1 /*
2 * Copyright (c) 2021-2021 Huawei Device Co., Ltd. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without modification,
5 * are permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice, this list of
8 * conditions and the following disclaimer.
9 *
10 * 2. Redistributions in binary form must reproduce the above copyright notice, this list
11 * of conditions and the following disclaimer in the documentation and/or other materials
12 * provided with the distribution.
13 *
14 * 3. Neither the name of the copyright holder nor the names of its contributors may be used
15 * to endorse or promote products derived from this software without specific prior written
16 * permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
20 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
22 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
25 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
26 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
27 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
28 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include <stdio.h>
32 #include <string.h>
33 #include <stdlib.h>
34 #include <stdint.h>
35
memset(void * dest,int c,size_t n)36 void *memset(void *dest, int c, size_t n)
37 {
38 char *pos = dest;
39 uint32_t c32 = 0;
40 uint64_t c64 = 0;
41 size_t num = n;
42
43 if (num == 0) {
44 return dest;
45 }
46
47 c = c & 0xFF;
48 if (c) {
49 c32 = c;
50 c32 |= c32 << 8; /* 8, Processed bits */
51 c32 |= c32 << 16; /* 16, Processed bits */
52 c64 = c32;
53 c64 |= c64 << 32; /* 32, Processed bits */
54 }
55
56 if (((uintptr_t)(pos) & 7) != 0) { /* 7, Processed align */
57 int unalignedCnt = 8 - ((uintptr_t)(pos) & 7); /* 7, 8, for calculate addr bits align */
58 if (num >= unalignedCnt) {
59 num = num - unalignedCnt;
60 } else {
61 unalignedCnt = num;
62 num = 0;
63 }
64 for (int loop = 1; loop <= unalignedCnt; ++loop) {
65 *pos = (char)c;
66 pos++;
67 }
68 }
69
70 /* L32_byte_aligned */
71 while (num >= 32) { /* 32, byte aligned */
72 *(uint64_t *)(pos) = c64;
73 *(uint64_t *)(pos + 8) = c64; /* 8, size of uint64_t */
74 *(uint64_t *)(pos + 16) = c64; /* 16, size of two uint64_t data */
75 *(uint64_t *)(pos + 24) = c64; /* 24, size of three uint64_t data */
76 num -= 32; /* 32, size of four uint64_t data */
77 pos += 32; /* 32, size of four uint64_t data */
78 }
79 if (num == 0) {
80 return dest;
81 }
82
83 /* L16_byte_aligned */
84 if (num >= 16) { /* 16, byte aligned */
85 *(uint64_t *)(pos) = c64;
86 *(uint64_t *)(pos + 8) = c64; /* 8, size of uint64_t */
87 num -= 16; /* 16, size of two uint64_t data */
88 pos += 16; /* 16, size of two uint64_t data */
89 if (num == 0) {
90 return dest;
91 }
92 }
93
94 /* L8_byte_aligned */
95 if (num >= 8) { /* 8, byte aligned */
96 *(uint64_t *)(pos) = c64;
97 num -= 8; /* 8, size of uint64_t */
98 pos += 8; /* 8, size of uint64_t */
99 if (num == 0) {
100 return dest;
101 }
102 }
103
104 /* L4_byte_aligned */
105 if (num >= 4) { /* 4, byte aligned */
106 *(uint32_t *)(pos) = c32;
107 num -= 4; /* 4, size of uint32_t */
108 pos += 4; /* 4, size of uint32_t */
109 if (num == 0) {
110 return dest;
111 }
112 }
113 while (num--) {
114 *pos++ = c;
115 }
116
117 return dest;
118 }