xref: /linux/arch/nios2/lib/memset.c (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
1 /*
2  * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
3  * Copyright (C) 2004 Microtronix Datacom Ltd
4  *
5  * This file is subject to the terms and conditions of the GNU General Public
6  * License.  See the file "COPYING" in the main directory of this archive
7  * for more details.
8  */
9 
10 #include <linux/types.h>
11 #include <linux/string.h>
12 
13 void *memset(void *s, int c, size_t count)
14 {
15 	int destptr, charcnt, dwordcnt, fill8reg, wrkrega;
16 
17 	if (!count)
18 		return s;
19 
20 	c &= 0xFF;
21 
22 	if (count <= 8) {
23 		char *xs = (char *) s;
24 
25 		while (count--)
26 			*xs++ = c;
27 		return s;
28 	}
29 
30 	__asm__ __volatile__ (
31 		/* fill8 %3, %5 (c & 0xff) */
32 		"	slli	%4, %5, 8\n"
33 		"	or	%4, %4, %5\n"
34 		"	slli    %3, %4, 16\n"
35 		"	or	%3, %3, %4\n"
36 		/* Word-align %0 (s) if necessary */
37 		"	andi	%4, %0, 0x01\n"
38 		"	beq	%4, zero, 1f\n"
39 		"	addi	%1, %1, -1\n"
40 		"	stb	%3, 0(%0)\n"
41 		"	addi	%0, %0, 1\n"
42 		"1:	mov	%2, %1\n"
43 		/* Dword-align %0 (s) if necessary */
44 		"	andi	%4, %0, 0x02\n"
45 		"	beq	%4, zero, 2f\n"
46 		"	addi	%1, %1, -2\n"
47 		"	sth	%3, 0(%0)\n"
48 		"	addi	%0, %0, 2\n"
49 		"	mov	%2, %1\n"
50 		/* %1 and %2 are how many more bytes to set */
51 		"2:	srli	%2, %2, 2\n"
52 		/* %2 is how many dwords to set */
53 		"3:	stw	%3, 0(%0)\n"
54 		"	addi	%0, %0, 4\n"
55 		"	addi    %2, %2, -1\n"
56 		"	bne	%2, zero, 3b\n"
57 		/* store residual word and/or byte if necessary */
58 		"	andi	%4, %1, 0x02\n"
59 		"	beq	%4, zero, 4f\n"
60 		"	sth	%3, 0(%0)\n"
61 		"	addi	%0, %0, 2\n"
62 		/* store residual byte if necessary */
63 		"4:	andi	%4, %1, 0x01\n"
64 		"	beq	%4, zero, 5f\n"
65 		"	stb	%3, 0(%0)\n"
66 		"5:\n"
67 		: "=r" (destptr),	/* %0  Output */
68 		  "=r" (charcnt),	/* %1  Output */
69 		  "=r" (dwordcnt),	/* %2  Output */
70 		  "=r" (fill8reg),	/* %3  Output */
71 		  "=&r" (wrkrega)	/* %4  Output only */
72 		: "r" (c),		/* %5  Input */
73 		  "0" (s),		/* %0  Input/Output */
74 		  "1" (count)		/* %1  Input/Output */
75 		: "memory"		/* clobbered */
76 	);
77 
78 	return s;
79 }
80