copper.py

"""Copper-list disassembler for the Amiga custom chips.

Used on `Lx_ChipI.cru`, the chip-RAM image the loader installs before the
game proper starts.  Register names cover the AGA set, since the CD32 is an
AGA machine and the game does use registers the ECS chipset does not have.
"""
import struct, sys

REG = {
 0x02:'DMACONR',0x04:'VPOSR',0x06:'VHPOSR',0x08:'DSKDATR',0x0A:'JOY0DAT',
 0x0C:'JOY1DAT',0x0E:'CLXDAT',0x10:'ADKCONR',0x12:'POT0DAT',0x14:'POT1DAT',
 0x16:'POTGOR',0x18:'SERDATR',0x1A:'DSKBYTR',0x1C:'INTENAR',0x1E:'INTREQR',
 0x20:'DSKPTH',0x22:'DSKPTL',0x24:'DSKLEN',0x26:'DSKDAT',0x28:'REFPTR',
 0x2A:'VPOSW',0x2C:'VHPOSW',0x2E:'COPCON',0x30:'SERDAT',0x32:'SERPER',
 0x34:'POTGO',0x36:'JOYTEST',0x38:'STREQU',0x3A:'STRVBL',0x3C:'STRHOR',
 0x3E:'STRLONG',0x40:'BLTCON0',0x42:'BLTCON1',0x44:'BLTAFWM',0x46:'BLTALWM',
 0x48:'BLTCPTH',0x4A:'BLTCPTL',0x4C:'BLTBPTH',0x4E:'BLTBPTL',0x50:'BLTAPTH',
 0x52:'BLTAPTL',0x54:'BLTDPTH',0x56:'BLTDPTL',0x58:'BLTSIZE',0x5A:'BLTCON0L',
 0x5C:'BLTSIZV',0x5E:'BLTSIZH',0x60:'BLTCMOD',0x62:'BLTBMOD',0x64:'BLTAMOD',
 0x66:'BLTDMOD',0x70:'BLTCDAT',0x72:'BLTBDAT',0x74:'BLTADAT',0x7C:'DENISEID',
 0x7E:'DSKSYNC',0x80:'COP1LCH',0x82:'COP1LCL',0x84:'COP2LCH',0x86:'COP2LCL',
 0x88:'COPJMP1',0x8A:'COPJMP2',0x8C:'COPINS',0x8E:'DIWSTRT',0x90:'DIWSTOP',
 0x92:'DDFSTRT',0x94:'DDFSTOP',0x96:'DMACON',0x98:'CLXCON',0x9A:'INTENA',
 0x9C:'INTREQ',0x9E:'ADKCON',0xA0:'AUD0LCH',0xA2:'AUD0LCL',0xA4:'AUD0LEN',
 0xA6:'AUD0PER',0xA8:'AUD0VOL',0xAA:'AUD0DAT',0xB0:'AUD1LCH',0xB2:'AUD1LCL',
 0xB4:'AUD1LEN',0xB6:'AUD1PER',0xB8:'AUD1VOL',0xBA:'AUD1DAT',0xC0:'AUD2LCH',
 0xC2:'AUD2LCL',0xC4:'AUD2LEN',0xC6:'AUD2PER',0xC8:'AUD2VOL',0xCA:'AUD2DAT',
 0xD0:'AUD3LCH',0xD2:'AUD3LCL',0xD4:'AUD3LEN',0xD6:'AUD3PER',0xD8:'AUD3VOL',
 0xDA:'AUD3DAT',0x100:'BPLCON0',0x102:'BPLCON1',0x104:'BPLCON2',0x106:'BPLCON3',
 0x108:'BPL1MOD',0x10A:'BPL2MOD',0x10C:'BPLCON4',0x10E:'CLXCON2',
 0x1FC:'FMODE',0x1DC:'BEAMCON0',0x1E4:'DIWHIGH',0x1C0:'HTOTAL',
 0x1C2:'HSSTOP',0x1C4:'HBSTRT',0x1C6:'HBSTOP',0x1C8:'VTOTAL',0x1CA:'VSSTOP',
 0x1CC:'VBSTRT',0x1CE:'VBSTOP',0x1DE:'HSSTRT',0x1E0:'VSSTRT',0x1E2:'HCENTER',
 0x1E6:'BPLHMOD',0x1E8:'SPRHPTH',0x1EA:'SPRHPTL',0x1EC:'BPLHPTH',0x1EE:'BPLHPTL',
}
for i in range(8):
    REG[0xE0+i*4] = 'BPL%dPTH' % (i+1)
    REG[0xE2+i*4] = 'BPL%dPTL' % (i+1)
    REG[0x110+i*2] = 'BPL%dDAT' % (i+1)
    REG[0x120+i*4] = 'SPR%dPTH' % i
    REG[0x122+i*4] = 'SPR%dPTL' % i
for i in range(32):
    REG[0x180+i*2] = 'COLOR%02d' % i


def disasm(data, off=0, limit=100000):
    """Yield (offset, text) until the list terminates or `limit` is hit."""
    o = off
    while o + 4 <= len(data) and o - off < limit:
        w1, w2 = struct.unpack_from('>HH', data, o)
        if w1 & 1:
            kind = 'SKIP' if (w2 & 1) else 'WAIT'
            vp, hp = (w1 >> 8) & 0xFF, w1 & 0xFE
            ve, he = (w2 >> 8) & 0x7F, w2 & 0xFE
            bfd = (w2 >> 15) & 1
            txt = '%s VP=$%02X HP=$%02X, VE=$%02X HE=$%02X%s' % (
                kind, vp, hp, ve, he, '' if bfd else ' (BFD=0)')
            if w1 == 0xFFFF and w2 == 0xFFFE:
                yield o, 'END  (WAIT $FFFF,$FFFE)'
                o += 4
                return
        else:
            reg = w1 & 0x1FE
            txt = 'MOVE %-8s, $%04X' % (REG.get(reg, '$%03X' % reg), w2)
        yield o, txt
        o += 4


if __name__ == '__main__':
    d = open(sys.argv[1], 'rb').read()
    start = int(sys.argv[2], 0) if len(sys.argv) > 2 else 0
    lim = int(sys.argv[3], 0) if len(sys.argv) > 3 else 100000
    for o, t in disasm(d, start, lim):
        print('%06X: %s' % (o, t))