4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1997, Thomas G. Lane.
6 * Modified 2002-2009 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2009-2011, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README file.
11 * This file contains master control logic for the JPEG decompressor.
12 * These routines are concerned with selecting the modules to be executed
13 * and with determining the number of passes and the work to be done in each
17 #define JPEG_INTERNALS
26 struct jpeg_decomp_master pub
; /* public fields */
28 int pass_number
; /* # of passes completed */
30 boolean using_merged_upsample
; /* TRUE if using merged upsample/cconvert */
32 /* Saved references to initialized quantizer modules,
33 * in case we need to switch modes.
35 struct jpeg_color_quantizer
* quantizer_1pass
;
36 struct jpeg_color_quantizer
* quantizer_2pass
;
39 typedef my_decomp_master
* my_master_ptr
;
43 * Determine whether merged upsample/color conversion should be used.
44 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
48 use_merged_upsample (j_decompress_ptr cinfo
)
50 #ifdef UPSAMPLE_MERGING_SUPPORTED
51 /* Merging is the equivalent of plain box-filter upsampling */
52 if (cinfo
->do_fancy_upsampling
|| cinfo
->CCIR601_sampling
)
54 /* jdmerge.c only supports YCC=>RGB color conversion */
55 if (cinfo
->jpeg_color_space
!= JCS_YCbCr
|| cinfo
->num_components
!= 3 ||
56 (cinfo
->out_color_space
!= JCS_RGB
&&
57 cinfo
->out_color_space
!= JCS_EXT_RGB
&&
58 cinfo
->out_color_space
!= JCS_EXT_RGBX
&&
59 cinfo
->out_color_space
!= JCS_EXT_BGR
&&
60 cinfo
->out_color_space
!= JCS_EXT_BGRX
&&
61 cinfo
->out_color_space
!= JCS_EXT_XBGR
&&
62 cinfo
->out_color_space
!= JCS_EXT_XRGB
&&
63 cinfo
->out_color_space
!= JCS_EXT_RGBA
&&
64 cinfo
->out_color_space
!= JCS_EXT_BGRA
&&
65 cinfo
->out_color_space
!= JCS_EXT_ABGR
&&
66 cinfo
->out_color_space
!= JCS_EXT_ARGB
) ||
67 cinfo
->out_color_components
!= rgb_pixelsize
[cinfo
->out_color_space
])
69 /* and it only handles 2h1v or 2h2v sampling ratios */
70 if (cinfo
->comp_info
[0].h_samp_factor
!= 2 ||
71 cinfo
->comp_info
[1].h_samp_factor
!= 1 ||
72 cinfo
->comp_info
[2].h_samp_factor
!= 1 ||
73 cinfo
->comp_info
[0].v_samp_factor
> 2 ||
74 cinfo
->comp_info
[1].v_samp_factor
!= 1 ||
75 cinfo
->comp_info
[2].v_samp_factor
!= 1)
77 /* furthermore, it doesn't work if we've scaled the IDCTs differently */
78 if (cinfo
->comp_info
[0]._DCT_scaled_size
!= cinfo
->_min_DCT_scaled_size
||
79 cinfo
->comp_info
[1]._DCT_scaled_size
!= cinfo
->_min_DCT_scaled_size
||
80 cinfo
->comp_info
[2]._DCT_scaled_size
!= cinfo
->_min_DCT_scaled_size
)
82 /* ??? also need to test for upsample-time rescaling, when & if supported */
83 return TRUE
; /* by golly, it'll work... */
91 * Compute output image dimensions and related values.
92 * NOTE: this is exported for possible use by application.
93 * Hence it mustn't do anything that can't be done twice.
96 #if JPEG_LIB_VERSION >= 80
101 jpeg_core_output_dimensions (j_decompress_ptr cinfo
)
102 /* Do computations that are needed before master selection phase.
103 * This function is used for transcoding and full decompression.
