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resumecontext.S revision 1.6 
      1  1.6     matt /*	$NetBSD: resumecontext.S,v 1.6 2013/07/16 20:49:42 matt Exp $	*/
      2  1.2  thorpej 
      3  1.2  thorpej /*-
      4  1.2  thorpej  * Copyright (c) 2001 The NetBSD Foundation, Inc.
      5  1.2  thorpej  * All rights reserved.
      6  1.2  thorpej  *
      7  1.2  thorpej  * This code is derived from software contributed to The NetBSD Foundation
      8  1.2  thorpej  * by Klaus Klein.
      9  1.2  thorpej  *
     10  1.2  thorpej  * Redistribution and use in source and binary forms, with or without
     11  1.2  thorpej  * modification, are permitted provided that the following conditions
     12  1.2  thorpej  * are met:
     13  1.2  thorpej  * 1. Redistributions of source code must retain the above copyright
     14  1.2  thorpej  *    notice, this list of conditions and the following disclaimer.
     15  1.2  thorpej  * 2. Redistributions in binary form must reproduce the above copyright
     16  1.2  thorpej  *    notice, this list of conditions and the following disclaimer in the
     17  1.2  thorpej  *    documentation and/or other materials provided with the distribution.
     18  1.2  thorpej  *
     19  1.2  thorpej  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  1.2  thorpej  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  1.2  thorpej  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  1.2  thorpej  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  1.2  thorpej  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  1.2  thorpej  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  1.2  thorpej  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  1.2  thorpej  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  1.2  thorpej  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  1.2  thorpej  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  1.2  thorpej  * POSSIBILITY OF SUCH DAMAGE.
     30  1.2  thorpej  */
     31  1.2  thorpej 
     32  1.2  thorpej #include <machine/asm.h>
     33  1.2  thorpej 
     34  1.2  thorpej #if defined(LIBC_SCCS) && !defined(lint)
     35  1.6     matt 	RCSID("$NetBSD: resumecontext.S,v 1.6 2013/07/16 20:49:42 matt Exp $")
     36  1.2  thorpej #endif /* LIBC_SCCS && !lint */
     37  1.2  thorpej 
     38  1.2  thorpej /*
     39  1.2  thorpej  * This assembly-language implementation differs from the (obvious)
     40  1.2  thorpej  * C-language implementation only in not clobbering the previous
     41  1.2  thorpej  * function's return address (us), which is the point of the exercise.
     42  1.2  thorpej  */
     43  1.2  thorpej 
     44  1.2  thorpej ENTRY(_resumecontext)
     45  1.3   kleink 	subl	#(4 + 1024),%sp		/* retaddr preservation + ucontext_t */
     46  1.6     matt 	lea	(%sp),%a0
     47  1.6     matt 	movl	%a0,-(%sp)
     48  1.2  thorpej 	jbsr	PIC_PLT(_C_LABEL(_getcontext))
     49  1.6     matt 	movl	(4 + 4)(%sp),(%sp)	/* uc_link */
     50  1.6     matt 	tstl	(%sp)			/* check for NULL */
     51  1.4   martin 	jne	1f
     52  1.4   martin 	jbsr	PIC_PLT(_C_LABEL(exit))	/* cleanly exit(0) */
     53  1.4   martin 	jmp	2f
     54  1.4   martin 1:	jbsr	PIC_PLT(_C_LABEL(setcontext))
     55  1.4   martin 	/* NOTREACHED */
     56  1.4   martin 	/* But just in case... */
     57  1.6     matt 2:	movl	#-1,(%sp)
     58  1.4   martin 	jbsr	PIC_PLT(_C_LABEL(_exit))
     59  1.2  thorpej 	/* NOTREACHED */
     60