1 files changed, 89 insertions, 0 deletions
diff --git a/src/cpu/6502.c b/src/cpu/6502.c
new file mode 100644
index 0000000..d78cd7e
--- /dev/null
+++ b/src/cpu/6502.c
@@ -0,0 +1,89 @@
+//	6502.h
+//	Main elements of the 6502 CPU
+
+#include"6502.h"
+
+
+byte getFlag(byte flag) {
+	return ((P & flag) == flag) ? 1 : 0;
+}
+
+void setFlag(byte flag, int x) {
+	if (x == 1){
+		if ((P & flag) == 0x0)	P += flag;
+	}else if (x == 0){
+		if ((P & flag) == flag)	P -= flag;
+	}
+	else{
+		fprintf(stderr, "setFlag() passed arg neither 0 or 1");
+	}
+}
+
+void flagSet(byte flag){
+	P |= flag;
+}
+
+void flagClear(byte flag){
+	P &= ~flag;
+}
+
+//	Functions which perform reusable routines for finding if a specific flag should be set.
+
+void setFlagN(byte x){
+	if (x & flag_N == flag_N)
+		setFlag(flag_N, 1);
+	else
+		setFlag(flag_N, 0);
+}
+
+//Perform prior to any changes
+void setFlagV(byte x, byte y){
+	if ((x & flag_N) == (y & flag_N)){
+		if (((x + y) & (flag_N ^ 0xFF)) > 0x7F) setFlag(flag_V, 1);
+		else setFlag(flag_V, 0);
+	}else{
+		if (((x - y) & (flag_N ^ 0xFF)) > 0x7F) setFlag(flag_V, 1);
+		else setFlag(flag_V, 0);
+	}
+}
+
+/*void setFlagB(){ //WORK ON
+	setFlag(flag_B, 1);
+}*/
+
+/*void setFlagD(){
+	setFlag(flag_D, 1);
+}*/
+
+/*void setFlagI(){ //WORK ON
+	setFlag(flag_Z, 1);
+}*/
+
+void setFlagZ(int x){
+	if (x == 0)
+		setFlag(flag_Z, 1);
+	else
+		setFlag(flag_Z, 0);
+}
+
+/*void setFlagC(){
+	setFlag(flag_Z, 1);
+}*/
+
+
+/*byte getMemory(address x){
+	return Memory[x];
+}
+
+void setMemory(address x, byte y){
+	Memory[x] = y;
+}*/
+
+
+byte getStack() {
+	return getMemory(0x01FF - S);
+}
+
+void setStack(byte z) {
+	setMemory(0x01FF - S, z);
+}
+\ No newline at end of file