From 983174a081c9c099aa8a745887070be0bbab8374 Mon Sep 17 00:00:00 2001
From: Tomas <kubecekt@gmail.com>
Date: Sun, 16 Feb 2025 20:32:19 +0100
Subject: [PATCH] Began work on tty driver

---
 kernel/include/kernel.h | 17 +++++++++++++++--
 kernel/include/tty.h    |  5 +++++
 kernel/src/kernel.c     |  5 +++--
 kernel/src/tty.c        | 31 +++++++++++++++++++++++++++++++
 makefile                |  2 +-
 5 files changed, 55 insertions(+), 5 deletions(-)
 create mode 100644 kernel/src/tty.c

diff --git a/kernel/include/kernel.h b/kernel/include/kernel.h
index 5963b15..babe17c 100644
--- a/kernel/include/kernel.h
+++ b/kernel/include/kernel.h
@@ -18,7 +18,20 @@
 #define __naked		__attribute__((naked))
 
 /*
- * Utility macros
+ * Standard int types
  */
-#define sizeof_array(_a) ()
+// Unsigned
+typedef unsigned char	uint8_t;
+typedef unsigned short	uint16_t;
+typedef unsigned int	uint32_t;
+typedef unsigned long	uint64_t;
+// Signed
+typedef signed char	int8_t;
+typedef signed short	int16_t;
+typedef signed int	int32_t;
+typedef signed long	int64_t;
+// Size
+typedef uint32_t	size_t;
+typedef int32_t		ssize_t;
+
 #endif
diff --git a/kernel/include/tty.h b/kernel/include/tty.h
index f5daf3e..1500210 100644
--- a/kernel/include/tty.h
+++ b/kernel/include/tty.h
@@ -1,6 +1,11 @@
 #ifndef _TTY_H
 #define _TTY_H
 
+/* VGA Text mode */
+#define VGA_WIDTH	80
+#define VGA_HEIGHT	25
+#define VGA_MEMORY	0xb8000
+
 int tty_init(void);
 int tty_write(char* buf, size_t len);
 int tty_putc(char c);
diff --git a/kernel/src/kernel.c b/kernel/src/kernel.c
index e4471fc..fed6b12 100644
--- a/kernel/src/kernel.c
+++ b/kernel/src/kernel.c
@@ -1,8 +1,9 @@
 #include <kernel.h>
+#include <tty.h>
 
 __noreturn
 void kmain(void) {
-	*(char*)0xb8000 = 'a';
-	while (1) __asm__ volatile ("movl $69, %eax");
+	tty_init();
+	printk("Hello, World!\n");
 }
 
diff --git a/kernel/src/tty.c b/kernel/src/tty.c
new file mode 100644
index 0000000..2504a9f
--- /dev/null
+++ b/kernel/src/tty.c
@@ -0,0 +1,31 @@
+#include <kernel.h>
+#include <tty.h>
+
+struct {
+	size_t row;
+	size_t col;
+	uint8_t attr;
+	uint8_t* buf;
+} ctx;
+
+void tty_init(void) {
+	ctx.row = 0;
+	ctx.col = 0;
+	ctx.attr = 0x07;
+	ctx.buf = (u8*)VGA_MEMORY;
+
+	for (size_t y = 0; y < VGA_HEIGHT; y++) {
+		for (size_t x = 0; x < VGA_WIDTH; x++) {
+			size_t i = (y * VGA_WIDTH + x) * 2;
+			ctx.buf[i] = ' ';
+			ctx.buf[i + 1] = ctx.attr;
+		}
+	}
+}
+
+int tty_write(char* buf, size_t len) {}
+
+int tty_putc(char c) {}
+
+int tty_puts(char* s) {}
+
diff --git a/makefile b/makefile
index 83707c2..f585576 100644
--- a/makefile
+++ b/makefile
@@ -14,7 +14,7 @@ clean:
 
 qemu:
 	qemu-system-x86_64\
-		-drive format=raw,file=$(IMG),index=0,media=disk\
+		-kernel ./kernel/kernel.elf
 		-m 256M -accel tcg -monitor stdio -net none\
 		-rtc base=localtime,clock=host,driftfix=slew\
 		-audiodev pipewire,id=audio0 -machine pcspk-audiodev=audio0