PICO-8 docs

PICO-8.TXT

PICO-8 v0.1.11g
 https://www.pico-8.com
 (c) Copyright 2014-2018 Lexaloffle Games LLP
 Author: Joseph White // <a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f8909d81b8949d809994979e9e949dd69b9795">[email&#160;protected]</a>
 
 PICO-8 is built with:
 	SDL2 http://www.libsdl.org
 	Lua 5.2 http://www.lua.org  // see license.txt
 	GIFLIB http://giflib.sourceforge.net/
 	WiringPi http://wiringpi.com/

============================================================================================

Welcome to PICO-8!

	PICO-8 is a fantasy console for making, sharing and playing tiny games and other computer 
	programs. When you turn it on, the machine greets you with a shell for typing in Lua programs 
	and provides simple built-in tools for creating sprites, maps and sound.

	The harsh limitations of PICO-8 are carefully chosen to be fun to work with, encourage small
	but expressive designs and hopefully to give PICO-8 cartridges their own particular look and 
	feel.


:: Keys

	Toggle Fullscreen: Alt+Enter 
	Quit: Alt+F4 or command-Q
	Reload/Run/Restart cart: Ctrl+R
	Quick-Save: Ctrl+S
	Mute/Unmute: Ctrl+M
	Player 1 defaults: Cursors + ZX / NM / CV
	Player 2 defaults: SDFE + tab,Q / shift A
	Enter or P for pause menu (while running)
	// use KEYCONFIG to change the defaults.
	

:: Specs

	Display: 128x128, fixed 16 colour palette
	Input: 6-button controllers
	Cartridge size: 32k
	Sound: 4 channel, 64 definable chip blerps
	Code: Lua (max 8192 tokens of code) 
	Sprites: Single bank of 128 8x8 sprites (+128 shared)
	Map: 128x32 8-bit cels (+128x32 shared)


:: Hello World

	After PICO-8 boots, try typing some of these commands followed by enter:

		PRINT("HELLO WORLD")
		RECTFILL(80,80,120,100,12)
		CIRCFILL(70,90,20,14)
		FOR I=1,4 DO PRINT(I) END
	
	(Note: PICO-8 only displays upper-case characters -- just type normally without capslock!)
	
	You can build up an interactive program by using commands like this in the code editing
	mode along with two special callback functions _UPDATE and _DRAW. For example, the following
	program allows you to move a circle around with the cursor keys. Press escape to switch
	to the code editor and type or copy & paste the following code:

	X = 64  Y = 64
	FUNCTION _UPDATE()
	 IF (BTN(0)) THEN X=X-1 END
	 IF (BTN(1)) THEN X=X+1 END
	 IF (BTN(2)) THEN Y=Y-1 END
	 IF (BTN(3)) THEN Y=Y+1 END
	END

	FUNCTION _DRAW()
	 RECTFILL(0,0,127,127,5)
	 CIRCFILL(X,Y,7,14)
	END

	Now press escape to return to the console and type RUN (or press CTRL-R) to see it 
	in action. See the example cartridges for more complex programs.
	
	If you want to store your program for later, use the SAVE command:
	
	> SAVE PINKCIRC
	
	And load it again:
	
	> LOAD PINKCIRC
	

:: Example Cartridges

	These cartridges are included with PICO-8 and can be installed by typing:
	
	INSTALL_DEMOS
	CD DEMOS
	
	HELLO      Greetings from PICO-8
	API        Demonstrates most PICO-8 functions
	JELPI      Platform game demo w/ 2p support 
	CAST       2.5D Raycaster demo
	MANDEL     Mandelbrot explorer
	COLLIDE    Example wall and actor collisions
	BUTTERFLY  Serpinsky triangles thing
	DRIPPY     Draw a drippy squiggle
	STOMPY     Music cart

	To run a cartridge, open PICO-8 and type:

	LOAD JELPI
	RUN
	
	Press escape to stop the program, and once more to enter editing mode.


:: File System

	These commands can be used to manage files and directories (folders):
	
	DIR         list the current directory
	CD BLAH     change directory
	CD ..       go up a directory
	CD /        change back to top directory (on PICO-8's virtual drive)
	MKDIR BLAH  make a directory
	FOLDER      open the current directory in the host operating system's file browser

	LOAD BLAH  load a cart from the current directory
	SAVE BLAH  save a cart to the current directory
	
	If you want to move files around, duplicate them or delete them, use the FOLDER 
	command and do it in the host operating system.
	
	The default location for PICO-8's drive is:
	
	Windows: C:/Users/Yourname/AppData/Roaming/pico-8/carts
	OSX: /Users/Yourname/Library/Application Support/pico-8/carts
	Linux: ~/.lexaloffle/pico-8/carts

	You can change this and other settings in pico-8/config.txt
	
	Tip: The drive directory can be mapped to a cloud drive (provided by Dropbox, Google
	Drive or similar) in order to provide a single disk shared between PICO-8 machines 
	spread across different host machines.


:: Loading and Saving

	When using LOAD and SAVE, the .P8 extention can be omitted and is added automatically.
		
	Saving to a .p8.png extention will save the cartridge in a special image format that
	looks like a cartridge.
	
	Use a filename of "@CLIP" to load or save to the clipboard.

	Once a cartridge has been loaded or saved, it can also be quick-saved with CTRL-S

	:: Saving .p8.png carts with a text label and preview image
	
		To generate a label image saved with the cart, run the program first and press F7 to grab
		whatever is on the screen. The first two lines of the program starting with '--' are also 
		drawn to the cart's label.

		e.g.
		-- OCEAN DIVER LEGENDS
		-- BY LOOPY
	

	:: Code size restrictions for .png format
	
		When saving in .png format, the compressed size of the code must be less than 15360 bytes.
		To find out the current size of your code, use the INFO command. The compressed size limit 
		is not enforced for saving in .p8 format.
		

:: Using an External Text Editor

	It is possible to edit .p8 files directly with a separate text editor. Using CTRL-R to run a
	cartridge will automatically re-load the file if:
	
		1. There are no unsaved changes in the PICO-8 editors, AND
		2. The file differs in content from the last loaded version
		
	If there are changes to the cart on disk /and/ in the editor, a notification is displayed:
	
		DIDN'T RELOAD; UNSAVED CHANGES
	
	PICO-8 does not fully support upper-case characters, and they are automatically converted to
	lower-case when viewed in the code editor. Note that this also causes unsaved changes to exist, 
	which means that CTRL-R will stop automatically re-loading the version on disk until it is
	manually LOAD()ed.
	
	Glyph characters (normally typed with shift-A..Z) are stored in .p8 format and in the
	host operating system's clipboard as rough unicode equivalents. 
	

:: Backups

	If you quit without saving changes, or overwrite an existing file, a backup of the 
	cartridge is saved to {appdata}/pico-8/backup.
	

:: Configuration

	:: config.txt
	
		You can find some settings in config.txt. Edit the file when PICO-8 is not running.
	
		Windows: C:/Users/Yourname/AppData/Roaming/pico-8/config.txt
		OSX: /Users/Yourname/Library/Application Support/pico-8/config.txt
		Linux: ~/.lexaloffle/pico-8/config.txt

		Use the -home switch (below) to use a different path to store config.txt and other data.
		

	:: Commandline parameters
	
		// note: these override settings found in config.txt
		
		pico-8 [switches] [filename.p8]
		
		-width n                 set the window width 
		-height n                set the window height 
		-windowed n              set windowed mode off (0) or on (1)
		-sound n                 sound volume 0..256
		-music n                 sound volume 0..256
		-joystick n              joystick controls starts at player n (0..7)
		-pixel_perfect n         1 for unfiltered screen stretching at integer scales (on by default)
		-draw_rect x,y,w,h       absolute window coordinates and size to draw pico-8's screen 
		-run filename            load and run a cartridge
		-x filename              execute a PICO-8 cart headless and then quit
		-p param_str             pass a parameter string to the specified cartridge
		-splore                  boot in splore mode
		-home path               set the path to store config.txt and other user data files
		-desktop path            set a location for screenshots and gifs to be saved
		-screenshot_scale n      scale of screenshots.  default: 3 (368x368 pixels)
		-gif_scale n             scale of gif captures. default: 2 (256x256 pixels)
		-gif_len n               set the maximum gif length in seconds (1..120)
		-gui_theme n             use 1 for a higher contrast editor colour scheme
		-timeout n               how many seconds to wait before downloads timeout (default: 30)
		-software_blit n         use software blitting mode off (0) or on (1)
		-foreground_sleep_ms n   how many milliseconds to sleep between frames.
		-background_sleep_ms n   how many milliseconds to sleep between frames when running in background


:: Controller Setup

	PICO-8 uses the SDL2 controller configuration scheme. It will detect common controllers
	on startup and also looks for custom mappings in sdl_controllers.txt in the same directory 
	as config.txt. sdl_controllers.txt has one mapping per line.

	To generate a custom mapping string for your controller, use either the controllermap
	program that comes with SDL2, or try http://www.generalarcade.com/gamepadtool/

	To set up which keyboard keys trigger joystick buttons presses, use KEYCONFIG.



:: Screenshots, Videos and Cartridge Labels

	While a cartridge is running use:

		F6 Save a screenshot to desktop
		F7 Capture cartridge label image
		F8 Start recording a video
		F9 Save GIF video to desktop (max: 8 seconds by default)
		
		// if F6..F9 are not available on your system, use CTRL-6..9
	
	You can save a video at any time (it is always recording) -- use F8 just to reset
	the video starting point if you want something less than 8 seconds long.

	To change the maximum gif length, edit gif_len in config.txt to specify the number
	of seconds to record for. The gif format can not match 30fps exactly, so PICO-8 
	instead uses the closest match: 33.3fps.
	
	

:: Sharing Cartridges

	There are three ways to share carts made in PICO-8:
	
		1. Share the .p8 or .p8.png file directly with other PICO-8 users
		
			Type FOLDER to open the current folder in your host operating system.
	
		2. Post the cart on the Lexaloffe BBS to get a web-playable version

			http://www.lexaloffle.com/pico-8.php?page=submit
			
		3. Export the cartridge to a stand-alone html/js or native binary player
			(see the exporters section for details)
		
		
:: Exporters / Importers

	The EXPORT command can be used to generate png, wav files and stand-alone html and native
	binary cartridge players. The output format is inferred from the filename extention (e.g.
	.png).
	
	You are free to distribute and use exported cartridges and data as you please, provided 
	that you have permission from the author and contributors.

