Setup a graphics 'driver' of sorts that can display a banner at the top of the screen.

.gitignore

@@ -3,3 +3,4 @@
 *.log
 *.iso
 *.bin
+*.ini

Makefile

@@ -29,6 +29,9 @@ kernel.iso: kernel.o
 	cp obj/bin/kernel.o iso/boot/kernel.bin
 	grub-mkrescue --output=kernel.iso iso
 	
+qemu: kernel.iso
+	qemu-system-x86_64 -m 256M -cdrom kernel.iso &
+
 .PHONY: clean
 clean:
 	rm -rf obj/* kernel.iso

build_numbers.c

@@ -1,3 +1,3 @@
 #ifndef KERNEL_VERSION_NUMBER
-#define KERNEL_VERSION_NUMBER "0.0.1-47"
+#define KERNEL_VERSION_NUMBER "0.0.1-239"
 #endif

includes/kernel.h

@@ -5,4 +5,5 @@ void write_screen(unsigned int, char, unsigned char, unsigned char);
 void move(unsigned short);
 void draw_s(char*, unsigned char, unsigned char);
 int strlen(char*);
+void clear_screen(void);
 #endif

includes/screen.h

@@ -2,4 +2,6 @@
 #define SCREEN_H
 void draw_string(char*, unsigned char, unsigned char);
 int strlen(char*);
+void clear_screen(void);
+void print_banner(void);
 #endif

kernel/kmain.c

@@ -1,20 +1,15 @@
 #include "../includes/io.h"
-#include "../includes/kernel.h"
+#include "../includes/screen.h"
-
-//char* msg = "Hello, World!";
 
 void kmain()
 {
-	draw_s("Hello, World!", 2, 9);/*
+	clear_screen();
-	write_screen(0, "k", 2, 9);
+	print_banner();
-	write_screen(2, 'e', 2, 9);
+	//draw_s("Hello, World!", 2, 9);
-	write_screen(4, 'r', 2, 9);
+	//row = 2;
-	write_screen(6, 'n', 2, 9);
+	///column = 80;
-	write_screen(8, 'e', 2, 9);
+	//draw_s("And 2nd Row. Now the 3rd row.", 2, 9);
-	write_screen(10, 'l', 2, 9);
+	asm("hlt");
-	write_screen(12, ' ', 2, 9);
-	write_screen(14, '3', 2, 9);
-	//asm("hlt");*/
 }
 
 void write_screen(unsigned int i, char c, unsigned char fg, unsigned char bg)
@@ -31,22 +26,3 @@ void move(unsigned short pos)
 	outb(0x3D4, 15);
 	outb(0x3D5, pos & 0x00FF);
 }
-
-void draw_s(char* string, unsigned char fg, unsigned char bg)
-{
-	char *video_buffer = 0x000B8000;
-	for(int i = 0; i < strlen(string); i++)
-	{
-		video_buffer[i] = string[i];
-		video_buffer[i+1] = ((fg & 0x0f) << 4) | (bg & 0x0F);
-	}
-}
-
-int strlen(char* string)
-{
-	int len = 0;
-	
-	for(int i = 0; string[i] != '\0'; i++) len++;
-	
-	return len;
-}

kernel/screen.c

@@ -0,0 +1,88 @@
+#include "../includes/screen.h"
+#include "../build_numbers.c"
+
+unsigned char row = 1;
+unsigned char column = 0;
+unsigned char screen_width = 80;
+
+
+void print_banner(){
+	unsigned short *buffer = 0x000B8000;
+	unsigned short attr = 0x1800;
+	
+	unsigned char* banner = "Project Code Name: kernel3";
+	char* version = KERNEL_VERSION_NUMBER;
+	unsigned char banner_length = (80 - strlen(banner)) / 2;
+	// Add 14 for the string "Kernel Version: ".
+	unsigned char version_length = (80 - (strlen(version) + 16)) / 2;
+	
+	for(unsigned char i = 0; i < screen_width; i++){
+		*buffer++ = ' ';
+		*buffer++ = attr;
+	}
+	
+	for(unsigned char i = 0; i < screen_width; i++){
+		if(i == banner_length){
+			for(unsigned short j = 0; j < strlen(banner); j++){
+				unsigned short *where = (unsigned short*) 0x000B8000 + j + i;
+				*where = banner[j] | attr;
+			}
+		}
+		
+		if(i == version_length){
+			unsigned short offset = 0;
+			char* tmp = "Kernel Version: ";
+			for(unsigned char j = 0; j < strlen(tmp); j++){
+				unsigned short *where = (unsigned short*) 0x000B8000 + j + 80 + i;
+				*where = tmp[j] | attr;
+				offset++;
+			}
+			
+			for(unsigned char j = 0; j < strlen(version); j++){
+				unsigned short *where = (unsigned short*) 0x000B8000 + j + 80 + offset + i;
+				*where = version[j] | attr;
+			}			
+		}
+	}
+}
+
+void draw_s(char* string, unsigned char fg, unsigned char bg)
+{
+	char *video_buffer = 0x000B8000;
+	
+	for(int i = 0; i < strlen(string); i++)
+	{
+		char current_char = string[i];
+		
+		if(current_char == '\n'){
+			//row++;
+			column = row * column;
+			row++;
+			continue;
+		}
+		
+		video_buffer[i*2 + (row * column)] = string[i];
+		video_buffer[i * 2 + 1 + (row * column)] = ((fg & 0x0f) << 4) | (bg & 0x0F);
+		//column++;
+	}
+}
+
+void clear_screen(){
+	char *video_buffer = 0x000B8000;
+	
+	for(unsigned char i = 0; i < 25; i++){
+		for(unsigned char j = 0; j < 80; j++){
+			*video_buffer++ = ' ';//0x20 | (0x0F << 8);
+			*video_buffer++ = 0x82;
+		}
+	}
+}
+
+int strlen(char* string)
+{
+	int len = 0;
+	
+	for(int i = 0; string[i] != '\0'; i++) len++;
+	
+	return len;
+}