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      1 /*	$NetBSD: swapcontext.S,v 1.3 2015/03/27 23:23:14 matt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 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 "SYS.h"
     33 #include "assym.h"
     34 
     35 __RCSID("$NetBSD: swapcontext.S,v 1.3 2015/03/27 23:23:14 matt Exp $")
     36 
     37 #define	CALLFRAME_UCP	CALLFRAME_S1
     38 #define	CALLFRAME_OUCP	CALLFRAME_S0
     39 
     40 ENTRY(swapcontext)
     41 	addi	sp, sp, -CALLFRAME_SIZ		# adjust stack
     42 	REG_S	ra, CALLFRAME_RA(sp)		# save return address
     43 	REG_S	a0, CALLFRAME_OUCP(sp)		# save oucp
     44 	REG_S	a1, CALLFRAME_UCP(sp)		# save ucp
     45 
     46 	call	PLT(_C_LABEL(_getcontext))	# getcontext(oucp)
     47 	mv	t0, a0				# save return value
     48 
     49 	REG_L	ra, CALLFRAME_RA(sp)		# restore return address
     50 	REG_L	a0, CALLFRAME_UCP(sp)		# load ucp
     51 	REG_L	a1, CALLFRAME_OUCP(sp)		# load oucp for adjustment
     52 	addi	sp, sp, CALLFRAME_SIZ		# restore stack
     53 
     54 	bnez	t0, 1f				# error? yes, cleanup
     55 
     56 	REG_S	ra, UC_GREGS_PC(a1)		# pc <- ra
     57 	REG_S	sp, UC_GREGS_SP(a1)		# adjust sp
     58 
     59 	tail	PLT(_C_LABEL(setcontext))	# setcontext(ucp)
     60 
     61 1:	ret					# simply return
     62 END(swapcontext)
     63