1 /*
2 * Copyright (C) 2004 Joakim Tjernlund
3 * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
4 *
5 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
6 */
7
8 /* These are carefully optimized mem*() functions for PPC written in C.
9 * Don't muck around with these function without checking the generated
10 * assembler code.
11 * It is possible to optimize these significantly more by using specific
12 * data cache instructions(mainly dcbz). However that requires knownledge
13 * about the CPU's cache line size.
14 *
15 * BUG ALERT!
16 * The cache instructions on MPC8xx CPU's are buggy(they don't update
17 * the DAR register when causing a DTLB Miss/Error) and cannot be
18 * used on 8xx CPU's without a kernel patch to work around this
19 * problem.
20 */
21
22 #include <string.h>
23
24
memmove(void * to,const void * from,size_t n)25 void *memmove(void *to, const void *from, size_t n)
26 {
27 unsigned long rem, chunks, tmp1, tmp2;
28 unsigned char *tmp_to;
29 unsigned char *tmp_from = (unsigned char *)from;
30
31 if (tmp_from >= (unsigned char *)to)
32 return memcpy(to, from, n);
33 chunks = n / 8;
34 tmp_from += n;
35 tmp_to = to + n;
36 if (!chunks)
37 goto lessthan8;
38 rem = (unsigned long )tmp_to % 4;
39 if (rem)
40 goto align;
41 copy_chunks:
42 do {
43 /* make gcc to load all data, then store it */
44 tmp1 = *(unsigned long *)(tmp_from-4);
45 tmp_from -= 8;
46 tmp2 = *(unsigned long *)tmp_from;
47 *(unsigned long *)(tmp_to-4) = tmp1;
48 tmp_to -= 8;
49 *(unsigned long *)tmp_to = tmp2;
50 } while (--chunks);
51 lessthan8:
52 n = n % 8;
53 if (n >= 4) {
54 *(unsigned long *)(tmp_to-4) = *(unsigned long *)(tmp_from-4);
55 tmp_from -= 4;
56 tmp_to -= 4;
57 n = n-4;
58 }
59 if (!n ) return to;
60 do {
61 *--tmp_to = *--tmp_from;
62 } while (--n);
63
64 return to;
65 align:
66 rem = 4 - rem;
67 n = n - rem;
68 do {
69 *--tmp_to = *--tmp_from;
70 } while (--rem);
71 chunks = n / 8;
72 if (chunks)
73 goto copy_chunks;
74 goto lessthan8;
75 }
76 libc_hidden_def(memmove)
77