1 | /* Extracted from GLIBC memcpy.c and memcopy.h, which is: |
2 | Copyright (C) 1991, 1992, 1993, 1997, 2004 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | Contributed by Torbjorn Granlund (tege@sics.se). |
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 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #include <linux/types.h> |
21 | |
22 | /* Type to use for aligned memory operations. |
23 | This should normally be the biggest type supported by a single load |
24 | and store. */ |
25 | #define op_t unsigned long int |
26 | #define OPSIZ (sizeof(op_t)) |
27 | |
28 | /* Optimal type for storing bytes in registers. */ |
29 | #define reg_char char |
30 | |
31 | #define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) | ((w1) << (sh_2))) |
32 | |
33 | /* Copy exactly NBYTES bytes from SRC_BP to DST_BP, |
34 | without any assumptions about alignment of the pointers. */ |
35 | #define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \ |
36 | do { \ |
37 | size_t __nbytes = (nbytes); \ |
38 | while (__nbytes > 0) { \ |
39 | unsigned char __x = ((unsigned char *) src_bp)[0]; \ |
40 | src_bp += 1; \ |
41 | __nbytes -= 1; \ |
42 | ((unsigned char *) dst_bp)[0] = __x; \ |
43 | dst_bp += 1; \ |
44 | } \ |
45 | } while (0) |
46 | |
47 | /* Copy *up to* NBYTES bytes from SRC_BP to DST_BP, with |
48 | the assumption that DST_BP is aligned on an OPSIZ multiple. If |
49 | not all bytes could be easily copied, store remaining number of bytes |
50 | in NBYTES_LEFT, otherwise store 0. */ |
51 | /* extern void _wordcopy_fwd_aligned __P ((long int, long int, size_t)); */ |
52 | /* extern void _wordcopy_fwd_dest_aligned __P ((long int, long int, size_t)); */ |
53 | #define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes) \ |
54 | do { \ |
55 | if (src_bp % OPSIZ == 0) \ |
56 | _wordcopy_fwd_aligned(dst_bp, src_bp, (nbytes) / OPSIZ);\ |
57 | else \ |
58 | _wordcopy_fwd_dest_aligned(dst_bp, src_bp, (nbytes) / OPSIZ);\ |
59 | src_bp += (nbytes) & -OPSIZ; \ |
60 | dst_bp += (nbytes) & -OPSIZ; \ |
61 | (nbytes_left) = (nbytes) % OPSIZ; \ |
62 | } while (0) |
63 | |
64 | |
65 | /* Threshold value for when to enter the unrolled loops. */ |
66 | #define OP_T_THRES 16 |
67 | |
68 | /* _wordcopy_fwd_aligned -- Copy block beginning at SRCP to |
69 | block beginning at DSTP with LEN `op_t' words (not LEN bytes!). |
70 | Both SRCP and DSTP should be aligned for memory operations on `op_t's. */ |
71 | /* stream-lined (read x8 + write x8) */ |
72 | static void _wordcopy_fwd_aligned(long int dstp, long int srcp, size_t len) |
73 | { |
74 | while (len > 7) { |
75 | register op_t a0, a1, a2, a3, a4, a5, a6, a7; |
76 | |
77 | a0 = ((op_t *) srcp)[0]; |
78 | a1 = ((op_t *) srcp)[1]; |
79 | a2 = ((op_t *) srcp)[2]; |
80 | a3 = ((op_t *) srcp)[3]; |
81 | a4 = ((op_t *) srcp)[4]; |
82 | a5 = ((op_t *) srcp)[5]; |
83 | a6 = ((op_t *) srcp)[6]; |
84 | a7 = ((op_t *) srcp)[7]; |
85 | ((op_t *) dstp)[0] = a0; |
86 | ((op_t *) dstp)[1] = a1; |
87 | ((op_t *) dstp)[2] = a2; |
88 | ((op_t *) dstp)[3] = a3; |
89 | ((op_t *) dstp)[4] = a4; |
90 | ((op_t *) dstp)[5] = a5; |
91 | ((op_t *) dstp)[6] = a6; |
92 | ((op_t *) dstp)[7] = a7; |
93 | |
94 | srcp += 8 * OPSIZ; |
95 | dstp += 8 * OPSIZ; |
96 | len -= 8; |
97 | } |
98 | while (len > 0) { |
