/src/freeimage-svn/FreeImage/trunk/Source/LibJPEG/jdapimin.c

Source
/*
 * jdapimin.c
 *
 * Copyright (C) 1994-1998, Thomas G. Lane.
 * Modified 2009-2013 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 application interface code for the decompression half
 * of the JPEG library.  These are the "minimum" API routines that may be
 * needed in either the normal full-decompression case or the
 * transcoding-only case.
 *
 * Most of the routines intended to be called directly by an application
 * are in this file or in jdapistd.c.  But also see jcomapi.c for routines
 * shared by compression and decompression, and jdtrans.c for the transcoding
 * case.
 */

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


/*
 * Initialization of a JPEG decompression object.
 * The error manager must already be set up (in case memory manager fails).
 */

GLOBAL(void)
jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)
{
  int i;

  /* Guard against version mismatches between library and caller. */
  cinfo->mem = NULL;   /* so jpeg_destroy knows mem mgr not called */
  if (version != JPEG_LIB_VERSION)
    ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
  if (structsize != SIZEOF(struct jpeg_decompress_struct))
    ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE, 
       (int) SIZEOF(struct jpeg_decompress_struct), (int) structsize);

  /* For debugging purposes, we zero the whole master structure.
   * But the application has already set the err pointer, and may have set
   * client_data, so we have to save and restore those fields.
   * Note: if application hasn't set client_data, tools like Purify may
   * complain here.
   */
  {
    struct jpeg_error_mgr * err = cinfo->err;
    void * client_data = cinfo->client_data; /* ignore Purify complaint here */
    MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
    cinfo->err = err;
    cinfo->client_data = client_data;
  }
  cinfo->is_decompressor = TRUE;

  /* Initialize a memory manager instance for this object */
  jinit_memory_mgr((j_common_ptr) cinfo);

  /* Zero out pointers to permanent structures. */
  cinfo->progress = NULL;
  cinfo->src = NULL;

  for (i = 0; i < NUM_QUANT_TBLS; i++)
    cinfo->quant_tbl_ptrs[i] = NULL;

  for (i = 0; i < NUM_HUFF_TBLS; i++) {
    cinfo->dc_huff_tbl_ptrs[i] = NULL;
    cinfo->ac_huff_tbl_ptrs[i] = NULL;
  }

  /* Initialize marker processor so application can override methods
   * for COM, APPn markers before calling jpeg_read_header.
   */
  cinfo->marker_list = NULL;
  jinit_marker_reader(cinfo);

  /* And initialize the overall input controller. */
  jinit_input_controller(cinfo);

  /* OK, I'm ready */
  cinfo->global_state = DSTATE_START;
}


/*
 * Destruction of a JPEG decompression object
 */

GLOBAL(void)
jpeg_destroy_decompress (j_decompress_ptr cinfo)
{
  jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
}


/*
 * Abort processing of a JPEG decompression operation,
 * but don't destroy the object itself.
 */

GLOBAL(void)
jpeg_abort_decompress (j_decompress_ptr cinfo)
{
  jpeg_abort((j_common_ptr) cinfo); /* use common routine */
}


/*
 * Set default decompression parameters.
 */

LOCAL(void)
default_decompress_parms (j_decompress_ptr cinfo)
{
  int cid0, cid1, cid2;

  /* Guess the input colorspace, and set output colorspace accordingly. */
  /* Note application may override our guesses. */
  switch (cinfo->num_components) {
  case 1:
    cinfo->jpeg_color_space = JCS_GRAYSCALE;
    cinfo->out_color_space = JCS_GRAYSCALE;
    break;
    
  case 3:
    cid0 = cinfo->comp_info[0].component_id;
    cid1 = cinfo->comp_info[1].component_id;
    cid2 = cinfo->comp_info[2].component_id;

