1 /* A memmove for CRIS.
2 Copyright (C) 2000-2005 Axis Communications.
3 All rights reserved.
4
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions
7 are met:
8
9 1. Redistributions of source code must retain the above copyright
10 notice, this list of conditions and the following disclaimer.
11
12 2. Neither the name of Axis Communications nor the names of its
13 contributors may be used to endorse or promote products derived
14 from this software without specific prior written permission.
15
16 THIS SOFTWARE IS PROVIDED BY AXIS COMMUNICATIONS AND ITS CONTRIBUTORS
17 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL AXIS
20 COMMUNICATIONS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
21 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
23 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
25 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
26 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27 POSSIBILITY OF SUCH DAMAGE. */
28
29 /* FIXME: This file should really only be used for reference, as the
30 result is somewhat depending on gcc generating what we expect rather
31 than what we describe. An assembly file should be used instead.
32
33 Even worse, we base it on memcpy, on the assumption that overlapping
34 moves are rare, and we will do no worse than the generic memmove. */
35
36 #include <stddef.h>
37
38 /* Break even between movem and move16 is really at 38.7 * 2, but
39 modulo 44, so up to the next multiple of 44, we use ordinary code. */
40 #define MEMMOVE_BY_BLOCK_THRESHOLD (44 * 2)
41
42 /* No name ambiguities in this file. */
43 __asm__ (".syntax no_register_prefix");
44
45 void *
memmove(void * pdst,const void * psrc,size_t pn)46 memmove(void *pdst, const void *psrc, size_t pn)
47 {
48 /* Now we want the parameters put in special registers.
49 Make sure the compiler is able to make something useful of this.
50 As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
51
52 If gcc was allright, it really would need no temporaries, and no
53 stack space to save stuff on. */
54
55 register void *return_dst __asm__ ("r10") = pdst;
56 register unsigned char *dst __asm__ ("r13") = pdst;
57 register unsigned const char *src __asm__ ("r11") = psrc;
58 register int n __asm__ ("r12") = pn;
59
60 /* Check and handle overlap. */
61 if (src < dst && dst < src + n)
62 {
63 /* Destructive overlap. We could optimize this, but we don't (for
64 the moment). */
65 src += n;
66 dst += n;
67 while (n--)
68 {
69 *--dst = *--src;
70 }
71
72 return return_dst;
73 }
74 /* Whew, no overlap. Proceed as with memcpy. We could call it instead
75 of having a copy here. That would spoil some of the optimization, so
76 we take the trouble with having two copies. */
77
78 /* When src is aligned but not dst, this makes a few extra needless
79 cycles. I believe it would take as many to check that the
80 re-alignment was unnecessary. */
81 if (((unsigned long) dst & 3) != 0
82 /* Don't align if we wouldn't copy more than a few bytes; so we
83 don't have to check further for overflows. */
84 && n >= 3)
85 {
86 if ((unsigned long) dst & 1)
87 {
88 n--;
89 *dst = *src;
90 src++;
91 dst++;
92 }
93
94 if ((unsigned long) dst & 2)
95 {
96 n -= 2;
97 *(short *) dst = *(short *) src;
98 src += 2;
99 dst += 2;
100 }
101 }
102
103 /* Decide which copying method to use. */
104 if (n >= MEMMOVE_BY_BLOCK_THRESHOLD)
105 {
106 /* It is not optimal to tell the compiler about clobbering any
107 registers; that will move the saving/restoring of those registers
108 to the function prologue/epilogue, and make non-movem sizes
109 suboptimal. */
110 __asm__ volatile
111 ("\
