Line data Source code
1 : /*
2 : * jccoefct.c
3 : *
4 : * This file was part of the Independent JPEG Group's software:
5 : * Copyright (C) 1994-1997, Thomas G. Lane.
6 : * It was modified by The libjpeg-turbo Project to include only code and
7 : * information relevant to libjpeg-turbo.
8 : * For conditions of distribution and use, see the accompanying README.ijg
9 : * file.
10 : *
11 : * This file contains the coefficient buffer controller for compression.
12 : * This controller is the top level of the JPEG compressor proper.
13 : * The coefficient buffer lies between forward-DCT and entropy encoding steps.
14 : */
15 :
16 : #define JPEG_INTERNALS
17 : #include "jinclude.h"
18 : #include "jpeglib.h"
19 :
20 :
21 : /* We use a full-image coefficient buffer when doing Huffman optimization,
22 : * and also for writing multiple-scan JPEG files. In all cases, the DCT
23 : * step is run during the first pass, and subsequent passes need only read
24 : * the buffered coefficients.
25 : */
26 : #ifdef ENTROPY_OPT_SUPPORTED
27 : #define FULL_COEF_BUFFER_SUPPORTED
28 : #else
29 : #ifdef C_MULTISCAN_FILES_SUPPORTED
30 : #define FULL_COEF_BUFFER_SUPPORTED
31 : #endif
32 : #endif
33 :
34 :
35 : /* Private buffer controller object */
36 :
37 : typedef struct {
38 : struct jpeg_c_coef_controller pub; /* public fields */
39 :
40 : JDIMENSION iMCU_row_num; /* iMCU row # within image */
41 : JDIMENSION mcu_ctr; /* counts MCUs processed in current row */
42 : int MCU_vert_offset; /* counts MCU rows within iMCU row */
43 : int MCU_rows_per_iMCU_row; /* number of such rows needed */
44 :
45 : /* For single-pass compression, it's sufficient to buffer just one MCU
46 : * (although this may prove a bit slow in practice). We allocate a
47 : * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each
48 : * MCU constructed and sent. In multi-pass modes, this array points to the
49 : * current MCU's blocks within the virtual arrays.
50 : */
51 : JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
52 :
53 : /* In multi-pass modes, we need a virtual block array for each component. */
54 : jvirt_barray_ptr whole_image[MAX_COMPONENTS];
55 : } my_coef_controller;
56 :
57 : typedef my_coef_controller *my_coef_ptr;
58 :
59 :
60 : /* Forward declarations */
61 : METHODDEF(boolean) compress_data
62 : (j_compress_ptr cinfo, JSAMPIMAGE input_buf);
63 : #ifdef FULL_COEF_BUFFER_SUPPORTED
64 : METHODDEF(boolean) compress_first_pass
65 : (j_compress_ptr cinfo, JSAMPIMAGE input_buf);
66 : METHODDEF(boolean) compress_output
67 : (j_compress_ptr cinfo, JSAMPIMAGE input_buf);
68 : #endif
69 :
70 :
71 : LOCAL(void)
72 0 : start_iMCU_row (j_compress_ptr cinfo)
73 : /* Reset within-iMCU-row counters for a new row */
74 : {
75 0 : my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
76 :
77 : /* In an interleaved scan, an MCU row is the same as an iMCU row.
78 : * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
79 : * But at the bottom of the image, process only what's left.
80 : */
81 0 : if (cinfo->comps_in_scan > 1) {
82 0 : coef->MCU_rows_per_iMCU_row = 1;
83 : } else {
84 0 : if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
85 0 : coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
86 : else
87 0 : coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
88 : }
89 :
90 0 : coef->mcu_ctr = 0;
91 0 : coef->MCU_vert_offset = 0;
92 0 : }
93 :
94 :
95 : /*
96 : * Initialize for a processing pass.
97 : */
98 :
99 : METHODDEF(void)
100 0 : start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
101 : {
102 0 : my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
103 :
104 0 : coef->iMCU_row_num = 0;
105 0 : start_iMCU_row(cinfo);
106 :
107 0 : switch (pass_mode) {
108 : case JBUF_PASS_THRU:
109 0 : if (coef->whole_image[0] != NULL)
110 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
111 0 : coef->pub.compress_data = compress_data;
112 0 : break;
113 : #ifdef FULL_COEF_BUFFER_SUPPORTED
114 : case JBUF_SAVE_AND_PASS:
115 0 : if (coef->whole_image[0] == NULL)
116 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
117 0 : coef->pub.compress_data = compress_first_pass;
118 0 : break;
119 : case JBUF_CRANK_DEST:
120 0 : if (coef->whole_image[0] == NULL)
121 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
122 0 : coef->pub.compress_data = compress_output;
123 0 : break;
124 : #endif
125 : default:
126 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
127 0 : break;
128 : }
129 0 : }
130 :
131 :
132 : /*
133 : * Process some data in the single-pass case.