	:: Sprite Sheet (.png)
	
		IMPORT BLAH.PNG     --  expects 128x128 png and colour-fits to the pico-8 palette
		EXPORT BLAH.PNG     --  use folder() to locate the exported png
	
	:: SFX and Music (.wav)
	
		EXPORT BLAH.WAV     --  export music from the current pattern (when editor mode is MUSIC)
		EXPORT BLAH.WAV     --  export the current SFX (when editor mode is SFX)
		EXPORT BLAH%D.WAV   --  exports all of the SFXs as blah0.wav, blah1.wav .. blah63.wav

	:: HTML Player (.html)
	
		To generate a stand-alone html player (foo.html and foo.js):
		> EXPORT FOO.HTML
		
		Or just the .js file:
		> EXPORT FOO.JS
		
		Optionally provide a custom html template with the -p switch:
		> EXPORT FOO.HTML -P ONE_BUTTON
		
		This will use the file {application data}/pico-8/plates/one_button.html as the
		html shell, replacing a special string, ##js_file##, with the .js filename.
		
	
	:: Binary Player (.bin)
	
		To generate stand-alone executables for Windows, Linux (64-bit) and Mac OSX:
		
		> EXPORT FOO.BIN
		
		By default, the cartridge label is used as an icon with no transparency. To 
		specificy an icon from the sprite sheet, use -i and optionally -s and/or -c 
		to control the size and transparency.
		
			-I N  Icon index N with a default transparent colour of 0 (black).
			-S N  Size NxN sprites. Size 3 would be produce a 24x24 icon.
			-C N  Treat colour N as transparent. Use 16 for no transparency.

		For example, to use a 2x2 sprite starting at index 32 in the spritesheet, 
		using colour 12 as transparent, and bundling an extra cartrige C0.P8:
		
			> EXPORT FOO.BIN -I 32 -S 2 -C 12 C0.P8

	
:: Exporting Multiple Cartridges

	Up to 16 cartridges can be bundled together by passing them to EXPORT, when generating
	stand-alone html or native binary players
	
	EXPORT FOO.HTML DAT1.P8 DAT2.P8 GAME2.P8
	
	During runtime, the extra carts can be accessed as if they were local files:
	
	RELOAD(0,0,0x2000, "DAT1.P8") -- load spritesheet from DAT1.P8
	LOAD("GAME2.P8") -- load and run another cart
	

:: Splore

	SPLORE is a built-in utility for browsing and organising both local and bbs (online)
	cartridges. Type SPLORE [enter] to launch it, or launch PICO-8 with -splore. 
	
	It is possible to control SPLORE entirely with a joystick:
	LEFT and RIGHT to navigate lists of cartridges
	UP AND DOWN to select items in each list
	X,O or MENU to launch the cartridge
	
	While inside a cart, press MENU to favourite a cartridge or exit to splore.
	If you're using a keyboard, it's also possible to press F to favourite an item
	while it is selected in the cartridge list view.
	
	When viewing a list of BBS carts, use the top list item to re-download a list of
	cartridges. If you are offline, the last downloaded list is displayed, and it is
	still possible to play any cartridges you have downloaded.
	
	If you have installed PICO-8 on a machine with no internet access, you can also
	use INSTALL_GAMES to add a small selection of pre-installed BBS carts to your
	favourites list.
	


:: Quirks of PICO-8

	Common gotchas to watch out for:
	
	- The bottom half of the spritesheet and bottom half of the map occupy the same memory.
		// Best use only one or the other if you're unsure how this works.
	- PICO-8 numbers only go up to 32767.99.
		// If you add 1 to a counter each frame, it will overflow after around 18 minutes!
	- Lua arrays are 1-based by default, not 0-based. FOREACH starts at T[1], not T[0].
	- cos() and sin() take 0..1 instead of 0..PI*2, and sin() is inverted.
	- sgn(0) returns 1.
	- Toggle fullscreen: use alt-enter on OSX (command-F is used for searching text).
	- When you want to export a .png cartridge, use SAVE, not EXPORT. EXPORT will save only the spritesheet!



============================================================================================
	Editor Modes
============================================================================================
	
	Press escape to toggle between console and editor
	Click editing mode tabs at top right to switch or press ALT+LEFT/RIGHT


	** WARNING: The second half of the sprite sheet (banks 2 and 3), and the bottom half
	of the map share the same cartridge space. It's up to you how you use the data, but
	be aware that drawing on the second half of the sprite sheet could clobber data on
	the map and vice versa.
	

:: Code Editor
	
	Hold shift to select (or click and drag with mouse)
	CTRL-X, C, V to cut copy or paste selected
	CTRL-Z, Y to undo, redo
	CTRL-F to search for text in the current tab
	CTRL-G to repeat the last search again
	CTRL-L to jump to a line number
	CTRL-UP, DOWN to jump to start or end
	ALT-UP, DOWN to navigate to the previous, next function
	CTRL-LEFT, RIGHT to jump by word
	CTRL-D to duplicate current line
	TAB to indent a selection (shift to un-indent)

	To enter special characters that represent buttons, use SHIFT-L,R,U,D,O,X
	Or press CTRL-K to toggle glyph mode
	
	:: Tabs
	
		Click the [+] button at the top to add a new tab.
		Navigate tabs by left-clicking, or with ctrl-tab, shift-ctrl-tab.
		To remove the last tab, delete any contents and then moving off it (CTRL-A, del, ctrl-tab)
		When running a cart, a single program is generated by concatenating all tabs in order.
	
	:: Code limits
	
		The current number of code tokens is shown at the bottom right. One program can have a
		maximum of 8192 tokens. Each token is a word (e.g. variable name) or operator. Pairs of
		brackets, and strings each count as 1 token. commas, periods, LOCALs, semi-colons, ENDs,
		and comments are not counted.
		
		Right click to toggle through other stats (character count, compressed size).
		If a limit is reached, a warning light will flash. This can be disabled by right-clicking.


:: Sprite Editor

	The sprite editor is designed to be used both for sprite-wise editing and for freeform 
	pixel-level editing. The sprite navigator at the bottom of the screen provides an 8x8-wise 
	view into the sprite-sheet, but it is possible to use freeform tools (pan, select) when
	dealing with larger or oddly sized areas.

	Draw Tool
		Click and drag on the sprite to plot pixels
		Applies to visible area
		Hold CTRL to search and replace a colour
		Use right mouse button to select colour

	Stamp Tool
		Click to stamp whatever is in the copy buffer
		Hold LCONTROL to treat colour 0 (black) as transparent 

	Select Tool // shortcut: LSHIFT or S
		Create a selection
		Enter or click to select none.
		
		If a pixel-wise selection is not present, many operations are instead applied
		to a sprite-wise selection. To select sprites, shift-drag in the sprite navigator.
	
	Pan Tool // shortcut: space
		View the spritesheet.
	
	Fill Tool
		Fill with the current colour
		Applies to the current selection
		If no selection, applies to visible area

	Extra keys
		CTRL-Z to undo // single step only in 0.2.0
		CTRL-C to copy selected area or selected sprites
		CTRL-V to paste to current sprite location
		Q,W to switch to previous/next sprite
		1,2 to switch to previous/next colour
		Tab to toggle fullscreen view
		Mousewheel or < and > to zoom (centered in fullscreen)
		
	
	Operations on selected area or selected sprites:
		f to flip
		v to flip vertically
		r to rotate (must be square selection)
		Cursor keys to move (loops if sprite selection)
		
	Sprite flags
		The 8 coloured circles are sprite flags for the current sprite.
		Each one can be true (on) or false (off), and are accessed by
		using the FSET and FGET functions. They are indexed from 0, from
		the left (0,1,2..7). See fset() for more information.
	

:: Map Editor

	The pico-8 map is a 128x32 (or 128x64 using shared space) block of 8-bit values.
	Each value is shown in the editor as a reference to a sprite (0..255), but you can
	of course use the data to represent whatever you like.

	The tools are similar to the ones used in sprite editing mode. Select a sprite
	and click and drag to paint values into the map.	

	To draw multiple sprites, select from sprite navigator with shift+drag
	To copy a block of values, use the selection tool and then stamp tool to paste
	To pan around the map, use the pan tool or hold space
	Q,W to switch to previous/next sprite
	Mousewheel or < and > to zoom (centered in fullscreen)
	

:: SFX Editor

	There are 64 SFX ("sound effects") in a cartridge, used for both sound and music.
	
	Each SFX has 32 notes, and each note has:
		A frequency   (C0..C5)
		An instrument (0..7)
		A volume      (0..7)
		An effect     (0..7)
	
	Each SFX also has these properties:
	
		A play speed (SPD) : the number of 'ticks' to play each note for.
			// This means that 1 is fastest, 3 is 3x as slow, etc.

		Loop start and end : this is the note index to loop back and to
			// Looping is turned off when the start index >= end index
	
	There are 2 modes for editing/viewing a SFX: Pitch mode (more suitable
	for sound effects) and tracker mode (more suitable for music). The mode
	can be changed using the top-left buttons, or toggled with TAB.
	
	
	1. Pitch Mode
	
		Click and drag on the pitch area to set the frequency for each note,
		using the currently selected instrument (indicated by colour).
		
		Hold shift to apply only the selected instrument
		Hold CTRL to snap entered notes to the C minor pentatonic scale
	
	
	2. Tracker Mode
	
		Each note shows: frequency octave instrument volume effect
		To enter a note, use q2w3er5t6y7ui zsxdcvgbhnjm (piano-like layout)
		Hold shift when entering a note to transpose -1 octave .. +1 octave
		New notes are given the selected instrument/effect values
		To delete a note, use backspace or set the volume to 0
		
		Click and then shift-click to select a range that can be copied
		(CTRL-C) and pasted (CTRL-V)
		
		Navigation:
			PAGEUP/DOWN or CTRL-UP/DOWN to skip up or down 4 notes
			HOME/END to jump to the first or last note
			CTRL-LEFT/RIGHT to jump across columns
			
		
	3. Controls for both modes
	
		- + to navigate the current SFX
		< > to change the speed.
		SPACE to play/stop
		SHIFT-SPACE to play from the current SFX quarter (group of 8 notes)
		A to release a looping sample
		Left click or right click to increase / decrease the SPD or LOOP values
			// Hold shift when clicking to increase / decrease by 4
			// Alternatively, click and drag left/right or up/down
		Shift-click an instrument, effect, or volume to apply to all notes.
	
