From edf9e71e2a7b6b89775c29cf28c19c6b89992c25 Mon Sep 17 00:00:00 2001
From: aqua <aqua@iserlohn-fortress.net>
Date: Mon, 28 Mar 2022 20:03:38 +0300
Subject: Initial commit

x86 kernel that prints a hello world message to com1
---
 lib/stdio/printf.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 lib/stdio/printf.c

(limited to 'lib/stdio/printf.c')

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;
+}
-- 
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