3rdparty/libjpeg/jccoefct.c

/*
 * jccoefct.c
 *
 * Copyright (C) 1994-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains the coefficient buffer controller for compression.
 * This controller is the top level of the JPEG compressor proper.
 * The coefficient buffer lies between forward-DCT and entropy encoding steps.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* We use a full-image coefficient buffer when doing Huffman optimization,
 * and also for writing multiple-scan JPEG files.  In all cases, the DCT
 * step is run during the first pass, and subsequent passes need only read
 * the buffered coefficients.
 */
#ifdef ENTROPY_OPT_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#else
#ifdef C_MULTISCAN_FILES_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#endif
#endif


/* Private buffer controller object */

typedef struct {
  struct jpeg_c_coef_controller pub; /* public fields */

  JDIMENSION iMCU_row_num;      /* iMCU row # within image */
  JDIMENSION mcu_ctr;           /* counts MCUs processed in current row */
  int MCU_vert_offset;          /* counts MCU rows within iMCU row */
  int MCU_rows_per_iMCU_row;    /* number of such rows needed */

  /* For single-pass compression, it's sufficient to buffer just one MCU
   * (although this may prove a bit slow in practice).  We allocate a
   * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each
   * MCU constructed and sent.  (On 80x86, the workspace is FAR even though
   * it's not really very big; this is to keep the module interfaces unchanged
   * when a large coefficient buffer is necessary.)
   * In multi-pass modes, this array points to the current MCU's blocks
   * within the virtual arrays.
   */
  JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];

  /* In multi-pass modes, we need a virtual block array for each component. */
  jvirt_barray_ptr whole_image[MAX_COMPONENTS];
} my_coef_controller;

typedef my_coef_controller * my_coef_ptr;


/* Forward declarations */
METHODDEF(boolean) compress_data
    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
#ifdef FULL_COEF_BUFFER_SUPPORTED
METHODDEF(boolean) compress_first_pass
    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
METHODDEF(boolean) compress_output
    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
#endif


LOCAL(void)
start_iMCU_row (j_compress_ptr cinfo)
/* Reset within-iMCU-row counters for a new row */
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  /* In an interleaved scan, an MCU row is the same as an iMCU row.
   * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
   * But at the bottom of the image, process only what's left.
   */
  if (cinfo->comps_in_scan > 1) {
    coef->MCU_rows_per_iMCU_row = 1;
  } else {
    if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
    else
      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
  }

  coef->mcu_ctr = 0;
  coef->MCU_vert_offset = 0;
}


/*
 * Initialize for a processing pass.
 */

METHODDEF(void)
start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  coef->iMCU_row_num = 0;
  start_iMCU_row(cinfo);

  switch (pass_mode) {
  case JBUF_PASS_THRU:
    if (coef->whole_image[0] != NULL)
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    coef->pub.compress_data = compress_data;
    break;
#ifdef FULL_COEF_BUFFER_SUPPORTED
  case JBUF_SAVE_AND_PASS:
    if (coef->whole_image[0] == NULL)
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    coef->pub.compress_data = compress_first_pass;
    break;
  case JBUF_CRANK_DEST:
    if (coef->whole_image[0] == NULL)
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    coef->pub.compress_data = compress_output;
    break;
#endif
  default:
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    break;
  }
}


/*
 * Process some data in the single-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the image.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf contains a plane for each component in image,
 * which we index according to the component's SOF position.
 */

METHODDEF(boolean)
compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
  JDIMENSION MCU_col_num;       /* index of current MCU within row */
  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
  int blkn, bi, ci, yindex, yoffset, blockcnt;
  JDIMENSION ypos, xpos;
  jpeg_component_info *compptr;
  forward_DCT_ptr forward_DCT;

