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Code: Select all

nasm -f aout ot.asm -o entry.o
gcc -c ot.c -o ot.o
ld -T link.ld -o OT.SYS entry.o ot.o
copy OT.SYS  A:\OT.SYS
pause

Code: Select all

bits 16					; we are still in real mode
global start
extern _k_main

; we are loaded at linear address 0x10000
start:
	call _k_main ;call our c source
	
	cli
	hlt ;stop execution

Code: Select all

void k_clear_screen();
unsigned int k_printf(char *message, unsigned int line);


k_main() // like main in a normal C program
{
	//k_clear_screen();
	k_printf("Starting OT-DOS..", 0);
};

void k_clear_screen() // clear the entire text screen
{
	char *vidmem = (char *) 0xb8000;
	unsigned int i=0;
	while(i < (80*25*2))
	{
		vidmem[i]=' ';
		i++;
		vidmem[i]=WHITE_TXT;
		i++;
	};
};

unsigned int k_printf(char *message, unsigned int line) // the message and then the line #
{
	char *vidmem = (char *) 0xb8000;
	unsigned int i=0;

	i=(line*80*2);

	while(*message!=0)
	{
		if(*message=='\n') // check for a new line
		{
			line++;
			i=(line*80*2);
			*message++;
		} else {
			vidmem[i]=*message;
			*message++;
			i++;
			vidmem[i]=WHITE_TXT;
			i++;
		};
	};

	return(1);
};

Code: Select all

OUTPUT_FORMAT("binary")
ENTRY(start)
SECTIONS
{
  .text  0x010000 : {
    code = .; _code = .; __code = .;
    *(.text)
  }
  .data  : {
    data = .; _data = .; __data = .;
    *(.data)
  }
  .bss  :
  {
    bss = .; _bss = .; __bss = .;
    *(.bss)
  }
  end = .; _end = .; __end = .;
}