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#define FALSE 0
#define TRUE 1
enum Addressing {
eImmediate,
eAbsolute,
eZeroPage,
eImplied,
eIndirectAbsolute,
eAbsoluteIndexedX,
eAbsoluteIndexedY,
eZeroPageIndexedX,
eZeroPageIndexedY,
eIndexedIndirect,
eIndirectIndexed,
eRelative,
eAccumulator
};
typedef int Addressing;
int getLength(Addressing addr){
switch(addr){
case eAbsolute: case eAbsoluteIndexedX: case eAbsoluteIndexedY:
return 3;
case eAccumulator:
return 1;
default:
return 2;
}
}
/*
* Any addressing method which is single line commented out without definition
* implies that handling should be hard-coded in the switch case of the
* instruction from which it came.
*/
int fAddressing(Addressing addr, short x) {
switch(addr){
case eImmediate: return x;
case eAccumulator: return acc;
case eAbsolute: return Memory[x];
case eAbsoluteIndexedX: return Memory[(x + X)];
case eAbsoluteIndexedY: return Memory[(x + Y)];
case eZeroPage: return Memory[(x & 0x00FF)];
case eZeroPageIndexedX: return Memory[((x = X) & 0x00FF)];
case eZeroPageIndexedY: return Memory[((x = Y) & 0x00FF)];
case eIndexedIndirect: return Memory[((x + X) << 8) + ((x + X) + 1)];
case eIndirectIndexed: return ((Memory[x] + Memory[(x+1 << 8)]) + Y);
//case eImplied: No reference
//case eIndirectAbsolute: Only used in the JMP instruction
//case eRelative: Only used in branch instructions
}
}
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