xref: /openbmc/linux/arch/openrisc/lib/memcpy.c (revision 862cf8d5)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * arch/openrisc/lib/memcpy.c
4  *
5  * Optimized memory copy routines for openrisc.  These are mostly copied
6  * from ohter sources but slightly entended based on ideas discuassed in
7  * #openrisc.
8  *
9  * The word unroll implementation is an extension to the arm byte
10  * unrolled implementation, but using word copies (if things are
11  * properly aligned)
12  *
13  * The great arm loop unroll algorithm can be found at:
14  *  arch/arm/boot/compressed/string.c
15  */
16 
17 #include <linux/export.h>
18 
19 #include <linux/string.h>
20 
21 #ifdef CONFIG_OR1K_1200
22 /*
23  * Do memcpy with word copies and loop unrolling. This gives the
24  * best performance on the OR1200 and MOR1KX archirectures
25  */
memcpy(void * dest,__const void * src,__kernel_size_t n)26 void *memcpy(void *dest, __const void *src, __kernel_size_t n)
27 {
28 	int i = 0;
29 	unsigned char *d, *s;
30 	uint32_t *dest_w = (uint32_t *)dest, *src_w = (uint32_t *)src;
31 
32 	/* If both source and dest are word aligned copy words */
33 	if (!((unsigned int)dest_w & 3) && !((unsigned int)src_w & 3)) {
34 		/* Copy 32 bytes per loop */
35 		for (i = n >> 5; i > 0; i--) {
36 			*dest_w++ = *src_w++;
37 			*dest_w++ = *src_w++;
38 			*dest_w++ = *src_w++;
39 			*dest_w++ = *src_w++;
40 			*dest_w++ = *src_w++;
41 			*dest_w++ = *src_w++;
42 			*dest_w++ = *src_w++;
43 			*dest_w++ = *src_w++;
44 		}
45 
46 		if (n & 1 << 4) {
47 			*dest_w++ = *src_w++;
48 			*dest_w++ = *src_w++;
49 			*dest_w++ = *src_w++;
50 			*dest_w++ = *src_w++;
51 		}
52 
53 		if (n & 1 << 3) {
54 			*dest_w++ = *src_w++;
55 			*dest_w++ = *src_w++;
56 		}
57 
58 		if (n & 1 << 2)
59 			*dest_w++ = *src_w++;
60 
61 		d = (unsigned char *)dest_w;
62 		s = (unsigned char *)src_w;
63 
64 	} else {
65 		d = (unsigned char *)dest_w;
66 		s = (unsigned char *)src_w;
67 
68 		for (i = n >> 3; i > 0; i--) {
69 			*d++ = *s++;
70 			*d++ = *s++;
71 			*d++ = *s++;
72 			*d++ = *s++;
73 			*d++ = *s++;
74 			*d++ = *s++;
75 			*d++ = *s++;
76 			*d++ = *s++;
77 		}
78 
79 		if (n & 1 << 2) {
80 			*d++ = *s++;
81 			*d++ = *s++;
82 			*d++ = *s++;
83 			*d++ = *s++;
84 		}
85 	}
86 
87 	if (n & 1 << 1) {
88 		*d++ = *s++;
89 		*d++ = *s++;
90 	}
91 
92 	if (n & 1)
93 		*d++ = *s++;
94 
95 	return dest;
96 }
97 #else
98 /*
99  * Use word copies but no loop unrolling as we cannot assume there
100  * will be benefits on the archirecture
101  */
memcpy(void * dest,__const void * src,__kernel_size_t n)102 void *memcpy(void *dest, __const void *src, __kernel_size_t n)
103 {
104 	unsigned char *d, *s;
105 	uint32_t *dest_w = (uint32_t *)dest, *src_w = (uint32_t *)src;
106 
107 	/* If both source and dest are word aligned copy words */
108 	if (!((unsigned int)dest_w & 3) && !((unsigned int)src_w & 3)) {
109 		for (; n >= 4; n -= 4)
110 			*dest_w++ = *src_w++;
111 	}
112 
113 	d = (unsigned char *)dest_w;
114 	s = (unsigned char *)src_w;
115 
116 	/* For remaining or if not aligned, copy bytes */
117 	for (; n >= 1; n -= 1)
118 		*d++ = *s++;
119 
120 	return dest;
121 
122 }
123 #endif
124 
125 EXPORT_SYMBOL(memcpy);
126