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
memset(void * s,int c,size_t count)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