author | jiefu |
Fri, 15 Nov 2019 20:39:26 +0800 | |
changeset 59110 | 8c4c358272a9 |
parent 47216 | 71c04702a3d5 |
permissions | -rw-r--r-- |
2 | 1 |
/* |
2 |
* reserved comment block |
|
3 |
* DO NOT REMOVE OR ALTER! |
|
4 |
*/ |
|
5 |
/* |
|
6 |
* jdhuff.c |
|
7 |
* |
|
8 |
* Copyright (C) 1991-1997, Thomas G. Lane. |
|
9 |
* This file is part of the Independent JPEG Group's software. |
|
10 |
* For conditions of distribution and use, see the accompanying README file. |
|
11 |
* |
|
12 |
* This file contains Huffman entropy decoding routines. |
|
13 |
* |
|
14 |
* Much of the complexity here has to do with supporting input suspension. |
|
15 |
* If the data source module demands suspension, we want to be able to back |
|
16 |
* up to the start of the current MCU. To do this, we copy state variables |
|
17 |
* into local working storage, and update them back to the permanent |
|
18 |
* storage only upon successful completion of an MCU. |
|
19 |
*/ |
|
20 |
||
21 |
#define JPEG_INTERNALS |
|
22 |
#include "jinclude.h" |
|
23 |
#include "jpeglib.h" |
|
24 |
#include "jdhuff.h" /* Declarations shared with jdphuff.c */ |
|
25 |
||
26 |
||
27 |
/* |
|
28 |
* Expanded entropy decoder object for Huffman decoding. |
|
29 |
* |
|
30 |
* The savable_state subrecord contains fields that change within an MCU, |
|
31 |
* but must not be updated permanently until we complete the MCU. |
|
32 |
*/ |
|
33 |
||
34 |
typedef struct { |
|
35 |
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |
|
36 |
} savable_state; |
|
37 |
||
38 |
/* This macro is to work around compilers with missing or broken |
|
39 |
* structure assignment. You'll need to fix this code if you have |
|
40 |
* such a compiler and you change MAX_COMPS_IN_SCAN. |
|
41 |
*/ |
|
42 |
||
43 |
#ifndef NO_STRUCT_ASSIGN |
|
44 |
#define ASSIGN_STATE(dest,src) ((dest) = (src)) |
|
45 |
#else |
|
46 |
#if MAX_COMPS_IN_SCAN == 4 |
|
47 |
#define ASSIGN_STATE(dest,src) \ |
|
48 |
((dest).last_dc_val[0] = (src).last_dc_val[0], \ |
|
49 |
(dest).last_dc_val[1] = (src).last_dc_val[1], \ |
|
50 |
(dest).last_dc_val[2] = (src).last_dc_val[2], \ |
|
51 |
(dest).last_dc_val[3] = (src).last_dc_val[3]) |
|
52 |
#endif |
|
53 |
#endif |
|
54 |
||
55 |
||
56 |
typedef struct { |
|
57 |
struct jpeg_entropy_decoder pub; /* public fields */ |
|
58 |
||
59 |
/* These fields are loaded into local variables at start of each MCU. |
|
60 |
* In case of suspension, we exit WITHOUT updating them. |
|
61 |
*/ |
|
62 |
bitread_perm_state bitstate; /* Bit buffer at start of MCU */ |
|
63 |
savable_state saved; /* Other state at start of MCU */ |
|
64 |
||
65 |
/* These fields are NOT loaded into local working state. */ |
|
66 |
unsigned int restarts_to_go; /* MCUs left in this restart interval */ |
|
67 |
||
68 |
/* Pointers to derived tables (these workspaces have image lifespan) */ |
|
69 |
d_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS]; |
|
70 |
d_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS]; |
|
71 |
||
72 |
/* Precalculated info set up by start_pass for use in decode_mcu: */ |
|
73 |
||
74 |
/* Pointers to derived tables to be used for each block within an MCU */ |
|
75 |
d_derived_tbl * dc_cur_tbls[D_MAX_BLOCKS_IN_MCU]; |
|
76 |
d_derived_tbl * ac_cur_tbls[D_MAX_BLOCKS_IN_MCU]; |
|
77 |
