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memset.c @ 444

Last change on this file since 444 was 444, checked in by satin@…, 6 years ago
add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc
File size: 7.3 KB

Line
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
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 412-1..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	}

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source: trunk/libs/newlib/src/newlib/libc/machine/cris/memset.c @ 444

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