1 | /* Copy memory to memory until the specified number of bytes |
2 | has been copied. Overlap is handled correctly. |
3 | Copyright (C) 1991-2022 Free Software Foundation, Inc. |
4 | This file is part of the GNU C Library. |
5 | |
6 | The GNU C Library is free software; you can redistribute it and/or |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either |
9 | version 2.1 of the License, or (at your option) any later version. |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
14 | Lesser General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, see |
18 | <https://www.gnu.org/licenses/>. */ |
19 | |
20 | #include <string.h> |
21 | #include <memcopy.h> |
22 | |
23 | /* All this is so that bcopy.c can #include |
24 | this file after defining some things. */ |
25 | #ifndef a1 |
26 | #define a1 dest /* First arg is DEST. */ |
27 | #define a1const |
28 | #define a2 src /* Second arg is SRC. */ |
29 | #define a2const const |
30 | #undef memmove |
31 | #endif |
32 | #if !defined(RETURN) || !defined(rettype) |
33 | #define RETURN(s) return (s) /* Return DEST. */ |
34 | #define rettype void * |
35 | #endif |
36 | |
37 | #ifndef MEMMOVE |
38 | #define MEMMOVE memmove |
39 | #endif |
40 | |
41 | rettype |
42 | inhibit_loop_to_libcall |
43 | MEMMOVE (a1const void *a1, a2const void *a2, size_t len) |
44 | { |
45 | unsigned long int dstp = (long int) dest; |
46 | unsigned long int srcp = (long int) src; |
47 | |
48 | /* This test makes the forward copying code be used whenever possible. |
49 | Reduces the working set. */ |
50 | if (dstp - srcp >= len) /* *Unsigned* compare! */ |
51 | { |
52 | /* Copy from the beginning to the end. */ |
53 | |
54 | #if MEMCPY_OK_FOR_FWD_MEMMOVE |
55 | dest = memcpy (dest, src, len); |
56 | #else |
57 | /* If there not too few bytes to copy, use word copy. */ |
58 | if (len >= OP_T_THRES) |
59 | { |
60 | /* Copy just a few bytes to make DSTP aligned. */ |
61 | len -= (-dstp) % OPSIZ; |
62 | BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ); |
63 | |
64 | /* Copy whole pages from SRCP to DSTP by virtual address |
65 | manipulation, as much as possible. */ |
66 | |
67 | PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len); |
68 | |
69 | /* Copy from SRCP to DSTP taking advantage of the known |
70 | alignment of DSTP. Number of bytes remaining is put |
71 | in the third argument, i.e. in LEN. This number may |
72 | vary from machine to machine. */ |
73 | |
74 | WORD_COPY_FWD (dstp, srcp, len, len); |
75 | |
76 | /* Fall out and copy the tail. */ |
77 | } |
78 | |
79 | /* There are just a few bytes to copy. Use byte memory operations. */ |
80 | BYTE_COPY_FWD (dstp, srcp, len); |
81 | #endif /* MEMCPY_OK_FOR_FWD_MEMMOVE */ |
82 | } |
83 | else |
84 | { |
85 | /* Copy from the end to the beginning. */ |
86 | srcp += len; |
87 | dstp += len; |
88 | |
89 | /* If there not too few bytes to copy, use word copy. */ |
90 | if (len >= OP_T_THRES) |
91 | { |
92 | /* Copy just a few bytes to make DSTP aligned. */ |
93 | len -= dstp % OPSIZ; |
94 | BYTE_COPY_BWD (dstp, srcp, dstp % OPSIZ); |
95 | |
96 | /* Copy from SRCP to DSTP taking advantage of the known |
97 | alignment of DSTP. Number of bytes remaining is put |
98 | in the third argument, i.e. in LEN. This number may |
99 | vary from machine to machine. */ |
100 | |
101 | WORD_COPY_BWD (dstp, srcp, len, len); |
102 | |
103 | /* Fall out and copy the tail. */ |
104 | } |
105 | |
106 | /* There are just a few bytes to copy. Use byte memory operations. */ |
107 | BYTE_COPY_BWD (dstp, srcp, len); |
108 | } |
109 | |
110 | RETURN (dest); |
111 | } |
112 | #ifndef memmove |
113 | libc_hidden_builtin_def (memmove) |
114 | #endif |
115 | |