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1394f032 BW |
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 | ||
44 | ENTRY(_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 | MNOP || R0 = [P0++] || R1 = [I0++]; | |
65 | CC = R0 == R1; | |
66 | IF !CC JUMP .Lquad_different; | |
67 | .Lquad_loop_e: | |
68 | NOP; | |
69 | ||
70 | P3 = I0; /* s2 */ | |
71 | .Ltoo_small: | |
72 | CC = P2 == 0; /* Check zero count*/ | |
73 | IF CC JUMP .Lfinished; /* very unlikely*/ | |
74 | ||
75 | .Lbytes: | |
76 | LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2; | |
77 | .Lbyte_loop_s: | |
78 | R1 = B[P3++](Z); /* *s2 */ | |
79 | R0 = B[P0++](Z); /* *s1 */ | |
80 | CC = R0 == R1; | |
81 | IF !CC JUMP .Ldifferent; | |
82 | .Lbyte_loop_e: | |
83 | NOP; | |
84 | ||
85 | .Ldifferent: | |
86 | R0 = R0 - R1; | |
87 | P3 = I1; | |
88 | RTS; | |
89 | ||
90 | .Lquad_different: | |
91 | /* We've read two quads which don't match. | |
92 | * Can't just compare them, because we're | |
93 | * a little-endian machine, so the MSBs of | |
94 | * the regs occur at later addresses in the | |
95 | * string. | |
96 | * Arrange to re-read those two quads again, | |
97 | * byte-by-byte. | |
98 | */ | |
99 | P0 += -4; /* back up to the start of the */ | |
100 | P3 = I0; /* quads, and increase the*/ | |
101 | P2 += 4; /* remainder count*/ | |
102 | P3 += -4; | |
103 | JUMP .Lbytes; | |
104 | ||
105 | .Lfinished: | |
106 | R0 = 0; | |
107 | P3 = I1; | |
108 | RTS; | |
109 | ||
51be24c3 | 110 | ENDPROC(_memcmp) |