source: trunk/libjpeg/jcmainct.c @ 15

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

needed libs update

File size: 9.2 KB
Line 
1/*
2 * jcmainct.c
3 *
4 * Copyright (C) 1994-1996, 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 the main buffer controller for compression.
9 * The main buffer lies between the pre-processor and the JPEG
10 * compressor proper; it holds downsampled data in the JPEG colorspace.
11 */
12
13#define JPEG_INTERNALS
14#include "jinclude.h"
15#include "jpeglib.h"
16
17
18/* Note: currently, there is no operating mode in which a full-image buffer
19 * is needed at this step.  If there were, that mode could not be used with
20 * "raw data" input, since this module is bypassed in that case.  However,
21 * we've left the code here for possible use in special applications.
22 */
23#undef FULL_MAIN_BUFFER_SUPPORTED
24
25
26/* Private buffer controller object */
27
28typedef struct {
29  struct jpeg_c_main_controller pub; /* public fields */
30
31  JDIMENSION cur_iMCU_row;      /* number of current iMCU row */
32  JDIMENSION rowgroup_ctr;      /* counts row groups received in iMCU row */
33  boolean suspended;            /* remember if we suspended output */
34  J_BUF_MODE pass_mode;         /* current operating mode */
35
36  /* If using just a strip buffer, this points to the entire set of buffers
37   * (we allocate one for each component).  In the full-image case, this
38   * points to the currently accessible strips of the virtual arrays.
39   */
40  JSAMPARRAY buffer[MAX_COMPONENTS];
41
42#ifdef FULL_MAIN_BUFFER_SUPPORTED
43  /* If using full-image storage, this array holds pointers to virtual-array
44   * control blocks for each component.  Unused if not full-image storage.
45   */
46  jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
47#endif
48} my_main_controller;
49
50typedef my_main_controller * my_main_ptr;
51
52
53/* Forward declarations */
54METHODDEF(void) process_data_simple_main
55        JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
56             JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
57#ifdef FULL_MAIN_BUFFER_SUPPORTED
58METHODDEF(void) process_data_buffer_main
59        JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
60             JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
61#endif
62
63
64/*
65 * Initialize for a processing pass.
66 */
67
68METHODDEF(void)
69start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
70{
71  my_main_ptr main = (my_main_ptr) cinfo->main;
72
73  /* Do nothing in raw-data mode. */
74  if (cinfo->raw_data_in)
75    return;
76
77  main->cur_iMCU_row = 0;       /* initialize counters */
78  main->rowgroup_ctr = 0;
79  main->suspended = FALSE;
80  main->pass_mode = pass_mode;  /* save mode for use by process_data */
81
82  switch (pass_mode) {
83  case JBUF_PASS_THRU:
84#ifdef FULL_MAIN_BUFFER_SUPPORTED
85    if (main->whole_image[0] != NULL)
86      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
87#endif
88    main->pub.process_data = process_data_simple_main;
89    break;
90#ifdef FULL_MAIN_BUFFER_SUPPORTED
91  case JBUF_SAVE_SOURCE:
92  case JBUF_CRANK_DEST:
93  case JBUF_SAVE_AND_PASS:
94    if (main->whole_image[0] == NULL)
95      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
96    main->pub.process_data = process_data_buffer_main;
97    break;
98#endif
99  default:
100    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
101    break;
102  }
103}
104
105
106/*
107 * Process some data.
108 * This routine handles the simple pass-through mode,
109 * where we have only a strip buffer.
110 */
111
112METHODDEF(void)
113process_data_simple_main (j_compress_ptr cinfo,
114                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
115                          JDIMENSION in_rows_avail)
116{
117  my_main_ptr main = (my_main_ptr) cinfo->main;
118
119  while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
120    /* Read input data if we haven't filled the main buffer yet */
121    if (main->rowgroup_ctr < DCTSIZE)
122      (*cinfo->prep->pre_process_data) (cinfo,
123                                        input_buf, in_row_ctr, in_rows_avail,
124                                        main->buffer, &main->rowgroup_ctr,
125                                        (JDIMENSION) DCTSIZE);
126
127    /* If we don't have a full iMCU row buffered, return to application for
128     * more data.  Note that preprocessor will always pad to fill the iMCU row
129     * at the bottom of the image.
130     */
131    if (main->rowgroup_ctr != DCTSIZE)
132      return;
133
134    /* Send the completed row to the compressor */
135    if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
136      /* If compressor did not consume the whole row, then we must need to
137       * suspend processing and return to the application.  In this situation
138       * we pretend we didn't yet consume the last input row; otherwise, if
139       * it happened to be the last row of the image, the application would
140       * think we were done.
141       */
142      if (! main->suspended) {
143        (*in_row_ctr)--;
144        main->suspended = TRUE;
145      }
146      return;
147    }
148    /* We did finish the row.  Undo our little suspension hack if a previous
149     * call suspended; then mark the main buffer empty.
