1 files changed, 85 insertions, 0 deletions
diff --git a/sys/kern/printf.c b/sys/kern/printf.c
new file mode 100644
index 0000000..dfd0657
--- /dev/null
+++ b/sys/kern/printf.c
@@ -0,0 +1,85 @@
+#include <printf.h>
+#include <stdint.h>
+#include <sbi.h>
+#include <stdarg.h>
+
+static char digits[] = "0123456789abcdef";
+
+int
+puts(const char *str)
+{
+	do {
+		sbi_console_putchar(*str);
+	} while (*(str++) != '\0');
+}
+
+#define PUTCHAR(c)      sbi_console_putchar(c)
+
+static void
+printint(int xx, int base, int sign)
+{
+        char buf[16];
+        int i;
+        unsigned int x;
+
+        if (sign && (sign = xx < 0))
+                x = -xx;
+        else 
+                x = xx; 
+
+        i = 0;
+        do {
+                buf[i++] = digits[x % base];
+        } while ((x /= base) != 0);
+
+        if (sign)
+                buf[i++] = '-';
+        while (--i >= 0)
+                PUTCHAR(buf[i]);
+
+}
+
+static void 
+printptr(uint64_t x)
+{
+        int i;
+        puts("0x");
+        for (i = 0; i < (sizeof(uint64_t) * 2); i++, x <<= 4)
+                PUTCHAR(digits[x >> (sizeof(int64_t) * 8 - 4)]);
+}
+
+void
+printf(const char *fmt, ...) 
+{
+        va_list ap;
+        int i, c;
+        char *s;
+
+        va_start(ap, fmt);
+
+        for (i = 0; (c = fmt[i] & 0xff) != 0; i++) {
+                if (c != '%') {
+                        PUTCHAR(c);
+                        continue;
+                }
+                c = fmt[++i] & 0xff;
+                if (!c) 
+                        break;
+
+                switch (c) {
+                        case 'd':
+                        case 'i':
+                                printint(va_arg(ap, int), 10, 1);
+                                break;
+                        case 'x':
+                                printint(va_arg(ap, int), 16, 1);
+                                break;
+                        case 'p':
+                                printptr(va_arg(ap, uint64_t));
+                                break;
+                        case '%':
+                                PUTCHAR('%');
+                                break;
+                }
+        }
+}