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      1 /*	$NetBSD: swapcontext.S,v 1.9 2025/05/03 19:55:32 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Klaus Klein.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <machine/asm.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 	RCSID("$NetBSD: swapcontext.S,v 1.9 2025/05/03 19:55:32 riastradh Exp $")
     35 #endif /* LIBC_SCCS && !lint */
     36 
     37 ENTRY(swapcontext)
     38 	movl	4(%esp),%ecx
     39 	PIC_PROLOGUE
     40 	pushl	%ecx			/* push oucp */
     41 	call	PIC_PLT(_C_LABEL(_getcontext))
     42 	addl	$4,%esp			/* pop oucp */
     43 	PIC_EPILOGUE
     44 	testl	%eax,%eax
     45 	jnz	2f
     46 	movl	4(%esp),%ecx
     47 	movl	0(%esp),%edx
     48 	movl	%edx,(36 + 14 * 4)(%ecx)	/*  Adjust saved %eip ... */
     49 #ifdef __PIC__
     50 	movl	%ebx,(36 +  8 * 4)(%ecx)	/* ... clobbered PIC reg ... */
     51 #endif
     52 	leal	4(%esp),%edx
     53 	movl	%edx,(36 + 17 * 4)(%ecx)	/* ... and %esp. */
     54 	/* Note: oucp->%eax has been cleared by getcontext(). */
     55 	movl	8(%esp),%ecx
     56 	PIC_PROLOGUE
     57 	pushl	%ecx			/* push ucp */
     58 	call	PIC_PLT(_C_LABEL(setcontext))
     59 	addl	$4,%esp			/* pop ucp */
     60 	PIC_EPILOGUE
     61 	/* No need to error-check: setcontext() must have failed. */
     62 2:	ret
     63 END(swapcontext)
     64