Add TSX, TXA and TXS instructions

src/6502/6502.h

@@ -28,6 +28,9 @@ typedef unsigned short word; // 16 bit
 
 #define INS_TAX 0xAA // TAX Implied
 #define INS_TAY 0xA8 // TAY Implied
+#define INS_TSX 0xBA // TSX Implied
+#define INS_TXA 0x8A // TXA Implied
+#define INS_TXS 0x9A // TXS Implied
 
 #define INS_JSR 0x20 // JSR
 #define INS_RTS 0x60 // RTS

src/6502/main.c

@@ -127,6 +127,7 @@ void execute() {
 				cpu.Z = (cpu.Y == 0);
 				cpu.N = (cpu.Y & 0b1000000) > 0;
 				break;
+				
 		        case INS_TAX:
 			        cpu.X = cpu.A;
 				cpu.Z = (cpu.X == 0);
@@ -139,7 +140,24 @@ void execute() {
 				cpu.N = (cpu.Y & 0b1000000) > 0;
 				cpu.PC++;
 			        break;
-			case INS_JSR:
+
+		        case INS_TSX:
+			        cpu.X = cpu.SP;
+			        cpu.Z = (cpu.X == 0);
+				cpu.N = (cpu.X & 0b1000000) > 0;
+				cpu.PC++;
+			        break;
+          		case INS_TXA:
+			        cpu.A = cpu.X;
+				cpu.Z = (cpu.A == 0);
+				cpu.N = (cpu.A & 0b1000000) > 0;
+				cpu.PC++;
+			        break;
+		        case INS_TXS:
+			        cpu.SP = cpu.X;
+				cpu.PC++;
+			        break;
+	   		case INS_JSR:
 				word jsr_addr = fetch_word();
 				write_word(cpu.PC - 1, cpu.SP);
 				cpu.SP++;

src/6502/test.bin

@@ -1 +1 @@
-<EFBFBD>Uｨ
+<EFBFBD>B<EFBFBD>