106 #ifdef IDCT_SCALING_SUPPORTED
108 jpeg_component_info
*compptr
;
110 /* Compute actual output image dimensions and DCT scaling choices. */
111 if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
) {
112 /* Provide 1/block_size scaling */
113 cinfo
->output_width
= (JDIMENSION
)
114 jdiv_round_up((long) cinfo
->image_width
, (long) DCTSIZE
);
115 cinfo
->output_height
= (JDIMENSION
)
116 jdiv_round_up((long) cinfo
->image_height
, (long) DCTSIZE
);
117 cinfo
->_min_DCT_h_scaled_size
= 1;
118 cinfo
->_min_DCT_v_scaled_size
= 1;
119 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 2) {
120 /* Provide 2/block_size scaling */
121 cinfo
->output_width
= (JDIMENSION
)
122 jdiv_round_up((long) cinfo
->image_width
* 2L, (long) DCTSIZE
);
123 cinfo
->output_height
= (JDIMENSION
)
124 jdiv_round_up((long) cinfo
->image_height
* 2L, (long) DCTSIZE
);
125 cinfo
->_min_DCT_h_scaled_size
= 2;
126 cinfo
->_min_DCT_v_scaled_size
= 2;
127 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 3) {
128 /* Provide 3/block_size scaling */
129 cinfo
->output_width
= (JDIMENSION
)
130 jdiv_round_up((long) cinfo
->image_width
* 3L, (long) DCTSIZE
);
131 cinfo
->output_height
= (JDIMENSION
)
132 jdiv_round_up((long) cinfo
->image_height
* 3L, (long) DCTSIZE
);
133 cinfo
->_min_DCT_h_scaled_size
= 3;
134 cinfo
->_min_DCT_v_scaled_size
= 3;
135 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 4) {
136 /* Provide 4/block_size scaling */
137 cinfo
->output_width
= (JDIMENSION
)
138 jdiv_round_up((long) cinfo
->image_width
* 4L, (long) DCTSIZE
);
139 cinfo
->output_height
= (JDIMENSION
)
140 jdiv_round_up((long) cinfo
->image_height
* 4L, (long) DCTSIZE
);
141 cinfo
->_min_DCT_h_scaled_size
= 4;
142 cinfo
->_min_DCT_v_scaled_size
= 4;
143 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 5) {
144 /* Provide 5/block_size scaling */
145 cinfo
->output_width
= (JDIMENSION
)
146 jdiv_round_up((long) cinfo
->image_width
* 5L, (long) DCTSIZE
);
147 cinfo
->output_height
= (JDIMENSION
)
148 jdiv_round_up((long) cinfo
->image_height
* 5L, (long) DCTSIZE
);
149 cinfo
->_min_DCT_h_scaled_size
= 5;
150 cinfo
->_min_DCT_v_scaled_size
= 5;
151 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 6) {
152 /* Provide 6/block_size scaling */
153 cinfo
->output_width
= (JDIMENSION
)
154 jdiv_round_up((long) cinfo
->image_width
* 6L, (long) DCTSIZE
);
155 cinfo
->output_height
= (JDIMENSION
)
156 jdiv_round_up((long) cinfo
->image_height
* 6L, (long) DCTSIZE
);
157 cinfo
->_min_DCT_h_scaled_size
= 6;
158 cinfo
->_min_DCT_v_scaled_size
= 6;
159 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 7) {
160 /* Provide 7/block_size scaling */
161 cinfo
->output_width
= (JDIMENSION
)
162 jdiv_round_up((long) cinfo
->image_width
* 7L, (long) DCTSIZE
);
163 cinfo
->output_height
= (JDIMENSION
)
164 jdiv_round_up((long) cinfo
->image_height
* 7L, (long) DCTSIZE
);
165 cinfo
->_min_DCT_h_scaled_size
= 7;
166 cinfo
->_min_DCT_v_scaled_size
= 7;
167 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 8) {
168 /* Provide 8/block_size scaling */
169 cinfo
->output_width
= (JDIMENSION
)
170 jdiv_round_up((long) cinfo
->image_width
* 8L, (long) DCTSIZE
);
171 cinfo
->output_height
= (JDIMENSION
)
172 jdiv_round_up((long) cinfo
->image_height
* 8L, (long) DCTSIZE
);
173 cinfo
->_min_DCT_h_scaled_size
= 8;
174 cinfo
->_min_DCT_v_scaled_size
= 8;
175 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 9) {
176 /* Provide 9/block_size scaling */
177 cinfo
->output_width
= (JDIMENSION
)
178 jdiv_round_up((long) cinfo
->image_width
* 9L, (long) DCTSIZE
