xref: /openbmc/linux/arch/arm/lib/memset.S (revision 1f9f6a78) 
1/*
2 *  linux/arch/arm/lib/memset.S
3 *
4 *  Copyright (C) 1995-2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *  ASM optimised string functions
11 */
12#include <linux/linkage.h>
13#include <asm/assembler.h>
14#include <asm/unwind.h>
15
16	.text
17	.align	5
18
19ENTRY(memset)
20UNWIND( .fnstart         )
21	ands	r3, r0, #3		@ 1 unaligned?
22	mov	ip, r0			@ preserve r0 as return value
23	bne	6f			@ 1
24/*
25 * we know that the pointer in ip is aligned to a word boundary.
26 */
271:	orr	r1, r1, r1, lsl #8
28	orr	r1, r1, r1, lsl #16
29	mov	r3, r1
30	cmp	r2, #16
31	blt	4f
32
33#if ! CALGN(1)+0
34
35/*
36 * We need 2 extra registers for this loop - use r8 and the LR
37 */
38	stmfd	sp!, {r8, lr}
39UNWIND( .fnend              )
40UNWIND( .fnstart            )
41UNWIND( .save {r8, lr}      )
42	mov	r8, r1
43	mov	lr, r1
44
452:	subs	r2, r2, #64
46	stmgeia	ip!, {r1, r3, r8, lr}	@ 64 bytes at a time.
47	stmgeia	ip!, {r1, r3, r8, lr}
48	stmgeia	ip!, {r1, r3, r8, lr}
49	stmgeia	ip!, {r1, r3, r8, lr}
50	bgt	2b
51	ldmeqfd	sp!, {r8, pc}		@ Now <64 bytes to go.
52/*
53 * No need to correct the count; we're only testing bits from now on
54 */
55	tst	r2, #32
56	stmneia	ip!, {r1, r3, r8, lr}
57	stmneia	ip!, {r1, r3, r8, lr}
58	tst	r2, #16
59	stmneia	ip!, {r1, r3, r8, lr}
60	ldmfd	sp!, {r8, lr}
61UNWIND( .fnend              )
62
63#else
64
65/*
66 * This version aligns the destination pointer in order to write
67 * whole cache lines at once.
68 */
69
70	stmfd	sp!, {r4-r8, lr}
71UNWIND( .fnend                 )
72UNWIND( .fnstart               )
73UNWIND( .save {r4-r8, lr}      )
74	mov	r4, r1
75	mov	r5, r1
76	mov	r6, r1
77	mov	r7, r1
78	mov	r8, r1
79	mov	lr, r1
80
81	cmp	r2, #96
82	tstgt	ip, #31
83	ble	3f
84
85	and	r8, ip, #31
86	rsb	r8, r8, #32
87	sub	r2, r2, r8
88	movs	r8, r8, lsl #(32 - 4)
89	stmcsia	ip!, {r4, r5, r6, r7}
90	stmmiia	ip!, {r4, r5}
91	tst	r8, #(1 << 30)
92	mov	r8, r1
93	strne	r1, [ip], #4
94
953:	subs	r2, r2, #64
96	stmgeia	ip!, {r1, r3-r8, lr}
97	stmgeia	ip!, {r1, r3-r8, lr}
98	bgt	3b
99	ldmeqfd	sp!, {r4-r8, pc}
100
101	tst	r2, #32
102	stmneia	ip!, {r1, r3-r8, lr}
103	tst	r2, #16
104	stmneia	ip!, {r4-r7}
105	ldmfd	sp!, {r4-r8, lr}
106UNWIND( .fnend                 )
107
108#endif
109
110UNWIND( .fnstart            )
1114:	tst	r2, #8
112	stmneia	ip!, {r1, r3}
113	tst	r2, #4
114	strne	r1, [ip], #4
115/*
116 * When we get here, we've got less than 4 bytes to zero.  We
117 * may have an unaligned pointer as well.
118 */
1195:	tst	r2, #2
120	strneb	r1, [ip], #1
121	strneb	r1, [ip], #1
122	tst	r2, #1
123	strneb	r1, [ip], #1
124	ret	lr
125
1266:	subs	r2, r2, #4		@ 1 do we have enough
127	blt	5b			@ 1 bytes to align with?
128	cmp	r3, #2			@ 1
129	strltb	r1, [ip], #1		@ 1
130	strleb	r1, [ip], #1		@ 1
131	strb	r1, [ip], #1		@ 1
132	add	r2, r2, r3		@ 1 (r2 = r2 - (4 - r3))
133	b	1b
134UNWIND( .fnend   )
135ENDPROC(memset)
136