From 00a8c3acac5e8d8af057aa766f8c97887835df6f Mon Sep 17 00:00:00 2001
From: Hojun-Cho <ghwns6743@gmail.com>
Date: Wed, 27 Nov 2024 21:29:33 +0900
Subject: [PATCH] add pio.h

---
 boot/boot.c | 50 ++++++++++++++++++++++++++++++++++++++------------
 boot/pio.h  |  8 ++++++++
 2 files changed, 46 insertions(+), 12 deletions(-)
 create mode 100644 boot/pio.h

diff --git a/boot/boot.c b/boot/boot.c
index dad5c78..5106edb 100644
--- a/boot/boot.c
+++ b/boot/boot.c
@@ -1,8 +1,11 @@
+#include "pio.h"
+
+typedef unsigned short u16;
+typedef unsigned char u8;
 typedef int dev_t;
 
-#define SCREEN_WIDTH           80
-#define SCREEN_LENGTH          25
-#define VGA_BUFFER_ADDR         0xb8000
+#define VGA_WIDTH 80
+#define VGA_LENGTH 25
 
 char*
 memcpy(char *a, char *b, int l)
@@ -37,20 +40,43 @@ itostr(int n, char *s)
 	return s;
 }
 
+void
+setcursor(int x, int y)
+{
+	u16 pos = y * VGA_WIDTH + x;
+
+	outb(0x3D4, 0x0F);
+	outb(0x3D5, (u8) (pos & 0xFF));
+	outb(0x3D4, 0x0E);
+	outb(0x3D5, (u8) ((pos >> 8) & 0xFF));
+}
+
+void
+wr8(u8 c, u8 fg, u8 bg, int x, int y)
+{
+     u16 attrib = (bg << 4) | (fg & 0x0F);
+     volatile u16 * where;
+     where = (volatile u16 *)0xB8000 + (y * 80 + x);
+     *where = c | (attrib << 8);
+}
+
+
 void
 boot(dev_t bootdev)
 {
 	char *p;
-    char s[SCREEN_WIDTH] = "booted on disk:0x";
-    short* vga = (short*)VGA_BUFFER_ADDR;
+	char s[VGA_WIDTH] = "booted on disk:0x";
 
 	p = s+strlen(s);
 	p = itostr((int)bootdev, p);
-	for(int j = 0; j < SCREEN_LENGTH; ++j){
-		for (int i = 0; i < sizeof(s); ++i) {
-			vga[(j*SCREEN_WIDTH)  + (i + SCREEN_WIDTH*2)] = 0x9100 | s[i];
-		}
-	}
-	while(1)
-		;
+	setcursor(0,0);
+	for (int i = 0; i < sizeof(s); ++i)
+		wr8(s[i], 0xe8, 0x00, i, 0);
+	for(int i = 1; i < VGA_LENGTH; ++i)
+		for(int j = 0; j < VGA_WIDTH; ++j)
+			wr8(0x00, 0x91, 0x00, j, i);
+	// disable cursor
+	outb(0x3D4, 0x0a);
+	outb(0x3D5, 0x20);
+	asm("hlt");
 }
diff --git a/boot/pio.h b/boot/pio.h
new file mode 100644
index 0000000..4c98414
--- /dev/null
+++ b/boot/pio.h
@@ -0,0 +1,8 @@
+#define outb(port, data) \
+	(__outb(port, data)) 
+
+static __inline void
+__outb(int port, unsigned char data)
+{
+	__asm volatile("outb %0,%w1" : : "a" (data), "d" (port));	
+}