xref: /openbmc/u-boot/arch/arm/lib/memset.S (revision 0c7fd8f4)
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
15	.text
16	.align	5
17
18	.syntax unified
19#if defined(CONFIG_SYS_THUMB_BUILD) && !defined(MEMSET_NO_THUMB_BUILD)
20	.thumb
21	.thumb_func
22#endif
23ENTRY(memset)
24	ands	r3, r0, #3		@ 1 unaligned?
25	mov	ip, r0			@ preserve r0 as return value
26	bne	6f			@ 1
27/*
28 * we know that the pointer in ip is aligned to a word boundary.
29 */
301:	orr	r1, r1, r1, lsl #8
31	orr	r1, r1, r1, lsl #16
32	mov	r3, r1
33	cmp	r2, #16
34	blt	4f
35
36#if ! CALGN(1)+0
37
38/*
39 * We need 2 extra registers for this loop - use r8 and the LR
40 */
41	stmfd	sp!, {r8, lr}
42	mov	r8, r1
43	mov	lr, r1
44
452:	subs	r2, r2, #64
46	stmiage	ip!, {r1, r3, r8, lr}	@ 64 bytes at a time.
47	stmiage	ip!, {r1, r3, r8, lr}
48	stmiage	ip!, {r1, r3, r8, lr}
49	stmiage	ip!, {r1, r3, r8, lr}
50	bgt	2b
51	ldmfdeq	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	stmiane	ip!, {r1, r3, r8, lr}
57	stmiane	ip!, {r1, r3, r8, lr}
58	tst	r2, #16
59	stmiane	ip!, {r1, r3, r8, lr}
60	ldmfd	sp!, {r8, lr}
61
62#else
63
64/*
65 * This version aligns the destination pointer in order to write
66 * whole cache lines at once.
67 */
68
69	stmfd	sp!, {r4-r8, lr}
70	mov	r4, r1
71	mov	r5, r1
72	mov	r6, r1
73	mov	r7, r1
74	mov	r8, r1
75	mov	lr, r1
76
77	cmp	r2, #96
78	tstgt	ip, #31
79	ble	3f
80
81	and	r8, ip, #31
82	rsb	r8, r8, #32
83	sub	r2, r2, r8
84	movs	r8, r8, lsl #(32 - 4)
85	stmiacs	ip!, {r4, r5, r6, r7}
86	stmiami	ip!, {r4, r5}
87	tst	r8, #(1 << 30)
88	mov	r8, r1
89	strne	r1, [ip], #4
90
913:	subs	r2, r2, #64
92	stmiage	ip!, {r1, r3-r8, lr}
93	stmiage	ip!, {r1, r3-r8, lr}
94	bgt	3b
95	ldmfdeq	sp!, {r4-r8, pc}
96
97	tst	r2, #32
98	stmiane	ip!, {r1, r3-r8, lr}
99	tst	r2, #16
100	stmiane	ip!, {r4-r7}
101	ldmfd	sp!, {r4-r8, lr}
102
103#endif
104
1054:	tst	r2, #8
106	stmiane	ip!, {r1, r3}
107	tst	r2, #4
108	strne	r1, [ip], #4
109/*
110 * When we get here, we've got less than 4 bytes to zero.  We
111 * may have an unaligned pointer as well.
112 */
1135:	tst	r2, #2
114	strbne	r1, [ip], #1
115	strbne	r1, [ip], #1
116	tst	r2, #1
117	strbne	r1, [ip], #1
118	ret	lr
119
1206:	subs	r2, r2, #4		@ 1 do we have enough
121	blt	5b			@ 1 bytes to align with?
122	cmp	r3, #2			@ 1
123	strblt	r1, [ip], #1		@ 1
124	strble	r1, [ip], #1		@ 1
125	strb	r1, [ip], #1		@ 1
126	add	r2, r2, r3		@ 1 (r2 = r2 - (4 - r3))
127	b	1b
128ENDPROC(memset)
129