/*      $NetBSD: swapcontext.S,v 1.6 2013/07/17 03:05:17 matt Exp $     */

/*-
 * Copyright (c) 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Klaus Klein.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "SYS.h"
#include "assym.h"

#if defined(LIBC_SCCS) && !defined(lint)
        RCSID("$NetBSD: swapcontext.S,v 1.6 2013/07/17 03:05:17 matt Exp $")
#endif /* LIBC_SCCS && !lint */

ENTRY(swapcontext)
        movl    4(%sp),-(%sp)           | push oucp on stack
        jbsr    PIC_PLT(_C_LABEL(_getcontext))  | getcontext(oucp)
        tstl    %d0                     | OK?
        jne     L1
        movl    (%sp),%a0
        addql   #8,UC_MCONTEXT_SP(%a0)  | adjust saved stack pointer (again)
        movl    %sp@(4),UC_MCONTEXT_PC(%a0) | adjust saved program counter (again)
        movl    12(%sp),(%sp)           | push ucp on stack
        jbsr    PIC_PLT(_C_LABEL(setcontext))   | setcontext(ucp)
L1:     addql   #4,%sp                  | pop ucp
        rts
END(swapcontext)