1 | /* Copy memory to memory until the specified number of bytes |
2 | has been copied. Overlap is handled correctly. |
3 | Copyright (C) 1991-2016 Free Software Foundation, Inc. |
4 | This file is part of the GNU C Library. |
5 | Contributed by Torbjorn Granlund (tege@sics.se). |
6 | |
7 | The GNU C Library is free software; you can redistribute it and/or |
8 | modify it under the terms of the GNU Lesser General Public |
9 | License as published by the Free Software Foundation; either |
10 | version 2.1 of the License, or (at your option) any later version. |
11 | |
12 | The GNU C Library is distributed in the hope that it will be useful, |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
15 | Lesser General Public License for more details. |
16 | |
17 | You should have received a copy of the GNU Lesser General Public |
18 | License along with the GNU C Library; if not, see |
19 | <http://www.gnu.org/licenses/>. */ |
20 | |
21 | #include <string.h> |
22 | #include <memcopy.h> |
23 | |
24 | /* All this is so that bcopy.c can #include |
25 | this file after defining some things. */ |
26 | #ifndef a1 |
27 | #define a1 dest /* First arg is DEST. */ |
28 | #define a1const |
29 | #define a2 src /* Second arg is SRC. */ |
30 | #define a2const const |
31 | #undef memmove |
32 | #endif |
33 | #if !defined(RETURN) || !defined(rettype) |
34 | #define RETURN(s) return (s) /* Return DEST. */ |
35 | #define rettype void * |
36 | #endif |
37 | |
38 | #ifndef MEMMOVE |
39 | #define MEMMOVE memmove |
40 | #endif |
41 | |
42 | rettype |
43 | inhibit_loop_to_libcall |
44 | MEMMOVE (a1const void *a1, a2const void *a2, size_t len) |
45 | { |
46 | unsigned long int dstp = (long int) dest; |
47 | unsigned long int srcp = (long int) src; |
48 | |
49 | /* This test makes the forward copying code be used whenever possible. |
50 | Reduces the working set. */ |
51 | if (dstp - srcp >= len) /* *Unsigned* compare! */ |
52 | { |
53 | /* Copy from the beginning to the end. */ |
54 | |
55 | #if MEMCPY_OK_FOR_FWD_MEMMOVE |
56 | dest = memcpy (dest, src, len); |
57 | #else |
58 | /* If there not too few bytes to copy, use word copy. */ |
59 | if (len >= OP_T_THRES) |
60 | { |
61 | /* Copy just a few bytes to make DSTP aligned. */ |
62 | len -= (-dstp) % OPSIZ; |
63 | BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ); |
64 | |
65 | /* Copy whole pages from SRCP to DSTP by virtual address |
66 | manipulation, as much as possible. */ |
67 | |
68 | PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len); |
69 | |
70 | /* Copy from SRCP to DSTP taking advantage of the known |
71 | alignment of DSTP. Number of bytes remaining is put |
72 | in the third argument, i.e. in LEN. This number may |
73 | vary from machine to machine. */ |
74 | |
75 | WORD_COPY_FWD (dstp, srcp, len, len); |
76 | |
77 | /* Fall out and copy the tail. */ |
78 | } |
79 | |
80 | /* There are just a few bytes to copy. Use byte memory operations. */ |
81 | BYTE_COPY_FWD (dstp, srcp, len); |
82 | #endif /* MEMCPY_OK_FOR_FWD_MEMMOVE */ |
83 | } |
84 | else |
85 | { |
86 | /* Copy from the end to the beginning. */ |
87 | srcp += len; |
88 | dstp += len; |
89 | |
90 | /* If there not too few bytes to copy, use word copy. */ |
91 | if (len >= OP_T_THRES) |
92 | { |
93 | /* Copy just a few bytes to make DSTP aligned. */ |
94 | len -= dstp % OPSIZ; |
95 | BYTE_COPY_BWD (dstp, srcp, dstp % OPSIZ); |
96 | |
97 | /* Copy from SRCP to DSTP taking advantage of the known |
98 | alignment of DSTP. Number of bytes remaining is put |
99 | in the third argument, i.e. in LEN. This number may |
100 | vary from machine to machine. */ |
101 | |
102 | WORD_COPY_BWD (dstp, srcp, len, len); |
103 | |
104 | /* Fall out and copy the tail. */ |
105 | } |
106 | |
107 | /* There are just a few bytes to copy. Use byte memory operations. */ |
108 | BYTE_COPY_BWD (dstp, srcp, len); |
109 | } |
110 | |
111 | RETURN (dest); |
112 | } |
113 | #ifndef memmove |
114 | libc_hidden_builtin_def (memmove) |
115 | #endif |
116 | |