a sensible source structure

The idea is that src/kernel/ is only allowed to interface with the
hardware using whatever's defined in src/arch/generic.h. I'll probably
write a small script for checking this later on.

This is a giant commit so I've probably fucked something up. It boots
fine on Bochs and QEMU, so at least there's that.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/arch/i386/tty.c b/src/arch/i386/tty.c
new file mode 100644
index 0000000..a7c74f5
--- /dev/null
+++ b/src/arch/i386/tty.c
@@ -0,0 +1,36 @@
+#include <arch/i386/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]);
+	}
+}
+
+void tty_clear() {
+	for (size_t i = 0; i < vga_len; i++)
+		vga[i].c = ' ';
+	vga_pos = 0;
+}