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gerrit-public.fairphone.software / kernel / msm-5.4 / 51533b615e605d86154ec1b4e585c8ca1b0b15b7 / . / arch / cris / arch-v32 / lib / string.c
blob: 98e282ac824af373cf75c85e252518ada91ded77 [file] [log] [blame]
Mikael Starvik51533b62005-07-27 11:44:44 -0700[diff] [blame^]1/*#************************************************************************#*/
2/*#-------------------------------------------------------------------------*/
3/*# */
4/*# FUNCTION NAME: memcpy() */
5/*# */
6/*# PARAMETERS: void* dst; Destination address. */
7/*# void* src; Source address. */
8/*# int len; Number of bytes to copy. */
9/*# */
10/*# RETURNS: dst. */
11/*# */
12/*# DESCRIPTION: Copies len bytes of memory from src to dst. No guarantees */
13/*# about copying of overlapping memory areas. This routine is */
14/*# very sensitive to compiler changes in register allocation. */
15/*# Should really be rewritten to avoid this problem. */
16/*# */
17/*#-------------------------------------------------------------------------*/
18/*# */
19/*# HISTORY */
20/*# */
21/*# DATE NAME CHANGES */
22/*# ---- ---- ------- */
23/*# 941007 Kenny R Creation */
24/*# 941011 Kenny R Lots of optimizations and inlining. */
25/*# 941129 Ulf A Adapted for use in libc. */
26/*# 950216 HP N==0 forgotten if non-aligned src/dst. */
27/*# Added some optimizations. */
28/*# 001025 HP Make src and dst char *. Align dst to */
29/*# dword, not just word-if-both-src-and-dst- */
30/*# are-misaligned. */
31/*# */
32/*#-------------------------------------------------------------------------*/
33
34#include <linux/types.h>
35
36void *memcpy(void *pdst,
37 const void *psrc,
38 size_t pn)
39{
40 /* Ok. Now we want the parameters put in special registers.
41 Make sure the compiler is able to make something useful of this.
42 As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
43
44 If gcc was allright, it really would need no temporaries, and no
45 stack space to save stuff on. */
46
47 register void *return_dst __asm__ ("r10") = pdst;
48 register char *dst __asm__ ("r13") = pdst;
49 register const char *src __asm__ ("r11") = psrc;
50 register int n __asm__ ("r12") = pn;
51
52
53 /* When src is aligned but not dst, this makes a few extra needless
54 cycles. I believe it would take as many to check that the
55 re-alignment was unnecessary. */
56 if (((unsigned long) dst & 3) != 0
57 /* Don't align if we wouldn't copy more than a few bytes; so we
58 don't have to check further for overflows. */
59 && n >= 3)
60 {
61 if ((unsigned long) dst & 1)
62 {
63 n--;
64 *(char*)dst = *(char*)src;
65 src++;
66 dst++;
67 }
68
69 if ((unsigned long) dst & 2)
70 {
71 n -= 2;
72 *(short*)dst = *(short*)src;
73 src += 2;
74 dst += 2;
75 }
76 }
77
78 /* Decide which copying method to use. Movem is dirt cheap, so the
79 overheap is low enough to always use the minimum block size as the
80 threshold. */
81 if (n >= 44)
82 {
83 /* For large copies we use 'movem' */
84
85 /* It is not optimal to tell the compiler about clobbering any
86 registers; that will move the saving/restoring of those registers
87 to the function prologue/epilogue, and make non-movem sizes
88 suboptimal. */
89 __asm__ volatile (" \n\
90 ;; Check that the register asm declaration got right. \n\
91 ;; The GCC manual explicitly says TRT will happen. \n\
92 .ifnc %0-%1-%2,$r13-$r11-$r12 \n\
93 .err \n\
94 .endif \n\
95 \n\
96 ;; Save the registers we'll use in the movem process \n\
97 \n\
98 ;; on the stack. \n\
99 subq 11*4,$sp \n\
100 movem $r10,[$sp] \n\
101 \n\
102 ;; Now we've got this: \n\
103 ;; r11 - src \n\
104 ;; r13 - dst \n\
105 ;; r12 - n \n\
106 \n\
107 ;; Update n for the first loop \n\
108 subq 44,$r12 \n\
1090: \n\
110 movem [$r11+],$r10 \n\
111 subq 44,$r12 \n\
112 bge 0b \n\
113 movem $r10,[$r13+] \n\
114 \n\
115 addq 44,$r12 ;; compensate for last loop underflowing n \n\
116 \n\
117 ;; Restore registers from stack \n\
118 movem [$sp+],$r10"
119
120 /* Outputs */ : "=r" (dst), "=r" (src), "=r" (n)
121 /* Inputs */ : "0" (dst), "1" (src), "2" (n));
122
123 }
124
125 /* Either we directly starts copying, using dword copying
126 in a loop, or we copy as much as possible with 'movem'
127 and then the last block (<44 bytes) is copied here.