134 : * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
135 : * per call, ie, v_samp_factor block rows for each component in the image.
136 : * Returns TRUE if the iMCU row is completed, FALSE if suspended.
137 : *
138 : * NB: input_buf contains a plane for each component in image,
139 : * which we index according to the component's SOF position.
140 : */
141 :
142 : METHODDEF(boolean)
143 0 : compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
144 : {
145 0 : my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
146 : JDIMENSION MCU_col_num; /* index of current MCU within row */
147 0 : JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
148 0 : JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
149 : int blkn, bi, ci, yindex, yoffset, blockcnt;
150 : JDIMENSION ypos, xpos;
151 : jpeg_component_info *compptr;
152 :
153 : /* Loop to write as much as one whole iMCU row */
154 0 : for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
155 0 : yoffset++) {
156 0 : for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;
157 0 : MCU_col_num++) {
158 : /* Determine where data comes from in input_buf and do the DCT thing.
159 : * Each call on forward_DCT processes a horizontal row of DCT blocks
160 : * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks
161 : * sequentially. Dummy blocks at the right or bottom edge are filled in
162 : * specially. The data in them does not matter for image reconstruction,
163 : * so we fill them with values that will encode to the smallest amount of
164 : * data, viz: all zeroes in the AC entries, DC entries equal to previous
165 : * block's DC value. (Thanks to Thomas Kinsman for this idea.)
166 : */
167 0 : blkn = 0;
168 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
169 0 : compptr = cinfo->cur_comp_info[ci];
170 0 : blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
171 0 : : compptr->last_col_width;
172 0 : xpos = MCU_col_num * compptr->MCU_sample_width;
173 0 : ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */
174 0 : for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
175 0 : if (coef->iMCU_row_num < last_iMCU_row ||
176 0 : yoffset+yindex < compptr->last_row_height) {
177 0 : (*cinfo->fdct->forward_DCT) (cinfo, compptr,
178 0 : input_buf[compptr->component_index],
179 : coef->MCU_buffer[blkn],
180 : ypos, xpos, (JDIMENSION) blockcnt);
181 0 : if (blockcnt < compptr->MCU_width) {
182 : /* Create some dummy blocks at the right edge of the image. */
183 0 : jzero_far((void *) coef->MCU_buffer[blkn + blockcnt],
184 0 : (compptr->MCU_width - blockcnt) * sizeof(JBLOCK));
185 0 : for (bi = blockcnt; bi < compptr->MCU_width; bi++) {
186 0 : coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0];
187 : }
188 : }
189 : } else {
190 : /* Create a row of dummy blocks at the bottom of the image. */
191 0 : jzero_far((void *) coef->MCU_buffer[blkn],
192 0 : compptr->MCU_width * sizeof(JBLOCK));
193 0 : for (bi = 0; bi < compptr->MCU_width; bi++) {
194 0 : coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0];
195 : }
196 : }
197 0 : blkn += compptr->MCU_width;
198 0 : ypos += DCTSIZE;
199 : }
200 : }
201 : /* Try to write the MCU. In event of a suspension failure, we will
202 : * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
203 : */
204 0 : if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
205 : /* Suspension forced; update state counters and exit */
206 0 : coef->MCU_vert_offset = yoffset;
207 0 : coef->mcu_ctr = MCU_col_num;
208 0 : return FALSE;
209 : }
210 : }
211 : /* Completed an MCU row, but perhaps not an iMCU row */
212 0 : coef->mcu_ctr = 0;
213 : }
214 : /* Completed the iMCU row, advance counters for next one */
215 0 : coef->iMCU_row_num++;
216 0 : start_iMCU_row(cinfo);
217 0 : return TRUE;
218 : }
219 :
220 :
221 : #ifdef FULL_COEF_BUFFER_SUPPORTED
222 :
223 : /*
224 : * Process some data in the first pass of a multi-pass case.
225 : * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
226 : * per call, ie, v_samp_factor block rows for each component in the image.
227 : * This amount of data is read from the source buffer, DCT'd and quantized,
228 : * and saved into the virtual arrays. We also generate suitable dummy blocks
229 : * as needed at the right and lower edges. (The dummy blocks are constructed
230 : * in the virtual arrays, which have been padded appropriately.) This makes
231 : * it possible for subsequent passes not to worry about real vs. dummy blocks.