);
179 cinfo
->output_height
= (JDIMENSION
)
180 jdiv_round_up((long) cinfo
->image_height
* 9L, (long) DCTSIZE
);
181 cinfo
->_min_DCT_h_scaled_size
= 9;
182 cinfo
->_min_DCT_v_scaled_size
= 9;
183 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 10) {
184 /* Provide 10/block_size scaling */
185 cinfo
->output_width
= (JDIMENSION
)
186 jdiv_round_up((long) cinfo
->image_width
* 10L, (long) DCTSIZE
);
187 cinfo
->output_height
= (JDIMENSION
)
188 jdiv_round_up((long) cinfo
->image_height
* 10L, (long) DCTSIZE
);
189 cinfo
->_min_DCT_h_scaled_size
= 10;
190 cinfo
->_min_DCT_v_scaled_size
= 10;
191 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 11) {
192 /* Provide 11/block_size scaling */
193 cinfo
->output_width
= (JDIMENSION
)
194 jdiv_round_up((long) cinfo
->image_width
* 11L, (long) DCTSIZE
);
195 cinfo
->output_height
= (JDIMENSION
)
196 jdiv_round_up((long) cinfo
->image_height
* 11L, (long) DCTSIZE
);
197 cinfo
->_min_DCT_h_scaled_size
= 11;
198 cinfo
->_min_DCT_v_scaled_size
= 11;
199 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 12) {
200 /* Provide 12/block_size scaling */
201 cinfo
->output_width
= (JDIMENSION
)
202 jdiv_round_up((long) cinfo
->image_width
* 12L, (long) DCTSIZE
);
203 cinfo
->output_height
= (JDIMENSION
)
204 jdiv_round_up((long) cinfo
->image_height
* 12L, (long) DCTSIZE
);
205 cinfo
->_min_DCT_h_scaled_size
= 12;
206 cinfo
->_min_DCT_v_scaled_size
= 12;
207 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 13) {
208 /* Provide 13/block_size scaling */
209 cinfo
->output_width
= (JDIMENSION
)
210 jdiv_round_up((long) cinfo
->image_width
* 13L, (long) DCTSIZE
);
211 cinfo
->output_height
= (JDIMENSION
)
212 jdiv_round_up((long) cinfo
->image_height
* 13L, (long) DCTSIZE
);
213 cinfo
->_min_DCT_h_scaled_size
= 13;
214 cinfo
->_min_DCT_v_scaled_size
= 13;
215 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 14) {
216 /* Provide 14/block_size scaling */
217 cinfo
->output_width
= (JDIMENSION
)
218 jdiv_round_up((long) cinfo
->image_width
* 14L, (long) DCTSIZE
);
219 cinfo
->output_height
= (JDIMENSION
)
220 jdiv_round_up((long) cinfo
->image_height
* 14L, (long) DCTSIZE
);
221 cinfo
->_min_DCT_h_scaled_size
= 14;
222 cinfo
->_min_DCT_v_scaled_size
= 14;
223 } else if (cinfo
->scale_num
* DCTSIZE
<= cinfo
->scale_denom
* 15) {
224 /* Provide 15/block_size scaling */
225 cinfo
->output_width
= (JDIMENSION
)
226 jdiv_round_up((long) cinfo
->image_width
* 15L, (long) DCTSIZE
);
227 cinfo
->output_height
= (JDIMENSION
)
228 jdiv_round_up((long) cinfo
->image_height
* 15L, (long) DCTSIZE
);
229 cinfo
->_min_DCT_h_scaled_size
= 15;
230 cinfo
->_min_DCT_v_scaled_size
= 15;
232 /* Provide 16/block_size scaling */
233 cinfo
->output_width
= (JDIMENSION
)
234 jdiv_round_up((long) cinfo
->image_width
* 16L, (long) DCTSIZE
);
235 cinfo
->output_height
= (JDIMENSION
)
236 jdiv_round_up((long) cinfo
->image_height
* 16L, (long) DCTSIZE
);
237 cinfo
->_min_DCT_h_scaled_size
= 16;
238 cinfo
->_min_DCT_v_scaled_size
= 16;
241 /* Recompute dimensions of components */
242 for (ci
= 0, compptr
= cinfo
->comp_info
; ci
< cinfo
->num_components
;
244 compptr
->_DCT_h_scaled_size
= cinfo
->_min_DCT_h_scaled_size
;
245 compptr
->_DCT_v_scaled_size
= cinfo
->_min_DCT_v_scaled_size
;
248 #else /* !IDCT_SCALING_SUPPORTED */
250 /* Hardwire it to "no scaling" */
251 cinfo
->output_width
= cinfo
->image_width
;
252 cinfo
->output_height
= cinfo
->image_height
;
253 /* jdinput.c has already initialized DCT_scaled_size,
254 * and has computed unscaled downsampled_width and downsampled_height.
