1/*
2 * File: memcmp.S
3 *
4 * Copyright 2004-2007 Analog Devices Inc.
5 * Enter bugs at http://blackfin.uclinux.org/
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, see the file COPYING, or write
19 * to the Free Software Foundation, Inc.,
20 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
21 */
22
23.align 2
24
25/*
26 * C Library function MEMCMP
27 * R0 = First Address
28 * R1 = Second Address
29 * R2 = count
30 * Favours word aligned data.
31 */
32
33.globl _memcmp;
34.type _memcmp, STT_FUNC;
35_memcmp:
36	I1 = P3;
37	P0 = R0;			/* P0 = s1 address */
38	P3 = R1;			/* P3 = s2 Address  */
39	P2 = R2 ;			/* P2 = count */
40	CC = R2 <= 7(IU);
41	IF CC JUMP  .Ltoo_small;
42	I0 = R1;			/* s2 */
43	R1 = R1 | R0;		/* OR addresses together */
44	R1 <<= 30;		/* check bottom two bits */
45	CC =  AZ;			/* AZ set if zero. */
46	IF !CC JUMP  .Lbytes ;	/* Jump if addrs not aligned. */
47
48	P1 = P2 >> 2;		/* count = n/4 */
49	R3 =  3;
50	R2 = R2 & R3;		/* remainder */
51	P2 = R2;			/* set remainder */
52
53	LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1;
54.Lquad_loop_s:
55	NOP;
56	R0 = [P0++];
57	R1 = [I0++];
58	CC = R0 == R1;
59	IF !CC JUMP .Lquad_different;
60.Lquad_loop_e:
61	NOP;
62
63	P3 = I0;			/* s2 */
64.Ltoo_small:
65	CC = P2 == 0;		/* Check zero count*/
66	IF CC JUMP .Lfinished;	/* very unlikely*/
67
68.Lbytes:
69	LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2;
70.Lbyte_loop_s:
71	R1 = B[P3++](Z);	/* *s2 */
72	R0 = B[P0++](Z);	/* *s1 */
73	CC = R0 == R1;
74	IF !CC JUMP .Ldifferent;
75.Lbyte_loop_e:
76	NOP;
77
78.Ldifferent:
79	R0 = R0 - R1;
80	P3 = I1;
81	RTS;
82
83.Lquad_different:
84/* We've read two quads which don't match.
85 * Can't just compare them, because we're
86 * a little-endian machine, so the MSBs of
87 * the regs occur at later addresses in the
88 * string.
89 * Arrange to re-read those two quads again,
90 * byte-by-byte.
91 */
92	P0 += -4;		/* back up to the start of the */
93	P3 = I0;		/* quads, and increase the*/
94	P2 += 4;		/* remainder count*/
95	P3 += -4;
96	JUMP .Lbytes;
97
98.Lfinished:
99	R0 = 0;
100	P3 = I1;
101	RTS;
102
103.size _memcmp, .-_memcmp
104