3rdparty/libjpeg/jdinput.c

/*
 * jdinput.c
 *
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * Modified 2002-2009 by Guido Vollbeding.
 * 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 input control logic for the JPEG decompressor.
 * These routines are concerned with controlling the decompressor's input
 * processing (marker reading and coefficient decoding).  The actual input
 * reading is done in jdmarker.c, jdhuff.c, and jdarith.c.
 */

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


/* Private state */

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

  boolean inheaders;            /* TRUE until first SOS is reached */
} my_input_controller;

typedef my_input_controller * my_inputctl_ptr;


/* Forward declarations */
METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));


/*
 * Routines to calculate various quantities related to the size of the image.
 */

LOCAL(void)
initial_setup (j_decompress_ptr cinfo)
/* Called once, when first SOS marker is reached */
{
  int ci;
  jpeg_component_info *compptr;

  /* Make sure image isn't bigger than I can handle */
  if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
      (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
    ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);

  /* For now, precision must match compiled-in value... */
  if (cinfo->data_precision != BITS_IN_JSAMPLE)
    ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);

  /* Check that number of components won't exceed internal array sizes */
  if (cinfo->num_components > MAX_COMPONENTS)
    ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
             MAX_COMPONENTS);

  /* Compute maximum sampling factors; check factor validity */
  cinfo->max_h_samp_factor = 1;
  cinfo->max_v_samp_factor = 1;
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
        compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
      ERREXIT(cinfo, JERR_BAD_SAMPLING);
    cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
                                   compptr->h_samp_factor);
    cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
                                   compptr->v_samp_factor);
  }

  /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
   * In the full decompressor, this will be overridden by jdmaster.c;
   * but in the transcoder, jdmaster.c is not used, so we must do it here.
   */
  cinfo->min_DCT_h_scaled_size = DCTSIZE;
  cinfo->min_DCT_v_scaled_size = DCTSIZE;

  /* Compute dimensions of components */
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    compptr->DCT_h_scaled_size = DCTSIZE;
    compptr->DCT_v_scaled_size = DCTSIZE;
    /* Size in DCT blocks */
    compptr->width_in_blocks = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
                    (long) (cinfo->max_h_samp_factor * DCTSIZE));
    compptr->height_in_blocks = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
                    (long) (cinfo->max_v_samp_factor * DCTSIZE));
    /* downsampled_width and downsampled_height will also be overridden by
     * jdmaster.c if we are doing full decompression.  The transcoder library
     * doesn't use these values, but the calling application might.
     */
    /* Size in samples */
    compptr->downsampled_width = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
                    (long) cinfo->max_h_samp_factor);
    compptr->downsampled_height = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
                    (long) cinfo->max_v_samp_factor);
    /* Mark component needed, until color conversion says otherwise */
    compptr->component_needed = TRUE;
    /* Mark no quantization table yet saved for component */
    compptr->quant_table = NULL;
  }

  /* Compute number of fully interleaved MCU rows. */
  cinfo->total_iMCU_rows = (JDIMENSION)
    jdiv_round_up((long) cinfo->image_height,
                  (long) (cinfo->max_v_samp_factor*DCTSIZE));

  /* Decide whether file contains multiple scans */
  if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
    cinfo->inputctl->has_multiple_scans = TRUE;
  else
    cinfo->inputctl->has_multiple_scans = FALSE;
}


LOCAL(void)
per_scan_setup (j_decompress_ptr cinfo)
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
{
  int ci, mcublks, tmp;
  jpeg_component_info *compptr;

  if (cinfo->comps_in_scan == 1) {

    /* Noninterleaved (single-component) scan */
    compptr = cinfo->cur_comp_info[0];

    /* Overall image size in MCUs */
    cinfo->MCUs_per_row = compptr->width_in_blocks;
    cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

    /* For noninterleaved scan, always one block per MCU */
    compptr->MCU_width = 1;
    compptr->MCU_height = 1;
    compptr->MCU_blocks = 1;
    compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
    compptr->last_col_width = 1;
    /* For noninterleaved scans, it is convenient to define last_row_height
     * as the number of block rows present in the last iMCU row.
     */
    tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
    if (tmp == 0) tmp = compptr->v_samp_factor;
    compptr->last_row_height = tmp;

