chip8as

chip8as

This is an assembler for the CHIP-8 and SCHIP, utilizing libc8.

Table of Contents

• Features
• Usage
• Example Code
• Instructions
• Notes

Features

• Label support (mylabel:)
• Support for strings (.DS), 16-bit data words (.DW), and data bytes (.DB)
• Support for hex (0x or x prefixed), and binary (0b) integers

Usage

chip8as [-vV] [-o outputfile] src

• -o sets an output file (default is a.c8).
• -v prints diagnostic messages and the resulting hex-encoded bytecode to standard output.
• -V prints the version number.

Example Code

JP main ; jump to main label
 
mysprite:
.DW 0x1234 ; sprite to draw
 
main:
  ADD V0, 1 ; set x coordinate
  ADD V1, 0xA ; set y coordinate
  LD I, mysprite ; load sprite
  DRW V0, V1, 1 ; draw sprite

Instructions

Assembly code	Bytecode	Notes
.DB ax	ax	Special instruction
.DW axyb	axyb	Special instruction
.DS "string"	axyb...	Special instruction. String will be stored as ASCII-encoded bytes.
SCD b	00Cb	SCHIP instruction
CLS	00E0	SCHIP instruction
RET	00EE	SCHIP instruction
SCR	00FB	SCHIP instruction
SCL	00FC	SCHIP instruction
EXIT	00FD	SCHIP instruction
LOW	00FE	SCHIP instruction
HIGH	00FF	SCHIP instruction
JP nnn	1nnn
CALL nnn	2nnn
SE Vx, kk	3xkk
SNE Vx kk	4xkk
SE Vx, Vy	5xy0
LD Vx, kk	6xkk
ADD Vx, kk	7xkk
LD Vx, Vy	8xy0
OR Vx, Vy	8xy1
AND Vx, Vy	8xy2
XOR Vx, Vy	8xy3
ADD Vx, Vy	8xy4
SUB Vx, Vy	8xy5
SHR Vx {, Vy}	8xy5	Vy is optional - it will be set to 0 in resulting bytecode if undefined
SUBN Vx, Vy	8xy7
SHL Vx {, Vy}	8xyE	Vy is optional - it will be set to 0 in resulting bytecode if undefined
SNE Vx, Vy	9xy0
LD I, nnn	Annn
JP V0, nnn	Bnnn
RND Vx, kk	Cxkk
DRW Vx, Vy, b	Dxyb
SKP Vx	Ex9E
SKNP Vx	ExA1
LD Vx, DT	Fx07
LD Vx, K	Fx0A
LD DT, Vx	Fx15
LD ST, Vx	Fx18
ADD I, Vx	Fx1E
LD F, Vx	Fx29
LD HF, Vx	Fx30	SCHIP instruction
LD B, Vx	Fx33
LD [I], Vx	Fx55
LD Vx, [I]	Fx65
LD R, Vx	Fx75	SCHIP instruction
LD Vx, R	Fx85	SCHIP instruction

Notes

• Hex integers, besides V register identifiers, must be formatted with 0x, x, or $ prefixes.
• Binary integers must be formatted with a 0b prefix.
• Data bytes and strings are not padded. If a .DB or .DS contains an odd number of bytes, following bytecode will be offset (the first byte of following instructions will be at odd-numbered addresses).
• Single-line comments start with ;
• Commas are optional for instruction parameters.
• This assembler is not case sensitive.