Added math library

lib/conv.c

@@ -4,10 +4,11 @@ void int_to_str(int i, char* buf) {
 	ulong num = (ulong)i; // convert to ulong
 	uint len = ulong_len(num); // number of digits
 
-	&buf[len] = '\0'; // add a "end-of-string" at the end
+	*(buf+len) = '\0'; // add a "end-of-string" at the end
 
 	int j;
 	for(j = 0; j < len; j++) // iterate over each digit and assign it to the buffer
-		&buf[j] = (char)(ndigit(num, len-1-j) + ASCII_OFFSET); // apply the ascii offset so that i becomes a char
+		// super dangerous memory write 
+		*(buf+j) = (char)(ndigit(num, len-1-j) + ASCII_OFFSET); // apply the ascii offset so that i becomes a char
 
 }

lib/math.c

@@ -0,0 +1,10 @@
+#include "math.h"
+
+long pow(int num, uint expon) {
+	long prod = 1;
+	while(expon > 0)	
+		prod *= num;
+		--expon;
+
+	return prod;
+}

lib/math.h

@@ -0,0 +1,3 @@
+#include "types.h"
+
+long pow(int, uint);

lib/util.c

@@ -10,5 +10,6 @@ uint ulong_len(ulong n) { // get the digit length of a number
 }
 
 uint ndigit(ulong n, uint i) { // OBS: index order is reversed
-	return (n/(10**i)) % 10
+	long den = pow(10, i);
+	return (n/den) % 10;
 }