summaryrefslogtreecommitdiff
path: root/sys/lib/libkern/arch/mips/memcpy.S
blob: 2a391516262a49b0d2121d7470e626d9b311b84e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
/*	$NetBSD: memcpy.S,v 1.7 2001/10/16 15:40:53 uch Exp $	*/
/* XXXX We need to define this in a way which supports multiple architectures */

#include <machine/cdefs.h>	/* Get SZREG correct */
#include <mips/asm.h>
#include <machine/endian.h>

.set	push
.set noreorder

	.text

/*
 * {ov}bcopy(from, to, len)
 */
LEAF(bcopy)
XLEAF(ovbcopy)
	move	v0, a0		# swap from and to for compat interface.
	move	a0, a1
	move	a1, v0

/*
 * memcpy(to, from, len)
 */
XLEAF(memmove)
XLEAF(memcpy)
	.set	noat

	move	v0, a1		# save dst for return value.

	/*
	 *	Make sure we can copy forwards.
	 */
	sltu	t0,a1,a0	# t0 == a1 < a0
	addu	a3,a1,a2	# a3 == end of source
	sltu	t1,a0,a3	# t1 == a0 < a1+a2
	and	t2,t0,t1	# overlap -- copy backwards
	bne	t2,zero,backcopy

	/*
	 * 	There are four alignment cases (with frequency)
	 *	(Based on measurements taken with a DECstation 5000/200
	 *	 inside a Mach kernel.)
	 *
	 * 	aligned   -> aligned		(mostly)
	 * 	unaligned -> aligned		(sometimes)
	 * 	aligned,unaligned -> unaligned	(almost never)
	 *
	 *	Note that we could add another case that checks if
	 *	the destination and source are unaligned but the 
	 *	copy is alignable.  eg if src and dest are both
	 *	on a halfword boundary.
	 */
	andi	t1,a0,3		# BDSLOT: get last 2 bits of dest
	bne	t1,zero,bytecopy
	andi	t0,a1,3		# BDSLOT: get last 2 bits of src
	bne	t0,zero,destaligned

	/*
	 *	Forward aligned->aligned copy, 8*4 bytes at a time.
	 */
	li	AT,-32		# BDSLOT
	and	t0,a2,AT	# count truncated to multiple of 32
	addu	a3,a1,t0	# run fast loop up to this address
	sltu	AT,a1,a3	# any work to do?
	beq	AT,zero,wordcopy
	subu	a2,t0		# BDSLOT

	/*
	 *	loop body
	 */
#if SZREG == 8
	.set	mips3

	or	t3,a0,a1	# 4 or 8 byte aligned?
	andi	t3,t3,7
	bne	t3,zero,cp
	nop			# BDSLOT
cp8:
	ld	t3,0(a1)
	ld	v1,8(a1)
	ld	t0,16(a1)
	ld	t1,24(a1)
	addu	a1,32
	sd	t3,0(a0)
	sd	v1,8(a0)
	sd	t0,16(a0)
	sd	t1,24(a0)
	bne	a1,a3,cp8
	addu	a0,32		# BDSLOT

	b	wordcopy
	nop			# BDSLOT
#endif
cp:
	lw	t3,0(a1)
	lw	v1,4(a1)
	lw	t0,8(a1)
	lw	t1,12(a1)
	addu	a1,32
	sw	t3,0(a0)
	sw	v1,4(a0)
	sw	t0,8(a0)
	sw	t1,12(a0)
	lw	t1,-4(a1)
	lw	t0,-8(a1)
	lw	v1,-12(a1)
	lw	t3,-16(a1)
	addu	a0,32
	sw	t1,-4(a0)
	sw	t0,-8(a0)
	sw	v1,-12(a0)
	bne	a1,a3,cp
	sw	t3,-16(a0)	# BDSLOT

	/*
	 *	Copy a word at a time, no loop unrolling.
	 */
wordcopy:
	andi	t2,a2,3		# get byte count / 4
	subu	t2,a2,t2	# t2 = number of words to copy * 4
	beq	t2,zero,bytecopy
	addu	t0,a1,t2	# BDSLOT stop at t0
	subu	a2,a2,t2
1:
	lw	t3,0(a1)
	addu	a1,4
	sw	t3,0(a0)
#ifdef MIPS3_5900	
	nop
	nop
#endif	
	bne	a1,t0,1b
	addu	a0,4		# BDSLOT

bytecopy:
	beq	a2,zero,copydone	# nothing left to do?
	nop
2:
	lb	t3,0(a1)
	addu	a1,1
	sb	t3,0(a0)
	subu	a2,1
#ifdef MIPS3_5900	
	nop
#endif	
	bgtz	a2,2b
	addu	a0,1		# BDSLOT

copydone:
	j	ra
	nop
	/*
	 *	Copy from unaligned source to aligned dest.
	 */
destaligned:
	andi	t0,a2,3		# t0 = bytecount mod 4
	subu	a3,a2,t0	# number of words to transfer
	beq	a3,zero,bytecopy
	addu	a3,a1,a3	# BDSLOT: stop point for destaligned
	move	a2,t0		# this many to do after we are done

3:
	LWHI	t3,0(a1)
	LWLO	t3,3(a1)
	addi	a1,4
	sw	t3,0(a0)
#ifdef MIPS3_5900
	nop
#endif	
	bne	a1,a3,3b
	addi	a0,4		# BDSLOT

	j	bytecopy
	nop

	/*
	 *	Copy by bytes backwards.
	 */
backcopy:
	blez	a2,copydone	# nothing left to do?
	addu	t0,a1,a2	# BDSLOT: end of source
	addu	t1,a0,a2	# end of destination
4:
	lb	t3,-1(t0)	
	subu	t0,1
	sb	t3,-1(t1)
#ifdef MIPS3_5900
	nop
	nop
#endif	
	bne	t0,a1,4b
	subu	t1,1		# BDSLOT
	j	ra
	nop
	
	.set	at
END(bcopy)
.set	pop