Mercurial > repos > blastem
changeset 2588:0ea26288d983
Implement abcd in new 68K core
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sat, 08 Feb 2025 22:41:36 -0800 |
| parents | e04c7e753bf6 |
| children | 6bca3c28e2ad |
| files | m68k.cpu |
| diffstat | 1 files changed, 78 insertions(+), 0 deletions(-) [+] |
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--- a/m68k.cpu Sat Feb 08 20:04:18 2025 -0800 +++ b/m68k.cpu Sat Feb 08 22:41:36 2025 -0800 @@ -673,6 +673,84 @@ update_flags NZV0C0 m68k_prefetch +1100XXX100000YYY abcd_dx_dy + local lowx 16 + local lowy 16 + local highx 16 + local highy 16 + lowx = dregs.X & 0xF + lowy = dregs.Y & 0xF + adc lowx lowy lowy + if lowy >=U 0xA + lowy += 6 + end + highx = dregs.X & 0xF0 + highy = dregs.Y & 0xF0 + highy += highx + highy += lowy + if highy >=U 0xA0 + dregs.X:0 = highy + 0x60 + update_flags X1C1VN + highy &= 0xFF + if highy + update_flags Z0 + end + else + dregs.X:0 = highy + nflag = highy & 128 + if highy + update_flags Z0 + end + update_flags X0C0V0 + end + cycles 2 + m68k_prefetch + +1100XXX100001YYY abcd_ax_ay + local lowx 32 + local lowy 32 + if Y = 7 + aregs.Y -= 2 + else + aregs.Y -= 1 + end + #predec penalty on src only + cycles 2 + scratch1 = aregs.Y + ocall read_8 + scratch2 = scratch1 + if X = 7 + aregs.X -= 2 + else + aregs.X -= 1 + end + scratch1 = aregs.X + ocall read_8 + lowx = scratch1 & 0xF + lowy = scratch2 & 0xF + scratch1 &= 0xF0 + scratch2 &= 0xF0 + adc lowx lowy lowy + if lowy >=U 0xA + lowy += 6 + end + scratch1 += scratch2 + scratch1 += lowy + if scratch1 >=U 0xA0 + scratch1:0 += 0x60 + update_flags X1C1VN + else + cmp 0 scratch1 0 + update_flags X0C0V0N + end + scratch1 &= 0xFF + if scratch1 + update_flags Z0 + end + scratch2 = aregs.X + ocall write_8 + m68k_prefetch + 1100XXX101000YYY exg_dn_dn scratch1 = dregs.X dregs.X = dregs.Y