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-rw-r--r--src/cpu/addressing.c184
1 files changed, 184 insertions, 0 deletions
diff --git a/src/cpu/addressing.c b/src/cpu/addressing.c
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index 0000000..6e7d950
--- /dev/null
+++ b/src/cpu/addressing.c
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+// addressing.h
+// Contains definitions relevant to addressing, as well as fAddress() which returns time, length, value, and address for an instruction function call.
+
+#include"addressing.h"
+
+#define getInstructionLength(c) fAddressGetLength(*getInstructionTableAddressing(c))
+
+int fAddressGetLength(Addressing addr){
+ switch(addr){
+ case eAbsolute: case eAbsoluteIndexedX: case eAbsoluteIndexedY:
+ return 3;
+ case eAccumulator: case eImplied:
+ return 1;
+ default:
+ return 2;
+ }
+}
+
+AddData fAddress(Addressing addr, short x) {
+ AddData ret;
+
+ // ADDRESS
+
+ switch(addr){
+ case eImplied:
+ case eIndirectAbsolute:
+ case eRelative:
+ case eImmediate:
+ case eAccumulator:
+ ret.add = 0x0000;
+ break;
+
+ case eAbsolute:
+ ret.add = x;
+ break;
+ case eAbsoluteIndexedX:
+ ret.add = (x + X);
+ break;
+ case eAbsoluteIndexedY:
+ ret.add = (x + Y);
+ break;
+
+ case eZeroPage:
+ ret.add = (x & 0x00FF);
+ break;
+ case eZeroPageIndexedX:
+ ret.add = ((x + X) & 0x00FF);
+ break;
+ case eZeroPageIndexedY:
+ ret.add = ((x + Y) & 0x00FF);
+ break;
+
+ case eIndexedIndirect:
+ ret.add = ((getMemory(x+X+1))<<8) + (getMemory(x+X));
+ break;
+ case eIndirectIndexed:
+ ret.add = ((getMemory(x+1))<<8) + (getMemory(x)) + Y;
+ break;
+ }
+
+ // VALUE
+
+ switch(addr){
+ case eImplied:
+ case eIndirectAbsolute:
+ case eRelative:
+ break;
+
+ case eImmediate:
+ ret.value = x;
+ break;
+
+ case eAccumulator:
+ ret.value = acc;
+ break;
+
+ default:
+ ret.value = getMemory(ret.add);
+ }
+
+ // LENGTH
+
+ ret.length = fAddressGetLength(addr);
+
+ // CYCLES
+
+ //case &fADC: case &fAND: case &fBIT: case &fCMP: case &fCPX: case &fCPY: case &fEOR: case &fLDA:
+ //case &fLDX: case &fLDY: case &fORA: case &fSBC: case &fSTX: case &fSTY:
+
+ if ( current_instruction == &fADC || current_instruction == &fAND || current_instruction == &fBIT || current_instruction == &fCMP || current_instruction == &fCPX
+ || current_instruction == &fCPY || current_instruction == &fEOR || current_instruction == &fLDA || current_instruction == &fLDX || current_instruction == &fLDY
+ || current_instruction == &fORA || current_instruction == &fSBC || current_instruction == &fSTX || current_instruction == &fSTY ){
+ switch(addr){
+ case eImmediate:
+ ret.cycles = 2; break;
+ case eZeroPage:
+ ret.cycles = 3; break;
+ case eZeroPageIndexedX: case eAbsolute: case eAbsoluteIndexedX: case eAbsoluteIndexedY:
+ ret.cycles = 4; break;
+ case eIndexedIndirect:
+ ret.cycles = 6; break;
+ case eIndirectIndexed:
+ ret.cycles = 5; break;
+ }
+ }
+
+ //case &fASL: case &fDEC: case &fINC: case &fLSR: case &fROL: case &fROR:
+ else if( current_instruction == &fASL || current_instruction == &fDEC || current_instruction == &fINC
+ || current_instruction == &fLSR || current_instruction == &fROL || current_instruction == &fROR ){
+ switch(addr){
+ case eAccumulator:
+ ret.cycles = 2; break;
+ case eZeroPage:
+ ret.cycles = 5; break;
+ case eZeroPageIndexedX: case eAbsolute:
+ ret.cycles = 6; break;
+ case eAbsoluteIndexedX:
+ ret.cycles = 7; break;
+ }
+ }
+
+ //case &fSTA:
+ else if (current_instruction == &fSTA){
+ switch(addr){
+ case eZeroPage:
+ ret.cycles = 3; break;
+ case eZeroPageIndexedX: case eAbsolute:
+ ret.cycles = 4; break;
+ case eAbsoluteIndexedX: case eAbsoluteIndexedY:
+ ret.cycles = 5; break;
+ case eIndexedIndirect: case eIndirectIndexed:
+ ret.cycles = 6; break;
+ }
+ }
+
+
+ //case &fBRK:
+ else if (current_instruction == &fBRK){
+ ret.cycles = 7;
+ }
+
+
+ //case &fRTI: case &fRTS: case &fJSR:
+ else if (current_instruction == &fRTI || current_instruction == &fRTS || current_instruction == &fJSR){
+ ret.cycles = 6;
+ }
+
+ //case &fJMP:
+ else if (current_instruction == &fJMP){
+ ret.cycles = 5;
+ }
+
+ //case &fPLA: case &fPLP:
+ else if (current_instruction == &fPLA || current_instruction == &fPLP){
+ ret.cycles = 4;
+ }
+
+ //case &fPHA: case &fPHP:
+ else if (current_instruction == &fPHA || current_instruction == &fPHP){
+ ret.cycles = 3;
+ }
+
+ else {
+ ret.cycles = 2;
+ }
+
+
+ // Page Boundary
+
+ //case &fADC: case &fSBC: case &fLDA: case &fLDX: case &fLDY: case &fEOR: case &fAND: case &fORA: case &fCMP:
+ if ( current_instruction == &fADC || current_instruction == &fSBC || current_instruction == &fLDA || current_instruction == &fLDX || current_instruction == &fLDY
+ || current_instruction == &fEOR || current_instruction == &fAND || current_instruction == &fORA || current_instruction == &fCMP ){
+ switch(addr){
+ case eAbsoluteIndexedX:
+ if ((x & 0xFF00) != ((x + X) & 0xFF00)) ret.cycles++; break;
+ case eAbsoluteIndexedY:
+ if ((x & 0xFF00) != ((x + Y) & 0xFF00)) ret.cycles++; break;
+ case eIndirectIndexed:
+ if ((ret.add & 0xFF00) != (ret.add - Y & 0xFF00)) ret.cycles++; break;
+ }
+ }
+
+ return ret;
+} \ No newline at end of file