    /* Prepare array describing MCU composition */
    cinfo->blocks_in_MCU = 1;
    cinfo->MCU_membership[0] = 0;

  } else {

    /* Interleaved (multi-component) scan */
    if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
               MAX_COMPS_IN_SCAN);

    /* Overall image size in MCUs */
    cinfo->MCUs_per_row = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width,
                    (long) (cinfo->max_h_samp_factor*DCTSIZE));
    cinfo->MCU_rows_in_scan = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height,
                    (long) (cinfo->max_v_samp_factor*DCTSIZE));

    cinfo->blocks_in_MCU = 0;

    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
      compptr = cinfo->cur_comp_info[ci];
      /* Sampling factors give # of blocks of component in each MCU */
      compptr->MCU_width = compptr->h_samp_factor;
      compptr->MCU_height = compptr->v_samp_factor;
      compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
      compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
      /* Figure number of non-dummy blocks in last MCU column & row */
      tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
      if (tmp == 0) tmp = compptr->MCU_width;
      compptr->last_col_width = tmp;
      tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
      if (tmp == 0) tmp = compptr->MCU_height;
      compptr->last_row_height = tmp;
      /* Prepare array describing MCU composition */
      mcublks = compptr->MCU_blocks;
      if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
        ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
      while (mcublks-- > 0) {
        cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
      }
    }

  }
}


/*
 * Save away a copy of the Q-table referenced by each component present
 * in the current scan, unless already saved during a prior scan.
 *
 * In a multiple-scan JPEG file, the encoder could assign different components
 * the same Q-table slot number, but change table definitions between scans
 * so that each component uses a different Q-table.  (The IJG encoder is not
 * currently capable of doing this, but other encoders might.)  Since we want
 * to be able to dequantize all the components at the end of the file, this
 * means that we have to save away the table actually used for each component.
 * We do this by copying the table at the start of the first scan containing
 * the component.
 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
 * slot between scans of a component using that slot.  If the encoder does so
 * anyway, this decoder will simply use the Q-table values that were current
 * at the start of the first scan for the component.
 *
 * The decompressor output side looks only at the saved quant tables,
 * not at the current Q-table slots.
 */

LOCAL(void)
latch_quant_tables (j_decompress_ptr cinfo)
{
  int ci, qtblno;
  jpeg_component_info *compptr;
  JQUANT_TBL * qtbl;

  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    compptr = cinfo->cur_comp_info[ci];
    /* No work if we already saved Q-table for this component */
    if (compptr->quant_table != NULL)
      continue;
    /* Make sure specified quantization table is present */
    qtblno = compptr->quant_tbl_no;
    if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
        cinfo->quant_tbl_ptrs[qtblno] == NULL)
      ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
    /* OK, save away the quantization table */
    qtbl = (JQUANT_TBL *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                  SIZEOF(JQUANT_TBL));
    MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
    compptr->quant_table = qtbl;
  }
}


/*
 * Initialize the input modules to read a scan of compressed data.
 * The first call to this is done by jdmaster.c after initializing
 * the entire decompressor (during jpeg_start_decompress).
 * Subsequent calls come from consume_markers, below.
 */

METHODDEF(void)
start_input_pass (j_decompress_ptr cinfo)
{
  per_scan_setup(cinfo);
  latch_quant_tables(cinfo);
  (*cinfo->entropy->start_pass) (cinfo);
  (*cinfo->coef->start_input_pass) (cinfo);
  cinfo->inputctl->consume_input = cinfo->coef->consume_data;
}


/*
 * Finish up after inputting a compressed-data scan.
 * This is called by the coefficient controller after it's read all
 * the expected data of the scan.
 */

METHODDEF(void)
finish_input_pass (j_decompress_ptr cinfo)
{
  cinfo->inputctl->consume_input = consume_markers;
}


/*
 * Read JPEG markers before, between, or after compressed-data scans.
 * Change state as necessary when a new scan is reached.
 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 *
 * The consume_input method pointer points either here or to the
 * coefficient controller's consume_data routine, depending on whether
 * we are reading a compressed data segment or inter-segment markers.
 */

