1 /*
2 * jddiffct.c
3 *
4 * Copyright (C) 1994-1998, 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 [un]difference buffer controller for decompression.
9 * This controller is the top level of the lossless JPEG decompressor proper.
10 * The difference buffer lies between the entropy decoding and
11 * prediction/undifferencing steps. The undifference buffer lies between the
12 * prediction/undifferencing and scaling steps.
13 *
14 * In buffered-image mode, this controller is the interface between
15 * input-oriented processing and output-oriented processing.
16 */
17
18 #define JPEG_INTERNALS
19 #include "jinclude16.h"
20 #include "jpeglib16.h"
21 #include "jlossls16.h"
22
23
24 #ifdef D_LOSSLESS_SUPPORTED
25
26 /* Private buffer controller object */
27
28 typedef struct {
29 /* These variables keep track of the current location of the input side. */
30 /* cinfo->input_iMCU_row is also used for this. */
31 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */
32 unsigned int restart_rows_to_go; /* MCU-rows left in this restart interval */
33 unsigned int MCU_vert_offset; /* counts MCU rows within iMCU row */
34 unsigned int MCU_rows_per_iMCU_row; /* number of such rows needed */
35
36 /* The output side's location is represented by cinfo->output_iMCU_row. */
37
38 JDIFFARRAY diff_buf[MAX_COMPONENTS]; /* iMCU row of differences */
39 JDIFFARRAY undiff_buf[MAX_COMPONENTS]; /* iMCU row of undiff'd samples */
40
41 #ifdef D_MULTISCAN_FILES_SUPPORTED
42 /* In multi-pass modes, we need a virtual sample array for each component. */
43 jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
44 #endif
45 } d_diff_controller;
46
47 typedef d_diff_controller * d_diff_ptr;
48
49 /* Forward declarations */
50 METHODDEF(int) decompress_data
51 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
52 #ifdef D_MULTISCAN_FILES_SUPPORTED
53 METHODDEF(int) output_data
54 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
55 #endif
56
57
58 LOCAL(void)
start_iMCU_row(j_decompress_ptr cinfo)59 start_iMCU_row (j_decompress_ptr cinfo)
60 /* Reset within-iMCU-row counters for a new row (input side) */
61 {
62 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
63 d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;
64
65 /* In an interleaved scan, an MCU row is the same as an iMCU row.
66 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
67 * But at the bottom of the image, process only what's left.
68 */
69 if (cinfo->comps_in_scan > 1) {
70 diff->MCU_rows_per_iMCU_row = 1;
71 } else {
72 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
73 diff->MCU_rows_per_iMCU_row = (JDIMENSION)cinfo->cur_comp_info[0]->v_samp_factor;
74 else
75 diff->MCU_rows_per_iMCU_row = (JDIMENSION)cinfo->cur_comp_info[0]->last_row_height;
76 }
77
78 diff->MCU_ctr = 0;
79 diff->MCU_vert_offset = 0;
80 }
81
82
83 /*
84 * Initialize for an input processing pass.
85 */
86
87 METHODDEF(void)
start_input_pass(j_decompress_ptr cinfo)88 start_input_pass (j_decompress_ptr cinfo)
89 {
90 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
91 d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;
92
93 /* Check that the restart interval is an integer multiple of the number
94 * of MCU in an MCU-row.
95 */
96 if (cinfo->restart_interval % cinfo->MCUs_per_row != 0)
97 ERREXIT2(cinfo, JERR_BAD_RESTART,
98 (int)cinfo->restart_interval, (int)cinfo->MCUs_per_row);
99
100 /* Initialize restart counter */
101 diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;
102
103 cinfo->input_iMCU_row = 0;
104 start_iMCU_row(cinfo);
105 }
106
107
108 /*
109 * Check for a restart marker & resynchronize decoder, undifferencer.
110 * Returns FALSE if must suspend.
111 */
112
113 METHODDEF(boolean)
process_restart(j_decompress_ptr cinfo)114 process_restart (j_decompress_ptr cinfo)
115 {
116 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
117 d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;
118
119 if (! (*losslsd->entropy_process_restart) (cinfo))
120 return FALSE;
121
122 (*losslsd->predict_process_restart) (cinfo);
123
124 /* Reset restart counter */
125 diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;
126
127 return TRUE;
128 }
129
130
131 /*
132 * Initialize for an output processing pass.
133 */
134
135 METHODDEF(void)
start_output_pass(j_decompress_ptr cinfo)136 start_output_pass (j_decompress_ptr cinfo)
137 {
138 cinfo->output_iMCU_row = 0;
139 }
140
141
142 /*
143 * Decompress and return some data in the supplied buffer.
144 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
145 * Input and output must run in lockstep since we have only a one-MCU buffer.
146 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
147 *
148 * NB: output_buf contains a plane for each component in image,
149 * which we index according to the component's SOF position.