  /* Loop to write as much as one whole iMCU row */
  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
       yoffset++) {
    for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;
         MCU_col_num++) {
      /* Determine where data comes from in input_buf and do the DCT thing.
       * Each call on forward_DCT processes a horizontal row of DCT blocks
       * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks
       * sequentially.  Dummy blocks at the right or bottom edge are filled in
       * specially.  The data in them does not matter for image reconstruction,
       * so we fill them with values that will encode to the smallest amount of
       * data, viz: all zeroes in the AC entries, DC entries equal to previous
       * block's DC value.  (Thanks to Thomas Kinsman for this idea.)
       */
      blkn = 0;
      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
        compptr = cinfo->cur_comp_info[ci];
        forward_DCT = cinfo->fdct->forward_DCT[compptr->component_index];
        blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
                                                : compptr->last_col_width;
        xpos = MCU_col_num * compptr->MCU_sample_width;
        ypos = yoffset * compptr->DCT_v_scaled_size;
        /* ypos == (yoffset+yindex) * DCTSIZE */
        for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
          if (coef->iMCU_row_num < last_iMCU_row ||
              yoffset+yindex < compptr->last_row_height) {
            (*forward_DCT) (cinfo, compptr,
                            input_buf[compptr->component_index],
                            coef->MCU_buffer[blkn],
                            ypos, xpos, (JDIMENSION) blockcnt);
            if (blockcnt < compptr->MCU_width) {
              /* Create some dummy blocks at the right edge of the image. */
              jzero_far((void FAR *) coef->MCU_buffer[blkn + blockcnt],
                        (compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK));
              for (bi = blockcnt; bi < compptr->MCU_width; bi++) {
                coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0];
              }
            }
          } else {
            /* Create a row of dummy blocks at the bottom of the image. */
            jzero_far((void FAR *) coef->MCU_buffer[blkn],
                      compptr->MCU_width * SIZEOF(JBLOCK));
            for (bi = 0; bi < compptr->MCU_width; bi++) {
              coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0];
            }
          }
          blkn += compptr->MCU_width;
          ypos += compptr->DCT_v_scaled_size;
        }
      }
      /* Try to write the MCU.  In event of a suspension failure, we will
       * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
       */
      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
        /* Suspension forced; update state counters and exit */
        coef->MCU_vert_offset = yoffset;
        coef->mcu_ctr = MCU_col_num;
        return FALSE;
      }
    }
    /* Completed an MCU row, but perhaps not an iMCU row */
    coef->mcu_ctr = 0;
  }
  /* Completed the iMCU row, advance counters for next one */
  coef->iMCU_row_num++;
  start_iMCU_row(cinfo);
  return TRUE;
}


#ifdef FULL_COEF_BUFFER_SUPPORTED

/*
 * Process some data in the first pass of a multi-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the image.
 * This amount of data is read from the source buffer, DCT'd and quantized,
 * and saved into the virtual arrays.  We also generate suitable dummy blocks
 * as needed at the right and lower edges.  (The dummy blocks are constructed
 * in the virtual arrays, which have been padded appropriately.)  This makes
 * it possible for subsequent passes not to worry about real vs. dummy blocks.
 *
 * We must also emit the data to the entropy encoder.  This is conveniently
 * done by calling compress_output() after we've loaded the current strip
 * of the virtual arrays.
 *
 * NB: input_buf contains a plane for each component in image.  All
 * components are DCT'd and loaded into the virtual arrays in this pass.
 * However, it may be that only a subset of the components are emitted to
 * the entropy encoder during this first pass; be careful about looking
 * at the scan-dependent variables (MCU dimensions, etc).
 */

METHODDEF(boolean)
compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
  JDIMENSION blocks_across, MCUs_across, MCUindex;
  int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
  JCOEF lastDC;
  jpeg_component_info *compptr;
  JBLOCKARRAY buffer;
  JBLOCKROW thisblockrow, lastblockrow;
  forward_DCT_ptr forward_DCT;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Align the virtual buffer for this component. */
    buffer = (*cinfo->mem->access_virt_barray)
      ((j_common_ptr) cinfo, coef->whole_image[ci],
       coef->iMCU_row_num * compptr->v_samp_factor,
       (JDIMENSION) compptr->v_samp_factor, TRUE);
    /* Count non-dummy DCT block rows in this iMCU row. */
    if (coef->iMCU_row_num < last_iMCU_row)
      block_rows = compptr->v_samp_factor;
    else {
      /* NB: can't use last_row_height here, since may not be set! */
      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
      if (block_rows == 0) block_rows = compptr->v_samp_factor;
    }
    blocks_across = compptr->width_in_blocks;
    h_samp_factor = compptr->h_samp_factor;
    /* Count number of dummy blocks to be added at the right margin. */
    ndummy = (int) (blocks_across % h_samp_factor);
    if (ndummy > 0)
      ndummy = h_samp_factor - ndummy;
    forward_DCT = cinfo->fdct->forward_DCT[ci];
    /* Perform DCT for all non-dummy blocks in this iMCU row.  Each call
     * on forward_DCT processes a complete horizontal row of DCT blocks.
     */
    for (block_row = 0; block_row < block_rows; block_row++) {
      thisblockrow = buffer[block_row];
      (*forward_DCT) (cinfo, compptr, input_buf[ci], thisblockrow,
                      (JDIMENSION) (block_row * compptr->DCT_v_scaled_size),
                      (JDIMENSION) 0, blocks_across);
      if (ndummy > 0) {
        /* Create dummy blocks at the right edge of the image. */
        thisblockrow += blocks_across; /* => first dummy block */
        jzero_far((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK));
        lastDC = thisblockrow[-1][0];
        for (bi = 0; bi < ndummy; bi++) {
          thisblockrow[bi][0] = lastDC;
        }
      }
    }
    /* If at end of image, create dummy block rows as needed.
     * The tricky part here is that within each MCU, we want the DC values
     * of the dummy blocks to match the last real block's DC value.
     * This squeezes a few more bytes out of the resulting file...
     */
    if (coef->iMCU_row_num == last_iMCU_row) {
      blocks_across += ndummy;  /* include lower right corner */
      MCUs_across = blocks_across / h_samp_factor;
      for (block_row = block_rows; block_row < compptr->v_samp_factor;
           block_row++) {
        thisblockrow = buffer[block_row];
        lastblockrow = buffer[block_row-1];
        jzero_far((void FAR *) thisblockrow,
                  (size_t) (blocks_across * SIZEOF(JBLOCK)));
        for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) {
          lastDC = lastblockrow[h_samp_factor-1][0];
          for (bi = 0; bi < h_samp_factor; bi++) {
            thisblockrow[bi][0] = lastDC;
          }
          thisblockrow += h_samp_factor; /* advance to next MCU in row */
          lastblockrow += h_samp_factor;
        }
      }
    }
  }
  /* NB: compress_output will increment iMCU_row_num if successful.
   * A suspension return will result in redoing all the work above next time.
   */