232 : *
233 : * We must also emit the data to the entropy encoder. This is conveniently
234 : * done by calling compress_output() after we've loaded the current strip
235 : * of the virtual arrays.
236 : *
237 : * NB: input_buf contains a plane for each component in image. All
238 : * components are DCT'd and loaded into the virtual arrays in this pass.
239 : * However, it may be that only a subset of the components are emitted to
240 : * the entropy encoder during this first pass; be careful about looking
241 : * at the scan-dependent variables (MCU dimensions, etc).
242 : */
243 :
244 : METHODDEF(boolean)
245 0 : compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
246 : {
247 0 : my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
248 0 : JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
249 : JDIMENSION blocks_across, MCUs_across, MCUindex;
250 : int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
251 : JCOEF lastDC;
252 : jpeg_component_info *compptr;
253 : JBLOCKARRAY buffer;
254 : JBLOCKROW thisblockrow, lastblockrow;
255 :
256 0 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
257 0 : ci++, compptr++) {
258 : /* Align the virtual buffer for this component. */
259 0 : buffer = (*cinfo->mem->access_virt_barray)
260 : ((j_common_ptr) cinfo, coef->whole_image[ci],
261 0 : coef->iMCU_row_num * compptr->v_samp_factor,
262 0 : (JDIMENSION) compptr->v_samp_factor, TRUE);
263 : /* Count non-dummy DCT block rows in this iMCU row. */
264 0 : if (coef->iMCU_row_num < last_iMCU_row)
265 0 : block_rows = compptr->v_samp_factor;
266 : else {
267 : /* NB: can't use last_row_height here, since may not be set! */
268 0 : block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
269 0 : if (block_rows == 0) block_rows = compptr->v_samp_factor;
270 : }
271 0 : blocks_across = compptr->width_in_blocks;
272 0 : h_samp_factor = compptr->h_samp_factor;
273 : /* Count number of dummy blocks to be added at the right margin. */
274 0 : ndummy = (int) (blocks_across % h_samp_factor);
275 0 : if (ndummy > 0)
276 0 : ndummy = h_samp_factor - ndummy;
277 : /* Perform DCT for all non-dummy blocks in this iMCU row. Each call
278 : * on forward_DCT processes a complete horizontal row of DCT blocks.
279 : */
280 0 : for (block_row = 0; block_row < block_rows; block_row++) {
281 0 : thisblockrow = buffer[block_row];
282 0 : (*cinfo->fdct->forward_DCT) (cinfo, compptr,
283 0 : input_buf[ci], thisblockrow,
284 0 : (JDIMENSION) (block_row * DCTSIZE),
285 : (JDIMENSION) 0, blocks_across);
286 0 : if (ndummy > 0) {
287 : /* Create dummy blocks at the right edge of the image. */
288 0 : thisblockrow += blocks_across; /* => first dummy block */
289 0 : jzero_far((void *) thisblockrow, ndummy * sizeof(JBLOCK));
290 0 : lastDC = thisblockrow[-1][0];
291 0 : for (bi = 0; bi < ndummy; bi++) {
292 0 : thisblockrow[bi][0] = lastDC;
293 : }
294 : }
295 : }
296 : /* If at end of image, create dummy block rows as needed.
297 : * The tricky part here is that within each MCU, we want the DC values
298 : * of the dummy blocks to match the last real block's DC value.
299 : * This squeezes a few more bytes out of the resulting file...
300 : */
301 0 : if (coef->iMCU_row_num == last_iMCU_row) {
302 0 : blocks_across += ndummy; /* include lower right corner */
303 0 : MCUs_across = blocks_across / h_samp_factor;
304 0 : for (block_row = block_rows; block_row < compptr->v_samp_factor;
305 0 : block_row++) {
306 0 : thisblockrow = buffer[block_row];
307 0 : lastblockrow = buffer[block_row-1];
308 0 : jzero_far((void *) thisblockrow,
309 : (size_t) (blocks_across * sizeof(JBLOCK)));
310 0 : for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) {
311 0 : lastDC = lastblockrow[h_samp_factor-1][0];
312 0 : for (bi = 0; bi < h_samp_factor; bi++) {
313 0 : thisblockrow[bi][0] = lastDC;
314 : }
315 0 : thisblockrow += h_samp_factor; /* advance to next MCU in row */
316 0 : lastblockrow += h_samp_factor;
317 : }
318 : }
319 : }
320 : }
321 : /* NB: compress_output will increment iMCU_row_num if successful.
322 : * A suspension return will result in redoing all the work above next time.
323 : */
324 :
325 : /* Emit data to the entropy encoder, sharing code with subsequent passes */
326 0 : return compress_output(cinfo, input_buf);
327 : }
328 :
329 :
330 : /*
331 : * Process some data in subsequent passes of a multi-pass case.
