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/src/FreeImage/Source/LibJPEG/jccoefct.c

https://bitbucket.org/cabalistic/ogredeps/
C | 454 lines | 282 code | 44 blank | 128 comment | 45 complexity | 2e66ee07c77c706f64cfb06865e4e848 MD5 | raw file
  1/*
  2 * jccoefct.c
  3 *
  4 * Copyright (C) 1994-1997, Thomas G. Lane.
  5 * Modified 2003-2011 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 coefficient buffer controller for compression.
 10 * This controller is the top level of the JPEG compressor proper.
 11 * The coefficient buffer lies between forward-DCT and entropy encoding steps.
 12 */
 13
 14#define JPEG_INTERNALS
 15#include "jinclude.h"
 16#include "jpeglib.h"
 17
 18
 19/* We use a full-image coefficient buffer when doing Huffman optimization,
 20 * and also for writing multiple-scan JPEG files.  In all cases, the DCT
 21 * step is run during the first pass, and subsequent passes need only read
 22 * the buffered coefficients.
 23 */
 24#ifdef ENTROPY_OPT_SUPPORTED
 25#define FULL_COEF_BUFFER_SUPPORTED
 26#else
 27#ifdef C_MULTISCAN_FILES_SUPPORTED
 28#define FULL_COEF_BUFFER_SUPPORTED
 29#endif
 30#endif
 31
 32
 33/* Private buffer controller object */
 34
 35typedef struct {
 36  struct jpeg_c_coef_controller pub; /* public fields */
 37
 38  JDIMENSION iMCU_row_num;	/* iMCU row # within image */
 39  JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */
 40  int MCU_vert_offset;		/* counts MCU rows within iMCU row */
 41  int MCU_rows_per_iMCU_row;	/* number of such rows needed */
 42
 43  /* For single-pass compression, it's sufficient to buffer just one MCU
 44   * (although this may prove a bit slow in practice).  We allocate a
 45   * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each
 46   * MCU constructed and sent.  (On 80x86, the workspace is FAR even though
 47   * it's not really very big; this is to keep the module interfaces unchanged
 48   * when a large coefficient buffer is necessary.)
 49   * In multi-pass modes, this array points to the current MCU's blocks
 50   * within the virtual arrays.
 51   */
 52  JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
 53
 54  /* In multi-pass modes, we need a virtual block array for each component. */
 55  jvirt_barray_ptr whole_image[MAX_COMPONENTS];
 56} my_coef_controller;
 57
 58typedef my_coef_controller * my_coef_ptr;
 59
 60
 61/* Forward declarations */
 62METHODDEF(boolean) compress_data
 63    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
 64#ifdef FULL_COEF_BUFFER_SUPPORTED
 65METHODDEF(boolean) compress_first_pass
 66    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
 67METHODDEF(boolean) compress_output
 68    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
 69#endif
 70
 71
 72LOCAL(void)
 73start_iMCU_row (j_compress_ptr cinfo)
 74/* Reset within-iMCU-row counters for a new row */
 75{
 76  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 77
 78  /* In an interleaved scan, an MCU row is the same as an iMCU row.
 79   * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
 80   * But at the bottom of the image, process only what's left.
 81   */
 82  if (cinfo->comps_in_scan > 1) {
 83    coef->MCU_rows_per_iMCU_row = 1;
 84  } else {
 85    if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
 86      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
 87    else
 88      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
 89  }
 90
 91  coef->mcu_ctr = 0;
 92  coef->MCU_vert_offset = 0;
 93}
 94
 95
 96/*
 97 * Initialize for a processing pass.
 98 */
 99
100METHODDEF(void)
101start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
102{
103  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
104
105  coef->iMCU_row_num = 0;
106  start_iMCU_row(cinfo);
107
108  switch (pass_mode) {
109  case JBUF_PASS_THRU:
110    if (coef->whole_image[0] != NULL)
111      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
112    coef->pub.compress_data = compress_data;
113    break;
114#ifdef FULL_COEF_BUFFER_SUPPORTED
115  case JBUF_SAVE_AND_PASS:
116    if (coef->whole_image[0] == NULL)
117      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
118    coef->pub.compress_data = compress_first_pass;
119    break;
120  case JBUF_CRANK_DEST:
121    if (coef->whole_image[0] == NULL)
122      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
123    coef->pub.compress_data = compress_output;
124    break;
125#endif
126  default:
127    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
128    break;
129  }
130}
131
132
133/*
134 * Process some data in the single-pass case.
