mango/kernel/printk.c

#include <socks/printk.h>
#include <socks/locks.h>
#include <socks/console.h>
#include <socks/libc/stdio.h>
#include <stdarg.h>

#define LOG_BUFFER_SIZE 0x40000
#define LOG_MSG_SIZE    0x100

static console_t *early_console = NULL;

static spin_lock_t log_buffer_lock = SPIN_LOCK_INIT;

static char log_buffer[LOG_BUFFER_SIZE] = {0};
/* index of the last character in log_buffer that has been written
   to the console */
static unsigned int log_buffer_readp = 0;
/* index of the last character in log_buffer that has been logged
   (but not necessarily written to the console) */
static unsigned int log_buffer_writep = 0;

static void flush_log_buffer(void)
{
	if (!early_console) {
		return;
	}
	
	console_write(early_console, log_buffer + log_buffer_readp, log_buffer_writep - log_buffer_readp);
	log_buffer_readp = log_buffer_writep;
}

static void save_log_message(const char *msg)
{
	unsigned int i = 0;
	while (1) {
		if (log_buffer_writep == LOG_BUFFER_SIZE - 1) {
			log_buffer[log_buffer_writep] = '\0';
			break;
		}

		if (msg[i] == '\0') {
			break;
		}
				   
		log_buffer[log_buffer_writep++] = msg[i++];
	}
}

void early_printk_init(console_t *con)
{
	early_console = con;
}

int printk(const char *format, ...)
{
	char msg[LOG_MSG_SIZE];

	va_list arg;
	va_start(arg, format);
        int len = vsnprintf(msg, sizeof msg - 1, format, arg);
	va_end(arg);

	msg[len] = '\n';
	msg[len + 1] = '\0';

	unsigned long flags;
	spin_lock_irqsave(&log_buffer_lock, &flags);
	save_log_message(msg);
	spin_unlock_irqrestore(&log_buffer_lock, flags);

	flush_log_buffer();
	
        return 0;
}