257 #endif /* IDCT_SCALING_SUPPORTED */
262 * Compute output image dimensions and related values.
263 * NOTE: this is exported for possible use by application.
264 * Hence it mustn't do anything that can't be done twice.
265 * Also note that it may be called before the master module is initialized!
269 jpeg_calc_output_dimensions (j_decompress_ptr cinfo
)
270 /* Do computations that are needed before master selection phase */
272 #ifdef IDCT_SCALING_SUPPORTED
274 jpeg_component_info
*compptr
;
277 /* Prevent application from calling me at wrong times */
278 if (cinfo
->global_state
!= DSTATE_READY
)
279 ERREXIT1(cinfo
, JERR_BAD_STATE
, cinfo
->global_state
);
281 /* Compute core output image dimensions and DCT scaling choices. */
282 jpeg_core_output_dimensions(cinfo
);
284 #ifdef IDCT_SCALING_SUPPORTED
286 /* In selecting the actual DCT scaling for each component, we try to
287 * scale up the chroma components via IDCT scaling rather than upsampling.
288 * This saves time if the upsampler gets to use 1:1 scaling.
289 * Note this code adapts subsampling ratios which are powers of 2.
291 for (ci
= 0, compptr
= cinfo
->comp_info
; ci
< cinfo
->num_components
;
293 int ssize
= cinfo
->_min_DCT_scaled_size
;
294 while (ssize
< DCTSIZE
&&
295 ((cinfo
->max_h_samp_factor
* cinfo
->_min_DCT_scaled_size
) %
296 (compptr
->h_samp_factor
* ssize
* 2) == 0) &&
297 ((cinfo
->max_v_samp_factor
* cinfo
->_min_DCT_scaled_size
) %
298 (compptr
->v_samp_factor
* ssize
* 2) == 0)) {
301 #if JPEG_LIB_VERSION >= 70
302 compptr
->DCT_h_scaled_size
= compptr
->DCT_v_scaled_size
= ssize
;
304 compptr
->DCT_scaled_size
= ssize
;
308 /* Recompute downsampled dimensions of components;
309 * application needs to know these if using raw downsampled data.
311 for (ci
= 0, compptr
= cinfo
->comp_info
; ci
< cinfo
->num_components
;
313 /* Size in samples, after IDCT scaling */
314 compptr
->downsampled_width
= (JDIMENSION
)
315 jdiv_round_up((long) cinfo
->image_width
*
316 (long) (compptr
->h_samp_factor
* compptr
->_DCT_scaled_size
),
317 (long) (cinfo
->max_h_samp_factor
* DCTSIZE
));
318 compptr
->downsampled_height
= (JDIMENSION
)
319 jdiv_round_up((long) cinfo
->image_height
*
320 (long) (compptr
->v_samp_factor
* compptr
->_DCT_scaled_size
),
321 (long) (cinfo
->max_v_samp_factor
* DCTSIZE
));
324 #else /* !IDCT_SCALING_SUPPORTED */
326 /* Hardwire it to "no scaling" */
327 cinfo
->output_width
= cinfo
->image_width
;
328 cinfo
->output_height
= cinfo
->image_height
;
329 /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
330 * and has computed unscaled downsampled_width and downsampled_height.
