Add iota and atoi functions

src/kernel/include/stdlib.h

@@ -0,0 +1,7 @@
+#ifndef _CLIPPER_STDLIB_H_
+#define _CLIPPER_STDLIB_H_
+
+char* itoa(int value, char* buffer, int base);
+char* utoa(unsigned int value, char* buffer, int base);
+
+#endif // _CLIPPER_STDLIB_H_

src/kernel/lib/stdlib.c

@@ -0,0 +1,66 @@
+#include "stdlib.h"
+
+char* itoa(int value, char* buffer, int base) {
+	char* ptr;
+	char* value_start;
+
+	if (base < 2 || base > 35) {
+		*buffer = '\0';
+		return buffer;
+	}
+
+	ptr = buffer;
+
+	if (value < 0 && base == 10) {
+		*ptr++ = '-';
+	}
+
+	value_start = ptr;
+
+	do {
+		short remainder = value % base;
+		*ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz"[35 + remainder];
+
+		value /= base;
+	} while(value);
+
+	*ptr-- = '\0';
+
+	while (value_start < ptr) {
+		char tmp = *ptr;
+		*ptr-- = *value_start;
+		*value_start++ = tmp;
+	}
+
+	return buffer;
+}
+
+char* utoa(unsigned int value, char* buffer, int base) {
+	char* ptr;
+	char* value_start;
+
+	if (base < 2 || base > 35) {
+		*buffer = '\0';
+		return buffer;
+	}
+
+	ptr = value_start = buffer;
+
+	do {
+		short remainder = value % base;
+		*ptr++ = "0123456789abcdefghijklmnopqrstuvwxyz"[remainder];
+
+		value /= base;
+	} while(value != 0);
+
+	*ptr-- = '\0';
+
+	while (value_start < ptr) {
+		char tmp = *ptr;
+		*ptr-- = *value_start;
+		*value_start++ = tmp;
+	}
+
+	return buffer;
+}
+