  /* Emit data to the entropy encoder, sharing code with subsequent passes */
  return compress_output(cinfo, input_buf);
}


/*
 * Process some data in subsequent passes of a multi-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the scan.
 * The data is obtained from the virtual arrays and fed to the entropy coder.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf is ignored; it is likely to be a NULL pointer.
 */

METHODDEF(boolean)
compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
{
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
  JDIMENSION MCU_col_num;       /* index of current MCU within row */
  int blkn, ci, xindex, yindex, yoffset;
  JDIMENSION start_col;
  JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
  JBLOCKROW buffer_ptr;
  jpeg_component_info *compptr;

  /* Align the virtual buffers for the components used in this scan.
   * NB: during first pass, this is safe only because the buffers will
   * already be aligned properly, so jmemmgr.c won't need to do any I/O.
   */
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    compptr = cinfo->cur_comp_info[ci];
    buffer[ci] = (*cinfo->mem->access_virt_barray)
      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
       coef->iMCU_row_num * compptr->v_samp_factor,
       (JDIMENSION) compptr->v_samp_factor, FALSE);
  }

  /* Loop to process one whole iMCU row */
  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
       yoffset++) {
    for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
         MCU_col_num++) {
      /* Construct list of pointers to DCT blocks belonging to this MCU */
      blkn = 0;                 /* index of current DCT block within MCU */
      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
        compptr = cinfo->cur_comp_info[ci];
        start_col = MCU_col_num * compptr->MCU_width;
        for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
          buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
          for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
            coef->MCU_buffer[blkn++] = buffer_ptr++;
          }
        }
      }
      /* Try to write the MCU. */
      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {
        /* Suspension forced; update state counters and exit */
        coef->MCU_vert_offset = yoffset;
        coef->mcu_ctr = MCU_col_num;
        return FALSE;
      }
    }
    /* Completed an MCU row, but perhaps not an iMCU row */
    coef->mcu_ctr = 0;
  }
  /* Completed the iMCU row, advance counters for next one */
  coef->iMCU_row_num++;
  start_iMCU_row(cinfo);
  return TRUE;
}

#endif /* FULL_COEF_BUFFER_SUPPORTED */


/*
 * Initialize coefficient buffer controller.
 */

GLOBAL(void)
jinit_c_coef_controller (j_compress_ptr cinfo, boolean need_full_buffer)
{
  my_coef_ptr coef;

  coef = (my_coef_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                SIZEOF(my_coef_controller));
  cinfo->coef = (struct jpeg_c_coef_controller *) coef;
  coef->pub.start_pass = start_pass_coef;

  /* Create the coefficient buffer. */
  if (need_full_buffer) {
#ifdef FULL_COEF_BUFFER_SUPPORTED
    /* Allocate a full-image virtual array for each component, */
    /* padded to a multiple of samp_factor DCT blocks in each direction. */
    int ci;
    jpeg_component_info *compptr;

    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
         ci++, compptr++) {
      coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
        ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
         (JDIMENSION) jround_up((long) compptr->width_in_blocks,
                                (long) compptr->h_samp_factor),
         (JDIMENSION) jround_up((long) compptr->height_in_blocks,
                                (long) compptr->v_samp_factor),
         (JDIMENSION) compptr->v_samp_factor);
    }
#else
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
#endif
  } else {
    /* We only need a single-MCU buffer. */
    JBLOCKROW buffer;
    int i;

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