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
29 typedef 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
51 typedef my_main_controller * my_main_ptr;
52
53
54 /* Forward declarations */
55 METHODDEF(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
59 METHODDEF(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
69 METHODDEF(void)
70 start_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
113 METHODDEF(void)
114 process_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
169 METHODDEF(void)
170 process_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
247 GLOBAL(void)
248 jinit_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 }