Search found 30 matches
- Thu Aug 14, 2008 11:52 pm
- Forum: Megadrive/Genesis
- Topic: Programming in C - Some doubts
- Replies: 10
- Views: 8101
Only if you compiled your binary with -O You'd have to be a fool not to use at least -O1, I think, unless maybe you're debugging. In any case, it's very stupid not to use the "volatile" because its inclusion will not hurt anything and its omission definitely can hurt something. Not to mention that ...
- Tue Aug 12, 2008 3:08 am
- Forum: Megadrive/Genesis
- Topic: Programming in C - Some doubts
- Replies: 10
- Views: 8101
Why the value changes, instead of just using bitwise operators (&, |, ^, ~)? You don't seem to quite understand how memory-mapped I/O (often abbreviated MMIO) works... you're still thinking in terms of RAM. MMIO doesn't work like RAM, so forget what you know about it. In particular, GFXCNTL doesn't...
- Mon Aug 11, 2008 9:58 pm
- Forum: Hardware
- Topic: An idea for a development pcb
- Replies: 9
- Views: 9624
I don't really think there's need for HW in MD dev anymore. You can do most debugging in Kmod, close to real HW testing in Fusion and that's really all you need. I use my MD2 usually to know that my code still runs on real HW and to listen music and play games as emu is still an emu. There's also t...
- Mon Aug 11, 2008 9:57 pm
- Forum: Controls
- Topic: About Peripherals
- Replies: 37
- Views: 68317
- Sun Aug 10, 2008 12:12 am
- Forum: Controls
- Topic: About Peripherals
- Replies: 37
- Views: 68317
- Fri Aug 01, 2008 10:55 pm
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
- Fri Aug 01, 2008 5:06 pm
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
At the end of the day, only two questions really matter: 1) Is the program free of bugs? 2) Does the program run fast enough to get everything done on every frame? As long as the answer to both questions is "yes", how you go about programming is irrelevant, really. It doesn't matter if your code is ...
- Mon Jul 28, 2008 3:38 pm
- Forum: Megadrive/Genesis
- Topic: Bug in genesis.c?
- Replies: 16
- Views: 13235
According to the manual, the instruction doesn't have to run from RAM (although that is one way to do it), it just has to use RAM. So do those games do something like this?
Or do they just do this?
Code: Select all
move.l d0, -(a7)
move.l (a7), GFXCTNL
move.l (a7)+, d0
Code: Select all
move.l d0, GFXCTNL
- Sun Jul 27, 2008 9:37 am
- Forum: Megadrive/Genesis
- Topic: Bug in genesis.c?
- Replies: 16
- Views: 13235
- Sun Jul 27, 2008 9:31 am
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
I think if you're using a word instruction with a byte in RAM, you have bigger problems... namely, loading/storing a garbage byte. Not to mention that loading a word from an odd boundary isn't slower, it's flat-out illegal (unless you write an appropriate exception handler as HardWareMan said, but I...
- Sun Jul 27, 2008 8:27 am
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
- Sun Jul 27, 2008 8:11 am
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
- Sun Jul 27, 2008 8:09 am
- Forum: Megadrive/Genesis
- Topic: Bug in genesis.c?
- Replies: 16
- Views: 13235
- Sat Jul 26, 2008 11:46 pm
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
- Sat Jul 26, 2008 8:50 pm
- Forum: Megadrive/Genesis
- Topic: ASM register management
- Replies: 32
- Views: 24212
I'd probably keep all 8bit values padded as 16bit. It's quicker for a couple of reasons on the 68k. I don't think it's quicker, because, looking at the instruction counts, there are no instructions where a word is processed faster than a byte. But neither are there any instructions where a word is ...