	
	:: Effects

		0 none
		1 slide          //  Slide to the next note and volume
		2 vibrato        //  Rapidly vary the pitch within one quarter-tone
		3 drop           //  Rapidly drop the frequency to very low values
		4 fade in        //  Ramp the volume up from 0
		5 fade out       //  Ramp the volume down to 0
		6 arpeggio fast  //  Iterate over groups of 4 notes at speed of 4
		7 arpeggio slow  //  Iterate over groups of 4 notes at speed of 8
		
		If the SFX speed is <= 8, arpeggio speeds are halved to 2, 4


:: Music Editor

	Music in PICO-8 is controlled by a sequence of 'patterns'. Each pattern is a list of
	4 numbers indicating which SFX will be played on that channel.
	
	
	:: Flow control
	
		Playback flow can be controlled using the 3 buttons at the top right.
	
		When a pattern has finished playing, the next pattern is played unless:
	
		- there is no data left to play (music stops)
		- a STOP command is set on that pattern (the third button)
		- a LOOP BACK command is set (the 2nd button), in which case the music player searches
			back for a pattern with the LOOP START command set (the first button) or returns to
			pattern 0 if none is found.
	
		When a pattern has SFXes with different speeds, the pattern finishes playing when
		the left-most non-looping channel has finished playing. This can be used to set up
		time signatures that don't divide into 32, or double-time drum beats etc.
	
	
	:: Copying music between or within cartridges
	
		To select a range of patterns: click once on the first pattern in the pattern 
		navigator, then shift-click on the last pattern. Selected patterns can be copied 
		and pasted with CTRL-C and CTRL-V. When pasting into another cartridge, the SFX 
		that each pattern points to will also be pasted (possibly with a different index) 
		if it does not already exist.


	:: SFX Instruments

		In addition to the 8 built-in instruments, custom instruments can be defined using 
		the first 8 SFX. Use the toggle button to the right of the instruments to select an 
		index, which will show up in the instrument channel as green instead of pink.

		When an SFX instrument note is played, it essentially triggers that SFX, but alters 
		the note's attributes:

			Pitch is added relative to C2
			Volume is multiplied
			Effects are applied on top of the SFX instrument's effects

		For example, a simple tremolo effect could be implemented by defining an instrument 
		in SFX 0 that rapidly alternates between volume 5 and 2. When using this instrument
		to play a note, the volume can further be altered as usual (via the volume channel
		or using the fade in/out effects). In this way, SFX instruments can be used to control 
		combinations of detailed changes in volume, pitch and texture.

		SFX instruments are only retriggered when the pitch changes, or the previous note
		has zero volume. This is useful for instruments that change more slowly over time.
		For example: a bell that gradually fades out. To invert this behaviour, effect 3
		(normally 'drop') can be used when triggering the note. All other effect values	have 
		their usual meaning when triggering SFX instruments.	

	
============================================================================================
	Lua Syntax Primer
============================================================================================

	PICO-8 programs are written using Lua syntax, but do not use the standard Lua library.
	The following is a brief summary of essential Lua syntax.

	For more details, or to find out about proper Lua, see www.lua.org.

	:: Comments

		-- use two hyphens like this to ignore everything until the end of the line
		--[[ multi-line
		comments ]]
	
	
	:: Types and assignment

		Types in Lua are numbers, strings, booleans and tables;

		NUM = 12/100
		S = "THIS IS A STRING"
		B = FALSE
		T = {1,2,3}
	
		Numbers in PICO-8 are all 16:16 fixed point. They range from -32768.0 to 32767.99999
		
		Hexadecimal notation with optional fractional parts can be used:
			0x11        -- 17
			0x11.4000   -- 17.25
	
		Numbers written in decimal are rounded to the closest fixed point value. To see the
		32-bit hexadecimal representation, use PRINT(TOSTR(VAL,TRUE)):
		
			?TOSTR(-32768,TRUE)      -- 0x8000.0000 
			?TOSTR(32767.99999,TRUE) -- 0x7fff.ffff
		
		Dividing by zero evaluates to 0x7fff.ffff if positive, or -0x7fff.ffff if negative. 
		

	:: Conditionals

		IF NOT B THEN
			PRINT("B IS FALSE")
		ELSE
			PRINT("B IS NOT FALSE")
		END
	
		-- with ELSEIF
	
		IF X == 0 THEN
			PRINT("X IS 0")
		ELSEIF X < 0 THEN
			PRINT("X IS NEGATIVE")
		ELSEIF X > 0 THEN
			PRINT("X IS POSITIVE")
		ELSE
			PRINT("THIS IS LINE IS NEVER REACHED")
		END
	
		IF (4 == 4) THEN PRINT("EQUAL") END
		IF (4 ~= 3) THEN PRINT("NOT EQUAL") END
		IF (4 <= 4) THEN PRINT("LESS THAN OR EQUAL") END
		IF (4 > 3) THEN PRINT("MORE THAN") END

	:: Loops

		FOR X=1,5 DO
			PRINT(X)
		END
		-- prints 1,2,3,4,5

		X = 1
		WHILE(X <= 5) DO
			PRINT(X)
			X = X + 1
		END
	
		FOR X=1,10,3 DO PRINT(X) END   -- 1,4,7,10

		FOR X=5,1,-2 DO PRINT(X) END  -- 5,3,1
	

	:: Functions and Local Variables

		Y=0 
		FUNCTION PLUSONE(X)
			LOCAL Y = X+1
			RETURN Y
		END
		PRINT(PLUSONE(2)) -- 3
		PRINT(Y)          -- 0


	:: Tables
	
		In Lua, tables are a collection of key-value pairs where the key and value types can both 
		be mixed. They can be used as arrays by indexing them with integers.

		A={} -- create an empty table
		A[1] = "BLAH"
		A[2] = 42
		A["FOO"] = {1,2,3}

		-- Arrays use 1-based indexing by default
	
		A = {11,12,13,14}
		PRINT(A[2]) -- 12
	
		-- The size of a table indexed with sequential 1-based integers:
	
		PRINT(#A)   -- 4
	
		-- Indexes that are strings can be written using dot notation
	
		PLAYER = {}
		PLAYER.X = 2 -- is equivalent to PLAYER["X"]
		PLAYER.Y = 3

		-- see also the tables section in the api reference below.

	
	:: PICO-8 Shorthand

		PICO-8 also allows several non-standard, shorter ways to write common patterns.
	
		1. IF THEN END statements on a single line can be expressed without the THEN & END
	
		IF (NOT B) I=1 J=2
	
		-- is equivalent to: IF (NOT B) THEN I=1 J=2 END
		-- everything must be written on the same line, and with the condition in brackets
		
	
		2. unary math operators
	
		a += 2  -- equivalent to: a = a + 2
		a -= 2  -- equivalent to: a = a - 2
		a *= 2  -- equivalent to: a = a * 2
		a /= 2  -- equivalent to: a = a / 2
		a %= 2  -- equivalent to: a = a % 2
	
	
		3. != operator
	
		Not shorthand, but pico-8 also accepts != instead of ~= for "not equal to"


============================================================================================
	API
============================================================================================

	PICO-8 is built on the Lua programming language, but does not include the Lua standard library.
	Instead, a small api is offered in keeping with PICO-8's minimal design and limited screen
	space. For an example program that uses most of the api functions, see /DEMOS/API.P8 
	
	Functions are written here as:
	function_name parameter [optional_parameter]

	System functions called from commandline can omit the usual brackets and string quotes:
	load blah.p8 --> load("blah.p8")

	
--------------------------------------------------------------------------------------------------------
	System
--------------------------------------------------------------------------------------------------------


	load filename [breadcrumb [param_str]]
	save filename
	
		Load or save a cartridge
		
		When loading from a running cartridge, the loaded cartridge is immediately run with
		parameter string param_str, and a menu item is inserted and named breadcrumb, that
		returns the user to the loading cartridge.
		
		Filenames that start with '#' are taken to be a BBS cart followed by its id:
		load("#1234") -- download [and run] cart number 1234
		
		If the id is of the cart's parent post, then the latest version is downloaded.
		BBS carts can be loaded from other BBS carts or local carts, but not from exported carts. 
		
		
	folder
	
		Open the carts folder in the host operating system.

	dir (also aliased as ls)

		List files in the current directory. When called from a running program, returns a list 
		of all .p8 and .p8.png files in the same directory.

	run
	
		Run from the start of the program
		Can be called from inside a program to reset program.

	stop [message]
	
		Stop the cart and optionally print a message

	resume
	
		Run from the existing cart state (flakey)

	reboot
		
		Reboot the machine
		Useful for starting a new project

	info
	
		Print out some information about the cartridge:
		Code size, tokens, compressed size
		
		Also displayed:
		
			UNSAVED CHANGES   When the cartridge in memory differs to the one on disk
			EXTERNAL CHANGES  When the cartridge on disk has changed since it was loaded
				(e.g. by editing the program using a separate text editor)
		
	flip
	
		Flip the back buffer to screen and wait for next frame (30fps)
		Don't normally need to do this -- _draw() calls it for you.
	
		If your program does not call flip before a frame is up, and a _draw() callback
		is not in progress, the current contents of the back buffer are copied to screen.

	printh str [filename] [overwrite]
	
		Print a string to host operating system's console for debugging.
	
		If filename is set, append the string to a file on the host operating system
			// (in the current directory -- use FOLDER to view)
		Setting overwrite to true causes that file to be overwritten rather than appended.
		
		Use a filename of "@clip" to write to the host's clipboard.
			// use stat(4) to read the clipboard, but the contents of the clipboard are only
			// available after pressing CTRL-V during runtime (for security reasons).

	stat x

		Get system status where x is:

		0  Memory usage (0..2048)
		1  CPU used since last flip (1.0 == 100% CPU at 30fps)
		4  Clipboard contents (after user has pressed CTRL-V)
		6  Parameter string
		7  Current framerate
		
		16..19  Index of currently playing SFX on channels 0..3
		20..23  Note number (0..31) on channel 0..3
		24      Currently playing pattern index
		25      Total patterns played
		26      Ticks played on current pattern

		80..85  UTC time: year, month, day, hour, minute, second
		90..95  Local time

		100     Current breadcrumb label, or nil


	extcmd x
	
		Special system command, where x is a string:
		
			"pause"      request the pause menu be opened
			"reset"      request a cart reset
			"go_back"    follow the current breadcrumb (if there is one)

		Additional commands that are ignored when running as a BBS cart:
		
			"label"      set cart label
			"screen"     save a screenshot
			"rec"        set video start point
			"video"      save a .gif to desktop
			"audio_rec"  start recording audio
			"audio_end"  save recorded audio to desktop

	
--------------------------------------------------------------------------------------------
	Program Structure
--------------------------------------------------------------------------------------------

	There are 3 special functions that, if defined by the user, are called during program 
	execution:
	
		_update()
			Called once per update at 30fps
	
		_draw()
			Called once per visible frame
		
		_init()
			Called once on program startup


	_draw() is normally called at 30fps, but if it can not complete in time, PICO-8 will
	attempt to run at 15fps and call _update() twice per visible frame to compensate.
	
