1/*
2 * jdapistd.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright (C) 2010, D. R. Commander.
8 * For conditions of distribution and use, see the accompanying README file.
9 *
10 * This file contains application interface code for the decompression half
11 * of the JPEG library.  These are the "standard" API routines that are
12 * used in the normal full-decompression case.  They are not used by a
13 * transcoding-only application.  Note that if an application links in
14 * jpeg_start_decompress, it will end up linking in the entire decompressor.
15 * We thus must separate this file from jdapimin.c to avoid linking the
16 * whole decompression library into a transcoder.
17 */
18
19#define JPEG_INTERNALS
20#include "jinclude.h"
21#include "jpeglib.h"
22#include "jpegcomp.h"
23
24
25/* Forward declarations */
26LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
27
28
29/*
30 * Decompression initialization.
31 * jpeg_read_header must be completed before calling this.
32 *
33 * If a multipass operating mode was selected, this will do all but the
34 * last pass, and thus may take a great deal of time.
35 *
36 * Returns FALSE if suspended.  The return value need be inspected only if
37 * a suspending data source is used.
38 */
39
40GLOBAL(boolean)
41jpeg_start_decompress (j_decompress_ptr cinfo)
42{
43  if (cinfo->global_state == DSTATE_READY) {
44    /* First call: initialize master control, select active modules */
45    jinit_master_decompress(cinfo);
46    if (cinfo->buffered_image) {
47      /* No more work here; expecting jpeg_start_output next */
48      cinfo->global_state = DSTATE_BUFIMAGE;
49      return TRUE;
50    }
51    cinfo->global_state = DSTATE_PRELOAD;
52  }
53  if (cinfo->global_state == DSTATE_PRELOAD) {
54    /* If file has multiple scans, absorb them all into the coef buffer */
55    if (cinfo->inputctl->has_multiple_scans) {
56#ifdef D_MULTISCAN_FILES_SUPPORTED
57      for (;;) {
58	int retcode;
59	/* Call progress monitor hook if present */
60	if (cinfo->progress != NULL)
61	  (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
62	/* Absorb some more input */
63	retcode = (*cinfo->inputctl->consume_input) (cinfo);
64	if (retcode == JPEG_SUSPENDED)
65	  return FALSE;
66	if (retcode == JPEG_REACHED_EOI)
67	  break;
68	/* Advance progress counter if appropriate */
69	if (cinfo->progress != NULL &&
70	    (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
71	  if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
72	    /* jdmaster underestimated number of scans; ratchet up one scan */
73	    cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
74	  }
75	}
76      }
77#else
78      ERREXIT(cinfo, JERR_NOT_COMPILED);
79#endif /* D_MULTISCAN_FILES_SUPPORTED */
80    }
81    cinfo->output_scan_number = cinfo->input_scan_number;
82  } else if (cinfo->global_state != DSTATE_PRESCAN)
83    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
84  /* Perform any dummy output passes, and set up for the final pass */
85  return output_pass_setup(cinfo);
86}
87
88
89/*
90 * Set up for an output pass, and perform any dummy pass(es) needed.
91 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
92 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
93 * Exit: If done, returns TRUE and sets global_state for proper output mode.
94 *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
95 */
96
97LOCAL(boolean)
98output_pass_setup (j_decompress_ptr cinfo)
99{
100  if (cinfo->global_state != DSTATE_PRESCAN) {
101    /* First call: do pass setup */
102    (*cinfo->master->prepare_for_output_pass) (cinfo);
103    cinfo->output_scanline = 0;
104    cinfo->global_state = DSTATE_PRESCAN;
105  }
106  /* Loop over any required dummy passes */
107  while (cinfo->master->is_dummy_pass) {
108#ifdef QUANT_2PASS_SUPPORTED
109    /* Crank through the dummy pass */
110    while (cinfo->output_scanline < cinfo->output_height) {
111      JDIMENSION last_scanline;
112      /* Call progress monitor hook if present */
113      if (cinfo->progress != NULL) {
114	cinfo->progress->pass_counter = (long) cinfo->output_scanline;
115	cinfo->progress->pass_limit = (long) cinfo->output_height;
116	(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
117      }
118      /* Process some data */
119      last_scanline = cinfo->output_scanline;
120      (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
121				    &cinfo->output_scanline, (JDIMENSION) 0);
122      if (cinfo->output_scanline == last_scanline)
123	return FALSE;		/* No progress made, must suspend */
124    }
125    /* Finish up dummy pass, and set up for another one */
126    (*cinfo->master->finish_output_pass) (cinfo);
127    (*cinfo->master->prepare_for_output_pass) (cinfo);
128    cinfo->output_scanline = 0;
129#else
130    ERREXIT(cinfo, JERR_NOT_COMPILED);
131#endif /* QUANT_2PASS_SUPPORTED */
132  }
133  /* Ready for application to drive output pass through
134   * jpeg_read_scanlines or jpeg_read_raw_data.
