source: rtems/cpukit/libfs/src/jffs2/src/compr_rtime.c @ 0c0f128

4.11
Last change on this file since 0c0f128 was 0c0f128, checked in by Sebastian Huber <sebastian.huber@…>, on Sep 12, 2013 at 1:57:47 PM

JFFS2: Import from Linux

Import of Journalling Flash File System, Version 2 from Linux 3.11.
This part of the Linux kernel is under a separate license which is
similar to the RTEMS license.

The file "cpukit/libfs/src/jffs2/include/linux/jffs2.h" is a copy of
"linux-3.11/include/uapi/linux/jffs2.h".

The file "LICENSE.JFFS2" is a copy of "linux-3.11/fs/jffs2/LICENCE".

The files

"linux-3.11/fs/jffs2/LICENCE",
"linux-3.11/fs/jffs2/acl.h",
"linux-3.11/fs/jffs2/build.c",
"linux-3.11/fs/jffs2/compr.c",
"linux-3.11/fs/jffs2/compr.h",
"linux-3.11/fs/jffs2/compr_rtime.c",
"linux-3.11/fs/jffs2/compr_rubin.c",
"linux-3.11/fs/jffs2/compr_zlib.c",
"linux-3.11/fs/jffs2/debug.c",
"linux-3.11/fs/jffs2/debug.h",
"linux-3.11/fs/jffs2/erase.c",
"linux-3.11/fs/jffs2/gc.c",
"linux-3.11/fs/jffs2/jffs2_fs_i.h",
"linux-3.11/fs/jffs2/jffs2_fs_sb.h",
"linux-3.11/fs/jffs2/nodelist.c",
"linux-3.11/fs/jffs2/nodelist.h",
"linux-3.11/fs/jffs2/nodemgmt.c",
"linux-3.11/fs/jffs2/read.c",
"linux-3.11/fs/jffs2/readinode.c",
"linux-3.11/fs/jffs2/scan.c",
"linux-3.11/fs/jffs2/summary.h",
"linux-3.11/fs/jffs2/write.c", and
"linux-3.11/fs/jffs2/xattr.h"

are copied to "cpukit/libfs/src/jffs2/src".

  • Property mode set to 100644
File size: 2.8 KB
Line 
1/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright © 2001-2007 Red Hat, Inc.
5 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
6 *
7 * Created by Arjan van de Ven <arjanv@redhat.com>
8 *
9 * For licensing information, see the file 'LICENCE' in this directory.
10 *
11 *
12 *
13 * Very simple lz77-ish encoder.
14 *
15 * Theory of operation: Both encoder and decoder have a list of "last
16 * occurrences" for every possible source-value; after sending the
17 * first source-byte, the second byte indicated the "run" length of
18 * matches
19 *
20 * The algorithm is intended to only send "whole bytes", no bit-messing.
21 *
22 */
23
24#include <linux/kernel.h>
25#include <linux/types.h>
26#include <linux/errno.h>
27#include <linux/string.h>
28#include <linux/jffs2.h>
29#include "compr.h"
30
31/* _compress returns the compressed size, -1 if bigger */
32static int jffs2_rtime_compress(unsigned char *data_in,
33                                unsigned char *cpage_out,
34                                uint32_t *sourcelen, uint32_t *dstlen)
35{
36        short positions[256];
37        int outpos = 0;
38        int pos=0;
39
40        memset(positions,0,sizeof(positions));
41
42        while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
43                int backpos, runlen=0;
44                unsigned char value;
45
46                value = data_in[pos];
47
48                cpage_out[outpos++] = data_in[pos++];
49
50                backpos = positions[value];
51                positions[value]=pos;
52
53                while ((backpos < pos) && (pos < (*sourcelen)) &&
54                       (data_in[pos]==data_in[backpos++]) && (runlen<255)) {
55                        pos++;
56                        runlen++;
57                }
58                cpage_out[outpos++] = runlen;
59        }
60
61        if (outpos >= pos) {
62                /* We failed */
63                return -1;
64        }
65
66        /* Tell the caller how much we managed to compress, and how much space it took */
67        *sourcelen = pos;
68        *dstlen = outpos;
69        return 0;
70}
71
72
73static int jffs2_rtime_decompress(unsigned char *data_in,
74                                  unsigned char *cpage_out,
75                                  uint32_t srclen, uint32_t destlen)
76{
77        short positions[256];
78        int outpos = 0;
79        int pos=0;
80
81        memset(positions,0,sizeof(positions));
82
83        while (outpos<destlen) {
84                unsigned char value;
85                int backoffs;
86                int repeat;
87
88                value = data_in[pos++];
89                cpage_out[outpos++] = value; /* first the verbatim copied byte */
90                repeat = data_in[pos++];
91                backoffs = positions[value];
92
93                positions[value]=outpos;
94                if (repeat) {
95                        if (backoffs + repeat >= outpos) {
96                                while(repeat) {
97                                        cpage_out[outpos++] = cpage_out[backoffs++];
98                                        repeat--;
99                                }
100                        } else {
101                                memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
102                                outpos+=repeat;
103                        }
104                }
105        }
106        return 0;
107}
108
109static struct jffs2_compressor jffs2_rtime_comp = {
110    .priority = JFFS2_RTIME_PRIORITY,
111    .name = "rtime",
112    .compr = JFFS2_COMPR_RTIME,
113    .compress = &jffs2_rtime_compress,
114    .decompress = &jffs2_rtime_decompress,
115#ifdef JFFS2_RTIME_DISABLED
116    .disabled = 1,
117#else
118    .disabled = 0,
119#endif
120};
121
122int jffs2_rtime_init(void)
123{
124    return jffs2_register_compressor(&jffs2_rtime_comp);
125}
126
127void jffs2_rtime_exit(void)
128{
129    jffs2_unregister_compressor(&jffs2_rtime_comp);
130}
Note: See TracBrowser for help on using the repository browser.