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git.ipfire.org Git - thirdparty/u-boot.git/blob - fs/jffs2/mini_inflate.c
1 // SPDX-License-Identifier: GPL-2.0+
2 /*-------------------------------------------------------------------------
3 * Filename: mini_inflate.c
4 * Version: $Id: mini_inflate.c,v 1.3 2002/01/24 22:58:42 rfeany Exp $
5 * Copyright: Copyright (C) 2001, Russ Dill
6 * Author: Russ Dill <Russ.Dill@asu.edu>
7 * Description: Mini inflate implementation (RFC 1951)
8 *-----------------------------------------------------------------------*/
11 #include <jffs2/mini_inflate.h>
13 /* The order that the code lengths in section 3.2.7 are in */
14 static unsigned char huffman_order
[] = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5,
15 11, 4, 12, 3, 13, 2, 14, 1, 15};
17 static inline void cramfs_memset(int *s
, const int c
, size n
)
20 for (;n
> 0; n
--) s
[n
] = c
;
24 /* associate a stream with a block of data and reset the stream */
25 static void init_stream(struct bitstream
*stream
, unsigned char *data
,
26 void *(*inflate_memcpy
)(void *, const void *, size
))
28 stream
->error
= NO_ERROR
;
29 stream
->memcpy
= inflate_memcpy
;
32 stream
->bit
= 0; /* The first bit of the stream is the lsb of the
35 /* really sorry about all this initialization, think of a better way,
36 * let me know and it will get cleaned up */
37 stream
->codes
.bits
= 8;
38 stream
->codes
.num_symbols
= 19;
39 stream
->codes
.lengths
= stream
->code_lengths
;
40 stream
->codes
.symbols
= stream
->code_symbols
;
41 stream
->codes
.count
= stream
->code_count
;
42 stream
->codes
.first
= stream
->code_first
;
43 stream
->codes
.pos
= stream
->code_pos
;
45 stream
->lengths
.bits
= 16;
46 stream
->lengths
.num_symbols
= 288;
47 stream
->lengths
.lengths
= stream
->length_lengths
;
48 stream
->lengths
.symbols
= stream
->length_symbols
;
49 stream
->lengths
.count
= stream
->length_count
;
50 stream
->lengths
.first
= stream
->length_first
;
51 stream
->lengths
.pos
= stream
->length_pos
;
53 stream
->distance
.bits
= 16;
54 stream
->distance
.num_symbols
= 32;
55 stream
->distance
.lengths
= stream
->distance_lengths
;
56 stream
->distance
.symbols
= stream
->distance_symbols
;
57 stream
->distance
.count
= stream
->distance_count
;
58 stream
->distance
.first
= stream
->distance_first
;
59 stream
->distance
.pos
= stream
->distance_pos
;
63 /* pull 'bits' bits out of the stream. The last bit pulled it returned as the
64 * msb. (section 3.1.1)
66 static inline unsigned long pull_bits(struct bitstream
*stream
,
67 const unsigned int bits
)
73 for (i
= 0; i
< bits
; i
++) {
74 ret
+= ((*(stream
->data
) >> stream
->bit
) & 1) << i
;
76 /* if, before incrementing, we are on bit 7,
77 * go to the lsb of the next byte */
78 if (stream
->bit
++ == 7) {
86 static inline int pull_bit(struct bitstream
*stream
)
88 int ret
= ((*(stream
->data
) >> stream
->bit
) & 1);
89 if (stream
->bit
++ == 7) {
96 /* discard bits up to the next whole byte */
97 static void discard_bits(struct bitstream
*stream
)
99 if (stream
->bit
!= 0) {
105 /* No decompression, the data is all literals (section 3.2.4) */
106 static void decompress_none(struct bitstream
*stream
, unsigned char *dest
)
110 discard_bits(stream
);
111 length
= *(stream
->data
++);
112 length
+= *(stream
->data
++) << 8;
113 pull_bits(stream
, 16); /* throw away the inverse of the size */
115 stream
->decoded
+= length
;
116 stream
->memcpy(dest
, stream
->data
, length
);
117 stream
->data
+= length
;
120 /* Read in a symbol from the stream (section 3.2.2) */
121 static int read_symbol(struct bitstream
*stream
, struct huffman_set
*set
)
125 while (!(set
->count
[bits
] && code
< set
->first
[bits
] +
127 code
= (code
<< 1) + pull_bit(stream
);
