1 /* 1 /*
2 * JFFS2 -- Journalling Flash File System, Ver 2 * JFFS2 -- Journalling Flash File System, Version 2.
3 * 3 *
4 * Copyright © 2001-2007 Red Hat, Inc. !! 4 * Copyright (C) 2001 Red Hat, Inc.
5 * Copyright © 2004-2010 David Woodhouse <dwm <<
6 * 5 *
7 * Created by Arjan van de Ven <arjanv@redhat. 6 * Created by Arjan van de Ven <arjanv@redhat.com>
8 * 7 *
9 * For licensing information, see the file 'LI !! 8 * The original JFFS, from which the design for JFFS2 was derived,
>> 9 * was designed and implemented by Axis Communications AB.
10 * 10 *
>> 11 * The contents of this file are subject to the Red Hat eCos Public
>> 12 * License Version 1.1 (the "Licence"); you may not use this file
>> 13 * except in compliance with the Licence. You may obtain a copy of
>> 14 * the Licence at http://www.redhat.com/
>> 15 *
>> 16 * Software distributed under the Licence is distributed on an "AS IS"
>> 17 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
>> 18 * See the Licence for the specific language governing rights and
>> 19 * limitations under the Licence.
>> 20 *
>> 21 * The Original Code is JFFS2 - Journalling Flash File System, version 2
>> 22 *
>> 23 * Alternatively, the contents of this file may be used under the
>> 24 * terms of the GNU General Public License version 2 (the "GPL"), in
>> 25 * which case the provisions of the GPL are applicable instead of the
>> 26 * above. If you wish to allow the use of your version of this file
>> 27 * only under the terms of the GPL and not to allow others to use your
>> 28 * version of this file under the RHEPL, indicate your decision by
>> 29 * deleting the provisions above and replace them with the notice and
>> 30 * other provisions required by the GPL. If you do not delete the
>> 31 * provisions above, a recipient may use your version of this file
>> 32 * under either the RHEPL or the GPL.
>> 33 *
>> 34 * $Id: compr_rtime.c,v 1.5 2001/03/15 15:38:23 dwmw2 Exp $
11 * 35 *
12 * 36 *
13 * Very simple lz77-ish encoder. 37 * Very simple lz77-ish encoder.
14 * 38 *
15 * Theory of operation: Both encoder and decod 39 * Theory of operation: Both encoder and decoder have a list of "last
16 * occurrences" for every possible source-valu !! 40 * occurances" for every possible source-value; after sending the
17 * first source-byte, the second byte indicate 41 * first source-byte, the second byte indicated the "run" length of
18 * matches 42 * matches
19 * 43 *
20 * The algorithm is intended to only send "who 44 * The algorithm is intended to only send "whole bytes", no bit-messing.
21 * 45 *
22 */ 46 */
23 47
24 #include <linux/kernel.h> 48 #include <linux/kernel.h>
25 #include <linux/types.h> 49 #include <linux/types.h>
26 #include <linux/errno.h> 50 #include <linux/errno.h>
27 #include <linux/string.h> !! 51 #include <linux/string.h>
28 #include <linux/jffs2.h> <<
29 #include "compr.h" <<
30 52
31 /* _compress returns the compressed size, -1 i 53 /* _compress returns the compressed size, -1 if bigger */
32 static int jffs2_rtime_compress(unsigned char !! 54 int rtime_compress(unsigned char *data_in, unsigned char *cpage_out,
33 unsigned char !! 55 __u32 *sourcelen, __u32 *dstlen)
34 uint32_t *sour <<
35 { 56 {
36 unsigned short positions[256]; !! 57 int positions[256];
37 int outpos = 0; 58 int outpos = 0;
38 int pos=0; 59 int pos=0;
39 60