	
	:: Running PICO-8 at 60fps

		If _update60() is defined instead of _update(), PICO-8 will run in 60fps mode:
	
		- both _update60() and _draw() are called at 60fps
		- half the PICO-8 CPU is available per frame before dropping down to 30fps
		
		Note that not all host machines are capable of running at 60fps. Older machines,
		and / or web versions might also request PICO-8 to run at 30 fps (or 15 fps), even
		when the PICO-8 CPU is not over capacity. In this case, multiple _update60 calls
		are made for every _draw call in the same way.


--------------------------------------------------------------------------------------------
	Graphics
--------------------------------------------------------------------------------------------
  
	PICO-8 has a fixed capacity of 128 8x8 sprites, plus another 128 that overlap with the
	bottom half of the map data ("shared data"). These 256 sprites are collectively called
	the sprite sheet, and can be thought of as a 128x128 pixel image.

	All of PICO-8's drawing operations are subject to the current draw-state. The draw-state
	includes a camera position (for adding an offset to all coordinates), palette mapping 
	(for recolouring sprites), clipping rectangle, a drawing colour, and a fill pattern.
	
	The draw state is reset each time a program is run. This is equivalent to calling:
	clip() camera() pal() color(6)

	Colours indexes:
	
	 0  black   1  dark_blue   2  dark_purple   3  dark_green  
	 4  brown   5  dark_gray   6  light_gray    7  white
	 8  red     9  orange     10  yellow       11  green       
	12  blue   13  indigo     14  pink         15  peach
		

	clip [x y w h]

		Sets the screen's clipping region in pixels
		clip() to reset
	
	
	pget x y
	pset x y [c]

		Get or set the colour (c) of a pixel at x, y.
	
	
	sget x y
	sset x y [c]

		Get or set the colour (c) of a spritesheet pixel.
	
	
	fget n [f]
	fset n [f] v

		Get or set the value (v) of a sprite's flag
		f is the flag index 0..7
		v is boolean and can be true or false
	
		The initial state of flags 0..7 are settable in the sprite editor,
		using the line of little colourful buttons.
	
		The meaning of sprite flags is up to the user, or can be used to
		indicate which group ('layer') of sprites should be drawn by map.

		If the flag index is omitted, all flags are retrieved/set as a bitfield
		fset(2, 1+2+8)   -- sets bits 0,1 and 3
		fset(2, 4, true) -- sets bit 4
		print(fget(2))   -- 27 (1+2+8+16)


	print str [x y [col]]

		Print a string
		If only str is supplied, and the cursor reaches the end of the screen,
		a carriage return and vertical scroll is automatically applied.
		

	cursor x y

		Set the cursor position and carriage return margin


	color col

		Set the default color to be used by drawing functions
	
	
	cls [col]

		Clear the screen and reset the clipping rectangle
		

	camera [x y]

		Set a screen offset of -x, -y for all drawing operations
		camera() to reset
	
	
	circ     x y r [col]
	circfill x y r [col]

		Draw a circle or filled circle at x,y with radius r
		If r is negative, the circle is not drawn

	line x0 y0 x1 y1 [col]

		draw line


	rect     x0 y0 x1 y1 [col]
	rectfill x0 y0 x1 y1 [col]

		Draw a rectangle or filled rectangle
	
	
	pal c0 c1 [p]

		Draw all instances of colour c0 as c1 in subsequent draw calls

		pal() to reset to system defaults (including transparency values and fill pattern)
		
		Two types of palette (p; defaults to 0)
			0 draw palette   : colours are remapped on draw    // e.g. to re-colour sprites
			1 screen palette : colours are remapped on display // e.g. for fades
		c0 colour index 0..15
		c1 colour index to map to
	

	palt c t

		Set transparency for colour index to t (boolean)
		Transparency is observed by spr(), sspr() and map()
		e.g. palt(8, true) -- red pixels not drawn
		palt() resets to default: all colours opaque except colour 0
	


	spr n x y [w h] [flip_x] [flip_y]

		draw sprite n (0..255) at position x,y
		width and height are 1,1 by default and specify how many sprites wide to blit.
		Colour 0 drawn as transparent by default (see palt())
		flip_x=true to flip horizontally
		flip_y=true to flip vertically


	sspr sx sy sw sh dx dy [dw dh] [flip_x] [flip_y]

		Stretch rectangle from sprite sheet (sx, sy, sw, sh) // given in pixels
		and draw in rectangle (dx, dy, dw, dh)
		Colour 0 drawn as transparent by default (see palt())
		dw, dh defaults to sw, sh
		flip_x=true to flip horizontally
		flip_y=true to flip vertically
		

	fillp p
	
		The PICO-8 fill pattern is a 4x4 2-colour tiled pattern observed by:
			circ() circfill() rect() rectfill() pset() line()
		
		p is a bitfield in reading order starting from the highest bit. To calculate the value
		of p for a desired pattern, add the bit values together:
		
			.-----------------------.
			|32768|16384| 8192| 4096|
			|-----|-----|-----|-----|
			| 2048| 1024| 512 | 256 |
			|-----|-----|-----|-----|
			| 128 |  64 |  32 |  16 |
			|-----|-----|-----|-----|
			|  8  |  4  |  2  |  1  |
			'-----------------------'
		
		For example, FILLP(4+8+64+128+  256+512+4096+8192) would create a checkerboard pattern.
		
		This can be more neatly expressed in binary: FILLP(0b0011001111001100)
		The default fill pattern is 0, which means a single solid colour is drawn.
		
		To specify a second colour for the pattern, use the high bits of any colour parameter:
		
			FILLP(0b0011010101101000)
			CIRCFILL(64,64,20, 0x4E) -- brown and pink
		
		An additional bit 0b0.1 can be set to indicate that the second colour is not drawn.
		
			FILLP(0b0011001111001100.1) -- checkboard with transparent squares
		
		The fill pattern can also be set by setting bits in any colour parameter:

			POKE(0x5F34, 1) -- sets integrated fillpattern + colour mode
			CIRCFILL(64,64,20, 0x114E.ABCD) -- sets fill pattern to ABCD

			-- bit  0x1000.0000 means the non-colour bits should be observed
			-- bit  0x0100.0000 transparency bit
			-- bits 0x00FF.0000 are the usual colour bits
			-- bits 0x0000.FFFF are interpreted as the fill pattern
	
--------------------------------------------------------------------------------------------
	Tables
--------------------------------------------------------------------------------------------
	
	
	add t v

		Add value v to the end of table t.
		Equivalent to t[#t+1] = v

			FOO={}        -- create empty table
			ADD(FOO, 11)
			ADD(FOO, 22)
			PRINT(FOO[2]) -- 22

	del t v

		Delete the first instance of value v in table t
		The remaining entries are shifted left one index to avoid holes.
		Note that v is the value of the item to be deleted, not the index into the table!
		del() can be called safely on a table's item while iterating over that table.

			A={1,10,2,11,3,12}
			FOR ITEM IN ALL(A) DO
				IF (ITEM < 10) THEN DEL(A, ITEM) END
			END
			FOREACH(A, PRINT) -- 10,11,12
			PRINT(A[3])       -- 12


	all t

		Used in FOR loops to iterate over all items in a table (that have a 1-based integer index), 
		in the order they were added.
	
			T = {11,12,13};
			ADD(T,14)
			ADD(T,"HI")
			FOR V IN ALL(T) DO PRINT(V) END -- 11 12 13 14 HI
			PRINT(#T) -- 5


	foreach t f

		For each item in table t, call function f with the item as a single parameter.
	
			FOREACH(T, PRINT)


	pairs t

		Used in FOR loops to iterate over table t, providing both the key and value for each item.
		Unlike all(), pairs() iterates over every item regardless of indexing scheme.
		Order is not guaranteed.
	
			T = {["HELLO"]=3, [10]="BLAH"}
			T.BLUE = 5;
			FOR K,V IN PAIRS(T) DO
				PRINT("K: "..K.."  V:"..V)
			END

		Output:
		
			K: 10  v:BLAH
			K: HELLO  v:3
			K: BLUE  v:5


--------------------------------------------------------------------------------------------
	Input
--------------------------------------------------------------------------------------------

	btn [i [p]]

		get button i state for player p (default 0) 
		i: 0..5: left right up down button_o button_x
		p: player index 0..7
	
		If no parameters supplied, returns a bitfield of all 12 button states for player 0 & 1
			// P0: bits 0..5  P1: bits 8..13
	
		Default keyboard mappings to player buttons:
			player 0: cursors, Z,X / C,V / N,M
			player 1: ESDF, LSHIFT,A / TAB,Q,E


	btnp [i [p]]

		btnp is short for "Button Pressed"; Instead of being true when a button is held down, 
		btnp returns true when a button is down AND it was not down the last frame. It also
		repeats after 15 frames, returning true every 4 frames after that (at 30fps -- double
		that at 60fp). This can be used for things like menu navigation or grid-wise player 
		movement.

		

--------------------------------------------------------------------------------------------
	Audio
--------------------------------------------------------------------------------------------

	sfx n [channel [offset [length]]]

		play sfx n on channel (0..3) from note offset (0..31) for length notes
		n -1 to stop sound on that channel
		n -2 to release sound on that channel from looping
		Any music playing on the channel will be halted
		offset in number of notes (0..31)
		
		channel -1 (default) to automatically choose a channel that is not being used
		channel -2 to stop the sound from playing on any channel
	
		
	music [n [fade_len [channel_mask]]]

		play music starting from pattern n (0..63)
		n -1 to stop music
		fade_len in ms (default: 0)
		channel_mask specifies which channels to reserve for music only
			e.g. to play on channels 0..2: 1+2+4 = 7
		
		Reserved channels can still be used to play sound effects on, but only when that
		channel index is explicitly requested by sfx().


