syscalls.md

number	mnemonic	a	b	c	d
0	exit	status
1	print	msg.data	msg.len
2	log	msg.data	msg.len
3	create	filename.data	filename.len	mode
4	open_reading	filename.data	filename.len	flags	mode
5	open_writing	filename.data	filename.len	flags	mode
6	read	file descriptor	buffer.data	buffer.len
7	write	file descriptor	buffer.data	buffer.len
8	close	file descriptor
9	argc
10	arg	arg index	buffer.data	buffer.len
11	read_input	buffer.data	buffer.len
12	execute	binary.data	binary.len
13	ui_dimensions
14	ui_render	buffer.data	buffer.width	buffer.height
15	get_key_pressed
16	instant_now
17	read_dir	path.data	path.len	out.data	out.len

• exit: Exits the program. This is guaranteed to never return.
• print: Writes the message to stdout.
• log: Writes the message to stderr.
• create: Creates the file. Sets a to a file descriptor or zero if it didn't work.
• open_reading: Opens the file for reading. Sets a to a file descriptor or zero if it didn't work.
• open_writing: Opens the file for writing. Sets a to a file descriptor or zero if it didn't work.
• read: Reads from the file descriptor into the buffer, at most buffer.len. Sets a to the amount of bytes that were read.
• write: Writes from the buffer to the file descriptor, at most buffer.len. Sets a to the amount of bytes that were written.
• close: Closes the file descriptor. Sets a to one if it worked or zero if it didn't work.
• argc: Sets a to the number of arguments given to the program, including the program name itself.
• arg: Fills the buffer with the indexth argument, at most buffer.len. Sets a to the amount of bytes that were written.
• read_input: Reads from stdin into the buffer, at most buffer.len. Sets a to the amount of bytes that were read.
• execute: Loads the given binary into the current VM, replacing the current execution.
• ui_dimensions: Loads the UI width into a, its height into b.
• ui_render: Renders the buffer as a UI. Outer dimension is height, inner dimensions is width, each pixel is three bytes (RGB).
• get_key_pressed: Sets a to the keycode of the next pressed key (0 if none is pressed).
• instant_now: Sets a to a value that represents the current time in nanoseconds since some undefined reference event. The reference event is consistent over multiple instant_now calls, so you can use this to measure time.
• read_dir: Stores the directory entries of the path in the out buffer in the format <kind:1><len:8><name:len>. The kind is 1 for files, 2 for directories, and other kind values should be handled by the code. Sets a to the number of bytes written in the out buffer, or a negative value if an error occurred.