METHODDEF(int)
consume_markers (j_decompress_ptr cinfo)
{
  my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
  int val;

  if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
    return JPEG_REACHED_EOI;

  val = (*cinfo->marker->read_markers) (cinfo);

  switch (val) {
  case JPEG_REACHED_SOS:        /* Found SOS */
    if (inputctl->inheaders) {  /* 1st SOS */
      initial_setup(cinfo);
      inputctl->inheaders = FALSE;
      /* Note: start_input_pass must be called by jdmaster.c
       * before any more input can be consumed.  jdapimin.c is
       * responsible for enforcing this sequencing.
       */
    } else {                    /* 2nd or later SOS marker */
      if (! inputctl->pub.has_multiple_scans)
        ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
      start_input_pass(cinfo);
    }
    break;
  case JPEG_REACHED_EOI:        /* Found EOI */
    inputctl->pub.eoi_reached = TRUE;
    if (inputctl->inheaders) {  /* Tables-only datastream, apparently */
      if (cinfo->marker->saw_SOF)
        ERREXIT(cinfo, JERR_SOF_NO_SOS);
    } else {
      /* Prevent infinite loop in coef ctlr's decompress_data routine
       * if user set output_scan_number larger than number of scans.
       */
      if (cinfo->output_scan_number > cinfo->input_scan_number)
        cinfo->output_scan_number = cinfo->input_scan_number;
    }
    break;
  case JPEG_SUSPENDED:
    break;
  }

  return val;
}


/*
 * Reset state to begin a fresh datastream.
 */

METHODDEF(void)
reset_input_controller (j_decompress_ptr cinfo)
{
  my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;

  inputctl->pub.consume_input = consume_markers;
  inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
  inputctl->pub.eoi_reached = FALSE;
  inputctl->inheaders = TRUE;
  /* Reset other modules */
  (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
  (*cinfo->marker->reset_marker_reader) (cinfo);
  /* Reset progression state -- would be cleaner if entropy decoder did this */
  cinfo->coef_bits = NULL;
}


/*
 * Initialize the input controller module.
 * This is called only once, when the decompression object is created.
 */

GLOBAL(void)
jinit_input_controller (j_decompress_ptr cinfo)
{
  my_inputctl_ptr inputctl;

