implement kprint_int and kprint_hex functions; add kprintf for formatted output

src/drivers/uart.c

@@ -1,5 +1,6 @@
 #include <stdint.h>
 #include <stddef.h>
+#include <stdarg.h>
 #include <drivers/uart.h>
 
 void uart_put(size_t base_addr, uint8_t data) {
@@ -17,6 +18,40 @@ void kprint(const char *str) {
 	}
 }
 
+void kprint_int(int num) {
+	char buffer[21];
+	int i = 0;
+	if (num == 0) {
+		kputchar('0');
+		return;
+	}
+	if (num < 0) {
+		kputchar('-');
+		num = -num;
+	}
+	while (num > 0) {
+		buffer[i++] = '0' + (num % 10);
+		num /= 10;
+	}
+	while (i > 0) {
+		kputchar(buffer[--i]);
+	}
+}
+
+void kprint_hex(uint64_t val) {
+    char *digits = "0123456789ABCDEF";
+    char buffer[16]; // 64-bit hex is 16 chars
+    
+    // We process from right to left
+    for (int i = 15; i >= 0; i--) {
+        buffer[i] = digits[val & 0xF];
+        val >>= 4;
+    }
+
+	kprint(buffer);    
+
+}
+
 void knewline(void) {
 	kputchar('\n');
 }
@@ -25,3 +60,42 @@ void kputs(const char *str) {
 	kprint(str);
 	knewline();
 }
+
+void kprintf(const char *format, ...) {
+	va_list args;
+	va_start(args, format);
+
+	for(char *p = format; *p != '\0'; p++) {
+		if (*p == '%') {
+			p++;
+			switch (*p) {
+				case 's': {
+					char *s = va_arg(args, char *);
+					kprint(s);
+					break;
+				}
+				case 'd': {
+					int d = va_arg(args, int);
+					kprint_int(d);
+					break;
+				}
+				case 'x':   // Hex
+				case 'p': { // Pointer
+					uint64_t x = va_arg(args, uint64_t);
+					kputchar('0'); kputchar('x');
+					kprint_hex(x);
+					break;
+				}
+				case '%':
+					kputchar('%');
+					break;
+				default:
+					kputchar('%');
+					kputchar(*p);
+			}
+		} else {
+			kputchar(*p);
+		}
+	}
+
+}

src/drivers/uart.h

@@ -4,6 +4,9 @@
 #define UART_ADDRESS 0x10000000
 void uart_put(size_t base_addr, uint8_t data);
 int kputchar(int ch);
+void kprint_hex(uint64_t val);
+void kprint_int(int num);
+void kprintf(const char *format, ...);
 void knewline();
 void kputs(const char *str);
 void kprint(const char *str);