    /* First try to guess from the component IDs */
    if      (cid0 == 0x01 && cid1 == 0x02 && cid2 == 0x03)
      cinfo->jpeg_color_space = JCS_YCbCr;
    else if (cid0 == 0x01 && cid1 == 0x22 && cid2 == 0x23)
      cinfo->jpeg_color_space = JCS_BG_YCC;
    else if (cid0 == 0x52 && cid1 == 0x47 && cid2 == 0x42)
      cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
    else if (cid0 == 0x72 && cid1 == 0x67 && cid2 == 0x62)
      cinfo->jpeg_color_space = JCS_BG_RGB; /* ASCII 'r', 'g', 'b' */
    else if (cinfo->saw_JFIF_marker)
      cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
    else if (cinfo->saw_Adobe_marker) {
      switch (cinfo->Adobe_transform) {
      case 0:
  cinfo->jpeg_color_space = JCS_RGB;
  break;
      case 1:
  cinfo->jpeg_color_space = JCS_YCbCr;
  break;
      default:
  WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
  cinfo->jpeg_color_space = JCS_YCbCr;  /* assume it's YCbCr */
  break;
      }
    } else {
      TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
      cinfo->jpeg_color_space = JCS_YCbCr;  /* assume it's YCbCr */
    }
    /* Always guess RGB is proper output colorspace. */
    cinfo->out_color_space = JCS_RGB;
    break;
    
  case 4:
    if (cinfo->saw_Adobe_marker) {
      switch (cinfo->Adobe_transform) {
      case 0:
  cinfo->jpeg_color_space = JCS_CMYK;
  break;
      case 2:
  cinfo->jpeg_color_space = JCS_YCCK;
  break;
      default:
  WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
  cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
  break;
      }
    } else {
      /* No special markers, assume straight CMYK. */
      cinfo->jpeg_color_space = JCS_CMYK;
    }
    cinfo->out_color_space = JCS_CMYK;
    break;
    
  default:
    cinfo->jpeg_color_space = JCS_UNKNOWN;
    cinfo->out_color_space = JCS_UNKNOWN;
    break;
  }

  /* Set defaults for other decompression parameters. */
  cinfo->scale_num = cinfo->block_size;   /* 1:1 scaling */
  cinfo->scale_denom = cinfo->block_size;
  cinfo->output_gamma = 1.0;
  cinfo->buffered_image = FALSE;
  cinfo->raw_data_out = FALSE;
  cinfo->dct_method = JDCT_DEFAULT;
  cinfo->do_fancy_upsampling = TRUE;
  cinfo->do_block_smoothing = TRUE;
  cinfo->quantize_colors = FALSE;
  /* We set these in case application only sets quantize_colors. */
  cinfo->dither_mode = JDITHER_FS;
#ifdef QUANT_2PASS_SUPPORTED
  cinfo->two_pass_quantize = TRUE;
#else
  cinfo->two_pass_quantize = FALSE;
#endif
  cinfo->desired_number_of_colors = 256;
  cinfo->colormap = NULL;
  /* Initialize for no mode change in buffered-image mode. */
  cinfo->enable_1pass_quant = FALSE;
  cinfo->enable_external_quant = FALSE;
  cinfo->enable_2pass_quant = FALSE;
}


/*
 * Decompression startup: read start of JPEG datastream to see what's there.
 * Need only initialize JPEG object and supply a data source before calling.
 *
 * This routine will read as far as the first SOS marker (ie, actual start of
 * compressed data), and will save all tables and parameters in the JPEG
 * object.  It will also initialize the decompression parameters to default
 * values, and finally return JPEG_HEADER_OK.  On return, the application may
 * adjust the decompression parameters and then call jpeg_start_decompress.
 * (Or, if the application only wanted to determine the image parameters,
 * the data need not be decompressed.  In that case, call jpeg_abort or
 * jpeg_destroy to release any temporary space.)
 * If an abbreviated (tables only) datastream is presented, the routine will
 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then
 * re-use the JPEG object to read the abbreviated image datastream(s).
 * It is unnecessary (but OK) to call jpeg_abort in this case.
 * The JPEG_SUSPENDED return code only occurs if the data source module
 * requests suspension of the decompressor.  In this case the application
 * should load more source data and then re-call jpeg_read_header to resume
 * processing.
 * If a non-suspending data source is used and require_image is TRUE, then the
 * return code need not be inspected since only JPEG_HEADER_OK is possible.
 *
 * This routine is now just a front end to jpeg_consume_input, with some
 * extra error checking.
 */

