xref: /minix3/lib/libc/arch/hppa/string/bzero.S (revision 2fe8fb192fe7e8720e3e7a77f928da545e872a6a)
1*2fe8fb19SBen Gras/*	$NetBSD: bzero.S,v 1.2 2003/10/06 05:30:21 matt Exp $	*/
2*2fe8fb19SBen Gras
3*2fe8fb19SBen Gras/*	$OpenBSD: bzero.S,v 1.3 2001/06/04 23:14:02 mickey Exp $	*/
4*2fe8fb19SBen Gras
5*2fe8fb19SBen Gras/*
6*2fe8fb19SBen Gras *  (c) Copyright 1988 HEWLETT-PACKARD COMPANY
7*2fe8fb19SBen Gras *
8*2fe8fb19SBen Gras *  To anyone who acknowledges that this file is provided "AS IS"
9*2fe8fb19SBen Gras *  without any express or implied warranty:
10*2fe8fb19SBen Gras *      permission to use, copy, modify, and distribute this file
11*2fe8fb19SBen Gras *  for any purpose is hereby granted without fee, provided that
12*2fe8fb19SBen Gras *  the above copyright notice and this notice appears in all
13*2fe8fb19SBen Gras *  copies, and that the name of Hewlett-Packard Company not be
14*2fe8fb19SBen Gras *  used in advertising or publicity pertaining to distribution
15*2fe8fb19SBen Gras *  of the software without specific, written prior permission.
16*2fe8fb19SBen Gras *  Hewlett-Packard Company makes no representations about the
17*2fe8fb19SBen Gras *  suitability of this software for any purpose.
18*2fe8fb19SBen Gras */
19*2fe8fb19SBen Gras/*
20*2fe8fb19SBen Gras * Copyright (c) 1990,1994 The University of Utah and
21*2fe8fb19SBen Gras * the Computer Systems Laboratory (CSL).  All rights reserved.
22*2fe8fb19SBen Gras *
23*2fe8fb19SBen Gras * THE UNIVERSITY OF UTAH AND CSL PROVIDE THIS SOFTWARE IN ITS "AS IS"
24*2fe8fb19SBen Gras * CONDITION, AND DISCLAIM ANY LIABILITY OF ANY KIND FOR ANY DAMAGES
25*2fe8fb19SBen Gras * WHATSOEVER RESULTING FROM ITS USE.
26*2fe8fb19SBen Gras *
27*2fe8fb19SBen Gras * CSL requests users of this software to return to csl-dist@cs.utah.edu any
28*2fe8fb19SBen Gras * improvements that they make and grant CSL redistribution rights.
29*2fe8fb19SBen Gras *
30*2fe8fb19SBen Gras * 	Utah $Hdr: bzero.s 1.9 94/12/14$
31*2fe8fb19SBen Gras *	Author: Bob Wheeler, University of Utah CSL
32*2fe8fb19SBen Gras */
33*2fe8fb19SBen Gras
34*2fe8fb19SBen Gras#include <machine/asm.h>
35*2fe8fb19SBen Gras
36*2fe8fb19SBen Gras#ifdef SYSLIBC_SCCS
37*2fe8fb19SBen Gras	.text
38*2fe8fb19SBen Gras	.asciz "$OpenBSD: bzero.S,v 1.3 2001/06/04 23:14:02 mickey Exp $"
39*2fe8fb19SBen Gras	.align	4
40*2fe8fb19SBen Gras#endif
41*2fe8fb19SBen Gras
42*2fe8fb19SBen Gras/*
43*2fe8fb19SBen Gras * void
44*2fe8fb19SBen Gras * bzero(dst, count)
45*2fe8fb19SBen Gras *	void *dst;
46*2fe8fb19SBen Gras *	size_t count;
47*2fe8fb19SBen Gras */
48*2fe8fb19SBen GrasLEAF_ENTRY(bzero)
49*2fe8fb19SBen Gras        comb,>=,n %r0,%arg1,$bzero_exit
50*2fe8fb19SBen Gras
51*2fe8fb19SBen Gras	/*
52*2fe8fb19SBen Gras	 * If we need to clear less than a word do it a byte at a time
53*2fe8fb19SBen Gras	 */
54*2fe8fb19SBen Gras
55*2fe8fb19SBen Gras	comib,>>,n 4,%arg1,$bzero_bytes
56*2fe8fb19SBen Gras
57*2fe8fb19SBen Gras	/*
58*2fe8fb19SBen Gras	 * Since we are only clearing memory the alignment restrictions
59*2fe8fb19SBen Gras	 * are simplified. Figure out how many "extra" bytes we need to
60*2fe8fb19SBen Gras	 * store with stbys.