  /* Create subobject in permanent pool */
  inputctl = (my_inputctl_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                SIZEOF(my_input_controller));
  cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
  /* Initialize method pointers */
  inputctl->pub.consume_input = consume_markers;
  inputctl->pub.reset_input_controller = reset_input_controller;
  inputctl->pub.start_input_pass = start_input_pass;
  inputctl->pub.finish_input_pass = finish_input_pass;
  /* Initialize state: can't use reset_input_controller since we don't
   * want to try to reset other modules yet.
   */
  inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
  inputctl->pub.eoi_reached = FALSE;
  inputctl->inheaders = TRUE;
}
1	/*
2	* jdinput.c
3	*
4	* Copyright (C) 1991-1997, Thomas G. Lane.
5	* Modified 2002-2009 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 input control logic for the JPEG decompressor.
10	* These routines are concerned with controlling the decompressor's input
11	* processing (marker reading and coefficient decoding). The actual input
12	* reading is done in jdmarker.c, jdhuff.c, and jdarith.c.
13	*/
14
15	#define JPEG_INTERNALS
16	#include "jinclude.h"
17	#include "jpeglib.h"
18
19
20	/* Private state */
21
22	typedef struct {
23	struct jpeg_input_controller pub; /* public fields */
24
25	boolean inheaders; /* TRUE until first SOS is reached */
26	} my_input_controller;
27
28	typedef my_input_controller * my_inputctl_ptr;
29
30
31	/* Forward declarations */
32	METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
33
34
35	/*
36	* Routines to calculate various quantities related to the size of the image.
37	*/
38
39	LOCAL(void)
40	initial_setup (j_decompress_ptr cinfo)
41	/* Called once, when first SOS marker is reached */
42	{
43	int ci;
44	jpeg_component_info *compptr;
45
46	/* Make sure image isn't bigger than I can handle */
47	if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION \|\|
48	(long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
49	ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
50
51	/* For now, precision must match compiled-in value... */
52	if (cinfo->data_precision != BITS_IN_JSAMPLE)
53	ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
54
55	/* Check that number of components won't exceed internal array sizes */
56	if (cinfo->num_components > MAX_COMPONENTS)
57	ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
58	MAX_COMPONENTS);
59
60	/* Compute maximum sampling factors; check factor validity */
61	cinfo->max_h_samp_factor = 1;
62	cinfo->max_v_samp_factor = 1;
63	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
64	ci++, compptr++) {
65	if (compptr->h_samp_factor<=0 \|\| compptr->h_samp_factor>MAX_SAMP_FACTOR \|\|
66	compptr->v_samp_factor<=0 \|\| compptr->v_samp_factor>MAX_SAMP_FACTOR)
67	ERREXIT(cinfo, JERR_BAD_SAMPLING);
68	cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
69	compptr->h_samp_factor);
70	cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
71	compptr->v_samp_factor);
72	}
73
74	/* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
75	* In the full decompressor, this will be overridden by jdmaster.c;
76	* but in the transcoder, jdmaster.c is not used, so we must do it here.
77	*/
78	cinfo->min_DCT_h_scaled_size = DCTSIZE;
79	cinfo->min_DCT_v_scaled_size = DCTSIZE;
80
81	/* Compute dimensions of components */
82	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
83	ci++, compptr++) {
84	compptr->DCT_h_scaled_size = DCTSIZE;
85	compptr->DCT_v_scaled_size = DCTSIZE;
86	/* Size in DCT blocks */
87	compptr->width_in_blocks = (JDIMENSION)
88	jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
89	(long) (cinfo->max_h_samp_factor * DCTSIZE));
90	compptr->height_in_blocks = (JDIMENSION)
91	jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
92	(long) (cinfo->max_v_samp_factor * DCTSIZE));
93	/* downsampled_width and downsampled_height will also be overridden by
94	* jdmaster.c if we are doing full decompression. The transcoder library
95	* doesn't use these values, but the calling application might.
96	*/
97	/* Size in samples */
98	compptr->downsampled_width = (JDIMENSION)
99	jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
100	(long) cinfo->max_h_samp_factor);
101	compptr->downsampled_height = (JDIMENSION)
102	jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
103	(long) cinfo->max_v_samp_factor);
104	/* Mark component needed, until color conversion says otherwise */
105	compptr->component_needed = TRUE;
106	/* Mark no quantization table yet saved for component */
107	compptr->quant_table = NULL;
108	}
109
110	/* Compute number of fully interleaved MCU rows. */
111	cinfo->total_iMCU_rows = (JDIMENSION)
112	jdiv_round_up((long) cinfo->image_height,
113	(long) (cinfo->max_v_samp_factor*DCTSIZE));