GLOBAL(int)
jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
{
  int retcode;

  if (cinfo->global_state != DSTATE_START &&
      cinfo->global_state != DSTATE_INHEADER)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  retcode = jpeg_consume_input(cinfo);

  switch (retcode) {
  case JPEG_REACHED_SOS:
    retcode = JPEG_HEADER_OK;
    break;
  case JPEG_REACHED_EOI:
    if (require_image)   /* Complain if application wanted an image */
      ERREXIT(cinfo, JERR_NO_IMAGE);
    /* Reset to start state; it would be safer to require the application to
     * call jpeg_abort, but we can't change it now for compatibility reasons.
     * A side effect is to free any temporary memory (there shouldn't be any).
     */
    jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
    retcode = JPEG_HEADER_TABLES_ONLY;
    break;
  case JPEG_SUSPENDED:
    /* no work */
    break;
  }

  return retcode;
}


/*
 * Consume data in advance of what the decompressor requires.
 * This can be called at any time once the decompressor object has
 * been created and a data source has been set up.
 *
 * This routine is essentially a state machine that handles a couple
 * of critical state-transition actions, namely initial setup and
 * transition from header scanning to ready-for-start_decompress.
 * All the actual input is done via the input controller's consume_input
 * method.
 */

GLOBAL(int)
jpeg_consume_input (j_decompress_ptr cinfo)
{
  int retcode = JPEG_SUSPENDED;

  /* NB: every possible DSTATE value should be listed in this switch */
  switch (cinfo->global_state) {
  case DSTATE_START:
    /* Start-of-datastream actions: reset appropriate modules */
    (*cinfo->inputctl->reset_input_controller) (cinfo);
    /* Initialize application's data source module */
    (*cinfo->src->init_source) (cinfo);
    cinfo->global_state = DSTATE_INHEADER;
    /*FALLTHROUGH*/
  case DSTATE_INHEADER:
    retcode = (*cinfo->inputctl->consume_input) (cinfo);
    if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
      /* Set up default parameters based on header data */
      default_decompress_parms(cinfo);
      /* Set global state: ready for start_decompress */
      cinfo->global_state = DSTATE_READY;
    }
    break;
  case DSTATE_READY:
    /* Can't advance past first SOS until start_decompress is called */
    retcode = JPEG_REACHED_SOS;
    break;
  case DSTATE_PRELOAD:
  case DSTATE_PRESCAN:
  case DSTATE_SCANNING:
  case DSTATE_RAW_OK:
  case DSTATE_BUFIMAGE:
  case DSTATE_BUFPOST:
  case DSTATE_STOPPING:
    retcode = (*cinfo->inputctl->consume_input) (cinfo);
    break;
  default:
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  }
  return retcode;
}


/*
 * Have we finished reading the input file?
 */

GLOBAL(boolean)
jpeg_input_complete (j_decompress_ptr cinfo)
{
  /* Check for valid jpeg object */
  if (cinfo->global_state < DSTATE_START ||
      cinfo->global_state > DSTATE_STOPPING)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  return cinfo->inputctl->eoi_reached;
}


/*
 * Is there more than one scan?
 */

GLOBAL(boolean)
jpeg_has_multiple_scans (j_decompress_ptr cinfo)
{
  /* Only valid after jpeg_read_header completes */
  if (cinfo->global_state < DSTATE_READY ||
      cinfo->global_state > DSTATE_STOPPING)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  return cinfo->inputctl->has_multiple_scans;
}