128 This will work since 'movem' will have updated src,dst,n. */
129
130 while ( n >= 16 )
131 {
132 *((long*)dst)++ = *((long*)src)++;
133 *((long*)dst)++ = *((long*)src)++;
134 *((long*)dst)++ = *((long*)src)++;
135 *((long*)dst)++ = *((long*)src)++;
136 n -= 16;
137 }
138
139 /* A switch() is definitely the fastest although it takes a LOT of code.
140 * Particularly if you inline code this.
141 */
142 switch (n)
143 {
144 case 0:
145 break;
146 case 1:
147 *(char*)dst = *(char*)src;
148 break;
149 case 2:
150 *(short*)dst = *(short*)src;
151 break;
152 case 3:
153 *((short*)dst)++ = *((short*)src)++;
154 *(char*)dst = *(char*)src;
155 break;
156 case 4:
157 *((long*)dst)++ = *((long*)src)++;
158 break;
159 case 5:
160 *((long*)dst)++ = *((long*)src)++;
161 *(char*)dst = *(char*)src;
162 break;
163 case 6:
164 *((long*)dst)++ = *((long*)src)++;
165 *(short*)dst = *(short*)src;
166 break;
167 case 7:
168 *((long*)dst)++ = *((long*)src)++;
169 *((short*)dst)++ = *((short*)src)++;
170 *(char*)dst = *(char*)src;
171 break;
172 case 8:
173 *((long*)dst)++ = *((long*)src)++;
174 *((long*)dst)++ = *((long*)src)++;
175 break;
176 case 9:
177 *((long*)dst)++ = *((long*)src)++;
178 *((long*)dst)++ = *((long*)src)++;
179 *(char*)dst = *(char*)src;
180 break;
181 case 10:
182 *((long*)dst)++ = *((long*)src)++;
183 *((long*)dst)++ = *((long*)src)++;
184 *(short*)dst = *(short*)src;
185 break;
186 case 11:
187 *((long*)dst)++ = *((long*)src)++;
188 *((long*)dst)++ = *((long*)src)++;
189 *((short*)dst)++ = *((short*)src)++;
190 *(char*)dst = *(char*)src;
191 break;
192 case 12:
193 *((long*)dst)++ = *((long*)src)++;
194 *((long*)dst)++ = *((long*)src)++;
195 *((long*)dst)++ = *((long*)src)++;
196 break;
197 case 13:
198 *((long*)dst)++ = *((long*)src)++;
199 *((long*)dst)++ = *((long*)src)++;
200 *((long*)dst)++ = *((long*)src)++;
201 *(char*)dst = *(char*)src;
202 break;
203 case 14:
204 *((long*)dst)++ = *((long*)src)++;
205 *((long*)dst)++ = *((long*)src)++;
206 *((long*)dst)++ = *((long*)src)++;
207 *(short*)dst = *(short*)src;
208 break;
209 case 15:
210 *((long*)dst)++ = *((long*)src)++;
211 *((long*)dst)++ = *((long*)src)++;
212 *((long*)dst)++ = *((long*)src)++;
213 *((short*)dst)++ = *((short*)src)++;
214 *(char*)dst = *(char*)src;
215 break;
216 }
217
218 return return_dst; /* destination pointer. */
219} /* memcpy() */