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jdinput.c (13500B)
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1 /*
2 * jdinput.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains input control logic for the JPEG decompressor.
9 * These routines are concerned with controlling the decompressor's input
10 * processing (marker reading and coefficient decoding). The actual input
11 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
12 */
13
14 #define JPEG_INTERNALS
15 #include "jinclude.h"
16 #include "jpeglib.h"
17
18
19 /* Private state */
20
21 typedef struct {
22 struct jpeg_input_controller pub; /* public fields */
23
24 boolean inheaders; /* TRUE until first SOS is reached */
25 } my_input_controller;
26
27 typedef my_input_controller * my_inputctl_ptr;
28
29
30 /* Forward declarations */
31 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
32
33
34 /*
35 * Routines to calculate various quantities related to the size of the image.
36 */
37
38 LOCAL(void)
39 initial_setup (j_decompress_ptr cinfo)
40 /* Called once, when first SOS marker is reached */
41 {
42 int ci;
43 jpeg_component_info *compptr;
44
45 /* Make sure image isn't bigger than I can handle */
46 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
47 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
48 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
49
50 /* For now, precision must match compiled-in value... */
51 if (cinfo->data_precision != BITS_IN_JSAMPLE)
52 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
53
54 /* Check that number of components won't exceed internal array sizes */
55 if (cinfo->num_components > MAX_COMPONENTS)
56 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
57 MAX_COMPONENTS);
58
59 /* Compute maximum sampling factors; check factor validity */
60 cinfo->max_h_samp_factor = 1;
61 cinfo->max_v_samp_factor = 1;
62 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
63 ci++, compptr++) {
64 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
65 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
66 ERREXIT(cinfo, JERR_BAD_SAMPLING);
67 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
68 compptr->h_samp_factor);
69 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
70 compptr->v_samp_factor);
71 }
72
73 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
74 * In the full decompressor, this will be overridden by jdmaster.c;
75 * but in the transcoder, jdmaster.c is not used, so we must do it here.
76 */
77 cinfo->min_DCT_scaled_size = DCTSIZE;
78
79 /* Compute dimensions of components */
80 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
81 ci++, compptr++) {
82 compptr->DCT_scaled_size = DCTSIZE;
83 /* Size in DCT blocks */
84 compptr->width_in_blocks = (JDIMENSION)
85 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
86 (long) (cinfo->max_h_samp_factor * DCTSIZE));
87 compptr->height_in_blocks = (JDIMENSION)
88 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
89 (long) (cinfo->max_v_samp_factor * DCTSIZE));
90 /* downsampled_width and downsampled_height will also be overridden by
91 * jdmaster.c if we are doing full decompression. The transcoder library
92 * doesn't use these values, but the calling application might.
93 */
94 /* Size in samples */
95 compptr->downsampled_width = (JDIMENSION)
96 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
97 (long) cinfo->max_h_samp_factor);
98 compptr->downsampled_height = (JDIMENSION)
99 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
100 (long) cinfo->max_v_samp_factor);
101 /* Mark component needed, until color conversion says otherwise */
102 compptr->component_needed = TRUE;
103 /* Mark no quantization table yet saved for component */
104 compptr->quant_table = NULL;
105 }
106
107 /* Compute number of fully interleaved MCU rows. */
108 cinfo->total_iMCU_rows = (JDIMENSION)
109 jdiv_round_up((long) cinfo->image_height,
110 (long) (cinfo->max_v_samp_factor*DCTSIZE));
111
112 /* Decide whether file contains multiple scans */
113 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
114 cinfo->inputctl->has_multiple_scans = TRUE;
115 else
116 cinfo->inputctl->has_multiple_scans = FALSE;
117 }
118
119
120 LOCAL(void)
121 per_scan_setup (j_decompress_ptr cinfo)
122 /* Do computations that are needed before processing a JPEG scan */
123 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
124 {
125 int ci, mcublks, tmp;
126 jpeg_component_info *compptr;
127
128 if (cinfo->comps_in_scan == 1) {
129
130 /* Noninterleaved (single-component) scan */
131 compptr = cinfo->cur_comp_info[0];
132
133 /* Overall image size in MCUs */
134 cinfo->MCUs_per_row = compptr->width_in_blocks;
135 cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
136
137 /* For noninterleaved scan, always one block per MCU */
138 compptr->MCU_width = 1;
139 compptr->MCU_height = 1;
140 compptr->MCU_blocks = 1;
141 compptr->MCU_sample_width = compptr->DCT_scaled_size;
142 compptr->last_col_width = 1;
143 /* For noninterleaved scans, it is convenient to define last_row_height
144 * as the number of block rows present in the last iMCU row.