/*
 * Finish JPEG decompression.
 *
 * This will normally just verify the file trailer and release temp storage.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL(boolean)
jpeg_finish_decompress (j_decompress_ptr cinfo)
{
  if ((cinfo->global_state == DSTATE_SCANNING ||
       cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
    /* Terminate final pass of non-buffered mode */
    if (cinfo->output_scanline < cinfo->output_height)
      ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
    (*cinfo->master->finish_output_pass) (cinfo);
    cinfo->global_state = DSTATE_STOPPING;
  } else if (cinfo->global_state == DSTATE_BUFIMAGE) {
    /* Finishing after a buffered-image operation */
    cinfo->global_state = DSTATE_STOPPING;
  } else if (cinfo->global_state != DSTATE_STOPPING) {
    /* STOPPING = repeat call after a suspension, anything else is error */
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  }
  /* Read until EOI */
  while (! cinfo->inputctl->eoi_reached) {
    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
      return FALSE;   /* Suspend, come back later */
  }
  /* Do final cleanup */
  (*cinfo->src->term_source) (cinfo);
  /* We can use jpeg_abort to release memory and reset global_state */
  jpeg_abort((j_common_ptr) cinfo);
  return TRUE;
}

Coverage Report

Created: 2025-10-28 06:24

Line	Count	Source
1		/*
2		* jdapimin.c
3		*
4		* Copyright (C) 1994-1998, Thomas G. Lane.
5		* Modified 2009-2013 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 application interface code for the decompression half
10		* of the JPEG library. These are the "minimum" API routines that may be
11		* needed in either the normal full-decompression case or the
12		* transcoding-only case.
13		*
14		* Most of the routines intended to be called directly by an application
15		* are in this file or in jdapistd.c. But also see jcomapi.c for routines
16		* shared by compression and decompression, and jdtrans.c for the transcoding
17		* case.
18		*/
19
20		#define JPEG_INTERNALS
21		#include "jinclude.h"
22		#include "jpeglib.h"
23
24
25		/*
26		* Initialization of a JPEG decompression object.
27		* The error manager must already be set up (in case memory manager fails).
28		*/
29
30		GLOBAL(void)
31		jpeg_CreateDecompress (j_decompress_ptr cinfo, int version, size_t structsize)
32	0	{
33	0	int i;
34
35		/* Guard against version mismatches between library and caller. */
36	0	cinfo->mem = NULL; /* so jpeg_destroy knows mem mgr not called */
37	0	if (version != JPEG_LIB_VERSION)
38	0	ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
39	0	if (structsize != SIZEOF(struct jpeg_decompress_struct))
40	0	ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
41	0	(int) SIZEOF(struct jpeg_decompress_struct), (int) structsize);
42
43		/* For debugging purposes, we zero the whole master structure.
44		* But the application has already set the err pointer, and may have set
45		* client_data, so we have to save and restore those fields.
46		* Note: if application hasn't set client_data, tools like Purify may
47		* complain here.
48		*/
49	0	{
50	0	struct jpeg_error_mgr * err = cinfo->err;
51	0	void * client_data = cinfo->client_data; /* ignore Purify complaint here */
52	0	MEMZERO(cinfo, SIZEOF(struct jpeg_decompress_struct));
53	0	cinfo->err = err;
54	0	cinfo->client_data = client_data;
55	0	}
56	0	cinfo->is_decompressor = TRUE;
57
58		/* Initialize a memory manager instance for this object */
59	0	jinit_memory_mgr((j_common_ptr) cinfo);
60
61		/* Zero out pointers to permanent structures. */
62	0	cinfo->progress = NULL;
63	0	cinfo->src = NULL;
64
65	0	for (i = 0; i < NUM_QUANT_TBLS; i++)
66	0	cinfo->quant_tbl_ptrs[i] = NULL;
67
68	0	for (i = 0; i < NUM_HUFF_TBLS; i++) {
69	0	cinfo->dc_huff_tbl_ptrs[i] = NULL;