/* Whether we care about the DC and AC coefficient values for each block */ |
|
78 |
boolean dc_needed[D_MAX_BLOCKS_IN_MCU]; |
|
79 |
boolean ac_needed[D_MAX_BLOCKS_IN_MCU]; |
|
80 |
} huff_entropy_decoder; |
|
81 |
||
82 |
typedef huff_entropy_decoder * huff_entropy_ptr; |
|
83 |
||
84 |
||
85 |
/* |
|
86 |
* Initialize for a Huffman-compressed scan. |
|
87 |
*/ |
|
88 |
||
89 |
METHODDEF(void) |
|
90 |
start_pass_huff_decoder (j_decompress_ptr cinfo) |
|
91 |
{ |
|
92 |
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
|
93 |
int ci, blkn, dctbl, actbl; |
|
94 |
jpeg_component_info * compptr; |
|
95 |
||
96 |
/* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG. |
|
97 |
* This ought to be an error condition, but we make it a warning because |
|
98 |
* there are some baseline files out there with all zeroes in these bytes. |
|
99 |
*/ |
|
100 |
if (cinfo->Ss != 0 || cinfo->Se != DCTSIZE2-1 || |
|
101 |
cinfo->Ah != 0 || cinfo->Al != 0) |
|
102 |
WARNMS(cinfo, JWRN_NOT_SEQUENTIAL); |
|
103 |
||
104 |
for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
|
105 |
compptr = cinfo->cur_comp_info[ci]; |
|
106 |
dctbl = compptr->dc_tbl_no; |
|
107 |
actbl = compptr->ac_tbl_no; |
|
108 |
/* Compute derived values for Huffman tables */ |
|
109 |
/* We may do this more than once for a table, but it's not expensive */ |
|
110 |
jpeg_make_d_derived_tbl(cinfo, TRUE, dctbl, |
|
111 |
& entropy->dc_derived_tbls[dctbl]); |
|
112 |
jpeg_make_d_derived_tbl(cinfo, FALSE, actbl, |
|
113 |
& entropy->ac_derived_tbls[actbl]); |
|
114 |
/* Initialize DC predictions to 0 */ |
|
115 |
entropy->saved.last_dc_val[ci] = 0; |
|
116 |
} |
|
117 |
||
118 |
/* Precalculate decoding info for each block in an MCU of this scan */ |
|
119 |
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
|
120 |
ci = cinfo->MCU_membership[blkn]; |
|
121 |
compptr = cinfo->cur_comp_info[ci]; |
|
122 |
/* Precalculate which table to use for each block */ |
|
123 |
entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no]; |
|
124 |
entropy->ac_cur_tbls[blkn] = entropy->ac_derived_tbls[compptr->ac_tbl_no]; |
|
125 |
/* Decide whether we really care about the coefficient values */ |
|
126 |
if (compptr->component_needed) { |
|
127 |
entropy->dc_needed[blkn] = TRUE; |
|
128 |
/* we don't need the ACs if producing a 1/8th-size image */ |
|
129 |
entropy->ac_needed[blkn] = (compptr->DCT_scaled_size > 1); |
|
130 |
} else { |
|
131 |
entropy->dc_needed[blkn] = entropy->ac_needed[blkn] = FALSE; |
|
132 |
} |
|
133 |
} |
|
134 |
||
135 |
/* Initialize bitread state variables */ |
|
136 |
entropy->bitstate.bits_left = 0; |
|
137 |
entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ |
|
138 |
entropy->pub.insufficient_data = FALSE; |
|
139 |
||
140 |
/* Initialize restart counter */ |
|
141 |
entropy->restarts_to_go = cinfo->restart_interval; |
|
142 |
} |
|
143 |
||
144 |
||
145 |
/* |
|
146 |
* Compute the derived values for a Huffman table. |
|
147 |
* This routine also performs some validation checks on the table. |
|
148 |
* |
|
149 |
* Note this is also used by jdphuff.c. |
|
150 |
*/ |
|
151 |
||
152 |
GLOBAL(void) |
|
153 |
jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, boolean isDC, int tblno, |
|
154 |
d_derived_tbl ** pdtbl) |
|
155 |
{ |
|
156 |
JHUFF_TBL *htbl; |
|
157 |
d_derived_tbl *dtbl; |
