This is a simple two-pass assembler originally written by Landon Dyer for fun. No warranty expressed or implied.
It supports:
- standard 6502 opcodes and opcode syntax (default)
- or opcodes of a toy 'tpo' CPU
The assembler should be quite easily extensible.
Binary output are:
- Kim-1 format (default)
- or a Python Array
Command line synopsis:
python kasm.py [--outFormat=(PythonArray|Kim1)] [--inFormat=(6502|tpo)] inputfile[.asm]
The files 'inputfile.lst' (an assembler listing) and 'inputfile.dat' (Kim-1 etc. format) are produced unconditionally.
General syntax:
Labels are case sensitive, and are followed with a colon. Assembler
mnemonics and psuedo-ops are not case sensitive. The special symbol
* is the location counter of the start of the current line of input.
; ----------------
; comments start with semicolons
include "filename.asm"
org expression ; set location counter
db byte, byte, byte...
dw word, word, word...
ds expression ; reserve bytes
Labels have colons:
label: op operand(s)
Equate values with =
symbol = expression
Labels starting with '.' are local between labels that don't start with '.'
func: lda #1
.loop: adc #1
bcc .loop
mumble: ldx #1
.loop: inx ; distinct from first '.loop'
bne .loop
Expressions use C operators, and C operator precedence. Operators are (in order of decreasing precedence):
( expression )
- (unary minus)
! (logical not, yields 0 or 1)
* / %
+ -
<< >>
< <= > >= == !=
& ^ |
Development status:
This assembles some moderately size files without fuss, and apparently correctly (I tried it on Microchess, for instance). There are probably bugs in it.
It would be nice if the listing file wasn't unconditionally created, but it's fine for me at the moment.
It would be nice to have macros and conditional assembly.
It would be nice to have (say) Atari output format, but I don't really need it.
More pseudo-ops might be interesting (e.g., EQU in addition to '=').