70	0	cinfo->ac_huff_tbl_ptrs[i] = NULL;
71	0	}
72
73		/* Initialize marker processor so application can override methods
74		* for COM, APPn markers before calling jpeg_read_header.
75		*/
76	0	cinfo->marker_list = NULL;
77	0	jinit_marker_reader(cinfo);
78
79		/* And initialize the overall input controller. */
80	0	jinit_input_controller(cinfo);
81
82		/* OK, I'm ready */
83	0	cinfo->global_state = DSTATE_START;
84	0	}
85
86
87		/*
88		* Destruction of a JPEG decompression object
89		*/
90
91		GLOBAL(void)
92		jpeg_destroy_decompress (j_decompress_ptr cinfo)
93	0	{
94	0	jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
95	0	}
96
97
98		/*
99		* Abort processing of a JPEG decompression operation,
100		* but don't destroy the object itself.
101		*/
102
103		GLOBAL(void)
104		jpeg_abort_decompress (j_decompress_ptr cinfo)
105	0	{
106	0	jpeg_abort((j_common_ptr) cinfo); /* use common routine */
107	0	}
108
109
110		/*
111		* Set default decompression parameters.
112		*/
113
114		LOCAL(void)
115		default_decompress_parms (j_decompress_ptr cinfo)
116	0	{
117	0	int cid0, cid1, cid2;
118
119		/* Guess the input colorspace, and set output colorspace accordingly. */
120		/* Note application may override our guesses. */
121	0	switch (cinfo->num_components) {
122	0	case 1:
123	0	cinfo->jpeg_color_space = JCS_GRAYSCALE;
124	0	cinfo->out_color_space = JCS_GRAYSCALE;
125	0	break;
126
127	0	case 3:
128	0	cid0 = cinfo->comp_info[0].component_id;
129	0	cid1 = cinfo->comp_info[1].component_id;
130	0	cid2 = cinfo->comp_info[2].component_id;
131
132		/* First try to guess from the component IDs */
133	0	if (cid0 == 0x01 && cid1 == 0x02 && cid2 == 0x03)
134	0	cinfo->jpeg_color_space = JCS_YCbCr;
135	0	else if (cid0 == 0x01 && cid1 == 0x22 && cid2 == 0x23)
136	0	cinfo->jpeg_color_space = JCS_BG_YCC;
137	0	else if (cid0 == 0x52 && cid1 == 0x47 && cid2 == 0x42)
138	0	cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
139	0	else if (cid0 == 0x72 && cid1 == 0x67 && cid2 == 0x62)
140	0	cinfo->jpeg_color_space = JCS_BG_RGB; /* ASCII 'r', 'g', 'b' */
141	0	else if (cinfo->saw_JFIF_marker)
142	0	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
143	0	else if (cinfo->saw_Adobe_marker) {
144	0	switch (cinfo->Adobe_transform) {
145	0	case 0:
146	0	cinfo->jpeg_color_space = JCS_RGB;
147	0	break;
148	0	case 1:
149	0	cinfo->jpeg_color_space = JCS_YCbCr;
150	0	break;
151	0	default:
152	0	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
153	0	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
154	0	break;
155	0	}
156	0	} else {
157	0	TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
158	0	cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
159	0	}
160		/* Always guess RGB is proper output colorspace. */
161	0	cinfo->out_color_space = JCS_RGB;
162	0	break;
163
164	0	case 4:
165	0	if (cinfo->saw_Adobe_marker) {
166	0	switch (cinfo->Adobe_transform) {
167	0	case 0:
168	0	cinfo->jpeg_color_space = JCS_CMYK;
169	0	break;
170	0	case 2:
171	0	cinfo->jpeg_color_space = JCS_YCCK;
172	0	break;
173	0	default:
174	0	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
175	0	cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
176	0	break;
177	0	}
178	0	} else {
179		/* No special markers, assume straight CMYK. */
180	0	cinfo->jpeg_color_space = JCS_CMYK;
181	0	}
182	0	cinfo->out_color_space = JCS_CMYK;
183	0	break;
184
185	0	default:
186	0	cinfo->jpeg_color_space = JCS_UNKNOWN;
187	0	cinfo->out_color_space = JCS_UNKNOWN;
188	0	break;
189	0	}
190
191		/* Set defaults for other decompression parameters. */
192	0	cinfo->scale_num = cinfo->block_size; /* 1:1 scaling */
193	0	cinfo->scale_denom = cinfo->block_size;
194	0	cinfo->output_gamma = 1.0;
195	0	cinfo->buffered_image = FALSE;
196	0	cinfo->raw_data_out = FALSE;
197	0	cinfo->dct_method = JDCT_DEFAULT;