99 | *(op_t *)dstp = *(op_t *)srcp; |
100 | |
101 | srcp += OPSIZ; |
102 | dstp += OPSIZ; |
103 | len -= 1; |
104 | } |
105 | } |
106 | |
107 | /* _wordcopy_fwd_dest_aligned -- Copy block beginning at SRCP to |
108 | block beginning at DSTP with LEN `op_t' words (not LEN bytes!). |
109 | DSTP should be aligned for memory operations on `op_t's, but SRCP must |
110 | *not* be aligned. */ |
111 | /* stream-lined (read x4 + write x4) */ |
112 | static void _wordcopy_fwd_dest_aligned(long int dstp, long int srcp, |
113 | size_t len) |
114 | { |
115 | op_t ap; |
116 | int sh_1, sh_2; |
117 | |
118 | /* Calculate how to shift a word read at the memory operation |
119 | aligned srcp to make it aligned for copy. */ |
120 | |
121 | sh_1 = 8 * (srcp % OPSIZ); |
122 | sh_2 = 8 * OPSIZ - sh_1; |
123 | |
124 | /* Make SRCP aligned by rounding it down to the beginning of the `op_t' |
125 | it points in the middle of. */ |
126 | srcp &= -OPSIZ; |
127 | ap = ((op_t *) srcp)[0]; |
128 | srcp += OPSIZ; |
129 | |
130 | while (len > 3) { |
131 | op_t a0, a1, a2, a3; |
132 | |
133 | a0 = ((op_t *) srcp)[0]; |
134 | a1 = ((op_t *) srcp)[1]; |
135 | a2 = ((op_t *) srcp)[2]; |
136 | a3 = ((op_t *) srcp)[3]; |
137 | ((op_t *) dstp)[0] = MERGE(ap, sh_1, a0, sh_2); |
138 | ((op_t *) dstp)[1] = MERGE(a0, sh_1, a1, sh_2); |
139 | ((op_t *) dstp)[2] = MERGE(a1, sh_1, a2, sh_2); |
140 | ((op_t *) dstp)[3] = MERGE(a2, sh_1, a3, sh_2); |
141 | |
142 | ap = a3; |
143 | srcp += 4 * OPSIZ; |
144 | dstp += 4 * OPSIZ; |
145 | len -= 4; |
146 | } |
147 | while (len > 0) { |
148 | register op_t a0; |
149 | |
150 | a0 = ((op_t *) srcp)[0]; |
151 | ((op_t *) dstp)[0] = MERGE(ap, sh_1, a0, sh_2); |
152 | |
153 | ap = a0; |
154 | srcp += OPSIZ; |
155 | dstp += OPSIZ; |
156 | len -= 1; |
157 | } |
158 | } |
159 | |
160 | void *memcpy(void *dstpp, const void *srcpp, size_t len) |
161 | { |
162 | unsigned long int dstp = (long int) dstpp; |
163 | unsigned long int srcp = (long int) srcpp; |
164 | |
165 | /* Copy from the beginning to the end. */ |
166 | |
167 | /* If there not too few bytes to copy, use word copy. */ |
168 | if (len >= OP_T_THRES) { |
169 | /* Copy just a few bytes to make DSTP aligned. */ |
170 | len -= (-dstp) % OPSIZ; |
171 | BYTE_COPY_FWD(dstp, srcp, (-dstp) % OPSIZ); |
172 | |
173 | /* Copy whole pages from SRCP to DSTP by virtual address |
174 | manipulation, as much as possible. */ |
175 | |
176 | /* PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len); */ |
177 | |
178 | /* Copy from SRCP to DSTP taking advantage of the known |
179 | alignment of DSTP. Number of bytes remaining is put in the |
180 | third argument, i.e. in LEN. This number may vary from |
181 | machine to machine. */ |
182 | |
183 | WORD_COPY_FWD(dstp, srcp, len, len); |
184 | |
185 | /* Fall out and copy the tail. */ |
186 | } |
187 | |
188 | /* There are just a few bytes to copy. Use byte memory operations. */ |
189 | BYTE_COPY_FWD(dstp, srcp, len); |
190 | |
191 | return dstpp; |
192 | } |
193 | |
194 | void *memcpyb(void *dstpp, const void *srcpp, unsigned len) |
195 | { |
196 | unsigned long int dstp = (long int) dstpp; |
197 | unsigned long int srcp = (long int) srcpp; |
198 | |
199 | BYTE_COPY_FWD(dstp, srcp, len); |
200 | |
201 | return dstpp; |
202 | } |
203 | |