114
115	/* Decide whether file contains multiple scans */
116	if (cinfo->comps_in_scan < cinfo->num_components \|\| cinfo->progressive_mode)
117	cinfo->inputctl->has_multiple_scans = TRUE;
118	else
119	cinfo->inputctl->has_multiple_scans = FALSE;
120	}
121
122
123	LOCAL(void)
124	per_scan_setup (j_decompress_ptr cinfo)
125	/* Do computations that are needed before processing a JPEG scan */
126	/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
127	{
128	int ci, mcublks, tmp;
129	jpeg_component_info *compptr;
130
131	if (cinfo->comps_in_scan == 1) {
132
133	/* Noninterleaved (single-component) scan */
134	compptr = cinfo->cur_comp_info[0];
135
136	/* Overall image size in MCUs */
137	cinfo->MCUs_per_row = compptr->width_in_blocks;
138	cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
139
140	/* For noninterleaved scan, always one block per MCU */
141	compptr->MCU_width = 1;
142	compptr->MCU_height = 1;
143	compptr->MCU_blocks = 1;
144	compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
145	compptr->last_col_width = 1;
146	/* For noninterleaved scans, it is convenient to define last_row_height
147	* as the number of block rows present in the last iMCU row.
148	*/
149	tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
150	if (tmp == 0) tmp = compptr->v_samp_factor;
151	compptr->last_row_height = tmp;
152
153	/* Prepare array describing MCU composition */
154	cinfo->blocks_in_MCU = 1;
155	cinfo->MCU_membership[0] = 0;
156
157	} else {
158
159	/* Interleaved (multi-component) scan */
160	if (cinfo->comps_in_scan <= 0 \|\| cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
161	ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
162	MAX_COMPS_IN_SCAN);
163
164	/* Overall image size in MCUs */
165	cinfo->MCUs_per_row = (JDIMENSION)
166	jdiv_round_up((long) cinfo->image_width,
167	(long) (cinfo->max_h_samp_factor*DCTSIZE));
168	cinfo->MCU_rows_in_scan = (JDIMENSION)
169	jdiv_round_up((long) cinfo->image_height,
170	(long) (cinfo->max_v_samp_factor*DCTSIZE));
171
172	cinfo->blocks_in_MCU = 0;
173
174	for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
175	compptr = cinfo->cur_comp_info[ci];
176	/* Sampling factors give # of blocks of component in each MCU */
177	compptr->MCU_width = compptr->h_samp_factor;
178	compptr->MCU_height = compptr->v_samp_factor;
179	compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
180	compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
181	/* Figure number of non-dummy blocks in last MCU column & row */
182	tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
183	if (tmp == 0) tmp = compptr->MCU_width;
184	compptr->last_col_width = tmp;
185	tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
186	if (tmp == 0) tmp = compptr->MCU_height;
187	compptr->last_row_height = tmp;
188	/* Prepare array describing MCU composition */
189	mcublks = compptr->MCU_blocks;
190	if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
191	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
192	while (mcublks-- > 0) {
193	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
194	}
195	}
196
197	}
198	}
199
200
201	/*
202	* Save away a copy of the Q-table referenced by each component present
203	* in the current scan, unless already saved during a prior scan.
204	*
205	* In a multiple-scan JPEG file, the encoder could assign different components
206	* the same Q-table slot number, but change table definitions between scans
207	* so that each component uses a different Q-table. (The IJG encoder is not
208	* currently capable of doing this, but other encoders might.) Since we want
209	* to be able to dequantize all the components at the end of the file, this
210	* means that we have to save away the table actually used for each component.
211	* We do this by copying the table at the start of the first scan containing
212	* the component.
213	* The JPEG spec prohibits the encoder from changing the contents of a Q-table
214	* slot between scans of a component using that slot. If the encoder does so
215	* anyway, this decoder will simply use the Q-table values that were current
216	* at the start of the first scan for the component.
217	*
218	* The decompressor output side looks only at the saved quant tables,
219	* not at the current Q-table slots.
220	*/
221
222	LOCAL(void)
223	latch_quant_tables (j_decompress_ptr cinfo)
224	{
225	int ci, qtblno;
226	jpeg_component_info *compptr;
227	JQUANT_TBL * qtbl;
228
229	for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
230	compptr = cinfo->cur_comp_info[ci];
231	/* No work if we already saved Q-table for this component */
232	if (compptr->quant_table != NULL)
233	continue;
234	/* Make sure specified quantization table is present */
235	qtblno = compptr->quant_tbl_no;
236	if (qtblno < 0 \|\| qtblno >= NUM_QUANT_TBLS \|\|
