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Change Invalid OPcodes to a print statement + NOP

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Some games (such as Puzznic) use invalid opcodes--there's a ton of them
documented in detail here:
* http://www.ffd2.com/fridge/docs/6502-NMOS.extra.opcodes
and
* http://wiki.nesdev.com/w/index.php/CPU_unofficial_opcodes#Games_using_unofficial_opcodes

Note that most of the opcodes used are NOPs, so I default to NOP +
warning. Proper emulation of all of the illegal opcodes is probably
warranted for full compatibility.
This commit is contained in:
Jeff Katz 2016-12-30 15:43:55 +01:00
parent 7c7ae08b39
commit d28e183469
1 changed files with 7 additions and 1 deletions
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8
src/cpu.cpp
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@ -1,5 +1,6 @@
#include <cstdlib>
#include <cstring>
#include <iostream>
#include "apu.hpp"
#include "cartridge.hpp"
#include "joypad.hpp"
@ -229,7 +230,12 @@ void exec()
case 0xF1: return SBC<izy>() ; case 0xF5: return SBC<zpx>() ;
case 0xF6: return INC<zpx>() ; case 0xF8: return flag<D,1>() ;
case 0xF9: return SBC<aby>() ; case 0xFD: return SBC<abx>() ;
case 0xFE: return INC<_abx>() ; default: return exit(1) ;
case 0xFE: return INC<_abx>() ;
default:
{
std::cout << "Invalid OPcode! PC: " << PC << " OPcode: 0x" << std::hex << (int)rd(PC-1) << "\n";
return NOP();
}
}
}