Fixed a bug that caused the kernel image to lose it multiboot signature. Added code to test printing a string to the screen.

kernel/kmain.c

@@ -1,13 +1,20 @@
 #include "../includes/io.h"
+#include "../includes/kernel.h"
 
-void write_screen(unsigned int, char, unsigned char, unsigned char);
-void move(unsigned short);
+//char* msg = "Hello, World!";
 
-extern void kmain()
+void kmain()
 {
-	write_screen(0, 'A', 2, 8);
-	move(80);
-	//asm("hlt");
+	draw_s("Hello, World!", 2, 9);/*
+	write_screen(0, "k", 2, 9);
+	write_screen(2, 'e', 2, 9);
+	write_screen(4, 'r', 2, 9);
+	write_screen(6, 'n', 2, 9);
+	write_screen(8, 'e', 2, 9);
+	write_screen(10, 'l', 2, 9);
+	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)
@@ -24,3 +31,22 @@ 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/loader.s

@@ -1,25 +1,23 @@
 global loader
 
+align 4
 MAGIC_NUMBER equ 0x1BADB002
 FLAGS equ 0x0
 CHECKSUM equ -MAGIC_NUMBER
-KERNEL_STACK_SIZE equ 4096							; size of stack in bytes
+KERNEL_STACK_SIZE equ 4096						; size of stack in bytes
 
-section .text:
-	align 4
 	dd MAGIC_NUMBER
 	dd FLAGS
 	dd CHECKSUM
 
 loader:
+	mov esp, kernel_stack; + KERNEL_STACK_SIZE 	; ont ESP to the start of the stack (end of memory area)
 	extern kmain
 	call kmain
 	;mov eax, 0xCAFEBABE
-	;mov esp, kernel_stack + KERNEL_STACK_SIZE	; piont ESP to the start of the stack (end of memory area)
 .loop:
 	jmp .loop
 
 section .bss
-	alignb 4
 	resb KERNEL_STACK_SIZE						; reserve stack for kernel
 	kernel_stack: