Annotation of sys/lib/libkern/arch/mips64/bzero.S, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: bzero.S,v 1.6 2004/10/08 14:42:09 pefo Exp $ */
2: /*-
3: * Copyright (c) 1991, 1993
4: * The Regents of the University of California. All rights reserved.
5: *
6: * This code is derived from software contributed to Berkeley by
7: * Ralph Campbell.
8: *
9: * Redistribution and use in source and binary forms, with or without
10: * modification, are permitted provided that the following conditions
11: * are met:
12: * 1. Redistributions of source code must retain the above copyright
13: * notice, this list of conditions and the following disclaimer.
14: * 2. Redistributions in binary form must reproduce the above copyright
15: * notice, this list of conditions and the following disclaimer in the
16: * documentation and/or other materials provided with the distribution.
17: * 3. Neither the name of the University nor the names of its contributors
18: * may be used to endorse or promote products derived from this software
19: * without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31: * SUCH DAMAGE.
32: */
33:
34:
35: #include "DEFS.h"
36:
37: /*
38: * bzero(void *p, size_t len)
39: */
40: LEAF(bzero, 0)
41: ALEAF(blkclr)
42: .set noreorder
43: #ifdef _STANDALONE
44: blt a1, 12, smallclr # small amount to clear?
45: PTR_SUBU a3, zero, a0 # compute # bytes to word align address
46: and a3, a3, 3
47: beq a3, zero, 1f # skip if word aligned
48: PTR_SUBU a1, a1, a3 # subtract from remaining count
49: SWHI zero, 0(a0) # clear 1, 2, or 3 bytes to align
50: PTR_ADDU a0, a0, a3
51: 1:
52: and v0, a1, 3 # compute number of words left
53: PTR_SUBU a3, a1, v0
54: move a1, v0
55: PTR_ADDU a3, a3, a0 # compute ending address
56: 2:
57: PTR_ADDU a0, a0, 4 # clear words
58: bne a0, a3, 2b # unrolling loop does not help
59: sw zero, -4(a0) # since we are limited by memory speed
60: #else
61: blt a1, 24, smallclr # small amount to clear?
62: PTR_SUBU a3, zero, a0 # compute # bytes to word align address
63: and a3, a3, 7
64: beq a3, zero, 1f # skip if word aligned
65: PTR_SUBU a1, a1, a3 # subtract from remaining count
66: SDHI zero, 0(a0) # clear 1, 2, or 3 bytes to align
67: PTR_ADDU a0, a0, a3
68: 1:
69: and v0, a1, 7 # compute number of words left
70: PTR_SUBU a3, a1, v0
71: move a1, v0
72: PTR_ADDU a3, a3, a0 # compute ending address
73: 2:
74: PTR_ADDU a0, a0, 8 # clear words
75: bne a0, a3, 2b # unrolling loop does not help
76: sd zero, -8(a0) # since we are limited by memory speed
77: #endif
78: smallclr:
79: ble a1, zero, 2f
80: PTR_ADDU a3, a1, a0 # compute ending address
81: 1:
82: PTR_ADDU a0, a0, 1 # clear bytes
83: bne a0, a3, 1b
84: sb zero, -1(a0)
85: 2:
86: j ra
87: nop
88: END(bzero)
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