minix/lib/libc/arch/m68k/gen/resumecontext.S

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/* $NetBSD: resumecontext.S,v 1.8 2013/07/17 03:04:54 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 <machine/asm.h>
#include "assym.h"
#if defined(LIBC_SCCS) && !defined(lint)
RCSID("$NetBSD: resumecontext.S,v 1.8 2013/07/17 03:04:54 matt Exp $")
#endif /* LIBC_SCCS && !lint */
/*
* This assembly-language implementation differs from the (obvious)
* C-language implementation only in not clobbering the previous
* function's return address (us), which is the point of the exercise.
*/
ENTRY(_resumecontext)
subl #(4 + UC_SIZE),%sp /* retaddr preservation + ucontext_t */
lea (%sp),%a0
movl %a0,-(%sp)
jbsr PIC_PLT(_C_LABEL(_getcontext))
movl (4 + UC_LINK)(%sp),(%sp) /* uc_link */
tstl (%sp) /* check for NULL */
jne 1f
jbsr PIC_PLT(_C_LABEL(exit)) /* cleanly exit(0) */
jmp 2f
1: jbsr PIC_PLT(_C_LABEL(setcontext))
/* NOTREACHED */
/* But just in case... */
2: movl #-1,(%sp)
jbsr PIC_PLT(_C_LABEL(_exit))
/* NOTREACHED */
END(_resumecontext)