198	0	cinfo->do_fancy_upsampling = TRUE;
199	0	cinfo->do_block_smoothing = TRUE;
200	0	cinfo->quantize_colors = FALSE;
201		/* We set these in case application only sets quantize_colors. */
202	0	cinfo->dither_mode = JDITHER_FS;
203	0	#ifdef QUANT_2PASS_SUPPORTED
204	0	cinfo->two_pass_quantize = TRUE;
205		#else
206		cinfo->two_pass_quantize = FALSE;
207		#endif
208	0	cinfo->desired_number_of_colors = 256;
209	0	cinfo->colormap = NULL;
210		/* Initialize for no mode change in buffered-image mode. */
211	0	cinfo->enable_1pass_quant = FALSE;
212	0	cinfo->enable_external_quant = FALSE;
213	0	cinfo->enable_2pass_quant = FALSE;
214	0	}
215
216
217		/*
218		* Decompression startup: read start of JPEG datastream to see what's there.
219		* Need only initialize JPEG object and supply a data source before calling.
220		*
221		* This routine will read as far as the first SOS marker (ie, actual start of
222		* compressed data), and will save all tables and parameters in the JPEG
223		* object. It will also initialize the decompression parameters to default
224		* values, and finally return JPEG_HEADER_OK. On return, the application may
225		* adjust the decompression parameters and then call jpeg_start_decompress.
226		* (Or, if the application only wanted to determine the image parameters,
227		* the data need not be decompressed. In that case, call jpeg_abort or
228		* jpeg_destroy to release any temporary space.)
229		* If an abbreviated (tables only) datastream is presented, the routine will
230		* return JPEG_HEADER_TABLES_ONLY upon reaching EOI. The application may then
231		* re-use the JPEG object to read the abbreviated image datastream(s).
232		* It is unnecessary (but OK) to call jpeg_abort in this case.
233		* The JPEG_SUSPENDED return code only occurs if the data source module
234		* requests suspension of the decompressor. In this case the application
235		* should load more source data and then re-call jpeg_read_header to resume
236		* processing.
237		* If a non-suspending data source is used and require_image is TRUE, then the
238		* return code need not be inspected since only JPEG_HEADER_OK is possible.
239		*
240		* This routine is now just a front end to jpeg_consume_input, with some
241		* extra error checking.
242		*/
243
244		GLOBAL(int)
245		jpeg_read_header (j_decompress_ptr cinfo, boolean require_image)
246	0	{
247	0	int retcode;
248
249	0	if (cinfo->global_state != DSTATE_START &&
250	0	cinfo->global_state != DSTATE_INHEADER)
251	0	ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
252
253	0	retcode = jpeg_consume_input(cinfo);
254
255	0	switch (retcode) {
256	0	case JPEG_REACHED_SOS:
257	0	retcode = JPEG_HEADER_OK;
258	0	break;
259	0	case JPEG_REACHED_EOI:
260	0	if (require_image) /* Complain if application wanted an image */
261	0	ERREXIT(cinfo, JERR_NO_IMAGE);
262		/* Reset to start state; it would be safer to require the application to
263		* call jpeg_abort, but we can't change it now for compatibility reasons.
264		* A side effect is to free any temporary memory (there shouldn't be any).
265		*/
266	0	jpeg_abort((j_common_ptr) cinfo); /* sets state = DSTATE_START */
267	0	retcode = JPEG_HEADER_TABLES_ONLY;
268	0	break;
269	0	case JPEG_SUSPENDED:
270		/* no work */
271	0	break;
272	0	}
273
274	0	return retcode;
275	0	}
276
277
278		/*
279		* Consume data in advance of what the decompressor requires.
280		* This can be called at any time once the decompressor object has
281		* been created and a data source has been set up.
282		*
283		* This routine is essentially a state machine that handles a couple
284		* of critical state-transition actions, namely initial setup and
285		* transition from header scanning to ready-for-start_decompress.
286		* All the actual input is done via the input controller's consume_input
