source: trunk/libjpeg/jdinput.c @ 136

Last change on this file since 136 was 15, checked in by Eugene Romanenko, 16 years ago

needed libs update

File size: 13.6 KB
Line 
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
21typedef struct {
22  struct jpeg_input_controller pub; /* public fields */
23
24  boolean inheaders;            /* TRUE until first SOS is reached */
25} my_input_controller;
26
27typedef my_input_controller * my_inputctl_ptr;
28
29
30/* Forward declarations */
31METHODDEF(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
38LOCAL(void)
39initial_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
120LOCAL(void)
121per_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
219LOCAL(void)
220latch_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
253METHODDEF(void)
254start_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
270METHODDEF(void)
271finish_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
287METHODDEF(int)
288consume_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
338METHODDEF(void)
339reset_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
360GLOBAL(void)
361jinit_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}
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