333 #endif /* IDCT_SCALING_SUPPORTED */
335 /* Report number of components in selected colorspace. */
336 /* Probably this should be in the color conversion module... */
337 switch (cinfo
->out_color_space
) {
339 cinfo
->out_color_components
= 1;
352 cinfo
->out_color_components
= rgb_pixelsize
[cinfo
->out_color_space
];
355 cinfo
->out_color_components
= 3;
359 cinfo
->out_color_components
= 4;
361 default: /* else must be same colorspace as in file */
362 cinfo
->out_color_components
= cinfo
->num_components
;
365 cinfo
->output_components
= (cinfo
->quantize_colors
? 1 :
366 cinfo
->out_color_components
);
368 /* See if upsampler will want to emit more than one row at a time */
369 if (use_merged_upsample(cinfo
))
370 cinfo
->rec_outbuf_height
= cinfo
->max_v_samp_factor
;
372 cinfo
->rec_outbuf_height
= 1;
377 * Several decompression processes need to range-limit values to the range
378 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
379 * due to noise introduced by quantization, roundoff error, etc. These
380 * processes are inner loops and need to be as fast as possible. On most
381 * machines, particularly CPUs with pipelines or instruction prefetch,
382 * a (subscript-check-less) C table lookup
383 * x = sample_range_limit[x];
384 * is faster than explicit tests
386 * else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
387 * These processes all use a common table prepared by the routine below.
389 * For most steps we can mathematically guarantee that the initial value
390 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
391 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
392 * limiting step (just after the IDCT), a wildly out-of-range value is
393 * possible if the input data is corrupt. To avoid any chance of indexing
394 * off the end of memory and getting a bad-pointer trap, we perform the
395 * post-IDCT limiting thus:
396 * x = range_limit[x & MASK];
397 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
398 * samples. Under normal circumstances this is more than enough range and
399 * a correct output will be generated; with bogus input data the mask will
400 * cause wraparound, and we will safely generate a bogus-but-in-range output.
401 * For the post-IDCT step, we want to convert the data from signed to unsigned
402 * representation by adding CENTERJSAMPLE at the same time that we limit it.
403 * So the post-IDCT limiting table ends up looking like this:
404 * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
405 * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
406 * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
407 * 0,1,...,CENTERJSAMPLE-1
408 * Negative inputs select values from the upper half of the table after
411 * We can save some space by overlapping the start of the post-IDCT table
412 * with the simpler range limiting table. The post-IDCT table begins at
413 * sample_range_limit + CENTERJSAMPLE.
415 * Note that the table is allocated in near data space on PCs; it's small
416 * enough and used often enough to justify this.
420 prepare_range_limit_table (j_decompress_ptr cinfo
)
421 /* Allocate and fill in the sample_range_limit table */
427 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
428 (5 * (MAXJSAMPLE
+1) + CENTERJSAMPLE
) * SIZEOF(JSAMPLE
));
429 table
+= (MAXJSAMPLE
+1); /* allow negative subscripts of simple table */
430 cinfo
->sample_range_limit
= table
;
431 /* First segment of "simple" table: limit[x] = 0 for x < 0 */
432 MEMZERO(table
- (MAXJSAMPLE
+1), (MAXJSAMPLE
+1) * SIZEOF(JSAMPLE
));
433 /* Main part of "simple" table: limit[x] = x */
434 for (i
= 0; i
<= MAXJSAMPLE
; i
++)
435 table
[i
] = (JSAMPLE
) i
;
436 table
+= CENTERJSAMPLE
; /* Point to where post-IDCT table starts */
437 /* End of simple table, rest of first half of post-IDCT table */
438 for (i
= CENTERJSAMPLE
; i
< 2*(MAXJSAMPLE
+1); i
++)
439 table
[i
] = MAXJSAMPLE
;
440 /* Second half of post-IDCT table */
441 MEMZERO(table
+ (2 * (MAXJSAMPLE
+1)),
442 (2 * (MAXJSAMPLE
+1) - CENTERJSAMPLE
) * SIZEOF(JSAMPLE
));
443 MEMCOPY(table
+ (4 * (MAXJSAMPLE
+1) - CENTERJSAMPLE
),
444 cinfo
->sample_range_limit
, CENTERJSAMPLE
* SIZEOF(JSAMPLE
));
449 * Master selection of decompression modules.