|
158 |
int p, i, l, si, numsymbols; |
|
159 |
int lookbits, ctr; |
|
160 |
char huffsize[257]; |
|
161 |
unsigned int huffcode[257]; |
|
162 |
unsigned int code; |
|
163 |
||
164 |
/* Note that huffsize[] and huffcode[] are filled in code-length order, |
|
165 |
* paralleling the order of the symbols themselves in htbl->huffval[]. |
|
166 |
*/ |
|
167 |
||
168 |
/* Find the input Huffman table */ |
|
169 |
if (tblno < 0 || tblno >= NUM_HUFF_TBLS) |
|
170 |
ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); |
|
171 |
htbl = |
|
172 |
isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno]; |
|
173 |
if (htbl == NULL) |
|
174 |
ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); |
|
175 |
||
176 |
/* Allocate a workspace if we haven't already done so. */ |
|
177 |
if (*pdtbl == NULL) |
|
178 |
*pdtbl = (d_derived_tbl *) |
|
179 |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
|
180 |
SIZEOF(d_derived_tbl)); |
|
181 |
dtbl = *pdtbl; |
|
182 |
dtbl->pub = htbl; /* fill in back link */ |
|
183 |
||
184 |
/* Figure C.1: make table of Huffman code length for each symbol */ |
|
185 |
||
186 |
p = 0; |
|
187 |
for (l = 1; l <= 16; l++) { |
|
188 |
i = (int) htbl->bits[l]; |
|
189 |
if (i < 0 || p + i > 256) /* protect against table overrun */ |
|
190 |
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
|
191 |
while (i--) |
|
192 |
huffsize[p++] = (char) l; |
|
193 |
} |
|
194 |
huffsize[p] = 0; |
|
195 |
numsymbols = p; |
|
196 |
||
197 |
/* Figure C.2: generate the codes themselves */ |
|
198 |
/* We also validate that the counts represent a legal Huffman code tree. */ |
|
199 |
||
200 |
code = 0; |
|
201 |
si = huffsize[0]; |
|
202 |
p = 0; |
|
203 |
while (huffsize[p]) { |
|
204 |
while (((int) huffsize[p]) == si) { |
|
205 |
huffcode[p++] = code; |
|
206 |
code++; |
|
207 |
} |
|
208 |
/* code is now 1 more than the last code used for codelength si; but |
|
209 |
* it must still fit in si bits, since no code is allowed to be all ones. |
|
210 |
*/ |
|
211 |
if (((INT32) code) >= (((INT32) 1) << si)) |
|
212 |
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
|
213 |
code <<= 1; |
|
214 |
si++; |
|
215 |
} |
|
216 |
||
217 |
/* Figure F.15: generate decoding tables for bit-sequential decoding */ |
|
218 |
||
219 |
p = 0; |
|
220 |
for (l = 1; l <= 16; l++) { |
|
221 |
if (htbl->bits[l]) { |
|
222 |
/* valoffset[l] = huffval[] index of 1st symbol of code length l, |
|
223 |
* minus the minimum code of length l |
|
224 |
*/ |
|
225 |
dtbl->valoffset[l] = (INT32) p - (INT32) huffcode[p]; |
|
226 |
p += htbl->bits[l]; |
|
227 |
dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */ |
|
228 |
} else { |
|
229 |
dtbl->maxcode[l] = -1; /* -1 if no codes of this length */ |
|
230 |
} |
|
231 |
} |
|
232 |
dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */ |
|
233 |
||
234 |
/* Compute lookahead tables to speed up decoding. |
|
235 |
* First we set all the table entries to 0, indicating "too long"; |
|
236 |
* then we iterate through the Huffman codes that are short enough and |
|
237 |
* fill in all the entries that correspond to bit sequences starting |
|
238 |
* with that code. |
|
239 |
*/ |
|
240 |
||
241 |
MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits)); |
|
242 |
||
243 |
p = 0; |
|
244 |
for (l = 1; l <= HUFF_LOOKAHEAD; l++) { |