128 if (++bits
> set
->bits
) {
129 /* error decoding (corrupted data?) */
130 stream
->error
= CODE_NOT_FOUND
;
134 return set
->symbols
[set
->pos
[bits
] + code
- set
->first
[bits
]];
137 /* decompress a stream of data encoded with the passed length and distance
139 static void decompress_huffman(struct bitstream
*stream
, unsigned char *dest
)
141 struct huffman_set
*lengths
= &(stream
->lengths
);
142 struct huffman_set
*distance
= &(stream
->distance
);
144 int symbol
, length
, dist
, i
;
147 if ((symbol
= read_symbol(stream
, lengths
)) < 0) return;
149 *(dest
++) = symbol
; /* symbol is a literal */
151 } else if (symbol
> 256) {
152 /* Determine the length of the repitition
154 if (symbol
< 265) length
= symbol
- 254;
155 else if (symbol
== 285) length
= 258;
157 length
= pull_bits(stream
, (symbol
- 261) >> 2);
158 length
+= (4 << ((symbol
- 261) >> 2)) + 3;
159 length
+= ((symbol
- 1) % 4) <<
160 ((symbol
- 261) >> 2);
163 /* Determine how far back to go */
164 if ((symbol
= read_symbol(stream
, distance
)) < 0)
166 if (symbol
< 4) dist
= symbol
+ 1;
168 dist
= pull_bits(stream
, (symbol
- 2) >> 1);
169 dist
+= (2 << ((symbol
- 2) >> 1)) + 1;
170 dist
+= (symbol
% 2) << ((symbol
- 2) >> 1);
172 stream
->decoded
+= length
;
173 for (i
= 0; i
< length
; i
++) {
178 } while (symbol
!= 256); /* 256 is the end of the data block */
181 /* Fill the lookup tables (section 3.2.2) */
182 static void fill_code_tables(struct huffman_set
*set
)
184 int code
= 0, i
, length
;
186 /* fill in the first code of each bit length, and the pos pointer */
188 for (i
= 1; i
< set
->bits
; i
++) {
189 code
= (code
+ set
->count
[i
- 1]) << 1;
190 set
->first
[i
] = code
;
191 set
->pos
[i
] = set
->pos
[i
- 1] + set
->count
[i
- 1];
194 /* Fill in the table of symbols in order of their huffman code */
195 for (i
= 0; i
< set
->num_symbols
; i
++) {
196 if ((length
= set
->lengths
[i
]))
197 set
->symbols
[set
->pos
[length
]++] = i
;
200 /* reset the pos pointer */
201 for (i
= 1; i
< set
->bits
; i
++) set
->pos
[i
] -= set
->count
[i
];
204 static void init_code_tables(struct huffman_set
*set
)
206 cramfs_memset(set
->lengths
, 0, set
->num_symbols
);
207 cramfs_memset(set
->count
, 0, set
->bits
);
208 cramfs_memset(set
->first
, 0, set
->bits
);
211 /* read in the huffman codes for dynamic decoding (section 3.2.7) */
212 static void decompress_dynamic(struct bitstream
*stream
, unsigned char *dest
)
214 /* I tried my best to minimize the memory footprint here, while still
215 * keeping up performance. I really dislike the _lengths[] tables, but
216 * I see no way of eliminating them without a sizable performance
217 * impact. The first struct table keeps track of stats on each bit
218 * length. The _length table keeps a record of the bit length of each
219 * symbol. The _symbols table is for looking up symbols by the huffman
220 * code (the pos element points to the first place in the symbol table
221 * where that bit length occurs). I also hate the initization of these
222 * structs, if someone knows how to compact these, lemme know. */
224 struct huffman_set
*codes
= &(stream
->codes
);
225 struct huffman_set
*lengths
= &(stream
->lengths
);
226 struct huffman_set
*distance
= &(stream
->distance
);
228 int hlit
= pull_bits(stream
, 5) + 257;
229 int hdist
= pull_bits(stream
, 5) + 1;
230 int hclen
= pull_bits(stream
, 4) + 4;
231 int length
, curr_code
, symbol
, i
, last_code
;
235 init_code_tables(codes
);
236 init_code_tables(lengths
);
237 init_code_tables(distance
);
239 /* fill in the count of each bit length' as well as the lengths
241 for (i
= 0; i
< hclen
; i
++) {
242 length
= pull_bits(stream
, 3);
243 codes
->lengths
[huffman_order
[i
]] = length
;
244 if (length
) codes
->count
[length
