wm: 5551

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add DEC, INC, simplify sub and add

--- a/5551.h

+++ b/5551.h

@@ -15,7 +15,9 @@

 	/* arithmatic */

 	SUB,

-	ADD,

+	ADD

+	INC,

+	DEC,

 	/* shift */

 	SHR,

--- a/5551e.c

+++ b/5551e.c

@@ -11,14 +11,6 @@

 	int regs[8];

 }reg_t;

-bool add_bit(bool a, bool b)

-{

-	bool out;

-	out = ((a ^ b) ^ carry);

-	carry = (((a ^ b) & carry) | (a & b));

-	return out;

-}

-

 int btoi(bool b[], int len)

 {

   char arr[10];

@@ -78,20 +70,20 @@

 				break;

 			case SUB:

 				b = ~b;

-				carry = 1;

+				r.regs[CARRY] = 1;

+				r.flags[NSIGN] = (a < b);

+				r.regs[c] = r.flags[NSIGN] ? b - a : a - b;

 			case ADD:

-				while (a > 0 && b > 0) {

-					int diga = a % 10;

-					int digb = b % 10;

-					barr[ind] = add_bit(diga, digb);

-					a /= 10;

-					b /= 10;

-					ind++;

-				}

-				barr[ind] = carry;

-				r.regs[c] = btoi(barr,ind);

+				r.flags[NSIGN] = false;

+				r.regs[c] = a + b;

 				break;

+				r.flags[NSIGN] = false;

+				r.regs[b] = a + 1;

 				break;

+			case DEC:

+				r.regs[b] = a - 1;

+				r.flags[NSIGN] = (r.regs[b] < 0);

+				break;

 			case SHR:

 				r.regs[c] = a >> b;

 				break;

@@ -118,8 +110,6 @@

 		b = 0;

 		op = 0;

 		string[0] = '\0'; 

-        ind = 0;

-        carry = 0;

 	}

 	return 0;

 }