This is a fully functional CHIP-8 and SCHIP interpreter with an integrated debug mode, utilizing libc8 with SDL2.

Usage

chip8 [-dsvV] [-c tickspeed] [-f small,big] [-p file] [-P colors] [-q quirks] file

Options

Option	Description
`-c`	Sets the number of instructions to be executed per second (default: 1000).
`-d`	Enables debug mode. This can be used to add breakpoints, display the current memory, and step through instructions individually.
`-f`	Loads the specified comma-separated fonts. Big font is optional.
`-p`	Loads a color palette from a file containing two newline-separated 24-bit hex codes (prefixed by `0x` or `x`).
`-P`	Sets the color palette from a string containing two comma-separated 24-bit hex codes (prefixed by `0x` or `x`).
`-q`	Sets the quirks to enable from string with non-separated quirk identifiers
`-s`	Enables SCHIP mode.
`-v`	Enables verbose mode. This will print each instruction that is executed.
`-V`	Prints the version number.

Keyboard Layout

  Key       CHIP-8 keycode
1 2 3 4        1 2 3 C
q w e r  ==>   4 5 6 D
a s d f        7 8 9 E
z x c v        A 0 B F

Fonts

Same as Octo.

Font	Small	Big
octo	☑	☑
schip	☑	☑
fish	☑	☑
vip	☑	❌
dream6800	☑	❌
eti660	☑	❌

Quirks

The following quirks are available:

Quirk	Definition	CHIP-8 Default	SCHIP Default
`c`	Clip sprites at bottom edge of screen instead of wrapping.	☑	☑
`j`	For `JP V0, nnn`: Jump to `nnn + V[(nnn>>8)&0xF]` instead.	❌	☑
`m`	After `LD [I], Vx` and `LD Vx, [I]`: Set `I` to address `I + x + 1`.	☑	❌
`r`	`DRW` halts execution until the next frame.	☑	☑
`s`	Before `SHL Vx, Vy` and `SHR Vx, Vy`: Shift `Vx` in place, ignore `Vy`.	❌	☑
`v`	After `AND`, `OR`, and `XOR`: Clear `VF`.	☑	❌

Debug mode

Debug mode can be enabled via the -d command-line argument or by pressing P at any time during execution. It can also be disabled at any time by pressing M.

The following commands and attributes are supported in debug mode:

Command	Description
`break [ADDRESS]`	Add breakpoint to `PC` or `ADDRESS`, if given.
`rmbreak [ADDRESS]`	Remove breakpoint at `PC` or `ADDRESS`, if given and exists.
`continue`	Exit debug mode until next breakpoint or until execution is complete.
`help`	Print a help string.
`load PATH`	Load program state from `PATH`.
`loadflags PATH`	Load flag registers from `PATH`.
`next`	Step to the next instruction.
`print [ATTRIBUTE]`	Print current value of the given attribute.
`quit`	Terminate the program.
`save PATH`	Save program state to `PATH`.
`saveflags PATH`	Save flag registers to `PATH`.
`set ATTRIBUTE VALUE`	Set the given attribute to the given value.

Attribute	Description
`PC`	Program counter
`SP`	Stack pointer
`DT`	Delay timer
`ST`	Sound timer
`I`	I value
`K`	Register to store next keypress
`V[x]`	All V register values or value of Vx, if given
`R[x]`	All R (flag) register values or value of Rx, if given
`bfont`	Big font name
`sfont`	Small font name
`stack`	All stack values
`bg`	Background color
`fg`	Foreground color
`$[address]`	Value at given address