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Code: Select all

#

.PHONY: all clean run 

NASM = nasm
CC = gcc
LD = ld

FLAGS = -nostdlib -nostartfiles -nodefaultlibs
OPT_FLAGS = -Wall -O2

KERNEL_SOURCE = ../src/kernel.c
MULTIBOOT_SOURCE = ../src/loader.s
LINK_SCRIPT = linker.ld

all: loader.o kernel.o kernel.bin fd.img

loader.o: $(MULTIBOOT_SOURCE)
	$(NASM) -f elf $< -o $@ 

kernel.o: $(KERNEL_SOURCE)
	$(CC) -c $< -o $@ $(FLAGS) $(OPT_FLAGS)

kernel.bin: loader.o kernel.o
	$(LD) -T $(LINK_SCRIPT) $< kernel.o -o $@

fd.img:
	cat stage1 stage2 pad kernel.bin > fd.img

clean:
	rm -r -f *~ *.o

run:
	qemu -vga std -fda fd.img

Code: Select all

/*
 * NoobOS by xfelix
 */

void Kernel_Main(void* mb, int mn) {
  unsigned char* vram = (unsigned char*)0xB8000;
  vram[0] = 0x41;
  vram[1] = 0x07;
}

Code: Select all

global loader
extern Kernel_Main

MODULEALIGN equ  1
MEMINFO     equ  1                   ; provide memory map
FLAGS       equ  MODULEALIGN | MEMINFO  ; this is the Multiboot 'flag' field
MAGIC       equ  0x1BADB002           
CHECKSUM    equ -(MAGIC + FLAGS)        ; checksum required
 
section .text
align 4
	jmp loader
MultiBootHeader:
   dd MAGIC
   dd FLAGS
   dd CHECKSUM
 
STACKSIZE equ 0x4000
 
loader:
   mov esp, stack+STACKSIZE           ; set up the stack
   push 0x0
   popf
   push eax                           ; pass Multiboot magic number
   push ebx                           ; pass Multiboot info structure
 
   call Kernel_Main                       ; call kernel proper
 
   cli
hang:
   hlt                                ; halt machine should kernel return
   jmp   hang
 
section .bss
align 4
stack:
   resb STACKSIZE

Code: Select all

/*
 * NoobOS by xfelix
 */

void Clear_Screen(void);

unsigned char* vram = (unsigned char*)0xB8000;

void Kernel_Main(void* mb, int mn) {
  Clear_Screen();
  vram[0] = 0x41;
  vram[1] = 0x07;

  while(1) {
  }
}

void Clear_Screen() {
  int i;
  for(i=0; i < 80*24; i++) {
    vram[i] = 0x0;
  }
}