450 * This is done once at jpeg_start_decompress time. We determine
451 * which modules will be used and give them appropriate initialization calls.
452 * We also initialize the decompressor input side to begin consuming data.
454 * Since jpeg_read_header has finished, we know what is in the SOF
455 * and (first) SOS markers. We also have all the application parameter
460 master_selection (j_decompress_ptr cinfo
)
462 my_master_ptr master
= (my_master_ptr
) cinfo
->master
;
463 boolean use_c_buffer
;
465 JDIMENSION jd_samplesperrow
;
467 /* Initialize dimensions and other stuff */
468 jpeg_calc_output_dimensions(cinfo
);
469 prepare_range_limit_table(cinfo
);
471 /* Width of an output scanline must be representable as JDIMENSION. */
472 samplesperrow
= (long) cinfo
->output_width
* (long) cinfo
->out_color_components
;
473 jd_samplesperrow
= (JDIMENSION
) samplesperrow
;
474 if ((long) jd_samplesperrow
!= samplesperrow
)
475 ERREXIT(cinfo
, JERR_WIDTH_OVERFLOW
);
477 /* Initialize my private state */
478 master
->pass_number
= 0;
479 master
->using_merged_upsample
= use_merged_upsample(cinfo
);
481 /* Color quantizer selection */
482 master
->quantizer_1pass
= NULL
;
483 master
->quantizer_2pass
= NULL
;
484 /* No mode changes if not using buffered-image mode. */
485 if (! cinfo
->quantize_colors
|| ! cinfo
->buffered_image
) {
486 cinfo
->enable_1pass_quant
= FALSE
;
487 cinfo
->enable_external_quant
= FALSE
;
488 cinfo
->enable_2pass_quant
= FALSE
;
490 if (cinfo
->quantize_colors
) {
491 if (cinfo
->raw_data_out
)
492 ERREXIT(cinfo
, JERR_NOTIMPL
);
493 /* 2-pass quantizer only works in 3-component color space. */
494 if (cinfo
->out_color_components
!= 3) {
495 cinfo
->enable_1pass_quant
= TRUE
;
496 cinfo
->enable_external_quant
= FALSE
;
497 cinfo
->enable_2pass_quant
= FALSE
;
498 cinfo
->colormap
= NULL
;
499 } else if (cinfo
->colormap
!= NULL
) {
500 cinfo
->enable_external_quant
= TRUE
;
501 } else if (cinfo
->two_pass_quantize
) {
502 cinfo
->enable_2pass_quant
= TRUE
;
504 cinfo
->enable_1pass_quant
= TRUE
;
507 if (cinfo
->enable_1pass_quant
) {
508 #ifdef QUANT_1PASS_SUPPORTED
509 jinit_1pass_quantizer(cinfo
);
510 master
->quantizer_1pass
= cinfo
->cquantize
;
512 ERREXIT(cinfo
, JERR_NOT_COMPILED
);
516 /* We use the 2-pass code to map to external colormaps. */
517 if (cinfo
->enable_2pass_quant
|| cinfo
->enable_external_quant
) {
518 #ifdef QUANT_2PASS_SUPPORTED
519 jinit_2pass_quantizer(cinfo
);
520 master
->quantizer_2pass
= cinfo
->cquantize
;
522 ERREXIT(cinfo
, JERR_NOT_COMPILED
);
525 /* If both quantizers are initialized, the 2-pass one is left active;
526 * this is necessary for starting with quantization to an external map.