|
245 |
for (i = 1; i <= (int) htbl->bits[l]; i++, p++) { |
|
246 |
/* l = current code's length, p = its index in huffcode[] & huffval[]. */ |
|
247 |
/* Generate left-justified code followed by all possible bit sequences */ |
|
248 |
lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l); |
|
249 |
for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) { |
|
250 |
dtbl->look_nbits[lookbits] = l; |
|
251 |
dtbl->look_sym[lookbits] = htbl->huffval[p]; |
|
252 |
lookbits++; |
|
253 |
} |
|
254 |
} |
|
255 |
} |
|
256 |
||
257 |
/* Validate symbols as being reasonable. |
|
258 |
* For AC tables, we make no check, but accept all byte values 0..255. |
|
259 |
* For DC tables, we require the symbols to be in range 0..15. |
|
260 |
* (Tighter bounds could be applied depending on the data depth and mode, |
|
261 |
* but this is sufficient to ensure safe decoding.) |
|
262 |
*/ |
|
263 |
if (isDC) { |
|
264 |
for (i = 0; i < numsymbols; i++) { |
|
265 |
int sym = htbl->huffval[i]; |
|
266 |
if (sym < 0 || sym > 15) |
|
267 |
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
|
268 |
} |
|
269 |
} |
|
270 |
} |
|
271 |
||
272 |
||
273 |
/* |
|
274 |
* Out-of-line code for bit fetching (shared with jdphuff.c). |
|
275 |
* See jdhuff.h for info about usage. |
|
276 |
* Note: current values of get_buffer and bits_left are passed as parameters, |
|
277 |
* but are returned in the corresponding fields of the state struct. |
|
278 |
* |
|
279 |
* On most machines MIN_GET_BITS should be 25 to allow the full 32-bit width |
|
280 |
* of get_buffer to be used. (On machines with wider words, an even larger |
|
281 |
* buffer could be used.) However, on some machines 32-bit shifts are |
|
282 |
* quite slow and take time proportional to the number of places shifted. |
|
283 |
* (This is true with most PC compilers, for instance.) In this case it may |
|
284 |
* be a win to set MIN_GET_BITS to the minimum value of 15. This reduces the |
|
285 |
* average shift distance at the cost of more calls to jpeg_fill_bit_buffer. |
|
286 |
*/ |
|
287 |
||
288 |
#ifdef SLOW_SHIFT_32 |
|
289 |
#define MIN_GET_BITS 15 /* minimum allowable value */ |
|
290 |
#else |
|
291 |
#define MIN_GET_BITS (BIT_BUF_SIZE-7) |
|
292 |
#endif |
|
293 |
||
294 |
||
295 |
GLOBAL(boolean) |
|
296 |
jpeg_fill_bit_buffer (bitread_working_state * state, |
|
297 |
register bit_buf_type get_buffer, register int bits_left, |
|
298 |
int nbits) |
|
299 |
/* Load up the bit buffer to a depth of at least nbits */ |
|
300 |
{ |
|
301 |
/* Copy heavily used state fields into locals (hopefully registers) */ |
|
302 |
register const JOCTET * next_input_byte = state->next_input_byte; |
|
303 |
register size_t bytes_in_buffer = state->bytes_in_buffer; |
|
304 |
j_decompress_ptr cinfo = state->cinfo; |
|
305 |
||
306 |
/* Attempt to load at least MIN_GET_BITS bits into get_buffer. */ |
|
307 |
/* (It is assumed that no request will be for more than that many bits.) */ |
|
308 |
/* We fail to do so only if we hit a marker or are forced to suspend. */ |
|
309 |
||
310 |
if (cinfo->unread_marker == 0) { /* cannot advance past a marker */ |
|
311 |
while (bits_left < MIN_GET_BITS) { |
|
312 |
register int c; |
|
313 |
||
314 |
/* Attempt to read a byte */ |
|
315 |
if (bytes_in_buffer == 0) { |
|
316 |