145 */
146 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
147 if (tmp == 0) tmp = compptr->v_samp_factor;
148 compptr->last_row_height = tmp;
149
150 /* Prepare array describing MCU composition */
151 cinfo->blocks_in_MCU = 1;
152 cinfo->MCU_membership[0] = 0;
153
154 } else {
155
156 /* Interleaved (multi-component) scan */
157 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
158 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
159 MAX_COMPS_IN_SCAN);
160
161 /* Overall image size in MCUs */
162 cinfo->MCUs_per_row = (JDIMENSION)
163 jdiv_round_up((long) cinfo->image_width,
164 (long) (cinfo->max_h_samp_factor*DCTSIZE));
165 cinfo->MCU_rows_in_scan = (JDIMENSION)
166 jdiv_round_up((long) cinfo->image_height,
167 (long) (cinfo->max_v_samp_factor*DCTSIZE));
168
169 cinfo->blocks_in_MCU = 0;
170
171 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
172 compptr = cinfo->cur_comp_info[ci];
173 /* Sampling factors give # of blocks of component in each MCU */
174 compptr->MCU_width = compptr->h_samp_factor;
175 compptr->MCU_height = compptr->v_samp_factor;
176 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
177 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
178 /* Figure number of non-dummy blocks in last MCU column & row */
179 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
180 if (tmp == 0) tmp = compptr->MCU_width;
181 compptr->last_col_width = tmp;
182 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
183 if (tmp == 0) tmp = compptr->MCU_height;
184 compptr->last_row_height = tmp;
185 /* Prepare array describing MCU composition */
186 mcublks = compptr->MCU_blocks;
187 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
188 ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
189 while (mcublks-- > 0) {
190 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
191 }
192 }
193
194 }
195 }
196
197
198 /*
199 * Save away a copy of the Q-table referenced by each component present
200 * in the current scan, unless already saved during a prior scan.
201 *
202 * In a multiple-scan JPEG file, the encoder could assign different components
203 * the same Q-table slot number, but change table definitions between scans
204 * so that each component uses a different Q-table. (The IJG encoder is not
205 * currently capable of doing this, but other encoders might.) Since we want
206 * to be able to dequantize all the components at the end of the file, this
207 * means that we have to save away the table actually used for each component.
208 * We do this by copying the table at the start of the first scan containing
209 * the component.
210 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
211 * slot between scans of a component using that slot. If the encoder does so
212 * anyway, this decoder will simply use the Q-table values that were current
213 * at the start of the first scan for the component.
214 *
215 * The decompressor output side looks only at the saved quant tables,
216 * not at the current Q-table slots.
217 */
218
219 LOCAL(void)
220 latch_quant_tables (j_decompress_ptr cinfo)
221 {
222 int ci, qtblno;
223 jpeg_component_info *compptr;
224 JQUANT_TBL * qtbl;
225
226 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
227 compptr = cinfo->cur_comp_info[ci];
228 /* No work if we already saved Q-table for this component */
229 if (compptr->quant_table != NULL)
230 continue;
231 /* Make sure specified quantization table is present */
232 qtblno = compptr->quant_tbl_no;
233 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
234 cinfo->quant_tbl_ptrs[qtblno] == NULL)
235 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
236 /* OK, save away the quantization table */
237 qtbl = (JQUANT_TBL *)
238 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
239 SIZEOF(JQUANT_TBL));
240 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
241 compptr->quant_table = qtbl;
242 }
243 }
244
245
246 /*
247 * Initialize the input modules to read a scan of compressed data.
248 * The first call to this is done by jdmaster.c after initializing
249 * the entire decompressor (during jpeg_start_decompress).
250 * Subsequent calls come from consume_markers, below.
