From fde20f86f5be5a39fd3eadf95ba71761d173e0ce Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Thu, 24 Jun 2021 20:41:07 +0200
Subject: Hello world o/

---
 kernel/main.c |  7 +++++++
 kernel/tty.c  | 32 ++++++++++++++++++++++++++++++++
 kernel/tty.h  |  6 ++++++
 3 files changed, 45 insertions(+)
 create mode 100644 kernel/main.c
 create mode 100644 kernel/tty.c
 create mode 100644 kernel/tty.h

(limited to 'kernel')

diff --git a/kernel/main.c b/kernel/main.c
new file mode 100644
index 0000000..73c66e2
--- /dev/null
+++ b/kernel/main.c
@@ -0,0 +1,7 @@
+#include <kernel/tty.h>
+
+void kmain()
+{
+	for (int i = 0; i < 400; i++)
+		tty_write("words ", 6);
+}
diff --git a/kernel/tty.c b/kernel/tty.c
new file mode 100644
index 0000000..45de728
--- /dev/null
+++ b/kernel/tty.c
@@ -0,0 +1,32 @@
+/* will be moved to userspace later on */
+
+#include <kernel/tty.h>
+
+struct vga_cell {
+	unsigned char c;
+	unsigned char style;
+} __attribute__((__packed__));
+
+static const size_t     vga_len = 80 * 25;
+static struct vga_cell *vga     = (void*) 0xB8000;
+static size_t           vga_pos = 0;
+
+static void tty_scroll() {
+	for (int i = 0; i < vga_len - 80; i++) {
+		vga[i] = vga[i + 80];
+	}
+	vga_pos -= 80;
+}
+
+void tty_putchar(char c)
+{
+	if (vga_pos >= vga_len - 80) tty_scroll();
+	vga[vga_pos++].c = c;
+}
+
+void tty_write(const char *buf, size_t len)
+{
+	for (size_t i = 0; i < len; i++) {
+		tty_putchar(buf[i]);
+	}
+}
diff --git a/kernel/tty.h b/kernel/tty.h
new file mode 100644
index 0000000..87a4744
--- /dev/null
+++ b/kernel/tty.h
@@ -0,0 +1,6 @@
+#pragma once
+
+#include <stddef.h>
+
+void tty_putchar(char c);
+void tty_write(const char *buf, size_t len);
-- 
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