--------------------------------------------------------------------------------------------------------
	Map
--------------------------------------------------------------------------------------------------------

	The PICO-8 map is a 128x32 grid of 8-bit cels, or 128x64 when using the shared memory. When 
	using the map editor, the meaning of each cel is taken to be an index into the spritesheet 
	(0..255). However, it can instead be used as a general block of data.
	
	
	mget x y
	mset x y v

		get or set map value (v) at x,y

	map cel_x cel_y sx sy cel_w cel_h [layer]

		draw section of map (in cels) at screen position sx, sy (pixels)
		if layer is specified, only cels with the same flag number set are drawn
			// Bitfield. So 0x5 means draw sprites with bit 0 and bit 2 set.
			// defaults to all sprites
	
		exception: sprite 0 is always taken to mean empty.
	
		e.g. map(0,0, 20,20, 4,2)
		-> draws a 4x2 blocks of cels starting from 0,0 in the map, to the screen at 20,20
		
		If cel_w and cel_h are not specified, defaults to 128,32 
		(the top half of the map -- use 128,64 for the full map including shared memory)


--------------------------------------------------------------------------------------------------------
	Memory
--------------------------------------------------------------------------------------------------------

	PICO-8 has 3 types of memory:

		1. Base RAM (32k): see layout below. Access with peek() poke() memcpy() memset()
		2. Cart ROM (32k): same layout as base ram until 0x4300
		3. Lua RAM (2MB): compiled program + variables

		Technical note: // you probably don't need to know this
		
			While using the editor, the data being modified is in cart rom, but api functions such as spr() 
			and sfx() only operate on base ram. PICO-8 automatically copies cart rom to base ram (i.e.
			calls reload()) in 3 cases:

			1. When a cartridge is loaded
			2. When a cartridge is run
			3. When exiting any of the editor modes


	:: Base ram memory layout
		0x0    gfx
		0x1000 gfx2/map2 (shared)
		0x2000 map
		0x3000 gfx_props
		0x3100 song
		0x3200 sfx
		0x4300 user data
		0x5e00 persistent cart data (256 bytes)
		0x5f00 draw state
		0x5f40 hardware state
		0x5f80 gpio pins (128 bytes)
		0x6000 screen (8k)

		User data has no particular meaning and can be used for anything via memcpy(), peek() & poke().
		Persistent cart data is mapped to 0x5e00..0x5eff but only stored if cartdata() has been called.
		Colour format (gfx/screen) is 2 pixels per byte: low bits encode the left pixel of each pair.
		Map format is one byte per cel, where each byte normally encodes a sprite index.


	peek addr
	poke addr val

		Read and write one byte to an address in base ram.
		Legal addresses are 0x0..0x7fff
		Reading out of range returns 0
		Writing out of range causes a fault
		
	peek4 addr
	poke4 addr val
	
		32-bit versions. Read and write one number (val) in little-endian format.
		addr does not need to be aligned to 4-byte boundaries.

	memcpy dest_addr source_addr len

		Copy len bytes of base ram from source to dest
		Sections can be overlapping

	reload dest_addr source_addr len [filename]

		Same as memcpy, but copies from cart rom
		The code section ( >= 0x4300) is protected and can not be read.
		If filename specified, load data from a different cartridge.
			// (must be local -- bbs cartridges can not be read in this way)

	cstore dest_addr source_addr len [filename]

		Same as memcpy, but copies from base ram to cart rom
		cstore() is equivalent to cstore(0, 0, 0x4300)
		Can use for writing tools to construct carts or to visualize the state 
		of the map / spritesheet using the map editor / gfx editor.
		The code section ( >= 0x4300) is protected and can not be written to.
		
		If a filename is specified, the data is written directly to that
		cartridge on disk. Up to 64 cartridges can be written in one session.
		See the 'Cartridge Data' section for additional notes on using cstore.
		
		
	memset dest_addr val len

		Set len bytes to val
		(quite fast -- can use to draw unclipped horizonal scanlines etc)
	

--------------------------------------------------------------------------------------------------------
	Math
--------------------------------------------------------------------------------------------------------

	max x y
	min x y
	mid x y z

		Returns the maximum, minimum, or middle value of parameters
		For example, mid(7,5,10) returns 7

	flr  x
	ceil x

		Returns the closest integer that is equal to or below / above x 
		
		?flr ( 4.1) -->  4
		?ceil( 4.1) -->  5
		?flr (-2.3) --> -3
		?ceil(-2.3) --> -2


	cos x
	sin x

		Returns the cosine of x, where 1.0 indicates a full circle
		sin is inverted to suit screenspace
		e.g. sin(0.25) returns -1

		If you'd prefer radian-based trig functions without the y inversion, 
		paste the following snippet near the start of your program:
	
		cos1 = cos function cos(angle) return cos1(angle/(3.1415*2)) end
		sin1 = sin function sin(angle) return sin1(-angle/(3.1415*2)) end
	

	atan2 dx dy

		Converts dx, dy into an angle from 0..1
		As with cos/sin, angle is taken to run anticlockwise in screenspace
		e.g. atan(1, -1) returns 0.125

	sqrt x

		Return the square root of x
	
	abs x

		Returns the absolute (positive) value of x

	rnd x
		Returns a random number n, where 0 <= n < x
		If you want an integer, use flr(rnd(x))
	
	srand x
		Sets the random number seed
		The seed is automatically randomized on cart startup


	Binary Operations

		band x y
		bor  x y
		bxor x y
		bnot x
		rotl x y
		rotr x y
		shl  x n -- shift left n bits
		shr  x n -- arithmetic right shift
		lshr x n -- logical right shift


--------------------------------------------------------------------------------------------------------
	Custom Menu Items
--------------------------------------------------------------------------------------------------------

	menuitem index [label callback]

		Add an extra item to the pause menu
	
		Index should be 1..5 and determines the order each menu item is displayed
		label should be a string up to 16 characters long
		callback is a function called when the item is selected by the users
	
		When no label or function is supplied, the menu item is removed
	
		example:
		menuitem(1, "restart puzzle", function() reset_puzzle() sfx(10) end)
	

--------------------------------------------------------------------------------------------------------
	Strings
--------------------------------------------------------------------------------------------------------

	s = "the quick brown fox"
	
	-- length
	
		print(#s)          --> 19
	
	
	-- joining strings
		
		print("three "..4) --> "three 4"
	
	
	-- sub() to grab substrings
	
		print(sub(s,5,9))  --> "quick"
		print(sub(s,5))  --> "quick brown fox"


--------------------------------------------------------------------------------------------------------
	Types
--------------------------------------------------------------------------------------------------------

	type val
	
		returns the name of the type of value x as a string
	
	tostr val [hex]

		returns val as a string
		
		if hex is true and val is a number, an unsigned hexadecimal writing of 
		the number is returned in the format "0x0000.0000". You can use this to
		inspect the internal representation of PICO-8 numbers.
		
		if val is a boolean, it is written as "true" or "false"
		
		all other val types are written as "[typename]"
		
	tonum val
	
		converts val to a number
		if val is a string, the number is taken to be decimal unless prefixed with "0x"
		if the conversion fails, tonum returns no value.

--------------------------------------------------------------------------------------------
	Cartridge Data
--------------------------------------------------------------------------------------------

	Using cartdata(), dset(), and dget(), 64 numbers (256 bytes) of persistent data 
	can be stored on the user's PICO-8 that persists after the cart is unloaded or
	PICO-8 is shutdown. This can be used as a lightweight way to store things like 
	high scores or to save player progress. It can also be used to share data across 
	cartridges / cartridge versions.
	
	If you need more than 256 bytes, it is also possible to write directly to the
	cartridge using cstore(). The disadvantage is that the data is tied to that
	particular version of the cartridge. e.g. if a game is updated, players will
	lose their savegames. Also, some space in the data sections of the cartridge
	need to be left available.
	
	Another alternative is to write directly to a second cartridge by specifying
	a fourth parameter to cstore(). This requires a cart swap (which in reality
	only means the user needs to watch a spinny cart animation for 1 second).
	
		CSTORE(0,0,0x2000, "spritesheet.p8")
		-- later:
		RELOAD(0,0,0x2000, "spritesheet.p8") -- restore the saved data
	

	cartdata id
	
		cartdata() opens a permanent data storage slot indexed by id, that can be
		used to store and retrieve up to 256 bytes (64 numbers) worth of data using 
		DSET() and DGET().
		
			CARTDATA("zep_dark_forest") -- can only be set once per session
			-- later in the program..
			DSET(0, score)
		
		id is a string up to 64 characters long, and should be unusual enough that 
		other cartridges do not accidentally use the same id.
	
		e.g. cartdata("zep_jelpi")
	
		legal characters are a..z, 0..9 and underscore (_)

		returns true if data was loaded, otherwise false

		cartdata can not be called more than once per cartridge execution.
	
		Once a cartdata id has been set, the area of memory 0x5e00..0x5eff is mapped 
		to permanent storage, and can either be accessed directly or via dget/dset.
	
	
	dget index

		Get the number stored at index (0..63)
		Use this only after you have called cartdata()

	dset index value

		Set the number stored at index (0..63)
		Use this only after you have called cartdata()
	
		There is no need to flush written data -- it is automatically
		saved to permanent storage even if POKE()'ed directly.


--------------------------------------------------------------------------------------------
	GPIO
--------------------------------------------------------------------------------------------

	GPIO stands for "General Purpose Input Output", and allows machines to comunicate with 
	each other. PICO-8 maps bytes in the range 0x5f80..0x5fff to gpio pins that can be
	poke()ed (to output a value -- e.g. to make an LED light up) or peek()ed (e.g. to read
	the state of a switch).
	
	GPIO means different things for different host platforms:
	
	CHIP:         0x5f80..0x5f87 mapped to xio-p0..xio-p7
	Pocket CHIP:  0x5f82..0x5f87 mapped to GPIO1..GPIO6
		// xio-p0 & p1 are exposed inside the prototyping area inside the case.
	Raspberry Pi: 0x5f80..0x5f8f mapped to wiringPi pins 0..7
		// see http://wiringpi.com/pins/ for mappings on different models
	
	CHIP and Raspberry Pi values are all digital: 0 (LOW) and 255 (HIGH)
	
	Note that to have access to gpio pins, you may need to run pico8 as root: 
	
	sudo pico8
	
	A simple program to blink any LEDs attached on and off:
	
	t = 0
	function _draw()
	 cls(5)
	 for i=0,7 do
	  val = 0
	  if (t % 2 < 1) val = 255
	  poke(0x5f80 + i, val)
	  circfill(20+i*12,64,4,val/11)
	 end
	 t += 0.1
	end
	
	:: HTML
	
	Cartridges exported as HTML / .js use a global array of integers (pico8_gpio) to 
	represent gpio pins. The shell HTML should define the array:
	
	var pico8_gpio = Array(128);


--------------------------------------------------------------------------------------------
	Mouse and Keyboard Input
--------------------------------------------------------------------------------------------

	// experimental! The html implementation is still limited & buggy.