135 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
136 * per call, ie, v_samp_factor block rows for each component in the image.
137 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
138 *
139 * NB: input_buf contains a plane for each component in image,
140 * which we index according to the component's SOF position.
141 */
142
143METHODDEF(boolean)
144compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
145{
146  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
147  JDIMENSION MCU_col_num;	/* index of current MCU within row */
148  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
149  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
150  int blkn, bi, ci, yindex, yoffset, blockcnt;
151  JDIMENSION ypos, xpos;
152  jpeg_component_info *compptr;
153  forward_DCT_ptr forward_DCT;
154
155  /* Loop to write as much as one whole iMCU row */
156  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
157       yoffset++) {
158    for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;
159	 MCU_col_num++) {
160      /* Determine where data comes from in input_buf and do the DCT thing.
161       * Each call on forward_DCT processes a horizontal row of DCT blocks
162       * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks
163       * sequentially.  Dummy blocks at the right or bottom edge are filled in
164       * specially.  The data in them does not matter for image reconstruction,
165       * so we fill them with values that will encode to the smallest amount of
166       * data, viz: all zeroes in the AC entries, DC entries equal to previous
167       * block's DC value.  (Thanks to Thomas Kinsman for this idea.)
168       */
169      blkn = 0;
170      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
171	compptr = cinfo->cur_comp_info[ci];
172	forward_DCT = cinfo->fdct->forward_DCT[compptr->component_index];
173	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
174						: compptr->last_col_width;
175	xpos = MCU_col_num * compptr->MCU_sample_width;
176	ypos = yoffset * compptr->DCT_v_scaled_size;
177	/* ypos == (yoffset+yindex) * DCTSIZE */
178	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
179	  if (coef->iMCU_row_num < last_iMCU_row ||
180	      yoffset+yindex < compptr->last_row_height) {
181	    (*forward_DCT) (cinfo, compptr,
182			    input_buf[compptr->component_index],
183			    coef->MCU_buffer[blkn],
184			    ypos, xpos, (JDIMENSION) blockcnt);
185	    if (blockcnt < compptr->MCU_width) {
186	      /* Create some dummy blocks at the right edge of the image. */
187	      FMEMZERO((void FAR *) coef->MCU_buffer[blkn + blockcnt],
188		       (compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK));
189	      for (bi = blockcnt; bi < compptr->MCU_width; bi++) {
190		coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0];
191	      }
192	    }
193	  } else {
194	    /* Create a row of dummy blocks at the bottom of the image. */
195	    FMEMZERO((void FAR *) coef->MCU_buffer[blkn],
196		     compptr->MCU_width * SIZEOF(JBLOCK));
197	    for (bi = 0; bi < compptr->MCU_width; bi++) {
198	      coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0];
199	    }
200	  }
201	  blkn += compptr->MCU_width;
202	  ypos += compptr->DCT_v_scaled_size;
203	}
204      }
205      /* Try to write the MCU.  In event of a suspension failure, we will
206       * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
207       */
208      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
209	/* Suspension forced; update state counters and exit */
210	coef->MCU_vert_offset = yoffset;
211	coef->mcu_ctr = MCU_col_num;
212	return FALSE;
213      }
214    }
215    /* Completed an MCU row, but perhaps not an iMCU row */
216    coef->mcu_ctr = 0;
217  }
218  /* Completed the iMCU row, advance counters for next one */
219  coef->iMCU_row_num++;
220  start_iMCU_row(cinfo);
221  return TRUE;
222}
223
224
225#ifdef FULL_COEF_BUFFER_SUPPORTED
226
227/*
228 * Process some data in the first pass of a multi-pass case.
229 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
230 * per call, ie, v_samp_factor block rows for each component in the image.
231 * This amount of data is read from the source buffer, DCT'd and quantized,
232 * and saved into the virtual arrays.  We also generate suitable dummy blocks
233 * as needed at the right and lower edges.  (The dummy blocks are constructed
234 * in the virtual arrays, which have been padded appropriately.)  This makes
235 * it possible for subsequent passes not to worry about real vs. dummy blocks.
