#!/usr/bin/env python3

import struct


OP = [
        # Mnemonic, mask, value, xmask, ymask, kmask, klabel
    ('CLS',   '',
                0xffff, 0x00e0,   0x0000, 0x0000, 0x0000, False),
    ('RET',   '',
                0xffff, 0x00ee,   0x0000, 0x0000, 0x0000, False),
    ('SYS',   '{k}',
                0xf000, 0x0000,   0x0000, 0x0000, 0x0fff, True),
    ('JP',    '{k}',
                0xf000, 0x1000,   0x0000, 0x0000, 0x0fff, True),
    ('CALL',  '{k}',
                0xf000, 0x2000,   0x0000, 0x0000, 0x0fff, True),
    ('SE',    'V{x:01x}, {k:02x}',
                0xf000, 0x3000,   0x0f00, 0x0000, 0x00ff, False),
    ('SNE',   'V{x:01x}, {k:02x}',
                0xf000, 0x4000,   0x0f00, 0x0000, 0x00ff, False),
    ('SE',    'V{x:01x}, V{y:01x}',
                0xf00f, 0x5000,   0x0f00, 0x00f0, 0x0000, False),
    ('LD',    'V{x:01x}, {k:02x}',
                0xf000, 0x6000,   0x0f00, 0x0000, 0x00ff, False),
    ('ADD',   'V{x:01x}, {k:02x}',
                0xf000, 0x7000,   0x0f00, 0x0000, 0x00ff, False),
    ('LD',    'V{x:01x}, V{y:01x}',
                0xf00f, 0x8000,   0x0f00, 0x00f0, 0x0000, False),
    ('OR',    'V{x:01x}, V{y:01x}',
                0xf00f, 0x8001,   0x0f00, 0x00f0, 0x0000, False),
    ('AND',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x8002,   0x0f00, 0x00f0, 0x0000, False),
    ('XOR',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x8003,   0x0f00, 0x00f0, 0x0000, False),
    ('ADD',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x8004,   0x0f00, 0x00f0, 0x0000, False),
    ('SUB',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x8005,   0x0f00, 0x00f0, 0x0000, False),
    ('SHR',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x8006,   0x0f00, 0x00f0, 0x0000, False),
    ('SHL',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x800e,   0x0f00, 0x00f0, 0x0000, False),
    ('SNE',   'V{x:01x}, V{y:01x}',
                0xf00f, 0x9000,   0x0f00, 0x00f0, 0x0000, False),
    ('LD',     'I, {k}',
                0xf000, 0xa000,   0x0000, 0x0000, 0x0fff, True),
    ('JP',     'V0, {k}',
                0xf000, 0xb000,   0x0000, 0x0000, 0x0fff, True),
    ('RND',    'V{x:01x}, {k:02x}',
                0xf000, 0xc000,   0x0f00, 0x0000, 0x00ff, False),
    ('DRW',    'V{x:01x}, V{y:01x}, {k:02x}',
                0xf000, 0xd000,   0x0f00, 0x00f0, 0x000f, False),
    ('SKP',    'V{x:01x}',
                0xf0ff, 0xe09e,   0x0f00, 0x0000, 0x0000, False),
    ('SKNP',   'V{x:01x}',
                0xf0ff, 0xe0a1,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'V{x:01x}, DT',
                0xf0ff, 0xf007,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'V{x:01x}, K',
                0xf0ff, 0xf00a,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'DT, V{x:01x}',
                0xf0ff, 0xf015,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'ST, V{x:01x}',
                0xf0ff, 0xf018,   0x0f00, 0x0000, 0x0000, False),
    ('ADD',    'I, V{x:01x}',
                0xf0ff, 0xf01e,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'F, V{x:01x}',
                0xf0ff, 0xf029,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'B, V{x:01x}',
                0xf0ff, 0xf033,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     '[I], V{x:01x}',
                0xf0ff, 0xf055,   0x0f00, 0x0000, 0x0000, False),
    ('LD',     'V{x:01x}, [I]',
                0xf0ff, 0xf065,   0x0f00, 0x0000, 0x0000, False),


    ('DATA',  '{k:04x}',
                0x0000, 0x0000,   0x0000, 0x0000, 0xffff, False)
] 


def c8decode(ins):

    def _unmask(v, m):
        if m == 0:
            return None
        r = v & m
        while (m & 1) == 0:
            m >>= 1
            r >>= 1
        return r

    for mn, fmt, mask, value, xmask, ymask, kmask, klabel in OP:
        if (ins & mask) == value:
            xo = _unmask(ins, xmask)
            yo = _unmask(ins, ymask)
            ko = _unmask(ins, kmask)
            return (mn, fmt, xo, yo, ko, klabel)


def disasm(filename, org=0x200):
    pc = org
    targets = set()
    listing = []
    with open(filename, 'rb') as f:
        while True:
            w = f.read(2)
            if len(w) != 2:
                break
            instr = struct.unpack('>H', w)[0]
            mn, fmt, xo, yo, ko, klabel = c8decode(instr)
            if klabel:
                targets.add(ko)
            listing.append((pc, instr, mn, fmt, xo, yo, ko, klabel))
            pc += 2
    end = pc

    print(f""";
; {filename}
; start={org:03x} end={end:03x} size={end-org}(dec)
;
        """)
    for pc, instr, mn, fmt, xo, yo, ko, klabel in listing:
        if pc in targets:
            label = "l%03x" % (pc,)
        else:
            label = ""
        if klabel:
            if org <= ko <= end:
                ko = f"l{ko:03x}"
            else:
                ko = f"{ko:03x}"
        o = fmt.format(x=xo, y=yo, k=ko)
        print(f"{label:8s} {mn:5s} {o:12s} ; {pc:03x}: {instr:04x}")


if __name__ == '__main__':
    import sys

    for fn in sys.argv[1:]:
        disasm(fn)