if (! (*cinfo->src->fill_input_buffer) (cinfo)) |
|
317 |
return FALSE; |
|
318 |
next_input_byte = cinfo->src->next_input_byte; |
|
319 |
bytes_in_buffer = cinfo->src->bytes_in_buffer; |
|
320 |
} |
|
321 |
bytes_in_buffer--; |
|
322 |
c = GETJOCTET(*next_input_byte++); |
|
323 |
||
324 |
/* If it's 0xFF, check and discard stuffed zero byte */ |
|
325 |
if (c == 0xFF) { |
|
326 |
/* Loop here to discard any padding FF's on terminating marker, |
|
327 |
* so that we can save a valid unread_marker value. NOTE: we will |
|
328 |
* accept multiple FF's followed by a 0 as meaning a single FF data |
|
329 |
* byte. This data pattern is not valid according to the standard. |
|
330 |
*/ |
|
331 |
do { |
|
332 |
if (bytes_in_buffer == 0) { |
|
333 |
if (! (*cinfo->src->fill_input_buffer) (cinfo)) |
|
334 |
return FALSE; |
|
335 |
next_input_byte = cinfo->src->next_input_byte; |
|
336 |
bytes_in_buffer = cinfo->src->bytes_in_buffer; |
|
337 |
} |
|
338 |
bytes_in_buffer--; |
|
339 |
c = GETJOCTET(*next_input_byte++); |
|
340 |
} while (c == 0xFF); |
|
341 |
||
342 |
if (c == 0) { |
|
343 |
/* Found FF/00, which represents an FF data byte */ |
|
344 |
c = 0xFF; |
|
345 |
} else { |
|
346 |
/* Oops, it's actually a marker indicating end of compressed data. |
|
347 |
* Save the marker code for later use. |
|
348 |
* Fine point: it might appear that we should save the marker into |
|
349 |
* bitread working state, not straight into permanent state. But |
|
350 |
* once we have hit a marker, we cannot need to suspend within the |
|
351 |
* current MCU, because we will read no more bytes from the data |
|
352 |
* source. So it is OK to update permanent state right away. |
|
353 |
*/ |
|
354 |
cinfo->unread_marker = c; |
|
355 |
/* See if we need to insert some fake zero bits. */ |
|
356 |
goto no_more_bytes; |
|
357 |
} |
|
358 |
} |
|
359 |
||
360 |
/* OK, load c into get_buffer */ |
|
361 |
get_buffer = (get_buffer << 8) | c; |
|
362 |
bits_left += 8; |
|
363 |
} /* end while */ |
|
364 |
} else { |
|
365 |
no_more_bytes: |
|
366 |
/* We get here if we've read the marker that terminates the compressed |
|
367 |
* data segment. There should be enough bits in the buffer register |
|
368 |
* to satisfy the request; if so, no problem. |
|
369 |
*/ |
|
370 |
if (nbits > bits_left) { |
|
371 |
/* Uh-oh. Report corrupted data to user and stuff zeroes into |
|
372 |
* the data stream, so that we can produce some kind of image. |
|
373 |
* We use a nonvolatile flag to ensure that only one warning message |
|
374 |
* appears per data segment. |
|
375 |
*/ |
|
376 |
if (! cinfo->entropy->insufficient_data) { |
|
377 |
WARNMS(cinfo, JWRN_HIT_MARKER); |
|
378 |
cinfo->entropy->insufficient_data = TRUE; |
|
379 |
} |
|
380 |
/* Fill the buffer with zero bits */ |
|
381 |
get_buffer <<= MIN_GET_BITS - bits_left; |
|
382 |
bits_left = MIN_GET_BITS; |
|
383 |
} |
|
384 |
} |
|
385 |
||
386 |
/* Unload the local registers */ |
|
387 |
state->next_input_byte = next_input_byte; |
|
388 |
state->bytes_in_buffer = bytes_in_buffer; |
|
389 |
state->get_buffer = get_buffer; |
|
390 |
state->bits_left = bits_left; |
|
391 |
||
392 |
return TRUE; |
|
393 |
} |
|
394 |
||
395 |
||
396 |
/* |
|
397 |
* Out-of-line code for Huffman code decoding. |
|
398 |
* See jdhuff.h for info about usage. |
|
