first commit I think

1 files changed, 51 insertions, 0 deletions

diff --git a/addressing.h b/addressing.h
new file mode 100644
index 0000000..ccde083
--- /dev/null
+++ b/addressing.h
@@ -0,0 +1,51 @@
+#define FALSE	0
+#define TRUE	1
+
+enum Addressing {
+	eImmediate,
+	eAbsolute,
+	eZeroPage,
+	eImplied,
+	eIndirectAbsolute,
+	eAbsoluteIndexedX,
+	eAbsoluteIndexedY,
+	eZeroPageIndexedX,
+	eZeroPageIndexedY,
+	eIndexedIndirect,
+	eIndirectIndexed,
+	eRelative,
+	eAccumulator
+};
+
+typedef int Addressing;
+
+	/*
+	*	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
+	}
+
+}
+