40 if (*dstlen <= 3) !! 61 memset(positions,0,sizeof(positions));
41 return -1; !! 62
42 <<
43 memset(positions,0,sizeof(positions)); <<
44 <<
45 while (pos < (*sourcelen) && outpos <= 63 while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
46 int backpos, runlen=0; 64 int backpos, runlen=0;
47 unsigned char value; 65 unsigned char value;
48 !! 66
49 value = data_in[pos]; 67 value = data_in[pos];
50 68
51 cpage_out[outpos++] = data_in[ 69 cpage_out[outpos++] = data_in[pos++];
52 !! 70
53 backpos = positions[value]; 71 backpos = positions[value];
54 positions[value]=pos; 72 positions[value]=pos;
55 !! 73
56 while ((backpos < pos) && (pos 74 while ((backpos < pos) && (pos < (*sourcelen)) &&
57 (data_in[pos]==data_in[ 75 (data_in[pos]==data_in[backpos++]) && (runlen<255)) {
58 pos++; 76 pos++;
59 runlen++; 77 runlen++;
60 } 78 }
61 cpage_out[outpos++] = runlen; 79 cpage_out[outpos++] = runlen;
62 } 80 }
63 81
64 if (outpos >= pos) { 82 if (outpos >= pos) {
65 /* We failed */ 83 /* We failed */
66 return -1; 84 return -1;
67 } 85 }
68 !! 86
69 /* Tell the caller how much we managed 87 /* Tell the caller how much we managed to compress, and how much space it took */
70 *sourcelen = pos; 88 *sourcelen = pos;
71 *dstlen = outpos; 89 *dstlen = outpos;
72 return 0; 90 return 0;
73 } !! 91 }
74 92
75 93
76 static int jffs2_rtime_decompress(unsigned cha !! 94 void rtime_decompress(unsigned char *data_in, unsigned char *cpage_out,
77 unsigned cha !! 95 __u32 srclen, __u32 destlen)
78 uint32_t src <<
79 { 96 {
80 unsigned short positions[256]; !! 97 int positions[256];
81 int outpos = 0; 98 int outpos = 0;
82 int pos=0; 99 int pos=0;
83 !! 100
84 memset(positions,0,sizeof(positions)); !! 101 memset(positions,0,sizeof(positions));
85 !! 102
86 while (outpos<destlen) { 103 while (outpos<destlen) {
87 unsigned char value; 104 unsigned char value;
88 int backoffs; 105 int backoffs;
89 int repeat; 106 int repeat;
90 !! 107
91 value = data_in[pos++]; 108 value = data_in[pos++];
92 cpage_out[outpos++] = value; / 109 cpage_out[outpos++] = value; /* first the verbatim copied byte */
93 repeat = data_in[pos++]; 110 repeat = data_in[pos++];
94 backoffs = positions[value]; 111 backoffs = positions[value];
95 !! 112
96 positions[value]=outpos; 113 positions[value]=outpos;
97 if (repeat) { 114 if (repeat) {
98 if (backoffs + repeat 115 if (backoffs + repeat >= outpos) {
99 while(repeat) 116 while(repeat) {
100 cpage_ 117 cpage_out[outpos++] = cpage_out[backoffs++];
101 repeat 118 repeat--;
102 } 119 }
103 } else { 120 } else {
104 memcpy(&cpage_ 121 memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
105 outpos+=repeat !! 122 outpos+=repeat;
106 } 123 }
107 } 124 }
108 } !! 125 }
109 return 0; !! 126 }
110 } <<
111 <<
112 static struct jffs2_compressor jffs2_rtime_com <<
113 .priority = JFFS2_RTIME_PRIORITY, <<
114 .name = "rtime", <<
115 .compr = JFFS2_COMPR_RTIME, <<
116 .compress = &jffs2_rtime_compress, <<
117 .decompress = &jffs2_rtime_decompress, <<
118 #ifdef JFFS2_RTIME_DISABLED <<
119 .disabled = 1, <<
120 #else <<
121 .disabled = 0, <<
122 #endif <<
123 }; <<
124 127
125 int jffs2_rtime_init(void) <<
126 { <<
127 return jffs2_register_compressor(&jffs2_rt <<
128 } <<
129 128
130 void jffs2_rtime_exit(void) <<
131 { <<
132 jffs2_unregister_compressor(&jffs2_rtime_c <<
133 } <<
134 129
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