implements integer printing into printf, and adds some testing logs

libc/stdio/printf.c

@@ -4,11 +4,56 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <kernel/_kernel.h>
+
+static void reverse(char* buf, int len)
+{
+	int start = 0;
+	int end = len - 1;
+	while (start < end) {
+		char tmp = buf[start];
+		buf[start] = buf[end];
+		buf[end] = tmp;
+		end--;
+		start++;
+	}
+}
+
+static char* itoa(int num, char* buf, int base)
+{
+	int i = 0;
+	bool neg = false;
+	
+	if (num == 0) { // Handle zero explicitly
+		buf[i++] = '0';
+		buf[i] = '\0';
+		return buf;
+	}
+
+	if (num < 0 && base == 10) { // only handle negative on base10
+		neg = true;
+		num = -num;
+	}
+
+	while (num != 0) {
+		int rem = num % base;
+		buf[i++] = (rem > 9) ? (rem - 10) + 'a' : rem + '0';
+		num = num / base;
+	}
+
+	if (neg) // lets reapply the negative sign
+		buf[i++] = '-'; 
+
+	buf[i] = '\0';
+
+	reverse(buf, i); // reverse, since we did it backwards!
+	return buf;
+}
+
 static bool print(const char* data, size_t length) {
 	const unsigned char* bytes = (const unsigned char*) data;
 	for (size_t i = 0; i < length; i++)
-		if (putchar(bytes[i]) == EOF)
-			return false;
+		if (putchar(bytes[i]) == EOF) return false;
 	return true;
 }
 
@@ -18,6 +63,8 @@ int printf(const char* restrict format, ...) {
 
 	int written = 0;
 
+	char buffer[512];
+
 	while (*format != '\0') {
 		size_t maxrem = INT_MAX - written;
 
@@ -61,6 +108,30 @@ int printf(const char* restrict format, ...) {
 			if (!print(str, len))
 				return -1;
 			written += len;
+		} else if (*format == 'd') {
+			format++;
+			int i = (int) va_arg(parameters, int);
+			itoa(i, buffer, 10);
+			size_t len = strlen(buffer);
+			if (maxrem < len) {
+				// TODO: Set errno to EOVERFLOW.
+				return -1;
+			}
+			if (!print(buffer, len))
+				return -1;
+			written += len;
+		} else if (*format == 'x') {
+			format++;
+			int i = (int) va_arg(parameters, int);
+			itoa(i, buffer, 16);
+			size_t len = strlen(buffer);
+			if (maxrem < len) {
+				// TODO: Set errno to EOVERFLOW.
+				return -1;
+			}
+			if (!print(buffer, len))
+				return -1;
+			written += len;
 		} else {
 			format = format_begun_at;
 			size_t len = strlen(format);