332 : * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
333 : * per call, ie, v_samp_factor block rows for each component in the scan.
334 : * The data is obtained from the virtual arrays and fed to the entropy coder.
335 : * Returns TRUE if the iMCU row is completed, FALSE if suspended.
336 : *
337 : * NB: input_buf is ignored; it is likely to be a NULL pointer.
338 : */
339 :
340 : METHODDEF(boolean)
341 0 : compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
342 : {
343 0 : my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
344 : JDIMENSION MCU_col_num; /* index of current MCU within row */
345 : int blkn, ci, xindex, yindex, yoffset;
346 : JDIMENSION start_col;
347 : JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
348 : JBLOCKROW buffer_ptr;
349 : jpeg_component_info *compptr;
350 :
351 : /* Align the virtual buffers for the components used in this scan.
352 : * NB: during first pass, this is safe only because the buffers will
353 : * already be aligned properly, so jmemmgr.c won't need to do any I/O.
354 : */
355 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
356 0 : compptr = cinfo->cur_comp_info[ci];
357 0 : buffer[ci] = (*cinfo->mem->access_virt_barray)
358 0 : ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
359 0 : coef->iMCU_row_num * compptr->v_samp_factor,
360 0 : (JDIMENSION) compptr->v_samp_factor, FALSE);
361 : }
362 :
363 : /* Loop to process one whole iMCU row */
364 0 : for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
365 0 : yoffset++) {
366 0 : for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
367 0 : MCU_col_num++) {
368 : /* Construct list of pointers to DCT blocks belonging to this MCU */
369 0 : blkn = 0; /* index of current DCT block within MCU */
370 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
371 0 : compptr = cinfo->cur_comp_info[ci];
372 0 : start_col = MCU_col_num * compptr->MCU_width;
373 0 : for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
374 0 : buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
375 0 : for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
376 0 : coef->MCU_buffer[blkn++] = buffer_ptr++;
377 : }
378 : }
379 : }
380 : /* Try to write the MCU. */
381 0 : if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
382 : /* Suspension forced; update state counters and exit */
383 0 : coef->MCU_vert_offset = yoffset;
384 0 : coef->mcu_ctr = MCU_col_num;
385 0 : return FALSE;
386 : }
387 : }
388 : /* Completed an MCU row, but perhaps not an iMCU row */
389 0 : coef->mcu_ctr = 0;
390 : }
391 : /* Completed the iMCU row, advance counters for next one */
392 0 : coef->iMCU_row_num++;
393 0 : start_iMCU_row(cinfo);
394 0 : return TRUE;
395 : }
396 :
397 : #endif /* FULL_COEF_BUFFER_SUPPORTED */
398 :
399 :
400 : /*
401 : * Initialize coefficient buffer controller.
402 : */
403 :
404 : GLOBAL(void)
405 0 : jinit_c_coef_controller (j_compress_ptr cinfo, boolean need_full_buffer)
406 : {
407 : my_coef_ptr coef;
408 :
409 0 : coef = (my_coef_ptr)
410 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
411 : sizeof(my_coef_controller));
412 0 : cinfo->coef = (struct jpeg_c_coef_controller *) coef;
413 0 : coef->pub.start_pass = start_pass_coef;
414 :
415 : /* Create the coefficient buffer. */
416 0 : if (need_full_buffer) {
417 : #ifdef FULL_COEF_BUFFER_SUPPORTED
418 : /* Allocate a full-image virtual array for each component, */
419 : /* padded to a multiple of samp_factor DCT blocks in each direction. */
420 : int ci;
421 : jpeg_component_info *compptr;
422 :
423 0 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
424 0 : ci++, compptr++) {
425 0 : coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
426 : ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
427 0 : (JDIMENSION) jround_up((long) compptr->width_in_blocks,
428 0 : (long) compptr->h_samp_factor),
429 0 : (JDIMENSION) jround_up((long) compptr->height_in_blocks,
430 0 : (long) compptr->v_samp_factor),
431 0 : (JDIMENSION) compptr->v_samp_factor);
432 : }
433 : #else
434 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
435 : #endif
436 : } else {
437 : /* We only need a single-MCU buffer. */
438 : JBLOCKROW buffer;
439 : int i;
440 :
441 0 : buffer = (JBLOCKROW)
442 0 : (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
443 : C_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
444 0 : for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
445 0 : coef->MCU_buffer[i] = buffer + i;
446 : }
447 0 : coef->whole_image[0] = NULL; /* flag for no virtual arrays */
448 : }
449 0 : }
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