1/*
2 * jcmainct.c
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * Modified 2003-2012 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains the main buffer controller for compression.
10 * The main buffer lies between the pre-processor and the JPEG
11 * compressor proper; it holds downsampled data in the JPEG colorspace.
12 */
13
14#define JPEG_INTERNALS
15#include "jinclude.h"
16#include "jpeglib.h"
17
18
19/* Note: currently, there is no operating mode in which a full-image buffer
20 * is needed at this step.  If there were, that mode could not be used with
21 * "raw data" input, since this module is bypassed in that case.  However,
22 * we've left the code here for possible use in special applications.
23 */
24#undef FULL_MAIN_BUFFER_SUPPORTED
25
26
27/* Private buffer controller object */
28
29typedef struct {
30  struct jpeg_c_main_controller pub; /* public fields */
31
32  JDIMENSION cur_iMCU_row;	/* number of current iMCU row */
33  JDIMENSION rowgroup_ctr;	/* counts row groups received in iMCU row */
34  boolean suspended;		/* remember if we suspended output */
35  J_BUF_MODE pass_mode;		/* current operating mode */
36
37  /* If using just a strip buffer, this points to the entire set of buffers
38   * (we allocate one for each component).  In the full-image case, this
39   * points to the currently accessible strips of the virtual arrays.
40   */
41  JSAMPARRAY buffer[MAX_COMPONENTS];
42
43#ifdef FULL_MAIN_BUFFER_SUPPORTED
44  /* If using full-image storage, this array holds pointers to virtual-array
45   * control blocks for each component.  Unused if not full-image storage.
46   */
47  jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
48#endif
49} my_main_controller;
50
51typedef my_main_controller * my_main_ptr;
52
53
54/* Forward declarations */
55METHODDEF(void) process_data_simple_main
56        JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
57             JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
58#ifdef FULL_MAIN_BUFFER_SUPPORTED
59METHODDEF(void) process_data_buffer_main
60        JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
61             JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
62#endif
63
64
65/*
66 * Initialize for a processing pass.
67 */
68
69METHODDEF(void)
70start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
71{
72  my_main_ptr mainp = (my_main_ptr) cinfo->main;
73
74  /* Do nothing in raw-data mode. */
75  if (cinfo->raw_data_in)
76    return;
77
78  mainp->cur_iMCU_row = 0;	/* initialize counters */
79  mainp->rowgroup_ctr = 0;
80  mainp->suspended = FALSE;
81  mainp->pass_mode = pass_mode;	/* save mode for use by process_data */
82
83  switch (pass_mode) {
84  case JBUF_PASS_THRU:
85#ifdef FULL_MAIN_BUFFER_SUPPORTED
86    if (mainp->whole_image[0] != NULL)
87      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
88#endif
89    mainp->pub.process_data = process_data_simple_main;
90    break;
91#ifdef FULL_MAIN_BUFFER_SUPPORTED
92  case JBUF_SAVE_SOURCE:
93  case JBUF_CRANK_DEST:
94  case JBUF_SAVE_AND_PASS:
95    if (mainp->whole_image[0] == NULL)
96      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
97    mainp->pub.process_data = process_data_buffer_main;
98    break;
99#endif
100  default:
101    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
102    break;
103  }
104}
105
106
107/*
108 * Process some data.
109 * This routine handles the simple pass-through mode,
110 * where we have only a strip buffer.
111 */
112
113METHODDEF(void)
114process_data_simple_main (j_compress_ptr cinfo,
115                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
116                          JDIMENSION in_rows_avail)
117{
118  my_main_ptr mainp = (my_main_ptr) cinfo->main;
119
120  while (mainp->cur_iMCU_row < cinfo->total_iMCU_rows) {
121    /* Read input data if we haven't filled the main buffer yet */
122    if (mainp->rowgroup_ctr < (JDIMENSION) cinfo->min_DCT_v_scaled_size)
123      (*cinfo->prep->pre_process_data) (cinfo,
124                                        input_buf, in_row_ctr, in_rows_avail,
125                                        mainp->buffer, &mainp->rowgroup_ctr,
126                                        (JDIMENSION) cinfo->min_DCT_v_scaled_size);
127
128    /* If we don't have a full iMCU row buffered, return to application for
129     * more data.  Note that preprocessor will always pad to fill the iMCU row
130     * at the bottom of the image.
131     */
132    if (mainp->rowgroup_ctr != (JDIMENSION) cinfo->min_DCT_v_scaled_size)
133      return;
134
135    /* Send the completed row to the compressor */
136    if (! (*cinfo->coef->compress_data) (cinfo, mainp->buffer)) {
137      /* If compressor did not consume the whole row, then we must need to
138       * suspend processing and return to the application.  In this situation
139       * we pretend we didn't yet consume the last input row; otherwise, if
140       * it happened to be the last row of the image, the application would
141       * think we were done.
142       */
143      if (! mainp->suspended) {
144        (*in_row_ctr)--;
145        mainp->suspended = TRUE;
146      }
147      return;
148    }
149    /* We did finish the row.  Undo our little suspension hack if a previous
150     * call suspended; then mark the main buffer empty.
151     */
152    if (mainp->suspended) {
153      (*in_row_ctr)++;
154      mainp->suspended = FALSE;
155    }
156    mainp->rowgroup_ctr = 0;
157    mainp->cur_iMCU_row++;
158  }
159}
160
161
162#ifdef FULL_MAIN_BUFFER_SUPPORTED
163
164/*
165 * Process some data.