237	cinfo->quant_tbl_ptrs[qtblno] == NULL)
238	ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
239	/* OK, save away the quantization table */
240	qtbl = (JQUANT_TBL *)
241	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
242	SIZEOF(JQUANT_TBL));
243	MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
244	compptr->quant_table = qtbl;
245	}
246	}
247
248
249	/*
250	* Initialize the input modules to read a scan of compressed data.
251	* The first call to this is done by jdmaster.c after initializing
252	* the entire decompressor (during jpeg_start_decompress).
253	* Subsequent calls come from consume_markers, below.
254	*/
255
256	METHODDEF(void)
257	start_input_pass (j_decompress_ptr cinfo)
258	{
259	per_scan_setup(cinfo);
260	latch_quant_tables(cinfo);
261	(*cinfo->entropy->start_pass) (cinfo);
262	(*cinfo->coef->start_input_pass) (cinfo);
263	cinfo->inputctl->consume_input = cinfo->coef->consume_data;
264	}
265
266
267	/*
268	* Finish up after inputting a compressed-data scan.
269	* This is called by the coefficient controller after it's read all
270	* the expected data of the scan.
271	*/
272
273	METHODDEF(void)
274	finish_input_pass (j_decompress_ptr cinfo)
275	{
276	cinfo->inputctl->consume_input = consume_markers;
277	}
278
279
280	/*
281	* Read JPEG markers before, between, or after compressed-data scans.
282	* Change state as necessary when a new scan is reached.
283	* Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
284	*
285	* The consume_input method pointer points either here or to the
286	* coefficient controller's consume_data routine, depending on whether
287	* we are reading a compressed data segment or inter-segment markers.
288	*/
289
290	METHODDEF(int)
291	consume_markers (j_decompress_ptr cinfo)
292	{
293	my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
294	int val;
295
296	if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
297	return JPEG_REACHED_EOI;
298
299	val = (*cinfo->marker->read_markers) (cinfo);
300
301	switch (val) {
302	case JPEG_REACHED_SOS: /* Found SOS */
303	if (inputctl->inheaders) { /* 1st SOS */
304	initial_setup(cinfo);
305	inputctl->inheaders = FALSE;
306	/* Note: start_input_pass must be called by jdmaster.c
307	* before any more input can be consumed. jdapimin.c is
308	* responsible for enforcing this sequencing.
309	*/
310	} else { /* 2nd or later SOS marker */
311	if (! inputctl->pub.has_multiple_scans)
312	ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
313	start_input_pass(cinfo);
314	}
315	break;
316	case JPEG_REACHED_EOI: /* Found EOI */
317	inputctl->pub.eoi_reached = TRUE;
318	if (inputctl->inheaders) { /* Tables-only datastream, apparently */
319	if (cinfo->marker->saw_SOF)
320	ERREXIT(cinfo, JERR_SOF_NO_SOS);
321	} else {
322	/* Prevent infinite loop in coef ctlr's decompress_data routine
323	* if user set output_scan_number larger than number of scans.
324	*/
325	if (cinfo->output_scan_number > cinfo->input_scan_number)
326	cinfo->output_scan_number = cinfo->input_scan_number;
327	}
328	break;
329	case JPEG_SUSPENDED:
330	break;
331	}
332
333	return val;
334	}
335
336
337	/*
338	* Reset state to begin a fresh datastream.
339	*/
340
341	METHODDEF(void)
342	reset_input_controller (j_decompress_ptr cinfo)
343	{
344	my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
345
346	inputctl->pub.consume_input = consume_markers;
347	inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
348	inputctl->pub.eoi_reached = FALSE;
349	inputctl->inheaders = TRUE;
350	/* Reset other modules */
351	(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
352	(*cinfo->marker->reset_marker_reader) (cinfo);
353	/* Reset progression state -- would be cleaner if entropy decoder did this */
354	cinfo->coef_bits = NULL;
355	}
356
357
358	/*
359	* Initialize the input controller module.
360	* This is called only once, when the decompression object is created.
361	*/
362
363	GLOBAL(void)
364	jinit_input_controller (j_decompress_ptr cinfo)
365	{
366	my_inputctl_ptr inputctl;
367
368	/* Create subobject in permanent pool */
369	inputctl = (my_inputctl_ptr)
370	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
371	SIZEOF(my_input_controller));
372	cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
373	/* Initialize method pointers */
374	inputctl->pub.consume_input = consume_markers;
375	inputctl->pub.reset_input_controller = reset_input_controller;
376	inputctl->pub.start_input_pass = start_input_pass;
377	inputctl->pub.finish_input_pass = finish_input_pass;
378	/* Initialize state: can't use reset_input_controller since we don't
379	* want to try to reset other modules yet.
380	*/
381	inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
382	inputctl->pub.eoi_reached = FALSE;
383	inputctl->inheaders = TRUE;
384	}