Chirp

How does an emulator work? I don't know!

So I wrote this, to see if i can find out.

Features:

• 64 * 128 1bpp pixel display, scaled 8x
• Full coverage of the original Chip-8 insn set
• Partial coverage of the Super Chip-8 extension set
• 64-bit floating point internal sound/delay timers
• Pause/Resume
• Set and unset breakpoints
• A fairly nice command-line interface

Keybinds:

• F1: Dump CPU registers
• F2: Dump screen to terminal
• F3: Dump screen to file
• F4: Enable/Disable live disassembly
• F5: Pause/Resume
• F6: Single-step instruction
• F7: Set breakpoint at current instruction
• F8: Unset breakpoint at current instruction
• F9: Soft-reset the CPU

Keypad mapping:

QWERTY:

1	2	3	4
Q	W	E	R
A	S	D	F
Z	X	C	V

Chip-8:

1	2	3	C
4	5	6	D
7	8	9	E
A	0	B	F

Command Line Interface:

Usage: chirp [OPTIONS]

Positional arguments:
  file                 Load a ROM to run on Chirp.

Optional arguments:
  -h, --help           Print this help message.
  -d, --debug          Enable debug mode at startup.
  -p, --pause          Enable pause mode at startup.
  -s, --speed SPEED    Set the instructions-per-frame rate.
  -S, --step STEP      Run the emulator as fast as possible for `step` instructions.
  -z, --vfreset        Disable setting vF to 0 after a bitwise operation.
  -x, --drawsync       Disable waiting for vblank after issuing a draw call.
  -c, --memory         Use CHIP-48 style DMA instructions, which don't touch I.
  -v, --shift          Use CHIP-48 style bit-shifts, which don't touch vY.
  -b, --jumping        Use SUPER-CHIP style indexed jump, which is indexed relative to v[adr].
  -B, --break BP       Set breakpoints for the emulator to stop at.
  -D, --data WORD      Load additional word at address 0x1fe
  -f, --frame-rate FR  Set the target framerate. (default: 60)

TODO:

• Move the screen, stack, charset, and program memory into the CPU
• Implement sound
• Finish unit tests for "quirks"
• Make pausing/unpausing the emulator less messy
• Make resetting the emulator possible
• Allow code to be passed in hex on the command line? Hmm
• Assembler for my assembly syntax
• Make a UI for realtime configuration
• Cycle accuracy with original Chip-8 interpreter