stuff

kernel/libc/libc.c

@@ -21,13 +21,65 @@ int memset(char *dst, char data, int amount) {
     return 0;
 }
 
-int itoa(int i, char *target) {
-    target[0] = (char) (i % 10 + '0');
-    target[1] = '\0';
-    if (i > 9) {
-        itoa(i / 10, target + 1);
+int abs(int val) {
+    if (val >= 0) {
+        return val;
     }
-    return 0;
+    return val * -1;
+}
+
+// next stolen form https://www.techiedelight.com/implement-itoa-function-in-c/
+// inline function to swap two numbers
+void swap(char *x, char *y) {
+    char t = *x; *x = *y; *y = t;
+}
+
+// function to reverse buffer[i..j]
+char* reverse(char *buffer, int i, int j)
+{
+    while (i < j)
+        swap(&buffer[i++], &buffer[j--]);
+
+    return buffer;
+}
+
+// Iterative function to implement itoa() function in C
+char* itoa(int value, char* buffer, int base)
+{
+    // invalid input
+    if (base < 2 || base > 32)
+        return buffer;
+
+    // consider absolute value of number
+    int n = abs(value);
+
+    int i = 0;
+    while (n)
+    {
+        int r = n % base;
+
+        if (r >= 10)
+            buffer[i++] = 65 + (r - 10);
+        else
+            buffer[i++] = 48 + r;
+
+        n = n / base;
+    }
+
+    // if number is 0
+    if (i == 0)
+        buffer[i++] = '0';
+
+    // If base is 10 and value is negative, the resulting string
+    // is preceded with a minus sign (-)
+    // With any other base, value is always considered unsigned
+    if (value < 0 && base == 10)
+        buffer[i++] = '-';
+
+    buffer[i] = '\0'; // null terminate string
+
+    // reverse the string and return it
+    return reverse(buffer, 0, i - 1);
 }
 
 int maxi(int a, int b) {