More instructions

src/RNG.ts

@@ -18,6 +18,10 @@ class RNG {
 	nextInt(min: number, max: number): number {
 		return Math.floor(this.next() * (max - min + 1)) + min;
 	}
+
+	next255(): number {
+		return Math.floor(this.next() * 255);
+	}
 }
 
 export default RNG;

src/cpu.ts

@@ -216,20 +216,28 @@ class CPU {
 					// Vx -= Vy
 					this.registers[0xF] = this.registers[secondNibble] > this.registers[thirdNibble] ? 1 : 0;
 					let subs = this.registers[secondNibble] - this.registers[thirdNibble];
+					this.registers[secondNibble] = subs;
 					this.incrementPC();
 				}else if(lastNibble == 0x6) {
 					// 8XY6
 					// Vx >>= 1
-					this.registers[secondNibble] >> 1;
+					this.registers[0xF] = this.registers[0xF] & 1; // ???? // Store the least significant bit of VX prior
+					this.registers[secondNibble] >>= 1;
 					this.incrementPC();
 				}else if(lastNibble == 0x7) {
 					// 8XY7
 					// Vx = Vy - Vx
-					this.registers[0xF] = this.registers[secondNibble] > this.registers[thirdNibble] ? 1 : 0;
+					this.registers[0xF] = this.registers[thirdNibble] > this.registers[secondNibble] ? 1 : 0;
-					let subs = this.registers[secondNibble] - this.registers[thirdNibble];
+					let subs = this.registers[thirdNibble] - this.registers[secondNibble];
+					this.registers[secondNibble] = subs;
 					this.incrementPC();
 				}else if(lastNibble == 0xE) {
-
+					// 8XYE
+					// Vx <<= 1
+					// Set VF to 1 if the most significant bit of VX prior to that shift was set
+					this.registers[0xF] = this.registers[0xF] >> 3;
+					this.registers[secondNibble] <<= 1;
+					this.incrementPC();
 				}
 
 				}
@@ -245,6 +253,58 @@ class CPU {
 				this.incrementPC();
 				}
 				break;
+			
+			case 0xA: {
+				// ANNN
+				// Sets I to the address NNN
+				this.indexReg = opcode & 0x0FFF;
+				this.incrementPC();
+				}
+				break;
+			case 0xB:{
+				// BNNN
+				// Jumps to the address NNN plus V0
+				this.pc = this.registers[0] + opcode & 0x0FFF;
+				}
+				break;
+			case 0xC: {
+				// CXNN
+				// Vx = rand() & NN
+				let secondNibble = firstOpcode & 0xF; //0X00
+				this.registers[secondNibble] = this.rng.next255() & secondOpcode;
+				this.incrementPC();
+				}
+				break;
+			case 0xD: {
+				// DXYN
+				// draw(Vx, Vy, N)
+				let secondNibble = firstOpcode & 0xF; //0X00
+				let thirdNibble = secondOpcode >> 4; //00Y0
+				let fourthNibble = secondOpcode & 0xF;
+				
+				this.registers[0xF] = 0;
+
+				let regX = this.registers[secondNibble];
+				let regY = this.registers[thirdNibble];
+				
+				let y = 0;
+				while(y < fourthNibble) {
+					// A sprite is always 8 bits horizontal
+					let pixel = this.memory[this.indexReg + y];
+					let x = 0;
+					while(x < 8) {
+						const msb = 0x80;
+						
+
+						x++;
+					}
+
+					y++;
+				}
+
+				this.incrementPC();
+				}
+				break;
 		}
 	}