1 /*
2 * jcmainct.c
3 *
4 * Copyright (C) 1994, 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
28 typedef struct {
29 struct jpeg_c_main_controller pub; /* public fields */
30
31 JDIMENSION cur_mcu_row; /* number of current iMCU row */
32 JDIMENSION rowgroup_ctr; /* counts row groups received in iMCU row */
33 JDIMENSION mcu_ctr; /* counts MCUs output from current 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
start_pass_main(j_compress_ptr cinfo,J_BUF_MODE pass_mode)70 start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
71 {
72 my_main_ptr main = (my_main_ptr) cinfo->main;
73
74 /* Do nothing in raw-data mode. */
75 if (cinfo->raw_data_in)
76 return;
77
78 main->cur_mcu_row = 0; /* initialize counters */
79 main->rowgroup_ctr = 0;
80 main->mcu_ctr = 0;
81 main->suspended = FALSE;
82 main->pass_mode = pass_mode; /* save mode for use by process_data */
83
84 switch (pass_mode) {
85 case JBUF_PASS_THRU:
86 #ifdef FULL_MAIN_BUFFER_SUPPORTED
87 if (main->whole_image[0] != NULL)
88 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
89 #endif
90 main->pub.process_data = process_data_simple_main;
91 break;
92 #ifdef FULL_MAIN_BUFFER_SUPPORTED
93 case JBUF_SAVE_SOURCE:
94 case JBUF_CRANK_DEST:
95 case JBUF_SAVE_AND_PASS:
96 if (main->whole_image[0] == NULL)
97 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
98 main->pub.process_data = process_data_buffer_main;
99 break;
100 #endif
101 default:
102 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
103 break;
104 }
105 }
106
107
108 /*
109 * Process some data.
110 * This routine handles the simple pass-through mode,
111 * where we have only a strip buffer.
112 */
113
114 METHODDEF void
process_data_simple_main(j_compress_ptr cinfo,JSAMPARRAY input_buf,JDIMENSION * in_row_ctr,JDIMENSION in_rows_avail)115 process_data_simple_main (j_compress_ptr cinfo,
116 JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
117 JDIMENSION in_rows_avail)
118 {
119 my_main_ptr main = (my_main_ptr) cinfo->main;
120
121 while (main->cur_mcu_row < cinfo->total_iMCU_rows) {
122 /* Read input data if we haven't filled the main buffer yet */
123 if (main->rowgroup_ctr < DCTSIZE)
124 (*cinfo->prep->pre_process_data) (cinfo,
125 input_buf, in_row_ctr, in_rows_avail,
126 main->buffer, &main->rowgroup_ctr,
127 (JDIMENSION) DCTSIZE);
128
129 /* If we don't have a full iMCU row buffered, return to application for
130 * more data. Note that preprocessor will always pad to fill the iMCU row
131 * at the bottom of the image.
132 */
133 if (main->rowgroup_ctr != DCTSIZE)
134 return;
135
136 /* Send the completed row to the compressor */
137 (*cinfo->coef->compress_data) (cinfo, main->buffer, &main->mcu_ctr);
138
139 /* If compressor did not consume the whole row, then we must need to
140 * suspend processing and return to the application. In this situation
141 * we pretend we didn't yet consume the last input row; otherwise, if
142 * it happened to be the last row of the image, the application would
143 * think we were done.
144 */
145 if (main->mcu_ctr < cinfo->MCUs_per_row) {
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->mcu_ctr = 0;
160 main->rowgroup_ctr = 0;
161 main->cur_mcu_row++;
162 }
163 }
164
165
166 #ifdef FULL_MAIN_BUFFER_SUPPORTED
167
168 /*
169 * Process some data.
170 * This routine handles all of the modes that use a full-size buffer.
171 */
172
173 METHODDEF void
process_data_buffer_main(j_compress_ptr cinfo,JSAMPARRAY input_buf,JDIMENSION * in_row_ctr,JDIMENSION in_rows_avail)174 process_data_buffer_main (j_compress_ptr cinfo,
175 JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
176 JDIMENSION in_rows_avail)
177 {
178 my_main_ptr main = (my_main_ptr) cinfo->main;
179 int ci;
180 jpeg_component_info *compptr;
181 boolean writing = (main->pass_mode != JBUF_CRANK_DEST);
182
183 while (main->cur_mcu_row < cinfo->total_iMCU_rows) {
184 /* Realign the virtual buffers if at the start of an iMCU row. */
185 if (main->rowgroup_ctr == 0) {
186 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
187 ci++, compptr++) {
188 main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
189 ((j_common_ptr) cinfo, main->whole_image[ci],
190 main->cur_mcu_row * (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 (*cinfo->coef->compress_data) (cinfo, main->buffer, &main->mcu_ctr);
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->mcu_ctr < cinfo->MCUs_per_row) {
221 if (! main->suspended) {
222 (*in_row_ctr)--;
223 main->suspended = TRUE;
224 }
225 return;
226 }
227 /* We did finish the row. Undo our little suspension hack if a previous
228 * call suspended; then mark the main buffer empty.
229 */
230 if (main->suspended) {
231 (*in_row_ctr)++;
232 main->suspended = FALSE;
233 }
234 }
235
236 /* If get here, we are done with this iMCU row. Mark buffer empty. */
237 main->mcu_ctr = 0;
238 main->rowgroup_ctr = 0;
239 main->cur_mcu_row++;
240 }
241 }
242
243 #endif /* FULL_MAIN_BUFFER_SUPPORTED */
244
245
246 /*
247 * Initialize main buffer controller.
248 */
249
250 GLOBAL void
jinit_c_main_controller(j_compress_ptr cinfo,boolean need_full_buffer)251 jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
252 {
253 my_main_ptr main;
254 int ci;
255 jpeg_component_info *compptr;
256
257 main = (my_main_ptr)
258 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
259 SIZEOF(my_main_controller));
260 cinfo->main = (struct jpeg_c_main_controller *) main;
261 main->pub.start_pass = start_pass_main;
262
263 /* We don't need to create a buffer in raw-data mode. */
264 if (cinfo->raw_data_in)
265 return;
266
267 /* Create the buffer. It holds downsampled data, so each component
268 * may be of a different size.
269 */
270 if (need_full_buffer) {
271 #ifdef FULL_MAIN_BUFFER_SUPPORTED
272 /* Allocate a full-image virtual array for each component */
273 /* Note we implicitly pad the bottom to a multiple of the iMCU height */
274 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
275 ci++, compptr++) {
276 main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
277 ((j_common_ptr) cinfo, JPOOL_IMAGE,
278 compptr->width_in_blocks * DCTSIZE,
279 compptr->height_in_blocks * DCTSIZE,
280 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
281 }
282 #else
283 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
284 #endif
285 } else {
286 #ifdef FULL_MAIN_BUFFER_SUPPORTED
287 main->whole_image[0] = NULL; /* flag for no virtual arrays */
288 #endif
289 /* Allocate a strip buffer for each component */
290 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
291 ci++, compptr++) {
292 main->buffer[ci] = (*cinfo->mem->alloc_sarray)
293 ((j_common_ptr) cinfo, JPOOL_IMAGE,
294 compptr->width_in_blocks * DCTSIZE,
295 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
296 }
297 }
298 }
299