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 #include <picolibc.h>
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 #include <picolibc.h>
137
138 #ifdef __arch_common_v10_v32
139 /* Cater to branch offset difference between v32 and v10. We
140 assume the branch below has an 8-bit offset. */
141 " setf\n"
142 #endif
143 " subq 12*4,r12 \n\
144 bge 0b \n\
145 movem r11,[r13+] \n\
146 \n\
147 ;; Compensate for last loop underflowing n. \n\
148 addq 12*4,r12 \n\
149 \n\
150 ;; Restore registers from stack. \n\
151 movem [sp+],r10"
152
153 /* Outputs. */
154 : "=r" (dst), "=r" (n)
155
156 /* Inputs. */
157 : "0" (dst), "1" (n), "r" (lc));
158 }
159
160 /* An ad-hoc unroll, used for 4*12-1..16 bytes. */
161 while (n >= 16)
162 {
163 *(long *) dst = lc; dst += 4;
164 *(long *) dst = lc; dst += 4;
165 *(long *) dst = lc; dst += 4;
166 *(long *) dst = lc; dst += 4;
167 n -= 16;
168 }
169
170 switch (n)
171 {
172 case 0:
173 break;
174
175 case 1:
176 *dst = (char) lc;
177 break;
178
179 case 2:
180 *(short *) dst = (short) lc;
181 break;
182
183 case 3:
184 *(short *) dst = (short) lc; dst += 2;
185 *dst = (char) lc;
186 break;
187
188 case 4:
189 *(long *) dst = lc;
190 break;
191
192 case 5:
193 *(long *) dst = lc; dst += 4;
194 *dst = (char) lc;
195 break;
196
197 case 6:
198 *(long *) dst = lc; dst += 4;
199 *(short *) dst = (short) lc;
200 break;
201
202 case 7:
203 *(long *) dst = lc; dst += 4;
204 *(short *) dst = (short) lc; dst += 2;
205 *dst = (char) lc;
206 break;
207
208 case 8:
209 *(long *) dst = lc; dst += 4;
210 *(long *) dst = lc;
211 break;
212
213 case 9:
214 *(long *) dst = lc; dst += 4;
215 *(long *) dst = lc; dst += 4;
216 *dst = (char) lc;
217 break;
218
219 case 10:
220 *(long *) dst = lc; dst += 4;
221 *(long *) dst = lc; dst += 4;
222 *(short *) dst = (short) lc;
223 break;
224
225 case 11:
226 *(long *) dst = lc; dst += 4;
227 *(long *) dst = lc; dst += 4;
228 *(short *) dst = (short) lc; dst += 2;
229 *dst = (char) lc;
230 break;
231
232 case 12:
233 *(long *) dst = lc; dst += 4;
234 *(long *) dst = lc; dst += 4;
235 *(long *) dst = lc;
236 break;
237
238 case 13:
239 *(long *) dst = lc; dst += 4;
240 *(long *) dst = lc; dst += 4;
241 *(long *) dst = lc; dst += 4;
242 *dst = (char) lc;
243 break;
244
245 case 14:
246 *(long *) dst = lc; dst += 4;
247 *(long *) dst = lc; dst += 4;
248 *(long *) dst = lc; dst += 4;
249 *(short *) dst = (short) lc;
250 break;
251
252 case 15:
253 *(long *) dst = lc; dst += 4;
254 *(long *) dst = lc; dst += 4;
255 *(long *) dst = lc; dst += 4;
256 *(short *) dst = (short) lc; dst += 2;
257 *dst = (char) lc;
258 break;
259 }
260 }
261
262 return return_dst;
263 }
264
