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 Post subject: AbsoluteY() Question
PostPosted: Fri Jul 29, 2005 9:25 am 
Nestress says my CPU cores passes all CPU tests except absolute Y. It passes all PPU tests except Palette write/read.

Here is my absoluteY() code:

unsigned short absY() {
return ((getMem(pc+2) << 8)| getMem(pc+1)) + y;
}


It's identical to my absoluteX() (which passes the test) code except I substitute X for Y. Most games I run in my emu crash or barely work, but I can't find any bugs in my core (comparing it to other cores). Mapper 2 games almost all crash before any graphics display. Very few mapper 0 games show much. I know my PPU is functional because I can get lots of demos and some mapper 0 title screens correct. I can even get one mapper 2 title screen correct so I know my bank switching is working correct. Any suggestions?


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 Post subject:
PostPosted: Fri Jul 29, 2005 9:39 am 
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Joined: Thu Mar 24, 2005 3:17 pm
Posts: 355
Perhaps you have addressing modes mixed up in one or more opcodes.

Not counting illegal opcodes, 0x19, 0x39, 0x59, 0x79, 0x99, 0xb9, 0xbe, 0xd9, 0xf9 use the absY addressing mode.


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 Post subject:
PostPosted: Fri Jul 29, 2005 10:23 am 
Thanks a lot! That was it

I had
0xb9
0xbe
0xf9

all doing absX instead of absY


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