	Mouse and keyboard input can be achieved by enabling devkit input mode:
	
	POKE(0x5F2D, 1)
	
	Note that not every PICO-8 will have a keyboard or mouse attached to it, so when posting
	carts to the Lexaloffle BBS, it is encouraged to make keyboard and/or mouse control 
	optional and off by default, if possible. When devkit input mode is enabled, a message is
	displayed to BBS users warning them that the program is expecting input beyond the 
	standard 6-button controllers.
	
	The state of the mouse and keyboard can be found in stat(x):
	
	STAT(30) -- (Boolean) True when a key
	STAT(31) -- (String) character returned by keyboard
	STAT(32) -- Mouse X
	STAT(33) -- Mouse Y
	STAT(34) -- Mouse buttons (bitfield)
	STAT(36) -- Mouse wheel event


--------------------------------------------------------------------------------------------
	Additional Lua Features
--------------------------------------------------------------------------------------------

	PICO-8 also exposes 2 features of Lua for advanced users: Metatables and Coroutines.
	
	For more information, please refer to the Lua 5.2 manual.
	
	:: Metatables
	
		Metatables can be used to define the behaviour of objects under particular operations.
		For example, to use tables to represent 2D vectors that can be added together, the 
		'+' operator is redefined by defining an "__add" function for the metatable:
	
			vec2d={
			 __add=function(a,b) 
			 	return {x=(a.x+b.x), y=(a.y+b.y)} 
			 end
			}
		
			v1={x=2,y=9} setmetatable(v1, vec2d)
			v2={x=1,y=5} setmetatable(v2, vec2d)
			v3 = v1+v2
			print(v3.x..","..v3.y) -- 3,14


		setmetatable t, m
	
			set table t metatable to m
		
		getmetatable t
		
			return the current metatable for table t, or nil if none is set
	
	:: Coroutines
	
		Coroutines offer a way to run different parts of a program in a somewhat concurrent 
		way, similar to threads. A function can be called as a coroutine, suspended with 
		yield() any number of times, and then resumed again at the same point.
		
			function hey()
				print("doing something")
				yield()
				print("doing the next thing")
				yield()
				print("finished")
			end
			
			c = cocreate(hey)
			for i=1,3 do coresume(c) end
		
		
		cocreate f
		
			Create a coroutine for function f.
			
		coresume c [p0 p1 ..]
		
			Run or continue the coroutine c. Parameters p0, p1.. are passed to the
			coroutine's function.
			
			Returns true if the coroutine completes without any errors
			Returns false, error_message if there is an error.
			
			** Runtime errors that occur inside coroutines do not cause the program
			to stop running. It is a good idea to wrap coresume() inside an assert().
			If the assert fails, it will print the error message generated by 
			coresume.
			
			assert(coresume(c))


		costatus c
		
			Return the status of coroutine c as a string:
				"running"
				"suspended"
				"dead"
		
		yield
			
			Suspend execution and return to the caller.


--------------------------------------------------------------------------------------------
	VERSION HISTORY
--------------------------------------------------------------------------------------------


	v0.1.11g
		
		Added: CTRL-C to copy contents of commandline
		Added: stat(100..102) for current breadcrumb label, bbs cart id, and hostname (web)
		Added: content_filter in config.txt
		Added: Cartverse cart id support (not live server-side yet though)
		Fixed: Tab preview does not show on mouseover
		Fixed: Can't paste uppercase characters into commandline
		Fixed: Preprocessor can't handle glyphs in form: "♥.x += 1"
		Fixed: Unsaved changes sometimes reported when filename is not set
		Fixed: Pause menu doesn't open inside infinite loop inside _draw
		Fixed: load() crashes when "parameter string" parameter is not a string
		Fixed: cstore(),reload() crash when external cart filename is not a string
		Fixed: printh(str, "@clip") fails for glyph characters in str


	v0.1.11f

		Fixed: Pause menu doesn't open inside an infinite loop
		Fixed: Binary and hex string digits outside of 0xffff.ffff alter result


	v0.1.11e

		Added: stat(30..31) for devkit keyboard input
		Added: extcmd("pause") extcmd("reset") extcmd("breadcrumb")
		Added: lshr(), ceil(), rotl(), rotr(), peek4(), poke4()
		Added: stat(12..15) to grab the position of the pause menu (x0,y0,y1,y1)
		Added: DPAD game controller buttons mapped to LRUD
		Added: CTRL-click on song navigator to scroll by 4 patterns
		Added: Can type and paste glyphs in commandline
		Added: Notification when CTRL-R fails to reload because of unsaved changes
		Added: Notification when code automatically converted to lower-case
		Added: INFO() checks for "external changes" (e.g. when using a separate text editor)
		Added: .p8.png format can be used with cstore() and carts bundled in multicarts
		Added: Can optionally set fill pattern using colour parameter 
		Changed: Glyphs can be used as variable names
		Changed: Glyphs stored in clipboard and .p8 format as roughly corresponding unicode
		Changed: .p8 format skips storing tailing rows of data that match default state
		Changed/Fixed: shr(x,n) is now equivalent to calling shr(x,1) n times when n >= 32
		Fixed: Error message and stack trace line numbers 0 or slightly out
		Fixed: Unclosed block error navigates cursor to <eof> rather than start of block
		Fixed: Exported binaries can load carts outside of bundle
		Fixed: BBS cart loaded from a local cart loses data cstore()ed during previous run
		Fixed: btn() returns same as btnp()
		Fixed: btnp(6) always returns false
		Fixed: Missing mask pixels in cart download animation frame
		Fixed: Crash when try to load a directory as a cart
		Fixed: Sometimes cursor position set by keyboard mouse emulation in code editor
		
		
	v0.1.11d

		Added: t() aliased to time()
		Fixed: time() always returns 0 when there is no _update function
		Fixed: (raspi) Keyboard stops responding after pressing CTRL-F, CTRL-Z
		Fixed: (raspi) Double keypresses in sound editor when entering notes
		Fixed: stat(6) pads parameter string with spaces

	
	v0.1.11c
		
		Added: Local and UT time queries using stat()
		Added: host_framerate_control (config.txt) to improve performance on slower machines and web 
		Added: Control over cpu usage when running in background (-background_sleep_ms / config.txt)
		Added: Windows icon in exported exe
		Added: F11 to toggle fullscreen
		Added: export -c switch to indicate transparent icon colour 
		Added: show_backup_messages (config.txt) to turn off backup notifications
		Added: SFX instruments documentation in pico8.txt
		Added: Error message when trying to export carts with code size over the compressed limit
		Changed: If config.txt is not found, the same directory as the executable is searched
		Changed: If sdl_controllers.txt exists in the same directory as the executeable, it is processed first
		Changed: Shorthand if () statements must be written on a single line
		Fixed: reload() from bundled, non-primary cart in exported html multicart reads only original data
		Fixed: Exported binaries wrongly observe F7 (capture label)
		Fixed: Loading carts from earlier versions alters SFX data not intended for audio
		Fixed: Old version of fill patterns documentation near end of pico8.txt
		Fixed: 'backed up unsaved changes' message displayed during runtime for cstored() carts
		Fixed: PICO-8 runs too slowly when in background (new default background_sleep_ms: 20)
		Fixed: Saving screenshots and videos from exported binaries are named 0_*
		Fixed: Compressed size limit warning on save doesn't mention exported carts
		Fixed: btn(), btnp() don't work in infinite loops
		Fixed: btnp() timing inconsistent between 30fps / 60fps / during frame-skipping / with no _update
		Fixed: Can't move between channels while music is playing in song mode


	v0.1.11b
	
		Fixed: Preprocessor bug regressions: "if (..) or", "a.b -= c - d"
		Fixed: Crash when pressing menu button on an empty favourites list


	v0.1.11
		
		Added: Binary exporters (Windows, Linux, Mac OSX)
		Added: Code tabs
		Added: Splore cart menu
		Added: Fill patterns
		Added: Custom sfx instruments
		Added: load("#1234") to load [and run] a BBS cart
		Added: -x switch // execute a cart headless, for making command-line tools
		Added: Compressed size display and limit warning lights in code editor
		Added: CTRL-L to jump to a line number in code editor
		Added: numbers can be written in binary: 0b10100010 
		Added: tostr(), tonum()
		Added: extcmd(): audio_rec, audio_end to record all audio output.
		Added: ls() returns a list of local files if called while running
		Added: getmetatable()
		Added: coroutine error reporting // wrap coresume() in assert()
		Added: sfx() can take a 4th parameter: number of notes to play
		Added: Live sfx and music editing + better navigation controls
		Added: Transpose selected sfx notes relative to C by entering a note w/ SHIFT held
		Added: Insert and delete sfx rows with enter and backspace
		Added: Hidden note data is shown in sfx editor when relevant (slide, arps)
		Added: Warning displayed when unsaved changes backed up
		Added: Separate animation for downloading vs. loading a cart
		Added: export -p switch to supply a customized html template 
		Added: Mousewheel when devkit mouse enabled: stat(36) // not supported in web
		Added: < > to change zoom level in gfx and map editors
		Changed: Rebalanced / fixed api cpu costs
		Changed: Screenshot and gif filenames based on current cart if available
		Changed: add() returns the added object
		Changed: removed global hpf on audio
		Changed: (sfx) can slide to volume 0
		Changed: removed master low pass filter
		Changed: assert() can take an optional error_message parameter
		Changed: ? (shorthand for print()) can be prefixed by whitespace 
		Changed: shl(), shr() return 0 if second parameter >= 32
		Changed: Automatically drop down to software blitting mode if opengl fails
		Changed: Lua memory limit set to 2MB (was 1MB)
		Changed: Some options (-width, -show_fps) apply only to the session; not saved to config.txt
		Updated: Internal game controller mappings from SDL_GameControllerDB
		Fixed: Pops & clicks in audio when switching between playing SFX
		Fixed: Crash in audio mixer because of bad locking
		Fixed: Crash when loading .p8 files with more than 64k of code
		Fixed: Indexing of sparse tables fails after removing n/2 elements
		Fixed: Calling stat() inside an infinite loop crashes
		Fixed: Resetting cartridge corrupts cartridge data in range 0x5e00..0x5eff
		Fixed: Can not recover from a cart error caused by glitchy data on resetting 
		Fixed: String->negative number conversion off by 0x0.0001 (-1 --> 0xffff0001)
		Fixed: Crash when running cart closed to 64k char limit
		Fixed: Cursor can't move to the right of last character in code editor
		Fixed: Missing highlighted keywords: in, add, del, menuitem
		Fixed: Preprocessor bugs: "a+=1+2\n*3", "a+=(1)ba=42", "a[(1)]+=1"
		Fixed: Preprocessor performs replacements inside a string printed with ?
		Fixed: Display freezes when terminating a program running at >100% cpu
		Fixed: Quick-running (CTRL-R) clobbers some editor state (e.g. current sprite page)
		Fixed: Loading a .p8 file with a future version reports a generic failure
		Fixed: alt-enter to toggle fullscreen also triggers pause menu
		Fixed: Splore scrolling jumps around when list gets too long