530 /* Post-processing: in particular, color conversion first */
531 if (! cinfo
->raw_data_out
) {
532 if (master
->using_merged_upsample
) {
533 #ifdef UPSAMPLE_MERGING_SUPPORTED
534 jinit_merged_upsampler(cinfo
); /* does color conversion too */
536 ERREXIT(cinfo
, JERR_NOT_COMPILED
);
539 jinit_color_deconverter(cinfo
);
540 jinit_upsampler(cinfo
);
542 jinit_d_post_controller(cinfo
, cinfo
->enable_2pass_quant
);
545 jinit_inverse_dct(cinfo
);
546 /* Entropy decoding: either Huffman or arithmetic coding. */
547 if (cinfo
->arith_code
) {
548 #ifdef D_ARITH_CODING_SUPPORTED
549 jinit_arith_decoder(cinfo
);
551 ERREXIT(cinfo
, JERR_ARITH_NOTIMPL
);
554 if (cinfo
->progressive_mode
) {
555 #ifdef D_PROGRESSIVE_SUPPORTED
556 jinit_phuff_decoder(cinfo
);
558 ERREXIT(cinfo
, JERR_NOT_COMPILED
);
561 jinit_huff_decoder(cinfo
);
564 /* Initialize principal buffer controllers. */
565 use_c_buffer
= cinfo
->inputctl
->has_multiple_scans
|| cinfo
->buffered_image
;
566 jinit_d_coef_controller(cinfo
, use_c_buffer
);
568 if (! cinfo
->raw_data_out
)
569 jinit_d_main_controller(cinfo
, FALSE
/* never need full buffer here */);
571 /* We can now tell the memory manager to allocate virtual arrays. */
572 (*cinfo
->mem
->realize_virt_arrays
) ((j_common_ptr
) cinfo
);
574 /* Initialize input side of decompressor to consume first scan. */
575 (*cinfo
->inputctl
->start_input_pass
) (cinfo
);
577 #ifdef D_MULTISCAN_FILES_SUPPORTED
578 /* If jpeg_start_decompress will read the whole file, initialize
579 * progress monitoring appropriately. The input step is counted
582 if (cinfo
->progress
!= NULL
&& ! cinfo
->buffered_image
&&
583 cinfo
->inputctl
->has_multiple_scans
) {
585 /* Estimate number of scans to set pass_limit. */
586 if (cinfo
->progressive_mode
) {
587 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
588 nscans
= 2 + 3 * cinfo
->num_components
;
590 /* For a nonprogressive multiscan file, estimate 1 scan per component. */
591 nscans
= cinfo
->num_components
;
593 cinfo
->progress
->pass_counter
= 0L;
594 cinfo
->progress
->pass_limit
= (long) cinfo
->total_iMCU_rows
* nscans
;
595 cinfo
->progress
->completed_passes
= 0;
596 cinfo
->progress
->total_passes
= (cinfo
->enable_2pass_quant
? 3 : 2);
597 /* Count the input pass as done */
598 master
->pass_number
++;
600 #endif /* D_MULTISCAN_FILES_SUPPORTED */
606 * This is called at the beginning of each output pass. We determine which
607 * modules will be active during this pass and give them appropriate
608 * start_pass calls. We also set is_dummy_pass to indicate whether this
609 * is a "real" output pass or a dummy pass for color quantization.
610 * (In the latter case, jdapistd.c will crank the pass to completion.)