287		* method.
288		*/
289
290		GLOBAL(int)
291		jpeg_consume_input (j_decompress_ptr cinfo)
292	0	{
293	0	int retcode = JPEG_SUSPENDED;
294
295		/* NB: every possible DSTATE value should be listed in this switch */
296	0	switch (cinfo->global_state) {
297	0	case DSTATE_START:
298		/* Start-of-datastream actions: reset appropriate modules */
299	0	(*cinfo->inputctl->reset_input_controller) (cinfo);
300		/* Initialize application's data source module */
301	0	(*cinfo->src->init_source) (cinfo);
302	0	cinfo->global_state = DSTATE_INHEADER;
303		/FALLTHROUGH/
304	0	case DSTATE_INHEADER:
305	0	retcode = (*cinfo->inputctl->consume_input) (cinfo);
306	0	if (retcode == JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
307		/* Set up default parameters based on header data */
308	0	default_decompress_parms(cinfo);
309		/* Set global state: ready for start_decompress */
310	0	cinfo->global_state = DSTATE_READY;
311	0	}
312	0	break;
313	0	case DSTATE_READY:
314		/* Can't advance past first SOS until start_decompress is called */
315	0	retcode = JPEG_REACHED_SOS;
316	0	break;
317	0	case DSTATE_PRELOAD:
318	0	case DSTATE_PRESCAN:
319	0	case DSTATE_SCANNING:
320	0	case DSTATE_RAW_OK:
321	0	case DSTATE_BUFIMAGE:
322	0	case DSTATE_BUFPOST:
323	0	case DSTATE_STOPPING:
324	0	retcode = (*cinfo->inputctl->consume_input) (cinfo);
325	0	break;
326	0	default:
327	0	ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
328	0	}
329	0	return retcode;
330	0	}
331
332
333		/*
334		* Have we finished reading the input file?
335		*/
336
337		GLOBAL(boolean)
338		jpeg_input_complete (j_decompress_ptr cinfo)
339	0	{
340		/* Check for valid jpeg object */
341	0	if (cinfo->global_state < DSTATE_START \|\|
342	0	cinfo->global_state > DSTATE_STOPPING)
343	0	ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
344	0	return cinfo->inputctl->eoi_reached;
345	0	}
346
347
348		/*
349		* Is there more than one scan?
350		*/
351
352		GLOBAL(boolean)
353		jpeg_has_multiple_scans (j_decompress_ptr cinfo)
354	0	{
355		/* Only valid after jpeg_read_header completes */
356	0	if (cinfo->global_state < DSTATE_READY \|\|
357	0	cinfo->global_state > DSTATE_STOPPING)
358	0	ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
359	0	return cinfo->inputctl->has_multiple_scans;
360	0	}
361
362
363		/*
364		* Finish JPEG decompression.
365		*
366		* This will normally just verify the file trailer and release temp storage.
367		*
368		* Returns FALSE if suspended. The return value need be inspected only if
369		* a suspending data source is used.
370		*/
371
372		GLOBAL(boolean)
373		jpeg_finish_decompress (j_decompress_ptr cinfo)
374	0	{
375	0	if ((cinfo->global_state == DSTATE_SCANNING \|\|
376	0	cinfo->global_state == DSTATE_RAW_OK) && ! cinfo->buffered_image) {
377		/* Terminate final pass of non-buffered mode */
378	0	if (cinfo->output_scanline < cinfo->output_height)
379	0	ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
380	0	(*cinfo->master->finish_output_pass) (cinfo);
381	0	cinfo->global_state = DSTATE_STOPPING;
382	0	} else if (cinfo->global_state == DSTATE_BUFIMAGE) {
383		/* Finishing after a buffered-image operation */
384	0	cinfo->global_state = DSTATE_STOPPING;
385	0	} else if (cinfo->global_state != DSTATE_STOPPING) {
386		/* STOPPING = repeat call after a suspension, anything else is error */
387	0	ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
388	0	}
389		/* Read until EOI */
390	0	while (! cinfo->inputctl->eoi_reached) {
391	0	if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
392	0	return FALSE; /* Suspend, come back later */
393	0	}
394		/* Do final cleanup */
395	0	(*cinfo->src->term_source) (cinfo);
396		/* We can use jpeg_abort to release memory and reset global_state */
397	0	jpeg_abort((j_common_ptr) cinfo);
398	0	return TRUE;
399	0	}