compr_rtime.c (1da177e4c3f41524e886b7f1b8a0c1fc7321cac2) compr_rtime.c (182ec4eee397543101a6db8906ed88727d3f7e53)
1/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright (C) 2001-2003 Red Hat, Inc.
5 *
6 * Created by Arjan van de Ven <arjanv@redhat.com>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.

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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>
1/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
4 * Copyright (C) 2001-2003 Red Hat, Inc.
5 *
6 * Created by Arjan van de Ven <arjanv@redhat.com>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.

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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>
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 void *model)
36{
37 short positions[256];
38 int outpos = 0;
39 int pos=0;
40
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 void *model)
36{
37 short positions[256];
38 int outpos = 0;
39 int pos=0;
40
41 memset(positions,0,sizeof(positions));
42
41 memset(positions,0,sizeof(positions));
42
43 while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
44 int backpos, runlen=0;
45 unsigned char value;
43 while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
44 int backpos, runlen=0;
45 unsigned char value;
46
46
47 value = data_in[pos];
48
49 cpage_out[outpos++] = data_in[pos++];
47 value = data_in[pos];
48
49 cpage_out[outpos++] = data_in[pos++];
50
50
51 backpos = positions[value];
52 positions[value]=pos;
51 backpos = positions[value];
52 positions[value]=pos;
53
53
54 while ((backpos < pos) && (pos < (*sourcelen)) &&
55 (data_in[pos]==data_in[backpos++]) && (runlen<255)) {
56 pos++;
57 runlen++;
58 }
59 cpage_out[outpos++] = runlen;
60 }
61
62 if (outpos >= pos) {
63 /* We failed */
64 return -1;
65 }
54 while ((backpos < pos) && (pos < (*sourcelen)) &&
55 (data_in[pos]==data_in[backpos++]) && (runlen<255)) {
56 pos++;
57 runlen++;
58 }
59 cpage_out[outpos++] = runlen;
60 }
61
62 if (outpos >= pos) {
63 /* We failed */
64 return -1;
65 }
66
66
67 /* Tell the caller how much we managed to compress, and how much space it took */
68 *sourcelen = pos;
69 *dstlen = outpos;
70 return 0;
67 /* Tell the caller how much we managed to compress, and how much space it took */
68 *sourcelen = pos;
69 *dstlen = outpos;
70 return 0;
71}
71}
72
73
74static int jffs2_rtime_decompress(unsigned char *data_in,
75 unsigned char *cpage_out,
76 uint32_t srclen, uint32_t destlen,
77 void *model)
78{
79 short positions[256];
80 int outpos = 0;
81 int pos=0;
72
73
74static int jffs2_rtime_decompress(unsigned char *data_in,
75 unsigned char *cpage_out,
76 uint32_t srclen, uint32_t destlen,
77 void *model)
78{
79 short positions[256];
80 int outpos = 0;
81 int pos=0;
82
83 memset(positions,0,sizeof(positions));
84
82
83 memset(positions,0,sizeof(positions));
84
85 while (outpos<destlen) {
86 unsigned char value;
87 int backoffs;
88 int repeat;
85 while (outpos<destlen) {
86 unsigned char value;
87 int backoffs;
88 int repeat;
89
89
90 value = data_in[pos++];
91 cpage_out[outpos++] = value; /* first the verbatim copied byte */
92 repeat = data_in[pos++];
93 backoffs = positions[value];
90 value = data_in[pos++];
91 cpage_out[outpos++] = value; /* first the verbatim copied byte */
92 repeat = data_in[pos++];
93 backoffs = positions[value];
94
94
95 positions[value]=outpos;
96 if (repeat) {
97 if (backoffs + repeat >= outpos) {
98 while(repeat) {
99 cpage_out[outpos++] = cpage_out[backoffs++];
100 repeat--;
101 }
102 } else {
103 memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
95 positions[value]=outpos;
96 if (repeat) {
97 if (backoffs + repeat >= outpos) {
98 while(repeat) {
99 cpage_out[outpos++] = cpage_out[backoffs++];
100 repeat--;
101 }
102 } else {
103 memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
104 outpos+=repeat;
104 outpos+=repeat;
105 }
106 }
107 }
108 return 0;
105 }
106 }
107 }
108 return 0;
109}
109}
110
111static struct jffs2_compressor jffs2_rtime_comp = {
112 .priority = JFFS2_RTIME_PRIORITY,
113 .name = "rtime",
114 .compr = JFFS2_COMPR_RTIME,
115 .compress = &jffs2_rtime_compress,
116 .decompress = &jffs2_rtime_decompress,
117#ifdef JFFS2_RTIME_DISABLED

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111static struct jffs2_compressor jffs2_rtime_comp = {
112 .priority = JFFS2_RTIME_PRIORITY,
113 .name = "rtime",
114 .compr = JFFS2_COMPR_RTIME,
115 .compress = &jffs2_rtime_compress,
116 .decompress = &jffs2_rtime_decompress,
117#ifdef JFFS2_RTIME_DISABLED

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