1 /* A memset for CRIS.
2 Copyright (C) 1999-2005 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 /* Note the multiple occurrence of the expression "12*4", including the
34 asm. It is hard to get it into the asm in a good way. Thus better to
35 expose the problem everywhere: no macro. */
36
37 /* Assuming one cycle per dword written or read (ok, not really true; the
38 world is not ideal), and one cycle per instruction, then 43+3*(n/48-1)
39 <= 24+24*(n/48-1) so n >= 45.7; n >= 0.9; we win on the first full
40 48-byte block to set. */
41
42 #define MEMSET_BY_BLOCK_THRESHOLD (1 * 48)
43
44 /* No name ambiguities in this file. */
45 __asm__ (".syntax no_register_prefix");
46
memset(void * pdst,int c,unsigned int plen)47 void *memset(void *pdst, int c, unsigned int plen)
48 {
49 /* Now we want the parameters in special registers. Make sure the
50 compiler does something usable with this. */
51
52 register char *return_dst __asm__ ("r10") = pdst;
53 register int n __asm__ ("r12") = plen;
54 register int lc __asm__ ("r11") = c;
55
56 /* Most apps use memset sanely. Memsetting about 3..4 bytes or less get
57 penalized here compared to the generic implementation. */
58
59 /* This is fragile performancewise at best. Check with newer GCC
60 releases, if they compile cascaded "x |= x << 8" to sane code. */
61 __asm__("movu.b %0,r13 \n\
62 lslq 8,r13 \n\
63 move.b %0,r13 \n\
64 move.d r13,%0 \n\
65 lslq 16,r13 \n\
66 or.d r13,%0"
67 : "=r" (lc) /* Inputs. */
68 : "0" (lc) /* Outputs. */
69 : "r13"); /* Trash. */
70
71 {
72 register char *dst __asm__ ("r13") = pdst;
73
74 if (((unsigned long) pdst & 3) != 0
75 /* Oops! n = 0 must be a valid call, regardless of alignment. */
76 && n >= 3)
77 {
78 if ((unsigned long) dst & 1)
79 {
80 *dst = (char) lc;
81 n--;
82 dst++;
83 }
84
85 if ((unsigned long) dst & 2)
86 {
87 *(short *) dst = lc;
88 n -= 2;
89 dst += 2;
90 }
91 }
92
93 /* Decide which setting method to use. */
94 if (n >= MEMSET_BY_BLOCK_THRESHOLD)
95 {
96 /* It is not optimal to tell the compiler about clobbering any
97 registers; that will move the saving/restoring of those registers
98 to the function prologue/epilogue, and make non-block sizes
99 suboptimal. */
100 __asm__ volatile
101 ("\
102 ;; GCC does promise correct register allocations, but let's \n\
103 ;; make sure it keeps its promises. \n\
104 .ifnc %0-%1-%4,$r13-$r12-$r11 \n\
105 .error \"GCC reg alloc bug: %0-%1-%4 != $r13-$r12-$r11\" \n\
106 .endif \n\
107 \n\
108 ;; Save the registers we'll clobber in the movem process \n\
109 ;; on the stack. Don't mention them to gcc, it will only be \n\
110 ;; upset. \n\
111 subq 11*4,sp \n\
112 movem r10,[sp] \n\
113 \n\
114 move.d r11,r0 \n\
115 move.d r11,r1 \n\
116 move.d r11,r2 \n\
117 move.d r11,r3 \n\
118 move.d r11,r4 \n\
119 move.d r11,r5 \n\
120 move.d r11,r6 \n\
121 move.d r11,r7 \n\
122 move.d r11,r8 \n\
123 move.d r11,r9 \n\
124 move.d r11,r10 \n\
125 \n\
126 ;; Now we've got this: \n\
127 ;; r13 - dst \n\
128 ;; r12 - n \n\
129 \n\
130 ;; Update n for the first loop \n\
131 subq 12*4,r12 \n\
132 0: \n\
133 "
134 #ifdef __arch_common_v10_v32
135 /* Cater to branch offset difference between v32 and v10. We
136 assume the branch below has an 8-bit offset. */
137 " setf\n"
138 #endif
139 " subq 12*4,r12 \n\
140 bge 0b \n\
141 movem r11,[r13+] \n\
142 \n\
143 ;; Compensate for last loop underflowing n. \n\
144 addq 12*4,r12 \n\
145 \n\
146 ;; Restore registers from stack. \n\
147 movem [sp+],r10"
148
149 /* Outputs. */
150 : "=r" (dst), "=r" (n)
151
152 /* Inputs. */
153 : "0" (dst), "1" (n), "r" (lc));
154 }
155
156 /* An ad-hoc unroll, used for 4*12-1..16 bytes. */
157 while (n >= 16)
158 {
159 *(long *) dst = lc; dst += 4;
160 *(long *) dst = lc; dst += 4;
161 *(long *) dst = lc; dst += 4;
162 *(long *) dst = lc; dst += 4;
163 n -= 16;
164 }
165
166 switch (n)
167 {
168 case 0:
169 break;
170
171 case 1:
172 *dst = (char) lc;
173 break;
174
175 case 2:
176 *(short *) dst = (short) lc;
177 break;
178
179 case 3:
180 *(short *) dst = (short) lc; dst += 2;
181 *dst = (char) lc;
182 break;
183
184 case 4:
185 *(long *) dst = lc;
186 break;
187
188 case 5:
189 *(long *) dst = lc; dst += 4;
190 *dst = (char) lc;
191 break;
192
193 case 6:
194 *(long *) dst = lc; dst += 4;
195 *(short *) dst = (short) lc;
196 break;
197
198 case 7:
199 *(long *) dst = lc; dst += 4;
200 *(short *) dst = (short) lc; dst += 2;
201 *dst = (char) lc;
202 break;
203
204 case 8:
205 *(long *) dst = lc; dst += 4;
206 *(long *) dst = lc;
207 break;
208
209 case 9:
210 *(long *) dst = lc; dst += 4;
211 *(long *) dst = lc; dst += 4;
212 *dst = (char) lc;
213 break;
214
215 case 10:
216 *(long *) dst = lc; dst += 4;
217 *(long *) dst = lc; dst += 4;
218 *(short *) dst = (short) lc;
219 break;
220
221 case 11:
222 *(long *) dst = lc; dst += 4;
223 *(long *) dst = lc; dst += 4;
224 *(short *) dst = (short) lc; dst += 2;
225 *dst = (char) lc;
226 break;
227
228 case 12:
229 *(long *) dst = lc; dst += 4;
230 *(long *) dst = lc; dst += 4;
231 *(long *) dst = lc;
232 break;
233
234 case 13:
235 *(long *) dst = lc; dst += 4;
236 *(long *) dst = lc; dst += 4;
237 *(long *) dst = lc; dst += 4;
238 *dst = (char) lc;
239 break;
240
241 case 14:
242 *(long *) dst = lc; dst += 4;
243 *(long *) dst = lc; dst += 4;
244 *(long *) dst = lc; dst += 4;
245 *(short *) dst = (short) lc;
246 break;
247
248 case 15:
249 *(long *) dst = lc; dst += 4;
250 *(long *) dst = lc; dst += 4;
251 *(long *) dst = lc; dst += 4;
252 *(short *) dst = (short) lc; dst += 2;
253 *dst = (char) lc;
254 break;
255 }
256 }
257
258 return return_dst;
259 }
260