source: bootcd/isolinux/syslinux-6.03/core/stack.inc

; -----------------------------------------------------------------------
;
;   Copyright 2005-2008 H. Peter Anvin - All Rights Reserved
;   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
;
;   This program is free software; you can redistribute it and/or modify
;   it under the terms of the GNU General Public License as published by
;   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;   Boston MA 02111-1307, USA; either version 2 of the License, or
;   (at your option) any later version; incorporated herein by reference.
;
; -----------------------------------------------------------------------

;
; stack.inc
;
; How to reset the stack pointer
;

%ifndef _STACK_INC
%define _STACK_INC

;
; This macro resets the stack pointer (including SS), and sets
; DS == ES == 0, interrupts on, DF = 0.
;
; It takes a 16-bit register that can be safely clobbered as parameter.
;
%macro RESET_STACK_AND_SEGS 1
                xor %1,%1
                mov ds,%1
                mov es,%1
                lss esp,[BaseStack]
                mov dword [PMESP],__stack_end   ; Reset PM stack
                sti
                cld
%endmacro

                section .data16
                alignz 4
                global BaseStack:data hidden
BaseStack       dd StackHome            ; ESP of the "home" stack pointer
                dw 0                    ; SS of the "home" stack pointer

                section .text16

%endif ; _STACK_INC