1 /* A memset for CRIS.
2 Copyright (C) 1999-2008 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 #include <string.h>
34
35 /* Note the multiple occurrence of the expression "12*4", including the
36 asm. It is hard to get it into the asm in a good way. Thus better to
37 expose the problem everywhere: no macro. */
38
39 /* Assuming one cycle per dword written or read (ok, not really true; the
40 world is not ideal), and one cycle per instruction, then 43+3*(n/48-1)
41 <= 24+24*(n/48-1) so n >= 45.7; n >= 0.9; we win on the first full
42 48-byte block to set. */
43
44 #define MEMSET_BY_BLOCK_THRESHOLD (1 * 48)
45
46 /* No name ambiguities in this file. */
47 __asm__ (".syntax no_register_prefix");
48
memset(void * pdst,int c,unsigned int plen)49 void *memset(void *pdst, int c, unsigned int plen)
50 {
51 /* Now we want the parameters in special registers. Make sure the
52 compiler does something usable with this. */
53
54 register char *return_dst __asm__ ("r10") = pdst;
55 register int n __asm__ ("r12") = plen;
56 register int lc __asm__ ("r11") = c;
57
58 /* Most apps use memset sanely. Memsetting about 3..4 bytes or less get
59 penalized here compared to the generic implementation. */
60
61 /* This is fragile performancewise at best. Check with newer GCC
62 releases, if they compile cascaded "x |= x << 8" to sane code. */
63 __asm__("movu.b %0,r13 \n\
64 lslq 8,r13 \n\
65 move.b %0,r13 \n\
66 move.d r13,%0 \n\
67 lslq 16,r13 \n\
68 or.d r13,%0"
69 : "=r" (lc) /* Inputs. */
70 : "0" (lc) /* Outputs. */
71 : "r13"); /* Trash. */
72
73 {
74 register char *dst __asm__ ("r13") = pdst;
75
76 if (((unsigned long) pdst & 3) != 0
77 /* Oops! n = 0 must be a valid call, regardless of alignment. */
78 && n >= 3)
79 {
80 if ((unsigned long) dst & 1)
81 {
82 *dst = (char) lc;
83 n--;
84 dst++;
85 }
86
87 if ((unsigned long) dst & 2)
88 {
89 *(short *) dst = lc;
90 n -= 2;
91 dst += 2;
92 }
93 }
94
95 /* Decide which setting method to use. */
96 if (n >= MEMSET_BY_BLOCK_THRESHOLD)
97 {
98 /* It is not optimal to tell the compiler about clobbering any
99 registers; that will move the saving/restoring of those registers
100 to the function prologue/epilogue, and make non-block sizes
101 suboptimal. */
102 __asm__ __volatile__
103 ("\
104 ;; GCC does promise correct register allocations, but let's \n\
105 ;; make sure it keeps its promises. \n\
106 .ifnc %0-%1-%4,$r13-$r12-$r11 \n\
107 .error \"GCC reg alloc bug: %0-%1-%4 != $r13-$r12-$r11\" \n\
108 .endif \n\
109 \n\
110 ;; Save the registers we'll clobber in the movem process \n\
111 ;; on the stack. Don't mention them to gcc, it will only be \n\
112 ;; upset. \n\
113 subq 11*4,sp \n\
114 movem r10,[sp] \n\
115 \n\
116 move.d r11,r0 \n\
117 move.d r11,r1 \n\
118 move.d r11,r2 \n\
119 move.d r11,r3 \n\
120 move.d r11,r4 \n\
121 move.d r11,r5 \n\
122 move.d r11,r6 \n\
123 move.d r11,r7 \n\
124 move.d r11,r8 \n\
125 move.d r11,r9 \n\
126 move.d r11,r10 \n\
127 \n\
128 ;; Now we've got this: \n\
129 ;; r13 - dst \n\
130 ;; r12 - n \n\
131 \n\
132 ;; Update n for the first loop \n\
133 subq 12*4,r12 \n\
134 0: \n\
135 "
136 #ifdef __arch_common_v10_v32
137 /* Cater to branch offset difference between v32 and v10. We
138 assume the branch below has an 8-bit offset. */
139 " setf\n"
140 #endif
141 " subq 12*4,r12 \n\
142 bge 0b \n\
143 movem r11,[r13+] \n\
144 \n\
145 ;; Compensate for last loop underflowing n. \n\
146 addq 12*4,r12 \n\
147 \n\
148 ;; Restore registers from stack. \n\
149 movem [sp+],r10"
150
151 /* Outputs. */
152 : "=r" (dst), "=r" (n)
153
154 /* Inputs. */
155 : "0" (dst), "1" (n), "r" (lc));
156 }
157
158 /* An ad-hoc unroll, used for 4*12-1..16 bytes. */
159 while (n >= 16)
160 {
161 *(long *) dst = lc; dst += 4;
162 *(long *) dst = lc; dst += 4;
163 *(long *) dst = lc; dst += 4;
164 *(long *) dst = lc; dst += 4;
165 n -= 16;
166 }
167
168 switch (n)
169 {
170 case 0:
171 break;
172
173 case 1:
174 *dst = (char) lc;
175 break;
176
177 case 2:
178 *(short *) dst = (short) lc;
179 break;
180
181 case 3:
182 *(short *) dst = (short) lc; dst += 2;
183 *dst = (char) lc;
184 break;
185
186 case 4:
187 *(long *) dst = lc;
188 break;
189
190 case 5:
191 *(long *) dst = lc; dst += 4;
192 *dst = (char) lc;
193 break;
194
195 case 6:
196 *(long *) dst = lc; dst += 4;
197 *(short *) dst = (short) lc;
198 break;
199
200 case 7:
201 *(long *) dst = lc; dst += 4;
202 *(short *) dst = (short) lc; dst += 2;
203 *dst = (char) lc;
204 break;
205
206 case 8:
207 *(long *) dst = lc; dst += 4;
208 *(long *) dst = lc;
209 break;
210
211 case 9:
212 *(long *) dst = lc; dst += 4;
213 *(long *) dst = lc; dst += 4;
214 *dst = (char) lc;
215 break;
216
217 case 10:
218 *(long *) dst = lc; dst += 4;
219 *(long *) dst = lc; dst += 4;
220 *(short *) dst = (short) lc;
221 break;
222
223 case 11:
224 *(long *) dst = lc; dst += 4;
225 *(long *) dst = lc; dst += 4;
226 *(short *) dst = (short) lc; dst += 2;
227 *dst = (char) lc;
228 break;
229
230 case 12:
231 *(long *) dst = lc; dst += 4;
232 *(long *) dst = lc; dst += 4;
233 *(long *) dst = lc;
234 break;
235
236 case 13:
237 *(long *) dst = lc; dst += 4;
238 *(long *) dst = lc; dst += 4;
239 *(long *) dst = lc; dst += 4;
240 *dst = (char) lc;
241 break;
242
243 case 14:
244 *(long *) dst = lc; dst += 4;
245 *(long *) dst = lc; dst += 4;
246 *(long *) dst = lc; dst += 4;
247 *(short *) dst = (short) lc;
248 break;
249
250 case 15:
251 *(long *) dst = lc; dst += 4;
252 *(long *) dst = lc; dst += 4;
253 *(long *) dst = lc; dst += 4;
254 *(short *) dst = (short) lc; dst += 2;
255 *dst = (char) lc;
256 break;
257 }
258 }
259
260 return return_dst;
261 }
262 libc_hidden_def(memset)
263