150     */
151    if (main->suspended) {
152      (*in_row_ctr)++;
153      main->suspended = FALSE;
154    }
155    main->rowgroup_ctr = 0;
156    main->cur_iMCU_row++;
157  }
158}
159
160
161#ifdef FULL_MAIN_BUFFER_SUPPORTED
162
163/*
164 * Process some data.
165 * This routine handles all of the modes that use a full-size buffer.
166 */
167
168METHODDEF(void)
169process_data_buffer_main (j_compress_ptr cinfo,
170                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
171                          JDIMENSION in_rows_avail)
172{
173  my_main_ptr main = (my_main_ptr) cinfo->main;
174  int ci;
175  jpeg_component_info *compptr;
176  boolean writing = (main->pass_mode != JBUF_CRANK_DEST);
177
178  while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
179    /* Realign the virtual buffers if at the start of an iMCU row. */
180    if (main->rowgroup_ctr == 0) {
181      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
182           ci++, compptr++) {
183        main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
184          ((j_common_ptr) cinfo, main->whole_image[ci],
185           main->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE),
186           (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing);
187      }
188      /* In a read pass, pretend we just read some source data. */
189      if (! writing) {
190        *in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
191        main->rowgroup_ctr = DCTSIZE;
192      }
193    }
194
195    /* If a write pass, read input data until the current iMCU row is full. */
196    /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
197    if (writing) {
198      (*cinfo->prep->pre_process_data) (cinfo,
199                                        input_buf, in_row_ctr, in_rows_avail,
200                                        main->buffer, &main->rowgroup_ctr,
201                                        (JDIMENSION) DCTSIZE);
202      /* Return to application if we need more data to fill the iMCU row. */
203      if (main->rowgroup_ctr < DCTSIZE)
204        return;
205    }
206
207    /* Emit data, unless this is a sink-only pass. */
208    if (main->pass_mode != JBUF_SAVE_SOURCE) {
209      if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
210        /* If compressor did not consume the whole row, then we must need to
211         * suspend processing and return to the application.  In this situation
212         * we pretend we didn't yet consume the last input row; otherwise, if
213         * it happened to be the last row of the image, the application would
214         * think we were done.
215         */
216        if (! main->suspended) {
217          (*in_row_ctr)--;
218          main->suspended = TRUE;
219        }
220        return;
221      }
222      /* We did finish the row.  Undo our little suspension hack if a previous
223       * call suspended; then mark the main buffer empty.
224       */
225      if (main->suspended) {
226        (*in_row_ctr)++;
227        main->suspended = FALSE;
228      }
229    }
230
231    /* If get here, we are done with this iMCU row.  Mark buffer empty. */
232    main->rowgroup_ctr = 0;
233    main->cur_iMCU_row++;
234  }
235}
236
237#endif /* FULL_MAIN_BUFFER_SUPPORTED */
238
239
240/*
241 * Initialize main buffer controller.
242 */
243
244GLOBAL(void)
245jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
246{
247  my_main_ptr main;
248  int ci;
249  jpeg_component_info *compptr;
250
251  main = (my_main_ptr)
252    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
253                                SIZEOF(my_main_controller));
254  cinfo->main = (struct jpeg_c_main_controller *) main;
255  main->pub.start_pass = start_pass_main;
256
257  /* We don't need to create a buffer in raw-data mode. */
258  if (cinfo->raw_data_in)
259    return;
260
261  /* Create the buffer.  It holds downsampled data, so each component
262   * may be of a different size.
263   */
264  if (need_full_buffer) {
265#ifdef FULL_MAIN_BUFFER_SUPPORTED
266    /* Allocate a full-image virtual array for each component */
267    /* Note we pad the bottom to a multiple of the iMCU height */
268    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
269         ci++, compptr++) {
270      main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
271        ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
272         compptr->width_in_blocks * DCTSIZE,
273         (JDIMENSION) jround_up((long) compptr->height_in_blocks,
274                                (long) compptr->v_samp_factor) * DCTSIZE,
275         (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
276    }
277#else
278    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
279#endif
280  } else {
281#ifdef FULL_MAIN_BUFFER_SUPPORTED
282    main->whole_image[0] = NULL; /* flag for no virtual arrays */
283#endif
284    /* Allocate a strip buffer for each component */
285    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
286         ci++, compptr++) {
287      main->buffer[ci] = (*cinfo->mem->alloc_sarray)
288        ((j_common_ptr) cinfo, JPOOL_IMAGE,
289         compptr->width_in_blocks * DCTSIZE,
290         (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
291    }
292  }
293}
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