The printk(), panic() and kernel.h update

kernel/src/printk.c

@@ -0,0 +1,28 @@
+#include <kernel.h>
+#include <serial.h>
+#include <stdarg.h>
+#include <ctype.h>
+
+uint8_t console_loglevel = CONSOLE_LOGLEVEL;
+
+int printk(const char *fmt, ...) {
+	va_list ap;
+	va_start(ap, fmt);
+	int ret = vprintk(fmt, ap);
+	va_end(ap);
+	return ret;
+}
+
+int vprintk(const char* fmt, va_list ap) {
+	int loglevel = LOGLEVEL_DEFAULT;
+	if (*fmt == KERN_SOH_ASCII) {
+		fmt++;
+		if (isdigit(*fmt)) loglevel = *fmt++ - '0';
+	}
+
+	if (loglevel > console_loglevel) return 0;
+
+	// TODO: debugf("[%4d.%6d] ", seconds, milliseconds);
+	return vdebugf(fmt, ap);
+}
+