251 */
252
253 METHODDEF(void)
254 start_input_pass (j_decompress_ptr cinfo)
255 {
256 per_scan_setup(cinfo);
257 latch_quant_tables(cinfo);
258 (*cinfo->entropy->start_pass) (cinfo);
259 (*cinfo->coef->start_input_pass) (cinfo);
260 cinfo->inputctl->consume_input = cinfo->coef->consume_data;
261 }
262
263
264 /*
265 * Finish up after inputting a compressed-data scan.
266 * This is called by the coefficient controller after it's read all
267 * the expected data of the scan.
268 */
269
270 METHODDEF(void)
271 finish_input_pass (j_decompress_ptr cinfo)
272 {
273 cinfo->inputctl->consume_input = consume_markers;
274 }
275
276
277 /*
278 * Read JPEG markers before, between, or after compressed-data scans.
279 * Change state as necessary when a new scan is reached.
280 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
281 *
282 * The consume_input method pointer points either here or to the
283 * coefficient controller's consume_data routine, depending on whether
284 * we are reading a compressed data segment or inter-segment markers.
285 */
286
287 METHODDEF(int)
288 consume_markers (j_decompress_ptr cinfo)
289 {
290 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
291 int val;
292
293 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
294 return JPEG_REACHED_EOI;
295
296 val = (*cinfo->marker->read_markers) (cinfo);
297
298 switch (val) {
299 case JPEG_REACHED_SOS: /* Found SOS */
300 if (inputctl->inheaders) { /* 1st SOS */
301 initial_setup(cinfo);
302 inputctl->inheaders = FALSE;
303 /* Note: start_input_pass must be called by jdmaster.c
304 * before any more input can be consumed. jdapimin.c is
305 * responsible for enforcing this sequencing.
306 */
307 } else { /* 2nd or later SOS marker */
308 if (! inputctl->pub.has_multiple_scans)
309 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
310 start_input_pass(cinfo);
311 }
312 break;
313 case JPEG_REACHED_EOI: /* Found EOI */
314 inputctl->pub.eoi_reached = TRUE;
315 if (inputctl->inheaders) { /* Tables-only datastream, apparently */
316 if (cinfo->marker->saw_SOF)
317 ERREXIT(cinfo, JERR_SOF_NO_SOS);
318 } else {
319 /* Prevent infinite loop in coef ctlr's decompress_data routine
320 * if user set output_scan_number larger than number of scans.
321 */
322 if (cinfo->output_scan_number > cinfo->input_scan_number)
323 cinfo->output_scan_number = cinfo->input_scan_number;
324 }
325 break;
326 case JPEG_SUSPENDED:
327 break;
328 }
329
330 return val;
331 }
332
333
334 /*
335 * Reset state to begin a fresh datastream.
336 */
337
338 METHODDEF(void)
339 reset_input_controller (j_decompress_ptr cinfo)
340 {
341 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
342
343 inputctl->pub.consume_input = consume_markers;
344 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
345 inputctl->pub.eoi_reached = FALSE;
346 inputctl->inheaders = TRUE;
347 /* Reset other modules */
348 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
349 (*cinfo->marker->reset_marker_reader) (cinfo);
350 /* Reset progression state -- would be cleaner if entropy decoder did this */
351 cinfo->coef_bits = NULL;
352 }
353
354
355 /*
356 * Initialize the input controller module.
357 * This is called only once, when the decompression object is created.
358 */
359
360 GLOBAL(void)
361 jinit_input_controller (j_decompress_ptr cinfo)
362 {
363 my_inputctl_ptr inputctl;
364
365 /* Create subobject in permanent pool */
366 inputctl = (my_inputctl_ptr)
367 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
368 SIZEOF(my_input_controller));
369 cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
370 /* Initialize method pointers */
371 inputctl->pub.consume_input = consume_markers;
372 inputctl->pub.reset_input_controller = reset_input_controller;
373 inputctl->pub.start_input_pass = start_input_pass;
374 inputctl->pub.finish_input_pass = finish_input_pass;
375 /* Initialize state: can't use reset_input_controller since we don't
376 * want to try to reset other modules yet.
377 */
378 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
379 inputctl->pub.eoi_reached = FALSE;
380 inputctl->inheaders = TRUE;
381 }