150 */
151
152 METHODDEF(int)
decompress_data(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)153 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
154 {
155 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
156 d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;
157 JDIMENSION MCU_col_num; /* index of current MCU within row */
158 JDIMENSION MCU_count; /* number of MCUs decoded */
159 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
160 int comp, ci, row, prev_row;
161 unsigned int yoffset;
162 jpeg_component_info *compptr;
163
164 /* Loop to process as much as one whole iMCU row */
165 for (yoffset = diff->MCU_vert_offset; yoffset < diff->MCU_rows_per_iMCU_row;
166 yoffset++) {
167
168 /* Process restart marker if needed; may have to suspend */
169 if (cinfo->restart_interval) {
170 if (diff->restart_rows_to_go == 0)
171 if (! process_restart(cinfo))
172 return JPEG_SUSPENDED;
173 }
174
175 MCU_col_num = diff->MCU_ctr;
176 /* Try to fetch an MCU-row (or remaining portion of suspended MCU-row). */
177 MCU_count =
178 (*losslsd->entropy_decode_mcus) (cinfo,
179 diff->diff_buf, yoffset, MCU_col_num,
180 cinfo->MCUs_per_row - MCU_col_num);
181 if (MCU_count != cinfo->MCUs_per_row - MCU_col_num) {
182 /* Suspension forced; update state counters and exit */
183 diff->MCU_vert_offset = yoffset;
184 diff->MCU_ctr += MCU_count;
185 return JPEG_SUSPENDED;
186 }
187
188 /* Account for restart interval (no-op if not using restarts) */
189 diff->restart_rows_to_go--;
190
191 /* Completed an MCU row, but perhaps not an iMCU row */
192 diff->MCU_ctr = 0;
193 }
194
195 /*
196 * Undifference and scale each scanline of the disassembled MCU-row
197 * separately. We do not process dummy samples at the end of a scanline
198 * or dummy rows at the end of the image.
199 */
200 for (comp = 0; comp < cinfo->comps_in_scan; comp++) {
201 compptr = cinfo->cur_comp_info[comp];
202 ci = compptr->component_index;
203 for (row = 0, prev_row = compptr->v_samp_factor - 1;
204 row < (cinfo->input_iMCU_row == last_iMCU_row ?
205 compptr->last_row_height : compptr->v_samp_factor);
206 prev_row = row, row++) {
207 (*losslsd->predict_undifference[ci]) (cinfo, ci,
208 diff->diff_buf[ci][row],
209 diff->undiff_buf[ci][prev_row],
210 diff->undiff_buf[ci][row],
211 compptr->width_in_data_units);
212 (*losslsd->scaler_scale) (cinfo, diff->undiff_buf[ci][row],
213 output_buf[ci][row],
214 compptr->width_in_data_units);
215 }
216 }
217
218 /* Completed the iMCU row, advance counters for next one.
219 *
220 * NB: output_data will increment output_iMCU_row.
221 * This counter is not needed for the single-pass case
222 * or the input side of the multi-pass case.
223 */
224 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
225 start_iMCU_row(cinfo);
226 return JPEG_ROW_COMPLETED;
227 }
228 /* Completed the scan */
229 (*cinfo->inputctl->finish_input_pass) (cinfo);
230 return JPEG_SCAN_COMPLETED;
231 }
232
233
234 /*
235 * Dummy consume-input routine for single-pass operation.
236 */
237
238 METHODDEF(int)
dummy_consume_data(j_decompress_ptr cinfo)239 dummy_consume_data (j_decompress_ptr cinfo)
240 {
241 return JPEG_SUSPENDED; /* Always indicate nothing was done */
242 }
243
244
245 #ifdef D_MULTISCAN_FILES_SUPPORTED
246
247 /*
248 * Consume input data and store it in the full-image sample buffer.
249 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
250 * ie, v_samp_factor rows for each component in the scan.
251 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
252 */
253
254 METHODDEF(int)
consume_data(j_decompress_ptr cinfo)255 consume_data (j_decompress_ptr cinfo)
256 {
257 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
258 d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;
259 /* JDIMENSION MCU_col_num; */ /* index of current MCU within row */
260 /* JDIMENSION MCU_count; */ /* number of MCUs decoded */
261 /* JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; */
262 int comp, ci /* , yoffset, row, prev_row */;
263 JSAMPARRAY buffer[MAX_COMPS_IN_SCAN];
264 jpeg_component_info *compptr;
265
266 /* Align the virtual buffers for the components used in this scan. */
267 for (comp = 0; comp < cinfo->comps_in_scan; comp++) {
268 compptr = cinfo->cur_comp_info[comp];
269 ci = compptr->component_index;
270 buffer[ci] = (*cinfo->mem->access_virt_sarray)
271 ((j_common_ptr) cinfo, diff->whole_image[ci],
272 cinfo->input_iMCU_row * (JDIMENSION)compptr->v_samp_factor,
273 (JDIMENSION) compptr->v_samp_factor, TRUE);
274 }
275
276 return decompress_data(cinfo, buffer);
277 }
278
279
280 /*
281 * Output some data from the full-image buffer sample in the multi-pass case.
