1 ///////////////////////////////////////////////////////////////////////////
2 //
3 // Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
4 // Digital Ltd. LLC
5 //
6 // All rights reserved.
7 //
8 // Redistribution and use in source and binary forms, with or without
9 // modification, are permitted provided that the following conditions are
10 // met:
11 // * Redistributions of source code must retain the above copyright
12 // notice, this list of conditions and the following disclaimer.
13 // * Redistributions in binary form must reproduce the above
14 // copyright notice, this list of conditions and the following disclaimer
15 // in the documentation and/or other materials provided with the
16 // distribution.
17 // * Neither the name of Industrial Light & Magic nor the names of
18 // its contributors may be used to endorse or promote products derived
19 // from this software without specific prior written permission.
20 //
21 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 //
33 ///////////////////////////////////////////////////////////////////////////
34
35 #include <string.h>
36 #include "ImfRle.h"
37 #include "ImfNamespace.h"
38
39 OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_ENTER
40
41 namespace {
42
43 const int MIN_RUN_LENGTH = 3;
44 const int MAX_RUN_LENGTH = 127;
45
46 }
47
48 //
49 // Compress an array of bytes, using run-length encoding,
50 // and return the length of the compressed data.
51 //
52
53 int
rleCompress(int inLength,const char in[],signed char out[])54 rleCompress (int inLength, const char in[], signed char out[])
55 {
56 const char *inEnd = in + inLength;
57 const char *runStart = in;
58 const char *runEnd = in + 1;
59 signed char *outWrite = out;
60
61 while (runStart < inEnd)
62 {
63 while (runEnd < inEnd &&
64 *runStart == *runEnd &&
65 runEnd - runStart - 1 < MAX_RUN_LENGTH)
66 {
67 ++runEnd;
68 }
69
70 if (runEnd - runStart >= MIN_RUN_LENGTH)
71 {
72 //
73 // Compressable run
74 //
75
76 *outWrite++ = (runEnd - runStart) - 1;
77 *outWrite++ = *(signed char *) runStart;
78 runStart = runEnd;
79 }
80 else
81 {
82 //
83 // Uncompressable run
84 //
85
86 while (runEnd < inEnd &&
87 ((runEnd + 1 >= inEnd ||
88 *runEnd != *(runEnd + 1)) ||
89 (runEnd + 2 >= inEnd ||
90 *(runEnd + 1) != *(runEnd + 2))) &&
91 runEnd - runStart < MAX_RUN_LENGTH)
92 {
93 ++runEnd;
94 }
95
96 *outWrite++ = runStart - runEnd;
97
98 while (runStart < runEnd)
99 {
100 *outWrite++ = *(signed char *) (runStart++);
101 }
102 }
103
104 ++runEnd;
105 }
106
107 return outWrite - out;
108 }
109
110
111 //
112 // Uncompress an array of bytes compressed with rleCompress().
113 // Returns the length of the oncompressed data, or 0 if the
114 // length of the uncompressed data would be more than maxLength.
115 //
116
117 int
rleUncompress(int inLength,int maxLength,const signed char in[],char out[])118 rleUncompress (int inLength, int maxLength, const signed char in[], char out[])
119 {
120 char *outStart = out;
121
122 while (inLength > 0)
123 {
124 if (*in < 0)
125 {
126 int count = -((int)*in++);
127 inLength -= count + 1;
128
129 if (0 > (maxLength -= count))
130 return 0;
131
132 memcpy(out, in, count);
133 out += count;
134 in += count;
135 }
136 else
137 {
138 int count = *in++;
139 inLength -= 2;
140
141 if (0 > (maxLength -= count + 1))
142 return 0;
143
144 memset(out, *(char*)in, count+1);
145 out += count+1;
146
147 in++;
148 }
149 }
150
151 return out - outStart;
152 }
153
154
155
156
157 OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_EXIT
158