399 |
*/ |
|
400 |
||
401 |
GLOBAL(int) |
|
402 |
jpeg_huff_decode (bitread_working_state * state, |
|
403 |
register bit_buf_type get_buffer, register int bits_left, |
|
404 |
d_derived_tbl * htbl, int min_bits) |
|
405 |
{ |
|
406 |
register int l = min_bits; |
|
407 |
register INT32 code; |
|
408 |
||
409 |
/* HUFF_DECODE has determined that the code is at least min_bits */ |
|
410 |
/* bits long, so fetch that many bits in one swoop. */ |
|
411 |
||
412 |
CHECK_BIT_BUFFER(*state, l, return -1); |
|
413 |
code = GET_BITS(l); |
|
414 |
||
415 |
/* Collect the rest of the Huffman code one bit at a time. */ |
|
416 |
/* This is per Figure F.16 in the JPEG spec. */ |
|
417 |
||
418 |
while (code > htbl->maxcode[l]) { |
|
419 |
code <<= 1; |
|
420 |
CHECK_BIT_BUFFER(*state, 1, return -1); |
|
421 |
code |= GET_BITS(1); |
|
422 |
l++; |
|
423 |
} |
|
424 |
||
425 |
/* Unload the local registers */ |
|
426 |
state->get_buffer = get_buffer; |
|
427 |
state->bits_left = bits_left; |
|
428 |
||
429 |
/* With garbage input we may reach the sentinel value l = 17. */ |
|
430 |
||
431 |
if (l > 16) { |
|
432 |
WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE); |
|
433 |
return 0; /* fake a zero as the safest result */ |
|
434 |
} |
|
435 |
||
436 |
return htbl->pub->huffval[ (int) (code + htbl->valoffset[l]) ]; |
|
437 |
} |
|
438 |
||
439 |
||
440 |
/* |
|
441 |
* Figure F.12: extend sign bit. |
|
442 |
* On some machines, a shift and add will be faster than a table lookup. |
|
443 |
*/ |
|
444 |
||
445 |
#ifdef AVOID_TABLES |
|
446 |
||
447 |
#define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x)) |
|
448 |
||
449 |
#else |
|
450 |
||
451 |
#define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) |
|
452 |
||
453 |
static const int extend_test[16] = /* entry n is 2**(n-1) */ |
|
454 |
{ 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, |
|
455 |
0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; |
|
456 |
||
457 |
static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ |
|
46874
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
458 |
{ 0, |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
459 |
(int)(((unsigned)(~0)<<1) + 1), (int)(((unsigned)(~0)<<2) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
460 |
(int)(((unsigned)(~0)<<3) + 1), (int)(((unsigned)(~0)<<4) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
461 |
(int)(((unsigned)(~0)<<5) + 1), (int)(((unsigned)(~0)<<6) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
462 |
(int)(((unsigned)(~0)<<7) + 1), (int)(((unsigned)(~0)<<8) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
463 |
(int)(((unsigned)(~0)<<9) + 1), (int)(((unsigned)(~0)<<10) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
464 |
(int)(((unsigned)(~0)<<11) + 1), (int)(((unsigned)(~0)<<12) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
465 |
(int)(((unsigned)(~0)<<13) + 1), (int)(((unsigned)(~0)<<14) + 1), |
13b399635568
8182299: Enable disabled clang warnings, build on OSX 10 + Xcode 8
phh
parents:
25859
diff
changeset
|
466 |
(int)(((unsigned)(~0)<<15) + 1) }; |
2 | 467 |
|
468 |
#endif /* AVOID_TABLES */ |
|
469 |
||
470 |
||
471 |
/* |
|
472 |
* Check for a restart marker & resynchronize decoder. |
|
473 |
* Returns FALSE if must suspend. |
|
474 |
*/ |
|
475 |
||
476 |
