32bit.asm

jserv写的orz小内核 有详细的注释

[BITS 32]
	align 4
Begin32c:
	mov ax, kernel_data - _GDT
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax
	mov esp, 0x2FFFF

	call TestMemory

	mov edi, memMap		; jiao: set first 32 bytes of memMap to 1
	mov ecx, 0x100 / 32
	xor eax, eax
	dec eax
	rep stosd

	mov ecx, 0x20000 / 4 - (0x100 / 32)	; jiao: others to 0
	xor eax,eax
	rep stosd

	; timer set to 1/100 s
	mov al, 0x34	; set to 100Hz
	out 0x43, al
	mov al, 0x9b	; lsb 1193180 / 1193
	out 0x40, al
	mov al, 0x2e	; msb
	out 0x40, al

	call EnableIRQs     ; 呼叫 irqs.asm 的子程式以啟動 IRQ 機制