1/* Copyright (C) 1991-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <string.h>
19#include <memcopy.h>
20
21#ifndef MEMSET
22# define MEMSET memset
23#endif
24
25void *
26inhibit_loop_to_libcall
27MEMSET (void *dstpp, int c, size_t len)
28{
29 long int dstp = (long int) dstpp;
30
31 if (len >= 8)
32 {
33 size_t xlen;
34 op_t cccc;
35
36 cccc = (unsigned char) c;
37 cccc |= cccc << 8;
38 cccc |= cccc << 16;
39 if (OPSIZ > 4)
40 /* Do the shift in two steps to avoid warning if long has 32 bits. */
41 cccc |= (cccc << 16) << 16;
42
43 /* There are at least some bytes to set.
44 No need to test for LEN == 0 in this alignment loop. */
45 while (dstp % OPSIZ != 0)
46 {
47 ((byte *) dstp)[0] = c;
48 dstp += 1;
49 len -= 1;
50 }
51
52 /* Write 8 `op_t' per iteration until less than 8 `op_t' remain. */
53 xlen = len / (OPSIZ * 8);
54 while (xlen > 0)
55 {
56 ((op_t *) dstp)[0] = cccc;
57 ((op_t *) dstp)[1] = cccc;
58 ((op_t *) dstp)[2] = cccc;
59 ((op_t *) dstp)[3] = cccc;
60 ((op_t *) dstp)[4] = cccc;
61 ((op_t *) dstp)[5] = cccc;
62 ((op_t *) dstp)[6] = cccc;
63 ((op_t *) dstp)[7] = cccc;
64 dstp += 8 * OPSIZ;
65 xlen -= 1;
66 }
67 len %= OPSIZ * 8;
68
69 /* Write 1 `op_t' per iteration until less than OPSIZ bytes remain. */
70 xlen = len / OPSIZ;
71 while (xlen > 0)
72 {
73 ((op_t *) dstp)[0] = cccc;
74 dstp += OPSIZ;
75 xlen -= 1;
76 }
77 len %= OPSIZ;
78 }
79
80 /* Write the last few bytes. */
81 while (len > 0)
82 {
83 ((byte *) dstp)[0] = c;
84 dstp += 1;
85 len -= 1;
86 }
87
88 return dstpp;
89}
90libc_hidden_builtin_def (MEMSET)
91

source code of glibc/string/memset.c