236 *
237 * We must also emit the data to the entropy encoder.  This is conveniently
238 * done by calling compress_output() after we've loaded the current strip
239 * of the virtual arrays.
240 *
241 * NB: input_buf contains a plane for each component in image.  All
242 * components are DCT'd and loaded into the virtual arrays in this pass.
243 * However, it may be that only a subset of the components are emitted to
244 * the entropy encoder during this first pass; be careful about looking
245 * at the scan-dependent variables (MCU dimensions, etc).
246 */
247
248METHODDEF(boolean)
249compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
250{
251  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
252  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
253  JDIMENSION blocks_across, MCUs_across, MCUindex;
254  int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
255  JCOEF lastDC;
256  jpeg_component_info *compptr;
257  JBLOCKARRAY buffer;
258  JBLOCKROW thisblockrow, lastblockrow;
259  forward_DCT_ptr forward_DCT;
260
261  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
262       ci++, compptr++) {
263    /* Align the virtual buffer for this component. */
264    buffer = (*cinfo->mem->access_virt_barray)
265      ((j_common_ptr) cinfo, coef->whole_image[ci],
266       coef->iMCU_row_num * compptr->v_samp_factor,
267       (JDIMENSION) compptr->v_samp_factor, TRUE);
268    /* Count non-dummy DCT block rows in this iMCU row. */
269    if (coef->iMCU_row_num < last_iMCU_row)
270      block_rows = compptr->v_samp_factor;
271    else {
272      /* NB: can't use last_row_height here, since may not be set! */
273      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
274      if (block_rows == 0) block_rows = compptr->v_samp_factor;
275    }
276    blocks_across = compptr->width_in_blocks;
277    h_samp_factor = compptr->h_samp_factor;
278    /* Count number of dummy blocks to be added at the right margin. */
279    ndummy = (int) (blocks_across % h_samp_factor);
280    if (ndummy > 0)
281      ndummy = h_samp_factor - ndummy;
282    forward_DCT = cinfo->fdct->forward_DCT[ci];
283    /* Perform DCT for all non-dummy blocks in this iMCU row.  Each call
284     * on forward_DCT processes a complete horizontal row of DCT blocks.
285     */
286    for (block_row = 0; block_row < block_rows; block_row++) {
287      thisblockrow = buffer[block_row];
288      (*forward_DCT) (cinfo, compptr, input_buf[ci], thisblockrow,
289		      (JDIMENSION) (block_row * compptr->DCT_v_scaled_size),
290		      (JDIMENSION) 0, blocks_across);
291      if (ndummy > 0) {
292	/* Create dummy blocks at the right edge of the image. */
293	thisblockrow += blocks_across; /* => first dummy block */
294	FMEMZERO((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK));
295	lastDC = thisblockrow[-1][0];
296	for (bi = 0; bi < ndummy; bi++) {
297	  thisblockrow[bi][0] = lastDC;
298	}
299      }
300    }
301    /* If at end of image, create dummy block rows as needed.
302     * The tricky part here is that within each MCU, we want the DC values
303     * of the dummy blocks to match the last real block's DC value.
304     * This squeezes a few more bytes out of the resulting file...
305     */
306    if (coef->iMCU_row_num == last_iMCU_row) {
307      blocks_across += ndummy;	/* include lower right corner */
308      MCUs_across = blocks_across / h_samp_factor;
309      for (block_row = block_rows; block_row < compptr->v_samp_factor;
310	   block_row++) {
311	thisblockrow = buffer[block_row];
312	lastblockrow = buffer[block_row-1];
313	FMEMZERO((void FAR *) thisblockrow,
314		 (size_t) (blocks_across * SIZEOF(JBLOCK)));
315	for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) {
316	  lastDC = lastblockrow[h_samp_factor-1][0];
317	  for (bi = 0; bi < h_samp_factor; bi++) {
318	    thisblockrow[bi][0] = lastDC;
319	  }
320	  thisblockrow += h_samp_factor; /* advance to next MCU in row */
321	  lastblockrow += h_samp_factor;
322	}
323      }
324    }
325  }
326  /* NB: compress_output will increment iMCU_row_num if successful.
