File: jdcoefct.h

package info (click to toggle)
libjpeg-turbo 1:1.5.1-2
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 9,068 kB
  • ctags: 6,369
  • sloc: ansic: 43,407; asm: 25,683; sh: 5,436; java: 3,123; makefile: 797; xml: 24
file content (82 lines) | stat: -rw-r--r-- 2,668 bytes parent folder | download | duplicates (12)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
/*
 * jdcoefct.h
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1997, Thomas G. Lane.
 * libjpeg-turbo Modifications:
 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 */

#define JPEG_INTERNALS
#include "jpeglib.h"


/* Block smoothing is only applicable for progressive JPEG, so: */
#ifndef D_PROGRESSIVE_SUPPORTED
#undef BLOCK_SMOOTHING_SUPPORTED
#endif


/* Private buffer controller object */

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

  /* These variables keep track of the current location of the input side. */
  /* cinfo->input_iMCU_row is also used for this. */
  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 */

  /* The output side's location is represented by cinfo->output_iMCU_row. */

  /* In single-pass modes, it's sufficient to buffer just one MCU.
   * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
   * and let the entropy decoder write into that workspace each time.
   * In multi-pass modes, this array points to the current MCU's blocks
   * within the virtual arrays; it is used only by the input side.
   */
  JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];

  /* Temporary workspace for one MCU */
  JCOEF *workspace;

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

#ifdef BLOCK_SMOOTHING_SUPPORTED
  /* When doing block smoothing, we latch coefficient Al values here */
  int *coef_bits_latch;
#define SAVED_COEFS  6          /* we save coef_bits[0..5] */
#endif
} my_coef_controller;

typedef my_coef_controller *my_coef_ptr;


LOCAL(void)
start_iMCU_row (j_decompress_ptr cinfo)
/* Reset within-iMCU-row counters for a new row (input side) */
{
  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 (cinfo->input_iMCU_row < (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;
}