61*2fe8fb19SBen Gras	 */
62*2fe8fb19SBen Gras
63*2fe8fb19SBen Gras        extru   %arg0,31,2,%t1
64*2fe8fb19SBen Gras        add     %arg1,%t1,%arg1
65*2fe8fb19SBen Gras
66*2fe8fb19SBen Gras	/*
67*2fe8fb19SBen Gras	 * We will zero the destination in blocks of 16 bytes as long as we
68*2fe8fb19SBen Gras	 * can and then we'll go to the 4 byte moves.
69*2fe8fb19SBen Gras	 */
70*2fe8fb19SBen Gras
71*2fe8fb19SBen Gras	comib,>>=	15, %arg1, $bzero_word
72*2fe8fb19SBen Gras	addi		-16, %arg1, %arg1
73*2fe8fb19SBen Gras
74*2fe8fb19SBen Gras$bzero_loop_16:
75*2fe8fb19SBen Gras        stbys,b,m %r0,4(%arg0)
76*2fe8fb19SBen Gras        stwm    %r0,4(%arg0)
77*2fe8fb19SBen Gras        stwm    %r0,4(%arg0)
78*2fe8fb19SBen Gras        stwm    %r0,4(%arg0)
79*2fe8fb19SBen Gras	comib,<<	15, %arg1, $bzero_loop_16
80*2fe8fb19SBen Gras	addi		-16, %arg1, %arg1
81*2fe8fb19SBen Gras
82*2fe8fb19SBen Gras	/*
83*2fe8fb19SBen Gras	 * see if there is anything left that needs to be zeroed in a word
84*2fe8fb19SBen Gras	 * move. Since the count was decremented by 16, add 12 to test if
85*2fe8fb19SBen Gras	 * there are any full word moves left to do.
86*2fe8fb19SBen Gras	 */
87*2fe8fb19SBen Gras
88*2fe8fb19SBen Gras$bzero_word:
89*2fe8fb19SBen Gras        addib,<,n 12,%arg1,$bzero_cleanup
90*2fe8fb19SBen Gras
91*2fe8fb19SBen Gras$bzero_loop_4:
92*2fe8fb19SBen Gras        addib,>= -4,%arg1,$bzero_loop_4
93*2fe8fb19SBen Gras        stbys,b,m %r0,4(%arg0)
94*2fe8fb19SBen Gras
95*2fe8fb19SBen Gras	/*
96*2fe8fb19SBen Gras	 * zero the last bytes that may be unaligned on a word boundary
97*2fe8fb19SBen Gras	 */
98*2fe8fb19SBen Gras
99*2fe8fb19SBen Gras$bzero_cleanup:
100*2fe8fb19SBen Gras        addib,=,n 4,%arg1,$bzero_exit
101*2fe8fb19SBen Gras        add	%arg0,%arg1,%arg0
102*2fe8fb19SBen Gras        b       $bzero_exit
103*2fe8fb19SBen Gras        stbys,e %r0,0(%arg0)
104*2fe8fb19SBen Gras	b,n	$bzero_exit
105*2fe8fb19SBen Gras
106*2fe8fb19SBen Gras
107*2fe8fb19SBen Gras	/*
108*2fe8fb19SBen Gras	 * zero by bytes
109*2fe8fb19SBen Gras	 */
110*2fe8fb19SBen Gras
111*2fe8fb19SBen Gras$bzero_bytes:
112*2fe8fb19SBen Gras        addib,> -1,%arg1,$bzero_bytes
113*2fe8fb19SBen Gras        stbs,ma %r0,1(%arg0)
114*2fe8fb19SBen Gras
115*2fe8fb19SBen Gras$bzero_exit:
116*2fe8fb19SBen Gras	bv,n	%r0(%rp)
117*2fe8fb19SBen GrasEXIT(bzero)
118*2fe8fb19SBen Gras
119*2fe8fb19SBen Gras	.end
120