	v0.1.10c
	
		Fixed: atan flips sign for very negative values of x close to zero


	v0.1.10b
		Fixed: HTML exporter carts don't run
		Fixed: HTML export 60fps support broken
		Fixed: HTML export when path has a space in it (common for OSX)
		Fixed: atan2 ignores sign of y
		Fixed: (Raspberry Pi) Crash when access gpio not as root
		

	v0.1.10
	
		Added: Multi-cart export in html
		Added: Cart reset glitch
		Added: Demo carts: bounce, sort
		Added: .p8 format can now store cart labels
		Added: Splore navigation keys: pageup/down, home, end
		Added: Splore usage hint shown on empty favourites list
		Added: Warning on boot when data folder is read-only or can't be created
		Added: Pressing tab with code selected indents those lines (shift-tab to un-indent)
		Added: Double click word to select it
		Added: Trigger screenshot/video/label capture from inside program: extcmd()
		Changed: CTRL+left/right in code editor skips to end of word or span of non-whitespace
		Changed: When a cart terminates from splore, button press is required to continue
		Changed: load("@clip") can only be called from commandline (security)
		Fixed: Can over-allocate host memory if exceed it within one frame
		Fixed: atan2(-1, -32768) crash, and error for small values of dy
		Fixed: (Web) using cstore() on self causes unloadable cart (bug introduced in 0.1.8?)
		Fixed: (web) Pressing ctrl-v crashes the player (should do nothing)
		Fixed: (Raspberry Pi) WiringPi library required in static build
		Fixed: (Raspberry Pi) Crash on exit when launching via desktop icon
		Fixed: (Raspberry Pi) keyboard input broken (observed on raspi2s)


	v0.1.9b

		Added: Alternative function key mapping: ctrl-6..9 for F6..F9
		Added: Alternative glyph entry method: (ctrl-k) to toggle glyph mode
		Changed: Enter glyphs with shift a..z, but can be disabled in config.txt 
		Changed: Increased emscripten ram to 128MB (some carts at risk of running out)
		Fixed: Crash when window size is tiny or minified
		Fixed: Crash on toggling fullscreen mode
		Fixed: printh can write files outside filetree (security issue)
		Fixed: show_fps (can also now be toggled with ctrl-1)
		Fixed: Shorthand if/then syntax error when using the form: (functionname)(param)
		Fixed: log.txt not saved in path specified by -home switch
		Fixed: Default application data folder created even when -home specified
		Fixed: Missing dynamic builds (pico8_dyn) from linux archives
		Fixed: Removed unneeded RPATH from linux binaries
		Fixed: export foo%d.wav fails to write multiple files 

	v0.1.9
	
		Added: Copy and paste sprites and whole cartridges directly to BBS posts 
		Added: JAM category in splore
		Added: GPIO support for Raspberry Pi
		Added: Read clipboard using stat(4) after user presses CTRL-V
		Added: printh() can optionally write to a file or the host clipboard
		Added: Editor tool information and tips shown on mouseover
		Added: Set desktop path with -desktop (screenshots and gifs are saved here)
		Added: Warning on saving .p8 when compressed code size exceeds .p8.png limit
		Added: Alternative editor colours // config.txt: gui_theme 1
		Added: Dotted line every 8 rows in song view
		Added: -screenshot_scale (default: 3) and -gif_scale (default: 2)
		Added: Can use ctrl-up, ctrl-down to jump to start and end of code
		Added: CTRL-M to mute/unmute sound
		Added: HTML5-exported carts support 60fps
		Added: Timeout switch for splore downloads: -timeout
		Changed: Glyph characters typed with alt + a..z 
		Changed: stat(0) does not include allocations waiting to be garbage collected
		Changed: Unfiltered screen stretching at integer scales by default
		Changed: Removed -aspect and -scale settings (use draw_rect instead)
		Fixed: -home has no effect under Windows
		Fixed: Sometimes frame skipping starts before CPU usage has reached 100%
		Fixed: Double-speed BTNP() timing in 60fps mode
		Fixed: Exported HTML fails when _update60 is used instead of _update
		Fixed: Can't copy and paste button glyphs
		Fixed: Lines containing glyphs do not scroll far enough horizontally 
		Fixed: Loading .p8 renamed as .p8.png from splore freezes
		Fixed: Bucketfill in map doesn't sync to shared memory
		Fixed: fset fails when de-setting flags
		Fixed: Syntax error when beginning with the form: IF (..) [OR|AND]\n  
		Fixed: cls() costs twice as much cpu as it should
		Fixed: wav file exporter missing some data / writing truncated buffers
		Fixed: Entering new notes in song view doesn't observe current volume, instrument
		Fixed: alt-tab sometimes generates alt character text entry event
		Fixed: Resuming a cancelled download in splore causes crash
		Fixed: Controller attributes in log.txt always shown as -1	
		
		
	v0.1.8
	
		Added: 60fps support
		Added: Music exporter
		Added: Custom GIF length (maximum 120 seconds)
		Added: -,+ to navigate sprite tabs, sfx, music patterns
		Added: sfx editor: navigate with home, end, pageup/down, mousewheel
		Added: <, > to modify sfx speed, or click and drag
		Added: Middle mouse button to pan around spritesheet / map
		Added: Shortcut command for splore: S
		Added: Pre-installed selection of BBS cart (use INSTALL_GAMES)
		Added: Warning when saving .p8.png with no label 
		Added: (OSX) logging to ~/Library/Logs (viewable with Console.app)
		Added: -pixel_perfect switch (on by default)
		Added: -draw_rect switch
		Changed: Can not CTRL-S save over a loaded bbs cart
		Changed: Only .p8 files listed by dir() and by splore
		Changed: Command history increased to 256
		Changed: exit() / shutdown() have no effect while running cart
		Fixed: Memory usage (stat(0)) inconsistent across host platforms
		Fixed: Spinny disks shows when reloading current cart with load()
		Fixed: GIF saver does not respect 64x64 / mirrored modes
		Fixed: Miscellaneous multi-line comments / strings issues
		Fixed: Empty map cels cost cpu in mapdraw()
		Fixed: mapdraw() slowdown when drawing bottom half of map
		Fixed: preprocess changes semantics when += and : operators on same line
		Fixed: Identifiers starting with underscore counted as extra token
		Fixed: Saving .png exceeding compressed code limit fails silently
		Fixed: Right-clicking a sprite does not set the currently edited sprite
		Fixed: (Windows) extra space added to pasted lines
		Fixed: spr() expensive when drawn with low negative coordinates
		Fixed: pipe character identical to colon character
		Fixed: (Raspberry Pi) shift key appends a character when entering text
		Fixed: Editor mode buttons are still clickable during cart runtime
		Fixed: When loading a .p8.png file, label is reset and needs to be re-captured
		Fixed: export() does not report failure
		Fixed: mset()'d changes in shared memory not readable via peek() / sget()
		Fixed: cstore() saving edited code
		Fixed: audio pop between patterns during music playback

	v0.1.7
	
		Added: menuitem()
		Added: button glyphs in code (shift-L, R, U, D, X, O)
		Added: Customisable data directory (e.g. pico8 -home mydata)
		Added: Web gpio pins: read and write pico8_gpio[] in javscript 
		Fixed: SPLORE search doesn't reset
		Fixed: Splore skipping 33rd cart listing after loading more items
		Fixed: Crash when selecting a local binary file in splore
		Fixed: Semicolon can't be used as a list or statement separator 
		Fixed: Exported html can not cstore self


	v0.1.6

		Added: SPLORE local & bbs cartridge explorer
		Added: setmetatable(), cocreate(), coresume(), costatus(), yield()
		Added: Spinning cart icon to show when a cart is swapped / written to
		Added: Permanent storage when carts played in a browser
		Added: Adjustable aspect ratio (-aspect 420 for 1:1)
		Changed: Lua memory limit: 1024k (was 512k)
		Changed: Music channel now resumes after being clobbered by an sfx 
		Changed: Arpeggios double speed when SFX speed <= 8
		Changed: Exceeding compressed code limit does not block saving in .p8 format 
		Changed: spr() half as expensive, to be consistent with map()
		Changed: Fractional hex number notation: 0x0.3 == 0x0.3000, (was 0x0.0003)
		Changed: : operator doesn't count as an extra token (same as .)
		Changed: cstore() writes directly to disk
		Changed: cstore(), reload() return number of bytes read / written
		Changed: save() while running does nothing. (use cstore() instead)
		Changed: load() while running loads and runs the specified cartridge 
		Fixed: Small pops in audio mixer caused by sound wave discontinuities
		Fixed: HTML5-exported sound clicks badly under Chrome
		Fixed: Display palette is not oberserved when exporting GIFs
		Fixed: Rapid keypresses causes duplicate readings in tracker & text editor
		Fixed: += inside comments breaks preprocessor
		Fixed: sspr() cpu cost the same when clipped
		Fixed: cartdata() with bad parameters crashes
		Fixed: EXPORT from commandline can not be used without brackets and quotes
		

	v0.1.5
	
		Added: Raspberry Pi Build
		Added: Keyboard configuration for player buttons (KEYCONFIG) 
		Added: Music tracker select / copy / paste
		Added: Single-level undo in audio tools
		Added: Live preview of frequencies in sound editor
		Fixed: Command history extends past last reboot
		Fixed: Sfx exporter broken
		Fixed: Slashes at end of path resolve to double slashes
		Fixed: Load cart from commandline under Windows
		

	v0.1.4d
	v0.1.4c
	
		Fixed: International character entry inserting extra characters
		Fixed: Lines with tabs have broken cursor placement and display boundary

