Initial commit

x86 kernel that prints a hello world message to com1

1 files changed, 38 insertions, 0 deletions

diff --git a/lib/stdio/printf.c b/lib/stdio/printf.c
new file mode 100644
index 0000000..f6b8ef6
--- /dev/null
+++ b/lib/stdio/printf.c
@@ -0,0 +1,38 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+#include <devices/uart_16550.h>
+
+int
+printf(const char *restrict format, ...)
+{
+  int written = 0;
+  va_list params;
+  va_start(params, format);
+
+  int s = 0;
+  int l = 0;
+  for (int i = 0; format[i] != '\0'; ++i) {
+    if (format[i] == '%') {
+      written += uart_puts(COM1, &format[s], l);
+      s = i + 2;
+      ++i;
+
+      switch (format[i]) {
+      case 's':
+        written += uart_puts(COM1, va_arg(params, const char *), -1);
+        break;
+      }
+
+      l = 0;
+    }
+
+    else
+      ++l;
+  }
+
+  if (l > 0) written += uart_puts(COM1, &format[s], l);
+
+  va_end(params);
+  return written;
+}