1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * jcmainct.c
7 *
8 * Copyright (C) 1994-1996, 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 the main buffer controller for compression.
13 * The main buffer lies between the pre-processor and the JPEG
14 * compressor proper; it holds downsampled data in the JPEG colorspace.
15 */
16
17#define JPEG_INTERNALS
18#include "jinclude.h"
19#include "jpeglib.h"
20
21
22/* Note: currently, there is no operating mode in which a full-image buffer
23 * is needed at this step.  If there were, that mode could not be used with
24 * "raw data" input, since this module is bypassed in that case.  However,
25 * we've left the code here for possible use in special applications.
26 */
27#undef FULL_MAIN_BUFFER_SUPPORTED
28
29
30/* Private buffer controller object */
31
32typedef struct {
33  struct jpeg_c_main_controller pub; /* public fields */
34
35  JDIMENSION cur_iMCU_row;      /* number of current iMCU row */
36  JDIMENSION rowgroup_ctr;      /* counts row groups received in iMCU row */
37  boolean suspended;            /* remember if we suspended output */
38  J_BUF_MODE pass_mode;         /* current operating mode */
39
40  /* If using just a strip buffer, this points to the entire set of buffers
41   * (we allocate one for each component).  In the full-image case, this
42   * points to the currently accessible strips of the virtual arrays.
43   */
44  JSAMPARRAY buffer[MAX_COMPONENTS];
45
46#ifdef FULL_MAIN_BUFFER_SUPPORTED
47  /* If using full-image storage, this array holds pointers to virtual-array
48   * control blocks for each component.  Unused if not full-image storage.
49   */
50  jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
51#endif
52} my_main_controller;
53
54typedef my_main_controller * my_main_ptr;
55
56
57/* Forward declarations */
58METHODDEF(void) process_data_simple_main
59        JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
60             JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
61#ifdef FULL_MAIN_BUFFER_SUPPORTED
62METHODDEF(void) process_data_buffer_main
63        JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
64             JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
65#endif
66
67
68/*
69 * Initialize for a processing pass.
70 */
71
72METHODDEF(void)
73start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
74{
75  my_main_ptr _main = (my_main_ptr) cinfo->main;
76
77  /* Do nothing in raw-data mode. */
78  if (cinfo->raw_data_in)
79    return;
80
81  _main->cur_iMCU_row = 0;      /* initialize counters */
82  _main->rowgroup_ctr = 0;
83  _main->suspended = FALSE;
84  _main->pass_mode = pass_mode; /* save mode for use by process_data */
85
86  switch (pass_mode) {
87  case JBUF_PASS_THRU:
88#ifdef FULL_MAIN_BUFFER_SUPPORTED
89    if (_main->whole_image[0] != NULL)
90      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
91#endif
92    _main->pub.process_data = process_data_simple_main;
93    break;
94#ifdef FULL_MAIN_BUFFER_SUPPORTED
95  case JBUF_SAVE_SOURCE:
96  case JBUF_CRANK_DEST:
97  case JBUF_SAVE_AND_PASS:
98    if (_main->whole_image[0] == NULL)
99      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
100    _main->pub.process_data = process_data_buffer_main;
101    break;
102#endif
103  default:
104    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
105    break;
106  }
107}
108
109
110/*
111 * Process some data.
112 * This routine handles the simple pass-through mode,
113 * where we have only a strip buffer.
114 */
115
116METHODDEF(void)
117process_data_simple_main (j_compress_ptr cinfo,
118                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
119                          JDIMENSION in_rows_avail)
120{
121  my_main_ptr _main = (my_main_ptr) cinfo->main;
122
123  while (_main->cur_iMCU_row < cinfo->total_iMCU_rows) {
124    /* Read input data if we haven't filled the main buffer yet */
125    if (_main->rowgroup_ctr < DCTSIZE)
126      (*cinfo->prep->pre_process_data) (cinfo,
127                                        input_buf, in_row_ctr, in_rows_avail,
128                                        _main->buffer, &_main->rowgroup_ctr,
129                                        (JDIMENSION) DCTSIZE);
130
131    /* If we don't have a full iMCU row buffered, return to application for
132     * more data.  Note that preprocessor will always pad to fill the iMCU row
133     * at the bottom of the image.
134     */
135    if (_main->rowgroup_ctr != DCTSIZE)
136      return;
137
138    /* Send the completed row to the compressor */
139    if (! (*cinfo->coef->compress_data) (cinfo, _main->buffer)) {
140      /* If compressor did not consume the whole row, then we must need to
141       * suspend processing and return to the application.  In this situation
142       * we pretend we didn't yet consume the last input row; otherwise, if
143       * it happened to be the last row of the image, the application would
144       * think we were done.
145       */
146      if (! _main->suspended) {
147        (*in_row_ctr)--;
148        _main->suspended = TRUE;
149      }
150      return;
151    }
152    /* We did finish the row.  Undo our little suspension hack if a previous
153     * call suspended; then mark the main buffer empty.
