====entry.S
.code16
.global _start
_start:
    call main


hang:
    jmp hang


====user.ld
ENTRY(_start)

SECTIONS {
    . = 0x0000;

    .text : {
        *(.text)
    }

    .data : {
        *(.data)
    }

    .bss : {
        *(.bss COMMON)
    }
}



====bootloader.asm
[org 0x7C00]
bits 16

start:
    cli
    xor ax, ax
    mov ds, ax
	call print_ok
	mov ax, 0x1000
    mov es, ax
	xor ax, ax
    mov ss, ax
    mov sp, 0x7C00

    mov ah, 0x02
    mov al, 1
    mov ch, 0
    mov cl, 2
    mov dh, 0
    mov dl, 0x00
    int 0x13

    jc error

    mov sp, 0xFFFE
	mov ax, 0x1000
	mov ds, ax

    jmp 0x1000:0000
print_ok:
	mov si, boot_msg
	call print
	ret
error:
    mov si, error_msg
print:
    lodsb
    or al, al
    jz .done
    mov ah, 0x0E
    int 0x10
    jmp print
.done:
    ret

error_msg db "Load error", 0
boot_msg db "Odpalanie program.c... ", 0

times 510 - ($ - $$) db 0
dw 0xAA55


====user.c
void print(const char* s) {
    while (*s) {
        __asm__ __volatile__ (
            "movb $0x0E, %%ah\n"
            "int $0x10"
            :
            : "a"(*s)
        );
        s++;
    }
}


void main() {
    print("Hello z C xD");
}


====make.bat
@echo off
cd C:\gcc\bin
i386-elf-gcc -m16 -ffreestanding -fno-pic -mno-red-zone -fno-builtin -nostdlib -c C:\Users\Piotrek\Desktop\tmp\entry.S -o C:\Users\Piotrek\Desktop\tmp\entry.o
i386-elf-gcc -m16 -ffreestanding -fno-pic -mno-red-zone -fno-builtin -nostdlib -c C:\Users\Piotrek\Desktop\tmp\user.c -o C:\Users\Piotrek\Desktop\tmp\user.o
i386-elf-ld -T C:\Users\Piotrek\Desktop\tmp\user.ld -o C:\Users\Piotrek\Desktop\tmp\user.elf C:\Users\Piotrek\Desktop\tmp\entry.o C:\Users\Piotrek\Desktop\tmp\user.o
i386-elf-objcopy -O binary C:\Users\Piotrek\Desktop\tmp\user.elf C:\Users\Piotrek\Desktop\tmp\user.bin
cd %localappdata%\bin\nasm
nasm -f bin C:\Users\Piotrek\Desktop\tmp\bootloader.asm -o C:\Users\Piotrek\Desktop\tmp\bootloader.bin
copy /b C:\Users\Piotrek\Desktop\tmp\bootloader.bin + C:\Users\Piotrek\Desktop\tmp\user.bin C:\Users\Piotrek\Desktop\tmp\full.img
echo Built full.img (bootloader + C program)
cd C:\Users\Piotrek\Desktop\tmp\