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setstack.S revision 1.2 
      1 /*	$NetBSD: setstack.S,v 1.2 2002/08/15 01:37:02 briggs Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1994 Mark Brinicombe.
      5  * Copyright (c) 1994 Brini.
      6  * All rights reserved.
      7  *
      8  * This code is derived from software written for Brini by Mark Brinicombe
      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  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by Brini.
     21  * 4. The name of the company nor the name of the author may be used to
     22  *    endorse or promote products derived from this software without specific
     23  *    prior written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
     26  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     27  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     28  * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
     29  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     30  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     31  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     35  * SUCH DAMAGE.
     36  *
     37  * RiscBSD kernel project
     38  *
     39  * setstack.S
     40  *
     41  * Miscellaneous routine to play with the stack pointer in different CPU modes
     42  *
     43  * Eventually this routine can be inline assembly.
     44  *
     45  * Created      : 17/09/94
     46  *
     47  * Based of kate/display/setstack.s
     48  */
     49 
     50 #include <machine/cpu.h>
     51 #include <machine/asm.h>
     52 
     53 /* To set the stack pointer for a particular mode we must switch
     54  * to that mode update the banked r13 and then switch back.
     55  * This routine provides an easy way of doing this for any mode
     56  *
     57  * r0 = CPU mode
     58  * r1 = stackptr
     59  */
     60 
     61 ENTRY(set_stackptr)
     62         mrs	r3, cpsr		/* Switch to the appropriate mode */
     63 	bic	r2, r3, #(PSR_MODE)
     64 	orr	r2, r2, r0
     65         msr	cpsr_all, r2
     66 
     67 	mov	sp, r1			/* Set the stack pointer */
     68 
     69         msr	cpsr_all, r3		/* Restore the old mode */
     70 
     71 	mov	pc, lr			/* Exit */
     72 
     73 /* To get the stack pointer for a particular mode we must switch
     74  * to that mode copy the banked r13 and then switch back.
     75  * This routine provides an easy way of doing this for any mode
     76  *
     77  * r0 = CPU mode
     78  */
     79 
     80 ENTRY(get_stackptr)
     81         mrs	r3, cpsr		/* Switch to the appropriate mode */
     82 	bic	r2, r3, #(PSR_MODE)
     83 	orr	r2, r2, r0
     84         msr	cpsr_all, r2
     85 
     86 	mov	r0, sp			/* Set the stack pointer */
     87 
     88         msr	cpsr_all, r3		/* Restore the old mode */
     89 
     90 	mov	pc, lr			/* Exit */
     91 
     92 /* End of setstack.S */
     93