1 files changed, 64 insertions, 0 deletions
diff --git a/src/loader/vga.c b/src/loader/vga.c
new file mode 100644
index 0000000..6cc9bfa
--- /dev/null
+++ b/src/loader/vga.c
@@ -0,0 +1,64 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <log.h>
+
+#define VGA_WIDTH 80
+#define VGA_HEIGHT 25
+#define VGA_ADDRESS 0xb8000
+
+void vga_clear(void)
+{
+	u16 *out = (u16 *)VGA_ADDRESS;
+	for (u16 i = 0; i < 80 * 25; i++)
+		out[i] = 0;
+}
+
+void vga_put_at(char ch, u8 x, u8 y, u8 color)
+{
+	u8 *out = (u8 *)(VGA_ADDRESS + 2 * (x + y * VGA_WIDTH));
+	*out++ = ch;
+	*out++ = color;
+}
+
+static void vga_put(char ch)
+{
+	static u8 x = 0;
+	static u8 y = 0;
+
+	if (ch == '\n') {
+		x = 0;
+		y++;
+		return;
+	} else if (x + 1 == VGA_WIDTH) {
+		x = 0;
+		y++;
+	} else if (y + 1 == VGA_HEIGHT) {
+		x = 0;
+		y = 0;
+		vga_clear();
+	}
+
+	u8 *out = (u8 *)(VGA_ADDRESS + 2 * (x + y * VGA_WIDTH));
+	*out++ = ch;
+	*out++ = 0x07;
+
+	x++;
+}
+
+static void vga_print(const char *data)
+{
+	for (const char *p = data; *p; p++)
+		vga_put(*p);
+}
+
+void vga_log(const char *format, ...)
+{
+	char buf[1024] = { 0 };
+
+	va_list ap;
+	va_start(ap, format);
+	vsnprintf(buf, sizeof(buf), format, ap);
+	va_end(ap);
+
+	vga_print(buf);
+}