LOCAL(boolean) |
|
477 |
process_restart (j_decompress_ptr cinfo) |
|
478 |
{ |
|
479 |
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
|
480 |
int ci; |
|
481 |
||
482 |
/* Throw away any unused bits remaining in bit buffer; */ |
|
483 |
/* include any full bytes in next_marker's count of discarded bytes */ |
|
484 |
cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; |
|
485 |
entropy->bitstate.bits_left = 0; |
|
486 |
||
487 |
/* Advance past the RSTn marker */ |
|
488 |
if (! (*cinfo->marker->read_restart_marker) (cinfo)) |
|
489 |
return FALSE; |
|
490 |
||
491 |
/* Re-initialize DC predictions to 0 */ |
|
492 |
for (ci = 0; ci < cinfo->comps_in_scan; ci++) |
|
493 |
entropy->saved.last_dc_val[ci] = 0; |
|
494 |
||
495 |
/* Reset restart counter */ |
|
496 |
entropy->restarts_to_go = cinfo->restart_interval; |
|
497 |
||
498 |
/* Reset out-of-data flag, unless read_restart_marker left us smack up |
|
499 |
* against a marker. In that case we will end up treating the next data |
|
500 |
* segment as empty, and we can avoid producing bogus output pixels by |
|
501 |
* leaving the flag set. |
|
502 |
*/ |
|
503 |
if (cinfo->unread_marker == 0) |
|
504 |
entropy->pub.insufficient_data = FALSE; |
|
505 |
||
506 |
return TRUE; |
|
507 |
} |
|
508 |
||
509 |
||
510 |
/* |
|
511 |
* Decode and return one MCU's worth of Huffman-compressed coefficients. |
|
512 |
* The coefficients are reordered from zigzag order into natural array order, |
|
513 |
* but are not dequantized. |
|
514 |
* |
|
515 |
* The i'th block of the MCU is stored into the block pointed to by |
|
516 |
* MCU_data[i]. WE ASSUME THIS AREA HAS BEEN ZEROED BY THE CALLER. |
|
517 |
* (Wholesale zeroing is usually a little faster than retail...) |
|
518 |
* |
|
519 |
* Returns FALSE if data source requested suspension. In that case no |
|
520 |
* changes have been made to permanent state. (Exception: some output |
|
521 |
* coefficients may already have been assigned. This is harmless for |
|
522 |
* this module, since we'll just re-assign them on the next call.) |
|
523 |
*/ |
|
524 |
||
525 |
METHODDEF(boolean) |
|
526 |
decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) |
|
527 |
{ |
|
528 |
huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
|
529 |
int blkn; |
|
530 |
BITREAD_STATE_VARS; |
|
531 |
savable_state state; |
|
532 |
||
533 |
/* Process restart marker if needed; may have to suspend */ |
|
534 |
if (cinfo->restart_interval) { |
|
535 |
if (entropy->restarts_to_go == 0) |
|
536 |
if (! process_restart(cinfo)) |
|
537 |
return FALSE; |
|
538 |
} |
|
539 |
||
540 |
/* If we've run out of data, just leave the MCU set to zeroes. |
|
541 |
* This way, we return uniform gray for the remainder of the segment. |
|
542 |
*/ |
|
543 |
if (! entropy->pub.insufficient_data) { |
|
544 |
||
545 |
/* Load up working state */ |
|
546 |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); |
|
547 |
ASSIGN_STATE(state, entropy->saved); |
|
548 |
||
549 |
/* Outer loop handles each block in the MCU */ |
|
550 |
||
551 |
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
|
552 |
JBLOCKROW block = MCU_data[blkn]; |
|
553 |
d_derived_tbl * dctbl = entropy->dc_cur_tbls[blkn]; |
|
554 |
d_derived_tbl * actbl = entropy->ac_cur_tbls[blkn]; |
|
555 |
register int s, k, r; |
|
556 |
||
557 |
