1/* memcmp.S
2 * Copyright (C) 2003-2007 Analog Devices Inc., All Rights Reserved.
3 *
4 * This file is subject to the terms and conditions of the GNU Library General
5 * Public License. See the file "COPYING.LIB" in the main directory of this
6 * archive for more details.
7 *
8 * Non-LGPL License also available as part of VisualDSP++
9 * http://www.analog.com/processors/resources/crosscore/visualDspDevSoftware.html
10 */
11
12#include <sysdep.h>
13
14/* int memcmp(const void *s1, const void *s2, size_t n);
15 * R0 = First Address (s1)
16 * R1 = Second Address (s2)
17 * R2 = count (n)
18 *
19 * Favours word aligned data.
20 */
21
22.text
23
24.align 2
25
26.weak _memcmp
27ENTRY(_memcmp)
28	I1 = P3;
29	P0 = R0;			/* P0 = s1 address */
30	P3 = R1;			/* P3 = s2 Address  */
31	P2 = R2 ;			/* P2 = count */
32	CC = R2 <= 7(IU);
33	IF CC JUMP .Ltoo_small;
34	I0 = R1;			/* s2 */
35	R1 = R1 | R0;		/* OR addresses together */
36	R1 <<= 30;		/* check bottom two bits */
37	CC =  AZ;			/* AZ set if zero. */
38	IF !CC JUMP .Lbytes ;	/* Jump if addrs not aligned. */
39
40	P1 = P2 >> 2;		/* count = n/4 */
41	R3 =  3;
42	R2 = R2 & R3;		/* remainder */
43	P2 = R2;			/* set remainder */
44
45	LSETUP (.Lquad_loop_s, .Lquad_loop_e) LC0=P1;
46.Lquad_loop_s:
47#if !defined(__WORKAROUND_AVOID_DAG1)
48	MNOP || R0 = [P0++] || R1 = [I0++];
49#else
50	R0 = [P0++];
51	R1 = [I0++];
52#endif
53	CC = R0 == R1;
54	IF !CC JUMP .Lquad_different;
55.Lquad_loop_e:
56	NOP;
57
58	P3 = I0;			/* s2 */
59.Ltoo_small:
60	CC = P2 == 0;		/* Check zero count*/
61	IF CC JUMP .Lfinished;	/* very unlikely*/
62
63.Lbytes:
64	LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2;
65.Lbyte_loop_s:
66	R1 = B[P3++](Z);	/* *s2 */
67	R0 = B[P0++](Z);	/* *s1 */
68	CC = R0 == R1;
69	IF !CC JUMP .Ldifferent;
70.Lbyte_loop_e:
71	NOP;
72
73.Ldifferent:
74	R0 = R0 - R1;
75	P3 = I1;
76	RTS;
77
78.Lquad_different:
79	/* We've read two quads which don't match.
80	 * Can't just compare them, because we're
81	 * a little-endian machine, so the MSBs of
82	 * the regs occur at later addresses in the
83	 * string.
84	 * Arrange to re-read those two quads again,
85	 * byte-by-byte.
86	 */
87	P0 += -4;		/* back up to the start of the */
88	P3 = I0;		/* quads, and increase the*/
89	P2 += 4;		/* remainder count*/
90	P3 += -4;
91	JUMP .Lbytes;
92
93.Lfinished:
94	R0 = 0;
95	P3 = I1;
96	RTS;
97
98.size _memcmp,.-_memcmp
99
100libc_hidden_def (memcmp)
101
102#ifdef __UCLIBC_SUSV3_LEGACY__
103weak_alias (memcmp,bcmp)
104#endif
105