diff options
Diffstat (limited to 'addressing.h')
-rw-r--r-- | addressing.h | 65 |
1 files changed, 38 insertions, 27 deletions
diff --git a/addressing.h b/addressing.h index 3d67b33..1a80466 100644 --- a/addressing.h +++ b/addressing.h @@ -3,33 +3,22 @@ enum Addressing { eImmediate, + eAccumulator, eAbsolute, - eZeroPage, - eImplied, - eIndirectAbsolute, eAbsoluteIndexedX, eAbsoluteIndexedY, + eZeroPage, eZeroPageIndexedX, eZeroPageIndexedY, eIndexedIndirect, eIndirectIndexed, - eRelative, - eAccumulator + eImplied, + eIndirectAbsolute, + eRelative }; 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 @@ -37,26 +26,48 @@ int getLength(Addressing addr){ */ -int fAddressing(Addressing addr, short x) { + +struct AddData{ + int cycles; + int length; + byte value; +}; + +AddData fAddress(Addressing addr, short x) { + AddData ret; switch(addr){ - case eImmediate: return x; - case eAccumulator: return acc; + case eImmediate: ret.value = x; break; + case eAccumulator: ret.value = acc; break; - case eAbsolute: return Memory[x]; - case eAbsoluteIndexedX: return Memory[(x + X)]; - case eAbsoluteIndexedY: return Memory[(x + Y)]; + case eAbsolute: ret.value = Memory[x]; break; + case eAbsoluteIndexedX: ret.value = Memory[(x + X)]; break; + case eAbsoluteIndexedY: ret.value = Memory[(x + Y)]; break; - case eZeroPage: return Memory[(x & 0x00FF)]; - case eZeroPageIndexedX: return Memory[((x = X) & 0x00FF)]; - case eZeroPageIndexedY: return Memory[((x = Y) & 0x00FF)]; + case eZeroPage: ret.value = Memory[(x & 0x00FF)]; break; + case eZeroPageIndexedX: ret.value = Memory[((x = X) & 0x00FF)]; break; + case eZeroPageIndexedY: ret.value = Memory[((x = Y) & 0x00FF)]; break; - case eIndexedIndirect: return Memory[((x + X) << 8) + ((x + X) + 1)]; - case eIndirectIndexed: return ((Memory[x] + Memory[(x+1 << 8)]) + Y); + case eIndexedIndirect: ret.value = Memory[((x + X) << 8) + ((x + X) + 1)]; break; + case eIndirectIndexed: ret.value = ((Memory[x] + Memory[(x+1 << 8)]) + Y); break; //case eImplied: No reference //case eIndirectAbsolute: Only used in the JMP instruction //case eRelative: Only used in branch instructions } + switch(addr){ + case eAbsolute: case eAbsoluteIndexedX: case eAbsoluteIndexedY: + ret.length = 3; break; + case eAccumulator: + ret.length = 1; break; + default: + ret.length = 2; break; + } + + + // FOR TIME, FIND THE PARTICULAR VALUE SET FOR THE FIRST TYPE, + // APPLY RELATIVE MOVEMENT + // THEN LET THE FUNCTION WHICH CALLED fAddress HANDLE A NON-TYPICAL VALUE. + } |