Root/arch/blackfin/lib/memcmp.S

1/*
2 * Copyright 2004-2009 Analog Devices Inc.
3 *
4 * Licensed under the ADI BSD license or the GPL-2 (or later)
5 */
6
7#include <linux/linkage.h>
8
9/* int memcmp(const void *s1, const void *s2, size_t n);
10 * R0 = First Address (s1)
11 * R1 = Second Address (s2)
12 * R2 = count (n)
13 *
14 * Favours word aligned data.
15 */
16
17.text
18
19.align 2
20
21ENTRY(_memcmp)
22    I1 = P3;
23    P0 = R0; /* P0 = s1 address */
24    P3 = R1; /* P3 = s2 Address */
25    P2 = R2 ; /* P2 = count */
26    CC = R2 <= 7(IU);
27    IF CC JUMP .Ltoo_small;
28    I0 = R1; /* s2 */
29    R1 = R1 | R0; /* OR addresses together */
30    R1 <<= 30; /* check bottom two bits */
31    CC = AZ; /* AZ set if zero. */
32    IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */
33
34    P1 = P2 >> 2; /* count = n/4 */
35    R3 = 3;
36    R2 = R2 & R3; /* remainder */
37    P2 = R2; /* set remainder */
38
39    LSETUP (.Lquad_loop_s, .Lquad_loop_e) LC0=P1;
40.Lquad_loop_s:
41#if ANOMALY_05000202
42    R0 = [P0++];
43    R1 = [I0++];
44#else
45    MNOP || R0 = [P0++] || R1 = [I0++];
46#endif
47    CC = R0 == R1;
48    IF !CC JUMP .Lquad_different;
49.Lquad_loop_e:
50    NOP;
51
52    P3 = I0; /* s2 */
53.Ltoo_small:
54    CC = P2 == 0; /* Check zero count*/
55    IF CC JUMP .Lfinished; /* very unlikely*/
56
57.Lbytes:
58    LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2;
59.Lbyte_loop_s:
60    R1 = B[P3++](Z); /* *s2 */
61    R0 = B[P0++](Z); /* *s1 */
62    CC = R0 == R1;
63    IF !CC JUMP .Ldifferent;
64.Lbyte_loop_e:
65    NOP;
66
67.Ldifferent:
68    R0 = R0 - R1;
69    P3 = I1;
70    RTS;
71
72.Lquad_different:
73    /* We've read two quads which don't match.
74     * Can't just compare them, because we're
75     * a little-endian machine, so the MSBs of
76     * the regs occur at later addresses in the
77     * string.
78     * Arrange to re-read those two quads again,
79     * byte-by-byte.
80     */
81    P0 += -4; /* back up to the start of the */
82    P3 = I0; /* quads, and increase the*/
83    P2 += 4; /* remainder count*/
84    P3 += -4;
85    JUMP .Lbytes;
86
87.Lfinished:
88    R0 = 0;
89    P3 = I1;
90    RTS;
91
92ENDPROC(_memcmp)
93

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