154     */
155    if (_main->suspended) {
156      (*in_row_ctr)++;
157      _main->suspended = FALSE;
158    }
159    _main->rowgroup_ctr = 0;
160    _main->cur_iMCU_row++;
161  }
162}
163
164
165#ifdef FULL_MAIN_BUFFER_SUPPORTED
166
167/*
168 * Process some data.
169 * This routine handles all of the modes that use a full-size buffer.
170 */
171
172METHODDEF(void)
173process_data_buffer_main (j_compress_ptr cinfo,
174                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
175                          JDIMENSION in_rows_avail)
176{
177  my_main_ptr _main = (my_main_ptr) cinfo->main;
178  int ci;
179  jpeg_component_info *compptr;
180  boolean writing = (_main->pass_mode != JBUF_CRANK_DEST);
181
182  while (_main->cur_iMCU_row < cinfo->total_iMCU_rows) {
183    /* Realign the virtual buffers if at the start of an iMCU row. */
184    if (_main->rowgroup_ctr == 0) {
185      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
186           ci++, compptr++) {
187        _main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
188          ((j_common_ptr) cinfo, _main->whole_image[ci],
189           _main->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE),
190           (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing);
191      }
192      /* In a read pass, pretend we just read some source data. */
193      if (! writing) {
194        *in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
195        _main->rowgroup_ctr = DCTSIZE;
196      }
197    }
198
199    /* If a write pass, read input data until the current iMCU row is full. */
200    /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
201    if (writing) {
202      (*cinfo->prep->pre_process_data) (cinfo,
203                                        input_buf, in_row_ctr, in_rows_avail,
204                                        _main->buffer, &_main->rowgroup_ctr,
205                                        (JDIMENSION) DCTSIZE);
206      /* Return to application if we need more data to fill the iMCU row. */
207      if (_main->rowgroup_ctr < DCTSIZE)
208        return;
209    }
210
211    /* Emit data, unless this is a sink-only pass. */
212    if (_main->pass_mode != JBUF_SAVE_SOURCE) {
213      if (! (*cinfo->coef->compress_data) (cinfo, _main->buffer)) {
214        /* If compressor did not consume the whole row, then we must need to
215         * suspend processing and return to the application.  In this situation
216         * we pretend we didn't yet consume the last input row; otherwise, if
217         * it happened to be the last row of the image, the application would
218         * think we were done.
219         */
220        if (! _main->suspended) {
221          (*in_row_ctr)--;
222          _main->suspended = TRUE;
223        }
224        return;
225      }
226      /* We did finish the row.  Undo our little suspension hack if a previous
227       * call suspended; then mark the main buffer empty.
228       */
229      if (_main->suspended) {
230        (*in_row_ctr)++;
231        _main->suspended = FALSE;
232      }
233    }
234
235    /* If get here, we are done with this iMCU row.  Mark buffer empty. */
236    _main->rowgroup_ctr = 0;
237    _main->cur_iMCU_row++;
238  }
239}
240
241#endif /* FULL_MAIN_BUFFER_SUPPORTED */
242
243
244/*
245 * Initialize main buffer controller.
246 */
247
248GLOBAL(void)
249jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
250{
251  my_main_ptr _main;
252  int ci;
253  jpeg_component_info *compptr;
254
255  _main = (my_main_ptr)
256    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
257                                SIZEOF(my_main_controller));
258  cinfo->main = (struct jpeg_c_main_controller *) _main;
259  _main->pub.start_pass = start_pass_main;
260
261  /* We don't need to create a buffer in raw-data mode. */
262  if (cinfo->raw_data_in)
263    return;
264
265  /* Create the buffer.  It holds downsampled data, so each component
266   * may be of a different size.
267   */
268  if (need_full_buffer) {
269#ifdef FULL_MAIN_BUFFER_SUPPORTED
270    /* Allocate a full-image virtual array for each component */
271    /* Note we pad the bottom to a multiple of the iMCU height */
272    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
273         ci++, compptr++) {
274      _main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
275        ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
276         compptr->width_in_blocks * DCTSIZE,
277         (JDIMENSION) jround_up((long) compptr->height_in_blocks,
278                                (long) compptr->v_samp_factor) * DCTSIZE,
279         (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
280    }
281#else
282    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
283#endif
284  } else {
285#ifdef FULL_MAIN_BUFFER_SUPPORTED
286    _main->whole_image[0] = NULL; /* flag for no virtual arrays */
287#endif
288    /* Allocate a strip buffer for each component */
289    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
290         ci++, compptr++) {
291      _main->buffer[ci] = (*cinfo->mem->alloc_sarray)
292        ((j_common_ptr) cinfo, JPOOL_IMAGE,
293         compptr->width_in_blocks * DCTSIZE,
294         (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
295    }
296  }
297}
298