xref: /minix/common/lib/libc/arch/or1k/string/memset.S (revision 0a6a1f1d) 
1/*	$NetBSD: memset.S,v 1.1 2014/09/03 19:34:25 matt Exp $ */
2
3/*-
4 * Copyright (c) 2014 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Matt Thomas of 3am Software Foundry.
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
34
35#if defined(LIBC_SCCS) && !defined(lint)
36__RCSID("$NetBSD: memset.S,v 1.1 2014/09/03 19:34:25 matt Exp $")
37#endif /* LIBC_SCCS && !lint */
38
39/*----------------------------------------------------------------------*/
40/*
41     void bzero(void *b r3, size_t len r4);
42     void * memset(void *b r3, int c r4, size_t len r5);
43*/
44/*----------------------------------------------------------------------*/
45
46
47#ifdef _BZERO
48#define r_fill	r0
49ENTRY(bzero)
50#else
51#define r_fill	r4
52ENTRY(memset)
53#endif
54#ifdef _BZERO
55		l.ori	r5, r4, 0
56		l.or	r4, r0, r0
57#else
58		l.or	r11, r3, r0		/* move start to return value */
59#endif
60		l.sfeqi	r5, 0			/* anything to do? */
61		l.bf	.Lret			/*   no, just return */
62		l.nop
63
64		l.sfgeui r5, 7			/* small buffer? */
65		l.add	r5, r5, r3		/* r5 is end pointer */
66		l.bnf	.Lbyte_fill		/*   yes.  just byte fill */
67		l.nop
68
69#ifndef _BZERO
70		// Let's see the fill type
71		l.sfeqi	r4, 0			/* filling with 0? */
72		l.bf	.Lalignment_check	/* don't to replicate */
73		l.nop
74		l.extbz	r4, r4			/* truncate to 8 bits */
75		l.slli	r13, r4, 8		/* shift left 8 bits */
76		l.or	r4, r4, r13		/* merge the two bytes */
77		l.slli	r13, r4, 16		/* shift left 16 bits */
78		l.or	r4, r4, r13		/* merge the two halves */
79
80.Lalignment_check:
81#endif
82		l.andi	r13, r3, 3		/* get low bits of start */
83		l.sfeqi	r13, 0			/* word aligned? */
84		l.bf	.Lword_fill		/*   yes, start setting */
85		l.nop
86
87		l.add	r5, r5, r13		/* increase length */
88		l.sub	r3, r3, r13		/* mask word aligned */
89		l.slli	r13, r13, 3		/* bytes to bits */
90		l.addi	r15, r13, -8		/* minus one byte */
91
92		l.lwz	r6, 0(r3)		/* get first word */
93		l.movhi	r7, 0xff00		/* 0xff000000 */
94		l.sra	r7, r7, r13		/* shift right align bytes */
95		l.and	r6, r6, r7		/* clear bytes to be filled */
96#ifndef _BZERO
97		l.srl	r7, r_fill, r13		/* clear bytes to preserve */
98		l.or	r6, r6, r7		/* merge existing with new */
99#endif
100		l.sw	0(r3), r6		/* store first word */
101		l.addi	r3, r3, 4		/* advance to next word */
102		l.addi	r5, r5, -4		/* one less word to do */
103
104.Lword_aligned:
105		l.srli	r6, r5, 2		/* clear low two bits of len */
106		l.srli	r6, r6, 2		/* ... */
107		l.sfgeu	r3, r6			/* any more full words? */
108		l.bf	.Lend_fill		/* no, handle the last bytes */
109		l.nop
110
111.Lword_fill:
112		l.sw	0(r3), r_fill		/* store a word */
113		l.addi	r3, r3, 4		/* advance */
114		l.sfgeu	r3, r6			/* any more full words? */
115		l.bnf	.Lword_fill		/*   yes, fill next word */
116		l.nop
117		l.j	.Lend_fill		/* fill any leftover bytes */
118		l.nop
119
120.Lbyte_fill:
121		l.sb	0(r3), r_fill		/* store a byte */
122		l.addi	r3, r3, 1		/* advance */
123.Lend_fill:
124		l.sfeq	r3, r5			/* at the end? */
125		l.bnf	.Lbyte_fill		/*   no, fill next byte */
126		l.nop
127
128.Lret:
129		l.jr	lr			/* return */
130		l.nop
131#ifdef _BZERO
132END(bzero)
133#else
134END(memset)
135#endif
136