1/*
2 * File:         arch/blackfin/lib/memcmp.S
3 * Based on:
4 * Author:
5 *
6 * Created:
7 * Description:
8 *
9 * Modified:
10 *               Copyright 2004-2006 Analog Devices Inc.
11 *
12 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
13 *
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
18 *
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22 * GNU General Public License for more details.
23 *
24 * You should have received a copy of the GNU General Public License
25 * along with this program; if not, see the file COPYING, or write
26 * to the Free Software Foundation, Inc.,
27 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
28 */
29
30#include <linux/linkage.h>
31
32/* int memcmp(const void *s1, const void *s2, size_t n);
33 * R0 = First Address (s1)
34 * R1 = Second Address (s2)
35 * R2 = count (n)
36 *
37 * Favours word aligned data.
38 */
39
40.text
41
42.align 2
43
44ENTRY(_memcmp)
45	I1 = P3;
46	P0 = R0;			/* P0 = s1 address */
47	P3 = R1;			/* P3 = s2 Address  */
48	P2 = R2 ;			/* P2 = count */
49	CC = R2 <= 7(IU);
50	IF CC JUMP .Ltoo_small;
51	I0 = R1;			/* s2 */
52	R1 = R1 | R0;		/* OR addresses together */
53	R1 <<= 30;		/* check bottom two bits */
54	CC =  AZ;			/* AZ set if zero. */
55	IF !CC JUMP .Lbytes ;	/* Jump if addrs not aligned. */
56
57	P1 = P2 >> 2;		/* count = n/4 */
58	R3 =  3;
59	R2 = R2 & R3;		/* remainder */
60	P2 = R2;			/* set remainder */
61
62	LSETUP (.Lquad_loop_s, .Lquad_loop_e) LC0=P1;
63.Lquad_loop_s:
64#ifdef ANOMALY_05000202
65	R0 = [P0++];
66	R1 = [I0++];
67#else
68	MNOP || R0 = [P0++] || R1 = [I0++];
69#endif
70	CC = R0 == R1;
71	IF !CC JUMP .Lquad_different;
72.Lquad_loop_e:
73	NOP;
74
75	P3 = I0;			/* s2 */
76.Ltoo_small:
77	CC = P2 == 0;		/* Check zero count*/
78	IF CC JUMP .Lfinished;	/* very unlikely*/
79
80.Lbytes:
81	LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2;
82.Lbyte_loop_s:
83	R1 = B[P3++](Z);	/* *s2 */
84	R0 = B[P0++](Z);	/* *s1 */
85	CC = R0 == R1;
86	IF !CC JUMP .Ldifferent;
87.Lbyte_loop_e:
88	NOP;
89
90.Ldifferent:
91	R0 = R0 - R1;
92	P3 = I1;
93	RTS;
94
95.Lquad_different:
96	/* We've read two quads which don't match.
97	 * Can't just compare them, because we're
98	 * a little-endian machine, so the MSBs of
99	 * the regs occur at later addresses in the
100	 * string.
101	 * Arrange to re-read those two quads again,
102	 * byte-by-byte.
103	 */
104	P0 += -4;		/* back up to the start of the */
105	P3 = I0;		/* quads, and increase the*/
106	P2 += 4;		/* remainder count*/
107	P3 += -4;
108	JUMP .Lbytes;
109
110.Lfinished:
111	R0 = 0;
112	P3 = I1;
113	RTS;
114
115ENDPROC(_memcmp)
116