fix jmp not working

fix arithmetic operations
add prog3 and prog4
add debug to instructions

programs/prog3.asm

@@ -0,0 +1,61 @@
+//
+// prog1.asm -- an assembler example with global variables
+//
+
+//
+// compute the gcd of two positive numbers
+//
+// global Integer x;
+// global Integer y;
+// x = readInteger();
+// y = readInteger();
+// while (x != y) {
+//   if (x > y) {
+//     x = x - y;
+//   } else {
+//     y = y - x;
+//   }
+// }
+// writeInteger(x);
+// writeCharacter('\n');
+
+	// x = readInteger();
+	rdint
+	popg	0
+	// y = readInteger();
+	rdint
+	popg	1
+	// while ...
+L1:
+	// x != y
+	pushg	0 // 4
+	pushg	1
+	ne
+	brf	L2
+	// if ...
+	pushg	0
+	pushg	1
+	gt
+	brf	L3
+	// x = x - y
+	pushg	0
+	pushg	1
+	sub
+	popg	0
+	jmp	L4
+L3:
+	// y = y - x
+	pushg	1 // 17
+	pushg	0
+	sub
+	popg	1
+L4:
+	jmp	L1 // 21
+L2:
+	// writeInteger(x);
+	pushg	0 // 22
+	wrint
+	// writeCharacter('\n');
+	pushc	'\n'
+	wrchr
+	halt

programs/prog4.asm

@@ -0,0 +1,63 @@
+//
+// prog2.asm -- an assembler example with local variables
+//
+
+//
+// compute the gcd of two positive numbers
+//
+// local Integer x;
+// local Integer y;
+// x = readInteger();
+// y = readInteger();
+// while (x != y) {
+//   if (x > y) {
+//     x = x - y;
+//   } else {
+//     y = y - x;
+//   }
+// }
+// writeInteger(x);
+// writeCharacter('\n');
+
+	asf	2
+	// x = readInteger();
+	rdint
+	popl	0
+	// y = readInteger();
+	rdint
+	popl	1
+	// while ...
+L1:
+	// x != y
+	pushl	0
+	pushl	1
+	ne
+	brf	L2
+	// if ...
+	pushl	0
+	pushl	1
+	gt
+	brf	L3
+	// x = x - y
+	pushl	0
+	pushl	1
+	sub
+	popl	0
+	jmp	L4
+L3:
+	// y = y - x
+	pushl	1
+	pushl	0
+	sub
+	popl	1
+L4:
+	jmp	L1
+L2:
+	// writeInteger(x);
+	pushl	0
+	wrint
+	// writeCharacter('\n');
+	pushc	'\n'
+	wrchr
+	rsf
+	halt