	v0.1.4b
	
		Fixed: OSX command-key combinations broken
		
	v0.1.4
		
		Added: spritesheet importing and exporting with import("blah.png"), export("blah.png")
		Added: sfx exporting with export("blah%d.wav")
		Added: External cartridge parameter for reload() and cstore()
		Added: Persistent cartridge data mapped to 0x5e00
		Added: Click token limit to toggle token & char limit display
		Added: assert(), type()
		Added: P to pause
		Changed: code char limit: 64k (was 32k)
		Changed: local declarations and semicolons not counted as tokens
		Changed: Pairs of brackets and block delimitations count as one token
		Changed: Only _update() or _draw() need to exist to enter main loop
		Changed: Allow forward-slash in code editor
		Changed: info() reports current (last loaded or saved) filename
		Changed: html5 version compiled with NO_DYNAMIC_EXECUTION 
		Changed: can only cstore up to 64 different files in one session
		Changed: load() automatically copies data section of cart to base ram
		Fixed: Shift-drag-copy sprites -> paste only pastes 1x1
		Fixed: ".." should count as one token
		Fixed: Tracker displaying D instead of .
		Fixed: Multi-line comments
		Fixed: Crash on run when code close to char limit
		Fixed: When over token limit, can not run any command
		Fixed: Unused high bits in SFX section not saved in .p8 format
		Fixed: Camera position memory mapping out of sync
		Fixed: pico8.txt link broken in windows installer
		Fixed: print() crashes when parameter is not a string or numbers
		Fixed: Multi-line strings & escape chars mess up tokenizer and print()
		Fixed: Joystick not responding when left stick is up to the left
		Fixed: Alt-F4 saves screenshot before quitting
		Fixed: Sprite editor mode button doesn't show fullscreen mode
		Fixed: -sound parameter not working in html5 version 
		
		
	v0.1.3
	
		Added: paste into commandline
		Fixed: lua standard libraries accessible
		Fixed: command-line loading doesn't work
		Fixed: music pattern finished too early when all tracks set to looping 
		Fixed: peek()ing odd bytes in sfx address space masks bit 7
		Fixed: cstore and reload from code space should have no effect
	
	v0.1.2
	
		Added: html5 cartridge exporter
		Added: Cartridge save data (64 fixed point numbers)
		Added: 8-player input
		Added: Demo carts: COLLIDE and BUTTERFLY
		Added: Command-line parameters // load cart, -run, settings
		Added: Alternative function keys (F6..F9 aliased as F1..F4)
		Added: pairs()
		Added: printh() for debugging
		Added: Tab completion for filenames in console
		Added: stack trace on runtime error
		Changed: music pattern length taken to be first non-looping channel's length
		Changed: noise instrument (6) has low frequency white noise scaled by volume
		Changed: screenshot captures whole window contents at display resolution
		Changed: del() moves remaining items up one index to maintain a packed table
		Changed: add(),del(),count(),all() no longer store extra fields
		Changed: removed count() from docs -- now just a legacy function. Use # operator instead.
		Changed: cursor only blinks while window is active
		Changed: peek(), poke() and binary operations (band()..) have no function call overhead
		Changed: yellow slightly warmer
		Changed: No camera snapping after pan in map mode
		Fixed: sqrt() crashing for 0 or >= 32761
		Fixed: Semi-colon characters in text editor
		Fixed: Long lines split when saving in .p8 format 
		Fixed: pget() does not respect camera position
		Fixed: Error message when peeking or poking outside of legal address space
		Fixed: Search replace colour fills one pixel outside of selected region
		Fixed: Playing an empty music pattern breaks subsequent music playback
		Fixed: Invalid sfx editing state on startup
		Fixed: Painting instruments values in frequency view also sets volumes
		Fixed: Inconsistent gif recording speeds
		Fixed: Unmapped joystick support
		Fixed: Compressed code size sometimes larger than uncompressed
		Fixed: mid() fails when first argument is not smallest
		Fixed: Scroll wheel changes sprite/map zoom while in code editor
		Fixed: CTRL-R (quick-run) drawing over current line in command mode
		Fixed: Label capture (F7) does not respect screen palette state
		Fixed: Syntax highlighting of api functions and hex numbers
		Fixed: Looping to 0 with negative step finishes at 1
		Fixed: nil values printed as false instead of nil
		Fixed: Hexadecimal fractional parts
		Fixed: btnp() unresponsive when skipping frames
		Fixed: Editing mode is lost when using ctrl-r to run
		Fixed: Tracker note entry keys mapped, messing up piano-like layout
		Fixed: Shared gfx/map memory out of sync after some editor operations
		Fixed: Alt-gr character entry
		Fixed: Can map display palette to entries >= 16 using poke()
		Fixed: Using shift to select in code editor has wrong selection range
		Fixed: Dragging above top of text causes selection to flip to end
		Fixed: Duplicate at end of file listing
		
		
	v0.1.1

		Added: Token-based code limiting (8192 tokens, 32k ascii text)
		Added: Freeform move, pan and selection in sprite and map editors
		Added: Flood-fill tool (sprite and map)
		Added: .GIF saver
		Added: CTRL-Stamp to stamp with transparency
		Added: Single-step undo for map and sprites
		Added: 2x2 brush
		Added: sqrt(), atan2()
		Added: CTRL-S to quick-save
		Added: CTRL-R reloads .p8 file and runs (useful for external text editing)
		Added: Automatic backups on overwriting or quitting without saving
		Added: Scroll wheel zooms in sprite editor
		Added: Customisable resolution //  e.g. pico8 -width 580
		Added: Strings highlighted as green
		Added: ALT-click can optionally simulate right click (see config.txt)
		Added: palt() to control transparency for spr(), sspr()
		Added: info()
		Changed: load() tries adding .p8.png, .png if file doesn't exist
		Changed: Draw operations apply only to selection when active
		Changed: Move operations (cursors) apply to selection if present
		Changed: Removed time()
		Changed: Random seed is random on cart startup
		Changed: api functions never read directly from cart rom
		Changed: sspr() can take negative values for dw, dh
		Fixed: Sparse table indexing with integers fails
		Fixed: Assignment operators and shortform if-then-else failing
		Fixed: sspr() failed when w0 == 128
		Fixed: Circle drawing broken when camera not (0,0)
		Fixed: CPU hogging
		Fixed: Noise instrument clobbers rnd() sequence
		Fixed: Audio system not resetting on program reset
		Fixed: % operator sometimes wrong for negative values
		Fixed: Length operator (#)
		Fixed: Power operator (^)
		Fixed: Line clipping bug on right and bottom edges
		Fixed: print() precision for whole numbers
		Fixed: print() broken for negative y values
		Fixed: tokenization and keyword highlighting
		Fixed: sprite properties not copied/pasted
		Fixed: Only sfx 0..32 could be used as music patterns
		Fixed: Saving and loading a .p8 file adds newline to end of code
		Fixed: Drag selection to left margin in code editor -> selects all
		
		
	v0.1.0

		Added: demo cart: hello.p8 (use install_demos)
		Added: CTRL-R from anywhere to run cart or restart cart
		Added: use a,s to select colour in gfx editor
		Added: consistent operation cpu costs
		Added: btn(), btnp() with no arguments returns bitfield
		Added: fget(id) returns bitfield of that sprite's flags
		Changed: renamed mapdraw() to map() for consistency
		Changed: default sleep time is 5ms (better cpu consumption for laptops)
		Fixed: memory limiter
		Fixed: wonky line and circle drawing
		Fixed: shift-click volume in sfx editor to set all
		Fixed: number formatting is now never in scientific notation
		Fixed: clipped error messages in console
		Fixed: text undo stores rollback points when chaning line number
		Fixed: print(str) carriage returns to previous x


	v0.0.5

		Added: help()
		Added: Ctrl+F / Ctrl+G to search for text, repeat search
		Added: del key in code editor
		Added: Short-hand single-line IF statements
		Added: Unary operators += -= /= *= %=
		Added: srand(), time(), added rnd() to docs
		Added: Ctrl+D to duplicate line
		Added: interactive ls() for multi-page file listings
		Added: band() bor() bxor() bnot() shl() shr()
		Added: runtime error line number
		Added: dir() (aliased to ls())
		Changed: print() only autoscrolls when called with no parameters
		Changed: alt+up/down to skip between function definitions (was ctrl)
		Changed: sspr() dw, dh defaults to sw, sh
		Fixed: Load crashes on files that are not .p8 format or directories
		Fixed: Misc editor cursor position glitches
		Fixed: Crash when syntax error occurs before viewing code
		Fixed: Broken newlines after rebooting
		Fixed: mkdir() called with no parameters creating "(null)" directory
		Fixed: scrolling past top of code with scrollwheel
		Fixed: alt-f4 to fastquit


	v0.0.4

		Added: Jelpi demo cart
		Added: Internal carts // use install_demos()
		Added: Joystick support
		Added: Undo/redo in code editor
		Added: Scroll wheel in code editor
		Added: LCTRL + UP/DOWN to navigate functions in code editor
		Added: LALT + LEFT/RIGHT to switch editing modes
		Added: btnp()
		Added: Release looping sample (a in editor , sfx(-2, channel) in code)
		Changed: Music stops when pausing program execution
		Changed: Allow 8 settable sprite flags
		Changed: Made noise instrument more bassy
		Fixed: Home, end keys
		Fixed: Sprite flags 4,5 not saved
		Fixed: mset() discarding 4 high bits
		Fixed: Crash when highlighting long strings


	v0.0.3

		Added: Palette mapping type 1 (on display)
		Added: Collections can be initialized with c={1,2,..}
		Added: holdframe() // used automatically by _draw(), update()
		Added: Sprite selections and operations across selections
		Added: Map selection and stamp tool
		Added: Immediate mode screen buffer preserved while switching views
		Added: Channel mask for music playback
		Added: Memory mapping for live sound data
		Added: .png cart format
		Added: Sprite navigation by keyboard (-, +)
		Fixed: Strict 4-channel sound
		Fixed: Automatic sfx channel selection (channel index: -1)


	v0.0.2

		Added: Command history
		Added: P2 keys
		Added: Boot sequence
		Added: Windows, 64-bit linux builds
		Added: CPU cost of internal api functions
		Added: Separate song channel index and mute status
		Added: Memory mapping
		Added: Search/replace colour in sprite editor
		Added: Copy/paste sprites and map regions
		Improved: Immediate mode command editing
		Improved: Editor cursor behaviour
		Fixed: Automatic audio channel selection


	v0.0.1 

		First Alpha