kernel/src/framebuffer.asm

;; x, y, brightness
putpixel:
	push ebp
	mov ebp, esp

	push eax
	push ebx
	push ecx
	push edi

	; check pixel is in screen
	mov ebx, [ebp+12]	;y
	cmp ebx, [mbootinfo.fb_height]
	jge .done
	mov ecx, [ebp+8]	;x
	cmp ecx, [mbootinfo.fb_width]
	jge .done

	; Destination
	mov edi, [mbootinfo.fb_addr]
	mov eax, [mbootinfo.fb_pitch]
	mul dword ebx   ;y
	add edi, eax

	mov eax, ecx   ;x
	movzx ecx, byte [mbootinfo.fb_bytespp]
	mul ecx
	add edi, eax


	; Brightness
	mov eax, [ebp + 16]

	; Poke videomemory
	cld
	rep stosb
.done:
	pop edi
	pop ecx
	pop ebx
	pop eax

	pop ebp
	ret