166 * This routine handles all of the modes that use a full-size buffer.
167 */
168
169METHODDEF(void)
170process_data_buffer_main (j_compress_ptr cinfo,
171                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
172                          JDIMENSION in_rows_avail)
173{
174  my_main_ptr mainp = (my_main_ptr) cinfo->main;
175  int ci;
176  jpeg_component_info *compptr;
177  boolean writing = (mainp->pass_mode != JBUF_CRANK_DEST);
178
179  while (mainp->cur_iMCU_row < cinfo->total_iMCU_rows) {
180    /* Realign the virtual buffers if at the start of an iMCU row. */
181    if (mainp->rowgroup_ctr == 0) {
182      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
183           ci++, compptr++) {
184        mainp->buffer[ci] = (*cinfo->mem->access_virt_sarray)
185          ((j_common_ptr) cinfo, mainp->whole_image[ci], mainp->cur_iMCU_row *
186           ((JDIMENSION) (compptr->v_samp_factor * cinfo->min_DCT_v_scaled_size)),
187           (JDIMENSION) (compptr->v_samp_factor * cinfo->min_DCT_v_scaled_size),
188           writing);
189      }
190      /* In a read pass, pretend we just read some source data. */
191      if (! writing) {
192        *in_row_ctr += (JDIMENSION)
193          (cinfo->max_v_samp_factor * cinfo->min_DCT_v_scaled_size);
194        mainp->rowgroup_ctr = (JDIMENSION) cinfo->min_DCT_v_scaled_size;
195      }
196    }
197
198    /* If a write pass, read input data until the current iMCU row is full. */
199    /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
200    if (writing) {
201      (*cinfo->prep->pre_process_data) (cinfo,
202                                        input_buf, in_row_ctr, in_rows_avail,
203                                        mainp->buffer, &mainp->rowgroup_ctr,
204                                        (JDIMENSION) cinfo->min_DCT_v_scaled_size);
205      /* Return to application if we need more data to fill the iMCU row. */
206      if (mainp->rowgroup_ctr < (JDIMENSION) cinfo->min_DCT_v_scaled_size)
207        return;
208    }
209
210    /* Emit data, unless this is a sink-only pass. */
211    if (mainp->pass_mode != JBUF_SAVE_SOURCE) {
212      if (! (*cinfo->coef->compress_data) (cinfo, mainp->buffer)) {
213        /* If compressor did not consume the whole row, then we must need to
214         * suspend processing and return to the application.  In this situation
215         * we pretend we didn't yet consume the last input row; otherwise, if
216         * it happened to be the last row of the image, the application would
217         * think we were done.
218         */
219        if (! mainp->suspended) {
220          (*in_row_ctr)--;
221          mainp->suspended = TRUE;
222        }
223        return;
224      }
225      /* We did finish the row.  Undo our little suspension hack if a previous
226       * call suspended; then mark the main buffer empty.
227       */
228      if (mainp->suspended) {
229        (*in_row_ctr)++;
230        mainp->suspended = FALSE;
231      }
232    }
233
234    /* If get here, we are done with this iMCU row.  Mark buffer empty. */
235    mainp->rowgroup_ctr = 0;
236    mainp->cur_iMCU_row++;
237  }
238}
239
240#endif /* FULL_MAIN_BUFFER_SUPPORTED */
241
242
243/*
244 * Initialize main buffer controller.
245 */
246
247GLOBAL(void)
248jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
249{
250  my_main_ptr mainp;
251  int ci;
252  jpeg_component_info *compptr;
253
254  mainp = (my_main_ptr)
255    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
256                                SIZEOF(my_main_controller));
257  cinfo->main = &mainp->pub;
258  mainp->pub.start_pass = start_pass_main;
259
260  /* We don't need to create a buffer in raw-data mode. */
261  if (cinfo->raw_data_in)
262    return;
263
264  /* Create the buffer.  It holds downsampled data, so each component
265   * may be of a different size.
266   */
267  if (need_full_buffer) {
268#ifdef FULL_MAIN_BUFFER_SUPPORTED
269    /* Allocate a full-image virtual array for each component */
270    /* Note we pad the bottom to a multiple of the iMCU height */
271    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
272         ci++, compptr++) {
273      mainp->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
274        ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
275         compptr->width_in_blocks * ((JDIMENSION) compptr->DCT_h_scaled_size),
276         ((JDIMENSION) jround_up((long) compptr->height_in_blocks,
277                                 (long) compptr->v_samp_factor)) *
278         ((JDIMENSION) cinfo->min_DCT_v_scaled_size),
279         (JDIMENSION) (compptr->v_samp_factor * compptr->DCT_v_scaled_size));
280    }
281#else
282    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
283#endif
284  } else {
285#ifdef FULL_MAIN_BUFFER_SUPPORTED
286    mainp->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      mainp->buffer[ci] = (*cinfo->mem->alloc_sarray)
292        ((j_common_ptr) cinfo, JPOOL_IMAGE,
293         compptr->width_in_blocks * ((JDIMENSION) compptr->DCT_h_scaled_size),
294         (JDIMENSION) (compptr->v_samp_factor * compptr->DCT_v_scaled_size));
295    }
296  }
297}
298