112 ;; GCC does promise correct register allocations, but let's \n\
113 ;; make sure it keeps its promises. \n\
114 .ifnc %0-%1-%2,$r13-$r11-$r12 \n\
115 .error \"GCC reg alloc bug: %0-%1-%4 != $r13-$r12-$r11\" \n\
116 .endif \n\
117 \n\
118 ;; Save the registers we'll use in the movem process \n\
119 ;; on the stack. \n\
120 subq 11*4,sp \n\
121 movem r10,[sp] \n\
122 \n\
123 ;; Now we've got this: \n\
124 ;; r11 - src \n\
125 ;; r13 - dst \n\
126 ;; r12 - n \n\
127 \n\
128 ;; Update n for the first loop. \n\
129 subq 44,r12 \n\
130 0: \n\
131 "
132 #ifdef __arch_common_v10_v32
133 /* Cater to branch offset difference between v32 and v10. We
134 assume the branch below has an 8-bit offset. */
135 " setf\n"
136 #endif
137 " movem [r11+],r10 \n\
138 subq 44,r12 \n\
139 bge 0b \n\
140 movem r10,[r13+] \n\
141 \n\
142 ;; Compensate for last loop underflowing n. \n\
143 addq 44,r12 \n\
144 \n\
145 ;; Restore registers from stack. \n\
146 movem [sp+],r10"
147
148 /* Outputs. */
149 : "=r" (dst), "=r" (src), "=r" (n)
150
151 /* Inputs. */
152 : "0" (dst), "1" (src), "2" (n));
153 }
154
155 while (n >= 16)
156 {
157 *(long *) dst = *(long *) src; dst += 4; src += 4;
158 *(long *) dst = *(long *) src; dst += 4; src += 4;
159 *(long *) dst = *(long *) src; dst += 4; src += 4;
160 *(long *) dst = *(long *) src; dst += 4; src += 4;
161
162 n -= 16;
163 }
164
165 switch (n)
166 {
167 case 0:
168 break;
169
170 case 1:
171 *dst = *src;
172 break;
173
174 case 2:
175 *(short *) dst = *(short *) src;
176 break;
177
178 case 3:
179 *(short *) dst = *(short *) src; dst += 2; src += 2;
180 *dst = *src;
181 break;
182
183 case 4:
184 *(long *) dst = *(long *) src;
185 break;
186
187 case 5:
188 *(long *) dst = *(long *) src; dst += 4; src += 4;
189 *dst = *src;
190 break;
191
192 case 6:
193 *(long *) dst = *(long *) src; dst += 4; src += 4;
194 *(short *) dst = *(short *) src;
195 break;
196
197 case 7:
198 *(long *) dst = *(long *) src; dst += 4; src += 4;
199 *(short *) dst = *(short *) src; dst += 2; src += 2;
200 *dst = *src;
201 break;
202
203 case 8:
204 *(long *) dst = *(long *) src; dst += 4; src += 4;
205 *(long *) dst = *(long *) src;
206 break;
207
208 case 9:
209 *(long *) dst = *(long *) src; dst += 4; src += 4;
210 *(long *) dst = *(long *) src; dst += 4; src += 4;
211 *dst = *src;
212 break;
213
214 case 10:
215 *(long *) dst = *(long *) src; dst += 4; src += 4;
216 *(long *) dst = *(long *) src; dst += 4; src += 4;
217 *(short *) dst = *(short *) src;
218 break;
219
220 case 11:
221 *(long *) dst = *(long *) src; dst += 4; src += 4;
222 *(long *) dst = *(long *) src; dst += 4; src += 4;
223 *(short *) dst = *(short *) src; dst += 2; src += 2;
224 *dst = *src;
225 break;
226
227 case 12:
228 *(long *) dst = *(long *) src; dst += 4; src += 4;
229 *(long *) dst = *(long *) src; dst += 4; src += 4;
230 *(long *) dst = *(long *) src;
231 break;
232
233 case 13:
234 *(long *) dst = *(long *) src; dst += 4; src += 4;
235 *(long *) dst = *(long *) src; dst += 4; src += 4;
236 *(long *) dst = *(long *) src; dst += 4; src += 4;
237 *dst = *src;
238 break;
239
240 case 14:
241 *(long *) dst = *(long *) src; dst += 4; src += 4;
242 *(long *) dst = *(long *) src; dst += 4; src += 4;
243 *(long *) dst = *(long *) src; dst += 4; src += 4;
244 *(short *) dst = *(short *) src;
245 break;
246
247 case 15:
248 *(long *) dst = *(long *) src; dst += 4; src += 4;
249 *(long *) dst = *(long *) src; dst += 4; src += 4;
250 *(long *) dst = *(long *) src; dst += 4; src += 4;
251 *(short *) dst = *(short *) src; dst += 2; src += 2;
252 *dst = *src;
253 break;
254 }
255
256 return return_dst;
257 }
258
