1 files changed, 107 insertions, 0 deletions
diff --git a/applesystem.h b/applesystem.h
new file mode 100644
index 0000000..a3a33f5
--- /dev/null
+++ b/applesystem.h
@@ -0,0 +1,107 @@
+typedef unsigned char byte;
+byte acc, X, Y, S, P = 0x00;
+byte Memory[4096]; // TO DO. Add expansion capability to memory.
+
+//	FLAGS
+const byte flag_N = 0x80;	// Negative (Note that byte cast is necessary here only)
+const byte flag_V = 0x40;	// Overflow
+const byte flag_B = 0x10;	// BRK command
+const byte flag_D = 0x08;	// Decimal mode
+const byte flag_I = 0x04;	// IRQ disable
+const byte flag_Z = 0x02;	// Zero
+const byte flag_C = 0x01;	// Carry
+
+byte getFlag(byte flag) {
+	return ((P & flag) == flag) ? 1 : 0;
+}
+
+void setFlag(byte flag, int x) { //OVERLOAD TO ACCEPT INT AS WELL
+	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 toggleFlag(byte flag) {
+	P = ((P & flag) == flag) ? (P + flag) : (P - flag);
+}
+
+//	BCD
+
+byte toBCD(byte x){
+	if (x < 100){
+		byte a = ((x / 10) << 4);
+		byte b = (x % 10);
+		return (a + b);
+	}
+	else{
+		fprintf(stderr, "Number greater than 99 passed to toBCD()");
+	}
+}
+
+byte fromBCD(byte x){
+	byte a = ((x >> 4) * 10);
+	byte b = (x & 0xF);
+	return (a + b);
+}
+
+
+
+
+
+// Class of instructions
+//each one has every type of addressing mode, inherited from a base class.
+// the different addressing modes will be distinguished when the bytecode is called, it will run the instructions function with a selection for the 
+/* example
+
+Immediate     ADC #$44      $69  2   2
+instruction(0x69); -> ADC({enum for immediate}); 
+
+Zero Page     ADC $44       $65  2   3
+instruction(0x65); -> ADC({enum for Zero Page}); 
+*/
+// Set particular flags
+void setFlagN(){
+	if (acc ^ 0x80){
+		setFlag(flag_N, 1);
+	}else{ //not sure if this should be present, I think it is
+		setFlag(flag_N, 0);
+	}
+}
+
+//Perform prior to any changes
+void setFlagV(byte x, byte y){ //This is pathetic.
+	if ((x & flag_N) == (y & flag_N)){
+		if (((x + y) & (flag_N ^ 0xFF)) > 0x8F) setFlag(flag_V, 1);
+	}else{
+		if (((x - y) & (flag_N ^ 0xFF)) > 0x8F) setFlag(flag_V, 1);
+	}
+}
+/*void setFlagB(){ //WORK ON
+	setFlag(flag_B, 1);
+}*/ //Dont really need since its dependent on the BRK insturction
+/*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);
+	}
+}
+void setFlagC(){ // NOTE. Must make setFlagC functional with independence. Look into carrying on 6502
+	setFlag(flag_Z, 1);
+}
+
+
+
+
+
+
+