]++;
247 fill_code_tables(codes
);
249 /* Do the same for the length codes, being carefull of wrap through
250 * to the distance table */
252 while (curr_code
< hlit
) {
253 if ((symbol
= read_symbol(stream
, codes
)) < 0) return;
257 } else if (symbol
< 16) { /* Literal length */
258 lengths
->lengths
[curr_code
] = last_code
= symbol
;
259 lengths
->count
[symbol
]++;
261 } else if (symbol
== 16) { /* repeat the last symbol 3 - 6
263 length
= 3 + pull_bits(stream
, 2);
264 for (;length
; length
--, curr_code
++)
265 if (curr_code
< hlit
) {
266 lengths
->lengths
[curr_code
] =
268 lengths
->count
[last_code
]++;
269 } else { /* wrap to the distance table */
270 distance
->lengths
[curr_code
- hlit
] =
272 distance
->count
[last_code
]++;
274 } else if (symbol
== 17) { /* repeat a bit length 0 */
275 curr_code
+= 3 + pull_bits(stream
, 3);
277 } else { /* same, but more times */
278 curr_code
+= 11 + pull_bits(stream
, 7);
282 fill_code_tables(lengths
);
284 /* Fill the distance table, don't need to worry about wrapthrough
287 while (curr_code
< hdist
) {
288 if ((symbol
= read_symbol(stream
, codes
)) < 0) return;
292 } else if (symbol
< 16) {
293 distance
->lengths
[curr_code
] = last_code
= symbol
;
294 distance
->count
[symbol
]++;
296 } else if (symbol
== 16) {
297 length
= 3 + pull_bits(stream
, 2);
298 for (;length
; length
--, curr_code
++) {
299 distance
->lengths
[curr_code
] =
301 distance
->count
[last_code
]++;
303 } else if (symbol
== 17) {
304 curr_code
+= 3 + pull_bits(stream
, 3);
307 curr_code
+= 11 + pull_bits(stream
, 7);
311 fill_code_tables(distance
);
313 decompress_huffman(stream
, dest
);
316 /* fill in the length and distance huffman codes for fixed encoding
318 static void decompress_fixed(struct bitstream
*stream
, unsigned char *dest
)
320 /* let gcc fill in the initial values */
321 struct huffman_set
*lengths
= &(stream
->lengths
);
322 struct huffman_set
*distance
= &(stream
->distance
);
324 cramfs_memset(lengths
->count
, 0, 16);
325 cramfs_memset(lengths
->first
, 0, 16);
326 cramfs_memset(lengths
->lengths
, 8, 144);
327 cramfs_memset(lengths
->lengths
+ 144, 9, 112);
328 cramfs_memset(lengths
->lengths
+ 256, 7, 24);
329 cramfs_memset(lengths
->lengths
+ 280, 8, 8);
330 lengths
->count
[7] = 24;
331 lengths
->count
[8] = 152;
332 lengths
->count
[9] = 112;
334 cramfs_memset(distance
->count
, 0, 16);
335 cramfs_memset(distance
->first
, 0, 16);
336 cramfs_memset(distance
->lengths
, 5, 32);
337 distance
->count
[5] = 32;
340 fill_code_tables(lengths
);
341 fill_code_tables(distance
);
344 decompress_huffman(stream
, dest
);
347 /* returns the number of bytes decoded, < 0 if there was an error. Note that
348 * this function assumes that the block starts on a byte boundry
349 * (non-compliant, but I don't see where this would happen). section 3.2.3 */
350 long decompress_block(unsigned char *dest
, unsigned char *source
,
351 void *(*inflate_memcpy
)(void *, const void *, size
))
354 struct bitstream stream
;
356 init_stream(&stream
, source
, inflate_memcpy
);
358 bfinal
= pull_bit(&stream
);
359 btype
= pull_bits(&stream
, 2);
360 if (btype
== NO_COMP
) decompress_none(&stream
, dest
+ stream
.decoded
);
361 else if (btype
== DYNAMIC_COMP
)
362 decompress_dynamic(&stream
, dest
+ stream
.decoded
);
363 else if (btype
== FIXED_COMP
) decompress_fixed(&stream
, dest
+ stream
.decoded
);
364 else stream
.error
= COMP_UNKNOWN
;
365 } while (!bfinal
&& !stream
.error
);
368 putstr("decompress_block start\r\n");
369 putLabeledWord("stream.error = ",stream
.error
);
370 putLabeledWord("stream.decoded = ",stream
.decoded
);
371 putLabeledWord("dest = ",dest
);
372 putstr("decompress_block end\r\n");
374 return stream
.error
? -stream
.error
: stream
.decoded
;