120 lines
3 KiB
ArmAsm
120 lines
3 KiB
ArmAsm
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/* $NetBSD: bzero.S,v 1.2 2003/10/06 05:30:21 matt Exp $ */
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/* $OpenBSD: bzero.S,v 1.3 2001/06/04 23:14:02 mickey Exp $ */
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/*
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* (c) Copyright 1988 HEWLETT-PACKARD COMPANY
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*
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* To anyone who acknowledges that this file is provided "AS IS"
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* without any express or implied warranty:
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* permission to use, copy, modify, and distribute this file
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* for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this notice appears in all
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* copies, and that the name of Hewlett-Packard Company not be
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* used in advertising or publicity pertaining to distribution
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* of the software without specific, written prior permission.
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* Hewlett-Packard Company makes no representations about the
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* suitability of this software for any purpose.
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*/
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/*
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* Copyright (c) 1990,1994 The University of Utah and
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* the Computer Systems Laboratory (CSL). All rights reserved.
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*
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* THE UNIVERSITY OF UTAH AND CSL PROVIDE THIS SOFTWARE IN ITS "AS IS"
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* CONDITION, AND DISCLAIM ANY LIABILITY OF ANY KIND FOR ANY DAMAGES
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* WHATSOEVER RESULTING FROM ITS USE.
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*
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* CSL requests users of this software to return to csl-dist@cs.utah.edu any
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* improvements that they make and grant CSL redistribution rights.
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*
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* Utah $Hdr: bzero.s 1.9 94/12/14$
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* Author: Bob Wheeler, University of Utah CSL
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*/
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#include <machine/asm.h>
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#ifdef SYSLIBC_SCCS
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.text
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.asciz "$OpenBSD: bzero.S,v 1.3 2001/06/04 23:14:02 mickey Exp $"
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.align 4
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#endif
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/*
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* void
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* bzero(dst, count)
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* void *dst;
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* size_t count;
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*/
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LEAF_ENTRY(bzero)
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comb,>=,n %r0,%arg1,$bzero_exit
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/*
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* If we need to clear less than a word do it a byte at a time
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*/
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comib,>>,n 4,%arg1,$bzero_bytes
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/*
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* Since we are only clearing memory the alignment restrictions
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* are simplified. Figure out how many "extra" bytes we need to
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* store with stbys.
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*/
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extru %arg0,31,2,%t1
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add %arg1,%t1,%arg1
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/*
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* We will zero the destination in blocks of 16 bytes as long as we
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* can and then we'll go to the 4 byte moves.
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*/
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comib,>>= 15, %arg1, $bzero_word
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addi -16, %arg1, %arg1
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$bzero_loop_16:
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stbys,b,m %r0,4(%arg0)
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stwm %r0,4(%arg0)
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stwm %r0,4(%arg0)
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stwm %r0,4(%arg0)
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comib,<< 15, %arg1, $bzero_loop_16
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addi -16, %arg1, %arg1
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/*
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* see if there is anything left that needs to be zeroed in a word
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* move. Since the count was decremented by 16, add 12 to test if
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* there are any full word moves left to do.
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*/
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$bzero_word:
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addib,<,n 12,%arg1,$bzero_cleanup
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$bzero_loop_4:
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addib,>= -4,%arg1,$bzero_loop_4
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stbys,b,m %r0,4(%arg0)
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/*
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* zero the last bytes that may be unaligned on a word boundary
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*/
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$bzero_cleanup:
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addib,=,n 4,%arg1,$bzero_exit
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add %arg0,%arg1,%arg0
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b $bzero_exit
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stbys,e %r0,0(%arg0)
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b,n $bzero_exit
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/*
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* zero by bytes
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*/
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$bzero_bytes:
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addib,> -1,%arg1,$bzero_bytes
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stbs,ma %r0,1(%arg0)
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$bzero_exit:
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bv,n %r0(%rp)
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EXIT(bzero)
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.end
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