command is operator specific.

		Example:

			E OP1 D1 MF7	; Set detune and multiplier for operator 1 on channel E


FM Operator select (CPS-1, Genesis)
	OPnum
		Used for the FM channels on the SEGA Genesis (channels E..J), and on the CPS-1.
		Each channel has four operators, which are set up in various configurations
		depending on the selected algorithm. Some commands are applied on the channel
		while others can be applied per operator. OP selects the operator to apply
		subsequent operator-specific commands to.
		Valid range of num is 0-4. If num==0 all operators are selected.

		Example:

			E OP0 ADSR1		; Set ADSR envelope for all operators on channel E


Pulse width (C64)
	pwnum = { ... | ... }
		Set the current waveform pulse width when the selected waveform is square (@2).
		num has a valid range of 0-15 (which corresponds to a pulse width range of
		about 0-93.8%).

		Example:

			A pw0 c1 pw12 d1


Ring modulation enable (C64)
	RINGnum
		When num == 1, the triangle waveform (@0) of channel X (where X == A, B or C) is
		replaced by a ring modulated combination of the osciallators of channel X and another
		channel according to the following list:

			A: A + C
			B: B + A
			C: C + B

		Ring modulation is disabled when num == 0.


FM rate scaling (CPS-1, Genesis, Master System)
	RSnum
		Used for the FM channels on the SEGA Genesis (channels E..J), and on the CPS-1.
		Specifies the amount with which envelopes scale to the note's pitch,
		creating narrower envelopes as the pitch rises.
		Valid range of num is 0-3 (3 being the maximum amount of scaling).
		The command is operator specific.

		Example:

			E OP1 RS2	; Set rate scaling for operator 1 on channel E


SSG envelope generator (Genesis)
	SSGnum
		Used for the FM channels on the SEGA Genesis (channels E..J).
		When the SSG is active, the ADSR envelope will repeat according to various patterns.
		The pattern to use is selected by num and has a valid range of 0-7. SSG is
		deactivated with SSGOF.
		When SSG is used you should set the attack rate to max (31) in the ADSR envelope
		used by the affected operator(s), or you might get distorted output.
		This command is operator specific.

		Example:

			@ADSR0 = {31 10 10 8}

			E @2 OP0 v100 SSG0 ADSR0 c1 SSGOF d1


Implementation specific notes
	
	SEGA Game Gear

		Volume range is 0..15. The lowest playable note is A in octave 2.
		Channels A, B, C are tone channels that output square waves.

		Channel D is used for noise. @0 selects white noise and @1 selects periodic
		noise.

		Limited panning is supported (negative values means full left, zero means center,
		positive values means full right).

		EP and MP can be used together, but they will interfere with eachother.

		For the noise channel the octave setting is irrelevant. The noise generator has
		four different clock settings that is determined by the current note MOD 4. Below
		is a list of what each note corresponds to:

			c, e, g+:	High pitch
			c+, f, a:	Medium pitch
			d, f+, a+:	Low pitch
			d+, g, b:	Pitch determined by channel C.

		By selecting periodic noise generation with pitch determined by channel C it is
		possible to use the noise channel as a kind of extra tone channel.

	
	SEGA Master System

		Volume range is 0..15.
		The lowest playable note is A in octave 2 for channels A..D, and C in octave 1 for
		channels E..J.

		Channels A, B, C are tone channels that output square waves.

		Channel D is used for noise. @0 selects white noise and @1 selects periodic
		noise. The noise's pitch is determined in the same way as for the SEGA Game Gear.

		Channels E, F, G, H, I, J are FM channels that can output a variety and sounds. Note
		that if you want to play a song using these channels on an actual console
		you will need a modified SMS / Mark-III with an added YM2413 (or a japanese SMS).

		EP and MP can be used together, but they will interfere with eachother.

	
	SEGA Genesis

		Volume range is 0..15 for channels A..D, and 0..127 for channels E..J. Note that it's
		possible to set the volume separately per operator for channels E..J.

		The lowest playable note is A in octave 2 for channels A..D, and C in ocatve 1 for
		channels E..J.
		Channels A, B, C are tone channels that output square waves.

		Channel D is used for noise. @0 selects white noise and @1 selects periodic
		noise. The noise's pitch is determined in the same way as for the SEGA Game Gear.

		Channels E, F, G, H, I, J are FM channels that can output a variety and sounds.

		Channel J can also be used for PCM playback, see the @XPCM and M commands for more
		info (Note that PCM playback only works when outputting to VGM).

		Due to the fact that effect tables are copied to the limited audio RAM, you've got
		harder restrictions on the number of effect macros you can declare. These limits are
		as follows:

			@:	20
			@v:	32
			@EN:	32
			@EP:	16
			@MP:	16
			@ADSR:	16
			@MOD:	10
			@FBM:	7

		The playback library doesn't handle bank switching, so the compiled size of your music data must
		be <= 32 kB and should start as close as possible to the beginning of a 32 kB page. (Note that
		this isn't relevant when outputting to VGM).

		Callbacks are currently not supported.

		EP and MP can be used together, but they will interfere with eachother.
		MP is ignored for channels E..J since MOD can achieve pretty much the same thing.

	
	Gameboy / Gameboy Color

		Volume range is 0..15 for channels A, B, D and 0..3 for channel C.
		The lowest playable note is C in octave 2.
		Channels A, B are tones channels that output square waves with
		controllable duty cycle (0..3, representing 12.5..75%).

		Channel C is used for Wave playback. You must execute at least one
		WT command on channel C to load a waveform, or the channel will not
		be activated.

		Channel D is used for noise.

		Limited panning is supported (negative values means full left, zero means center,
		positive values means full right).

		It is preferred to use @ve rather than @v on channels A, B and D.
		The reason for that being that the envelope effect specified by the @ve command is handled
		by the Gameboy hardware, while an @v command causes the player to update the volume bits for
		the selected channel(s) and reset the waveform, which causes distortion.

	
	CPS-1 (Capcom Play System)

		Only VGM output is supported for this target. Also, only the YM2151 is supported - no ADPCM.

		Volume range is 0..127 for channels A..H. Note that it's possble to set the volume separately
		per operator.

		The lowest playable note is C in ocatve 1.

		Channels A..H are FM channels that can output a variety and sounds.

		Channel H can also output noise, see the M command for more info.

		EP and MP can be used together, but they will interfere with eachother.
		MP is ignored since MOD can achieve pretty much the same thing.

	
	Commodore 64

		Volume range is 0..15 for channels A..C. See the notes about volume on the C64.
		The lowest playable note is C in ocatve 0.

		Channels A..C are tone channels that can output the waveform of one of four different
		oscillators, with adjustable ADSR envelopes and filtering.

		Ring modulation can be used to combine the waveforms of two channels.


	General

		Effects are stepped through once per frame.



TODO

Things that would be nice to do, time permitting:

Fix bugs.
Write playback libraries for other platforms.
Implement more effects.
Create a player for Windows.
Optimize the playback libraries.