/* Decode a single block's worth of coefficients */ |
|
558 |
||
559 |
/* Section F.2.2.1: decode the DC coefficient difference */ |
|
560 |
HUFF_DECODE(s, br_state, dctbl, return FALSE, label1); |
|
561 |
if (s) { |
|
562 |
CHECK_BIT_BUFFER(br_state, s, return FALSE); |
|
563 |
r = GET_BITS(s); |
|
564 |
s = HUFF_EXTEND(r, s); |
|
565 |
} |
|
566 |
||
567 |
if (entropy->dc_needed[blkn]) { |
|
568 |
/* Convert DC difference to actual value, update last_dc_val */ |
|
569 |
int ci = cinfo->MCU_membership[blkn]; |
|
570 |
s += state.last_dc_val[ci]; |
|
571 |
state.last_dc_val[ci] = s; |
|
572 |
/* Output the DC coefficient (assumes jpeg_natural_order[0] = 0) */ |
|
573 |
(*block)[0] = (JCOEF) s; |
|
574 |
} |
|
575 |
||
576 |
if (entropy->ac_needed[blkn]) { |
|
577 |
||
578 |
/* Section F.2.2.2: decode the AC coefficients */ |
|
579 |
/* Since zeroes are skipped, output area must be cleared beforehand */ |
|
580 |
for (k = 1; k < DCTSIZE2; k++) { |
|
581 |
HUFF_DECODE(s, br_state, actbl, return FALSE, label2); |
|
582 |
||
583 |
r = s >> 4; |
|
584 |
s &= 15; |
|
585 |
||
586 |
if (s) { |
|
587 |
k += r; |
|
588 |
CHECK_BIT_BUFFER(br_state, s, return FALSE); |
|
589 |
r = GET_BITS(s); |
|
590 |
s = HUFF_EXTEND(r, s); |
|
591 |
/* Output coefficient in natural (dezigzagged) order. |
|
592 |
* Note: the extra entries in jpeg_natural_order[] will save us |
|
593 |
* if k >= DCTSIZE2, which could happen if the data is corrupted. |
|
594 |
*/ |
|
595 |
(*block)[jpeg_natural_order[k]] = (JCOEF) s; |
|
596 |
} else { |
|
597 |
if (r != 15) |
|
598 |
break; |
|
599 |
k += 15; |
|
600 |
} |
|
601 |
} |
|
602 |
||
603 |
} else { |
|
604 |
||
605 |
/* Section F.2.2.2: decode the AC coefficients */ |
|
606 |
/* In this path we just discard the values */ |
|
607 |
for (k = 1; k < DCTSIZE2; k++) { |
|
608 |
HUFF_DECODE(s, br_state, actbl, return FALSE, label3); |
|
609 |
||
610 |
r = s >> 4; |
|
611 |
s &= 15; |
|
612 |
||
613 |
if (s) { |
|
614 |
k += r; |
|
615 |
CHECK_BIT_BUFFER(br_state, s, return FALSE); |
|
616 |
DROP_BITS(s); |
|
617 |
} else { |
|
618 |
if (r != 15) |
|
619 |
break; |
|
620 |
k += 15; |
|
621 |
} |
|
622 |
} |
|
623 |
||
624 |
} |
|
625 |
} |
|
626 |
||
627 |
/* Completed MCU, so update state */ |
|
628 |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); |
|
629 |
ASSIGN_STATE(entropy->saved, state); |
|
630 |
} |
|
631 |
||
632 |
/* Account for restart interval (no-op if not using restarts) */ |
|
633 |
entropy->restarts_to_go--; |
|
634 |
||
635 |
return TRUE; |
|
636 |
} |
|
637 |
||
638 |
||
639 |
/* |
|
640 |
* Module initialization routine for Huffman entropy decoding. |
|
641 |
*/ |
|
642 |
||
643 |
GLOBAL(void) |
|
644 |
jinit_huff_decoder (j_decompress_ptr cinfo) |
|
645 |
{ |
|
646 |
huff_entropy_ptr entropy; |
|
647 |
int i; |
|
648 |
||
649 |
entropy = (huff_entropy_ptr) |
|
650 |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
|
651 |
SIZEOF(huff_entropy_decoder)); |
|
652 |
cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; |
|
653 |
entropy->pub.start_pass = start_pass_huff_decoder; |
|
654 |
entropy->pub.decode_mcu = decode_mcu; |
|
655 |
||
656 |
/* Mark tables unallocated */ |
|
657 |
for (i = 0; i < NUM_HUFF_TBLS; i++) { |
|
658 |
entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL; |
|
659 |
} |
|
660 |
} |