Subroutines implemented

Co-authored-by: sigonasr2 <sigonasr2@gmail.com>

main.cpp

@@ -65,15 +65,18 @@ public:
 
 	bool OnUserCreate() override
 	{
-		/*std::ifstream file("IBM Logo.ch8",std::ios_base::binary);
+		for (int i=0;i<display.size();i++){
+			display[i]=0;
+		}
+		std::ifstream file("test_opcode.ch8",std::ios_base::binary);
 		uint16_t counter=0x200;
 		while (file.good()){
 			int val = file.get();
 			if (val!=-1){
 				memory[counter++]=val;
 			}
-		}*/
-		memory[0x200]=0x00;
+		}
+		/*memory[0x200]=0x00;
 		memory[0x201]=0xE0;
 		memory[0x202]=0xA0;
 		memory[0x203]=0x50;
@@ -81,8 +84,10 @@ public:
 		memory[0x205]=0x04;
 		memory[0x206]=0xD0;
 		memory[0x207]=0x05;
-		memory[0x208]=0x12;
-		memory[0x209]=0x08;
+		memory[0x208]=0xD0;
+		memory[0x209]=0x05;
+		memory[0x210]=0x12;
+		memory[0x211]=0x10;*/
 		//0x200 program start
 		return true;
 	}
@@ -104,6 +109,7 @@ public:
 				//FETCH
 				uint16_t opcode = memory[pc]<<8|memory[pc+1];
 				pc+=2;
+				//std::cout<<"Next instruction is 0x"<<std::hex<<pc<<std::endl;
 
 				//DECODE
 				uint8_t nibble1 = opcode>>12;
@@ -121,13 +127,26 @@ public:
 									display[i]=0;
 								}
 							}break;
+							case 0x0EE:{ //Return from subroutine.
+								uint8_t byte1,byte2;
+								byte1=stack.top();
+								stack.pop();
+								byte2=stack.top();
+								stack.pop();
+								pc=byte2<<8|byte1;
+								//std::cout<<"Exiting subroutine to 0x"<<std::hex<<pc<<std::endl;
+							}break;
 						}
 					}break;
 					case 0x1:{ //Jump.
 						pc=NNN;
 					}break;
-					case 0x2:{
-
+					case 0x2:{ //calls the subroutine at memory location NNN
+						stack.push(pc>>8);
+						stack.push(pc&0xFF);
+						//std::cout<<"Pushed 0x"<<std::hex<<pc<<" onto stack"<<std::endl;
+						pc=NNN;
+						//std::cout<<"Entering subroutine @ 0x"<<std::hex<<NNN<<std::endl;
 					}break;
 					case 0x3:{
 
@@ -174,17 +193,12 @@ public:
 									//0xF0,0x90,0x90,0x90,0xF0
 									bool pixel = spriteRow>>(8-x-1)&0x1;
 									if (display[(start_Y+y)*ScreenWidth()+(start_X+x)]&&pixel){
+										//std::cout<<"Double on."<<std::endl;
 										reg[0xF]=0;
 									}
-									display[(start_Y+y)*ScreenWidth()+(start_X+x)]^=pixel;
-									if (pixel){
-										std::cout<<"X";
-									} else {
-										std::cout<<" ";
-									}
+									display[(start_Y+y)*ScreenWidth()+(start_X+x)]=display[(start_Y+y)*ScreenWidth()+(start_X+x)]^pixel;
 								}
 							}
-							std::cout<<std::endl;
 						}
 					}break;
 					case 0xE:{