614 prepare_for_output_pass (j_decompress_ptr cinfo
)
616 my_master_ptr master
= (my_master_ptr
) cinfo
->master
;
618 if (master
->pub
.is_dummy_pass
) {
619 #ifdef QUANT_2PASS_SUPPORTED
620 /* Final pass of 2-pass quantization */
621 master
->pub
.is_dummy_pass
= FALSE
;
622 (*cinfo
->cquantize
->start_pass
) (cinfo
, FALSE
);
623 (*cinfo
->post
->start_pass
) (cinfo
, JBUF_CRANK_DEST
);
624 (*cinfo
->main
->start_pass
) (cinfo
, JBUF_CRANK_DEST
);
626 ERREXIT(cinfo
, JERR_NOT_COMPILED
);
627 #endif /* QUANT_2PASS_SUPPORTED */
629 if (cinfo
->quantize_colors
&& cinfo
->colormap
== NULL
) {
630 /* Select new quantization method */
631 if (cinfo
->two_pass_quantize
&& cinfo
->enable_2pass_quant
) {
632 cinfo
->cquantize
= master
->quantizer_2pass
;
633 master
->pub
.is_dummy_pass
= TRUE
;
634 } else if (cinfo
->enable_1pass_quant
) {
635 cinfo
->cquantize
= master
->quantizer_1pass
;
637 ERREXIT(cinfo
, JERR_MODE_CHANGE
);
640 (*cinfo
->idct
->start_pass
) (cinfo
);
641 (*cinfo
->coef
->start_output_pass
) (cinfo
);
642 if (! cinfo
->raw_data_out
) {
643 if (! master
->using_merged_upsample
)
644 (*cinfo
->cconvert
->start_pass
) (cinfo
);
645 (*cinfo
->upsample
->start_pass
) (cinfo
);
646 if (cinfo
->quantize_colors
)
647 (*cinfo
->cquantize
->start_pass
) (cinfo
, master
->pub
.is_dummy_pass
);
648 (*cinfo
->post
->start_pass
) (cinfo
,
649 (master
->pub
.is_dummy_pass
? JBUF_SAVE_AND_PASS
: JBUF_PASS_THRU
));
650 (*cinfo
->main
->start_pass
) (cinfo
, JBUF_PASS_THRU
);
654 /* Set up progress monitor's pass info if present */
655 if (cinfo
->progress
!= NULL
) {
656 cinfo
->progress
->completed_passes
= master
->pass_number
;
657 cinfo
->progress
->total_passes
= master
->pass_number
+
658 (master
->pub
.is_dummy_pass
? 2 : 1);
659 /* In buffered-image mode, we assume one more output pass if EOI not
660 * yet reached, but no more passes if EOI has been reached.
662 if (cinfo
->buffered_image
&& ! cinfo
->inputctl
->eoi_reached
) {
663 cinfo
->progress
->total_passes
+= (cinfo
->enable_2pass_quant
? 2 : 1);
670 * Finish up at end of an output pass.
674 finish_output_pass (j_decompress_ptr cinfo
)
676 my_master_ptr master
= (my_master_ptr
) cinfo
->master
;
678 if (cinfo
->quantize_colors
)
679 (*cinfo
->cquantize
->finish_pass
) (cinfo
);
680 master
->pass_number
++;
684 #ifdef D_MULTISCAN_FILES_SUPPORTED
687 * Switch to a new external colormap between output passes.
691 jpeg_new_colormap (j_decompress_ptr cinfo
)
693 my_master_ptr master
= (my_master_ptr
) cinfo
->master
;
695 /* Prevent application from calling me at wrong times */
696 if (cinfo
->global_state
!= DSTATE_BUFIMAGE
)
697 ERREXIT1(cinfo
, JERR_BAD_STATE
, cinfo
->global_state
);
699 if (cinfo
->quantize_colors
&& cinfo
->enable_external_quant
&&
700 cinfo
->colormap
!= NULL
) {
701 /* Select 2-pass quantizer for external colormap use */
702 cinfo
->cquantize
= master
->quantizer_2pass
;
703 /* Notify quantizer of colormap change */
704 (*cinfo
->cquantize
->new_color_map
) (cinfo
);
705 master
->pub
.is_dummy_pass
= FALSE
; /* just in case */
707 ERREXIT(cinfo
, JERR_MODE_CHANGE
);
710 #endif /* D_MULTISCAN_FILES_SUPPORTED */
714 * Initialize master decompression control and select active modules.
715 * This is performed at the start of jpeg_start_decompress.
719 jinit_master_decompress (j_decompress_ptr cinfo
)
721 my_master_ptr master
;
723 master
= (my_master_ptr
)
724 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
725 SIZEOF(my_decomp_master
));
726 cinfo
->master
= (struct jpeg_decomp_master
*) master
;
727 master
->pub
.prepare_for_output_pass
= prepare_for_output_pass
;
728 master
->pub
.finish_output_pass
= finish_output_pass
;
730 master
->pub
.is_dummy_pass
= FALSE
;
732 master_selection(cinfo
);