327   * A suspension return will result in redoing all the work above next time.
328   */
329
330  /* Emit data to the entropy encoder, sharing code with subsequent passes */
331  return compress_output(cinfo, input_buf);
332}
333
334
335/*
336 * Process some data in subsequent passes of a multi-pass case.
337 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
338 * per call, ie, v_samp_factor block rows for each component in the scan.
339 * The data is obtained from the virtual arrays and fed to the entropy coder.
340 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
341 *
342 * NB: input_buf is ignored; it is likely to be a NULL pointer.
343 */
344
345METHODDEF(boolean)
346compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
347{
348  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
349  JDIMENSION MCU_col_num;	/* index of current MCU within row */
350  int blkn, ci, xindex, yindex, yoffset;
351  JDIMENSION start_col;
352  JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
353  JBLOCKROW buffer_ptr;
354  jpeg_component_info *compptr;
355
356  /* Align the virtual buffers for the components used in this scan.
357   * NB: during first pass, this is safe only because the buffers will
358   * already be aligned properly, so jmemmgr.c won't need to do any I/O.
359   */
360  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
361    compptr = cinfo->cur_comp_info[ci];
362    buffer[ci] = (*cinfo->mem->access_virt_barray)
363      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
364       coef->iMCU_row_num * compptr->v_samp_factor,
365       (JDIMENSION) compptr->v_samp_factor, FALSE);
366  }
367
368  /* Loop to process one whole iMCU row */
369  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
370       yoffset++) {
371    for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
372	 MCU_col_num++) {
373      /* Construct list of pointers to DCT blocks belonging to this MCU */
374      blkn = 0;			/* index of current DCT block within MCU */
375      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
376	compptr = cinfo->cur_comp_info[ci];
377	start_col = MCU_col_num * compptr->MCU_width;
378	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
379	  buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
380	  for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
381	    coef->MCU_buffer[blkn++] = buffer_ptr++;
382	  }
383	}
384      }
385      /* Try to write the MCU. */
386      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
387	/* Suspension forced; update state counters and exit */
388	coef->MCU_vert_offset = yoffset;
389	coef->mcu_ctr = MCU_col_num;
390	return FALSE;
391      }
392    }
393    /* Completed an MCU row, but perhaps not an iMCU row */
394    coef->mcu_ctr = 0;
395  }
396  /* Completed the iMCU row, advance counters for next one */
397  coef->iMCU_row_num++;
398  start_iMCU_row(cinfo);
399  return TRUE;
400}
401
402#endif /* FULL_COEF_BUFFER_SUPPORTED */
403
404
405/*
406 * Initialize coefficient buffer controller.
407 */
408
409GLOBAL(void)
410jinit_c_coef_controller (j_compress_ptr cinfo, boolean need_full_buffer)
411{
412  my_coef_ptr coef;
413
414  coef = (my_coef_ptr)
415    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
416				SIZEOF(my_coef_controller));
417  cinfo->coef = (struct jpeg_c_coef_controller *) coef;
418  coef->pub.start_pass = start_pass_coef;
419
420  /* Create the coefficient buffer. */
421  if (need_full_buffer) {
422#ifdef FULL_COEF_BUFFER_SUPPORTED
423    /* Allocate a full-image virtual array for each component, */
424    /* padded to a multiple of samp_factor DCT blocks in each direction. */
425    int ci;
426    jpeg_component_info *compptr;
427
428    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
429	 ci++, compptr++) {
430      coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
431	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
432	 (JDIMENSION) jround_up((long) compptr->width_in_blocks,
433				(long) compptr->h_samp_factor),
434	 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
435				(long) compptr->v_samp_factor),
436	 (JDIMENSION) compptr->v_samp_factor);
437    }
438#else
439    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
440#endif
441  } else {
442    /* We only need a single-MCU buffer. */
443    JBLOCKROW buffer;
444    int i;
445
446    buffer = (JBLOCKROW)
447      (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
448				  C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
449    for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
450      coef->MCU_buffer[i] = buffer + i;
451    }
452    coef->whole_image[0] = NULL; /* flag for no virtual arrays */
453  }
454}