Annotation of sys/lib/libkern/arch/mips64/bcopy.S, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: bcopy.S,v 1.4 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: #include "DEFS.h"
35:
36:
37: /*
38: * memcpy(to, from, len)
39: * {ov}bcopy(from, to, len)
40: */
41: LEAF(memcpy, 0)
42: .set noreorder
43: move v0, a0 # swap from and to
44: move a0, a1
45: move a1, v0
46: ALEAF(bcopy)
47: ALEAF(ovbcopy)
48: .set noreorder
49: PTR_ADDU t0, a0, a2 # t0 = end of s1 region
50: sltu t1, a1, t0
51: sltu t2, a0, a1
52: and t1, t1, t2 # t1 = true if from < to < (from+len)
53: beq t1, zero, forward # non overlapping, do forward copy
54: slt t2, a2, 12 # check for small copy
55:
56: ble a2, zero, 2f
57: PTR_ADDU t1, a1, a2 # t1 = end of to region
58: 1:
59: lb v1, -1(t0) # copy bytes backwards,
60: PTR_SUBU t0, t0, 1 # doesnt happen often so do slow way
61: PTR_SUBU t1, t1, 1
62: bne t0, a0, 1b
63: sb v1, 0(t1)
64: 2:
65: j ra
66: nop
67: forward:
68: bne t2, zero, smallcpy # do a small bcopy
69: xor v1, a0, a1 # compare low two bits of addresses
70: and v1, v1, 3
71: PTR_SUBU a3, zero, a1 # compute # bytes to word align address
72: beq v1, zero, aligned # addresses can be word aligned
73: and a3, a3, 3
74:
75: beq a3, zero, 1f
76: PTR_SUBU a2, a2, a3 # subtract from remaining count
77: LWHI v1, 0(a0) # get next 4 bytes (unaligned)
78: LWLO v1, 3(a0)
79: PTR_ADDU a0, a0, a3
80: SWHI v1, 0(a1) # store 1, 2, or 3 bytes to align a1
81: PTR_ADDU a1, a1, a3
82: 1:
83: and v1, a2, 3 # compute number of words left
84: PTR_SUBU a3, a2, v1
85: move a2, v1
86: PTR_ADDU a3, a3, a0 # compute ending address
87: 2:
88: LWHI v1, 0(a0) # copy words a0 unaligned, a1 aligned
89: LWLO v1, 3(a0)
90: PTR_ADDU a0, a0, 4
91: sw v1, 0(a1)
92: PTR_ADDU a1, a1, 4
93: bne a0, a3, 2b
94: nop # We have to do this mmu-bug.
95: b smallcpy
96: nop
97: aligned:
98: beq a3, zero, 1f
99: PTR_SUBU a2, a2, a3 # subtract from remaining count
100: LWHI v1, 0(a0) # copy 1, 2, or 3 bytes to align
101: PTR_ADDU a0, a0, a3
102: SWHI v1, 0(a1)
103: PTR_ADDU a1, a1, a3
104: 1:
105: and v1, a2, 3 # compute number of whole words left
106: PTR_SUBU a3, a2, v1
107: move a2, v1
108: PTR_ADDU a3, a3, a0 # compute ending address
109: 2:
110: lw v1, 0(a0) # copy words
111: PTR_ADDU a0, a0, 4
112: sw v1, 0(a1)
113: bne a0, a3, 2b
114: PTR_ADDU a1, a1, 4
115: smallcpy:
116: ble a2, zero, 2f
117: PTR_ADDU a3, a2, a0 # compute ending address
118: 1:
119: lbu v1, 0(a0) # copy bytes
120: PTR_ADDU a0, a0, 1
121: sb v1, 0(a1)
122: bne a0, a3, 1b
123: PTR_ADDU a1, a1, 1 # MMU BUG ? can not do -1(a1) at 0x80000000!!
124: 2:
125: j ra
126: nop
127: END(memcpy)
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