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
28 typedef 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
50 typedef my_main_controller * my_main_ptr;
51
52
53 /* Forward declarations */
54 METHODDEF(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
58 METHODDEF(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
68 METHODDEF(void)
69 start_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
112 METHODDEF(void)
113 process_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 < (JDIMENSION) cinfo->min_DCT_v_scaled_size)
122 (*cinfo->prep->pre_process_data) (cinfo,
123 input_buf, in_row_ctr, in_rows_avail,
124 main->buffer, &main->rowgroup_ctr,
125 (JDIMENSION) cinfo->min_DCT_v_scaled_size);
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 != (JDIMENSION) cinfo->min_DCT_v_scaled_size)
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
168 METHODDEF(void)
169 process_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
244 GLOBAL(void)
245 jinit_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 * compptr->DCT_h_scaled_size,
273 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
274 (long) compptr->v_samp_factor) * DCTSIZE,
275 (JDIMENSION) (compptr->v_samp_factor * compptr->DCT_v_scaled_size));
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 * compptr->DCT_h_scaled_size,
290 (JDIMENSION) (compptr->v_samp_factor * compptr->DCT_v_scaled_size));
291 }
292 }
293 }