282 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
283 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
284 *
285 * NB: output_buf contains a plane for each component in image.
286 */
287
288 METHODDEF(int)
output_data(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)289 output_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
290 {
291 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
292 d_diff_ptr diff = (d_diff_ptr) losslsd->diff_private;
293 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
294 int ci, samp_rows, row;
295 JSAMPARRAY buffer;
296 jpeg_component_info *compptr;
297
298 /* Force some input to be done if we are getting ahead of the input. */
299 while (cinfo->input_scan_number < cinfo->output_scan_number ||
300 (cinfo->input_scan_number == cinfo->output_scan_number &&
301 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
302 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
303 return JPEG_SUSPENDED;
304 }
305
306 /* OK, output from the virtual arrays. */
307 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
308 ci++, compptr++) {
309 /* Align the virtual buffer for this component. */
310 buffer = (*cinfo->mem->access_virt_sarray)
311 ((j_common_ptr) cinfo, diff->whole_image[ci],
312 cinfo->output_iMCU_row * (JDIMENSION)compptr->v_samp_factor,
313 (JDIMENSION) compptr->v_samp_factor, FALSE);
314
315 if (cinfo->output_iMCU_row < last_iMCU_row)
316 samp_rows = compptr->v_samp_factor;
317 else {
318 /* NB: can't use last_row_height here; it is input-side-dependent! */
319 samp_rows = (int)compptr->height_in_data_units % compptr->v_samp_factor;
320 if (samp_rows == 0) samp_rows = compptr->v_samp_factor;
321 }
322
323 for (row = 0; row < samp_rows; row++) {
324 MEMCOPY(output_buf[ci][row], buffer[row],
325 compptr->width_in_data_units * SIZEOF(JSAMPLE));
326 }
327 }
328
329 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
330 return JPEG_ROW_COMPLETED;
331 return JPEG_SCAN_COMPLETED;
332 }
333
334 #endif /* D_MULTISCAN_FILES_SUPPORTED */
335
336
337 /*
338 * Initialize difference buffer controller.
339 */
340
341 GLOBAL(void)
jinit_d_diff_controller(j_decompress_ptr cinfo,boolean need_full_buffer)342 jinit_d_diff_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
343 {
344 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
345 d_diff_ptr diff;
346 int ci;
347 jpeg_component_info *compptr;
348
349 diff = (d_diff_ptr)
350 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
351 SIZEOF(d_diff_controller));
352 losslsd->diff_private = (void *) diff;
353 losslsd->diff_start_input_pass = start_input_pass;
354 losslsd->pub.start_output_pass = start_output_pass;
355
356 /* Create the [un]difference buffers. */
357 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
358 ci++, compptr++) {
359 diff->diff_buf[ci] = (*cinfo->mem->alloc_darray)
360 ((j_common_ptr) cinfo, JPOOL_IMAGE,
361 (JDIMENSION) jround_up((long) compptr->width_in_data_units,
362 (long) compptr->h_samp_factor),
363 (JDIMENSION) compptr->v_samp_factor);
364 diff->undiff_buf[ci] = (*cinfo->mem->alloc_darray)
365 ((j_common_ptr) cinfo, JPOOL_IMAGE,
366 (JDIMENSION) jround_up((long) compptr->width_in_data_units,
367 (long) compptr->h_samp_factor),
368 (JDIMENSION) compptr->v_samp_factor);
369 }
370
371 if (need_full_buffer) {
372 #ifdef D_MULTISCAN_FILES_SUPPORTED
373 /* Allocate a full-image virtual array for each component. */
374 int access_rows;
375
376 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
377 ci++, compptr++) {
378 access_rows = compptr->v_samp_factor;
379 diff->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
380 ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
381 (JDIMENSION) jround_up((long) compptr->width_in_data_units,
382 (long) compptr->h_samp_factor),
383 (JDIMENSION) jround_up((long) compptr->height_in_data_units,
384 (long) compptr->v_samp_factor),
385 (JDIMENSION) access_rows);
386 }
387 losslsd->pub.consume_data = consume_data;
388 losslsd->pub.decompress_data = output_data;
389 #else
390 ERREXIT(cinfo, JERR_NOT_COMPILED);
391 #endif
392 } else {
393 losslsd->pub.consume_data = dummy_consume_data;
394 losslsd->pub.decompress_data = decompress_data;
395 diff->whole_image[0] = NULL; /* flag for no virtual arrays */
396 }
397 }
398
399 #endif /* D_LOSSLESS_SUPPORTED */
400