135   */
136  cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
137  return TRUE;
138}
139
140
141/*
142 * Read some scanlines of data from the JPEG decompressor.
143 *
144 * The return value will be the number of lines actually read.
145 * This may be less than the number requested in several cases,
146 * including bottom of image, data source suspension, and operating
147 * modes that emit multiple scanlines at a time.
148 *
149 * Note: we warn about excess calls to jpeg_read_scanlines() since
150 * this likely signals an application programmer error.  However,
151 * an oversize buffer (max_lines > scanlines remaining) is not an error.
152 */
153
154GLOBAL(JDIMENSION)
155jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
156		     JDIMENSION max_lines)
157{
158  JDIMENSION row_ctr;
159
160  if (cinfo->global_state != DSTATE_SCANNING)
161    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
162  if (cinfo->output_scanline >= cinfo->output_height) {
163    WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
164    return 0;
165  }
166
167  /* Call progress monitor hook if present */
168  if (cinfo->progress != NULL) {
169    cinfo->progress->pass_counter = (long) cinfo->output_scanline;
170    cinfo->progress->pass_limit = (long) cinfo->output_height;
171    (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
172  }
173
174  /* Process some data */
175  row_ctr = 0;
176  (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
177  cinfo->output_scanline += row_ctr;
178  return row_ctr;
179}
180
181
182/*
183 * Alternate entry point to read raw data.
184 * Processes exactly one iMCU row per call, unless suspended.
185 */
186
187GLOBAL(JDIMENSION)
188jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
189		    JDIMENSION max_lines)
190{
191  JDIMENSION lines_per_iMCU_row;
192
193  if (cinfo->global_state != DSTATE_RAW_OK)
194    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
195  if (cinfo->output_scanline >= cinfo->output_height) {
196    WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
197    return 0;
198  }
199
200  /* Call progress monitor hook if present */
201  if (cinfo->progress != NULL) {
202    cinfo->progress->pass_counter = (long) cinfo->output_scanline;
203    cinfo->progress->pass_limit = (long) cinfo->output_height;
204    (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
205  }
206
207  /* Verify that at least one iMCU row can be returned. */
208  lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size;
209  if (max_lines < lines_per_iMCU_row)
210    ERREXIT(cinfo, JERR_BUFFER_SIZE);
211
212  /* Decompress directly into user's buffer. */
213  if (! (*cinfo->coef->decompress_data) (cinfo, data))
214    return 0;			/* suspension forced, can do nothing more */
215
216  /* OK, we processed one iMCU row. */
217  cinfo->output_scanline += lines_per_iMCU_row;
218  return lines_per_iMCU_row;
219}
220
221
222/* Additional entry points for buffered-image mode. */
223
224#ifdef D_MULTISCAN_FILES_SUPPORTED
225
226/*
227 * Initialize for an output pass in buffered-image mode.
228 */
229
230GLOBAL(boolean)
231jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
232{
233  if (cinfo->global_state != DSTATE_BUFIMAGE &&
234      cinfo->global_state != DSTATE_PRESCAN)
235    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
236  /* Limit scan number to valid range */
237  if (scan_number <= 0)
238    scan_number = 1;
239  if (cinfo->inputctl->eoi_reached &&
240      scan_number > cinfo->input_scan_number)
241    scan_number = cinfo->input_scan_number;
242  cinfo->output_scan_number = scan_number;
243  /* Perform any dummy output passes, and set up for the real pass */
244  return output_pass_setup(cinfo);
245}
246
247
248/*
249 * Finish up after an output pass in buffered-image mode.
250 *
251 * Returns FALSE if suspended.  The return value need be inspected only if
252 * a suspending data source is used.
253 */
254
255GLOBAL(boolean)
256jpeg_finish_output (j_decompress_ptr cinfo)
257{
258  if ((cinfo->global_state == DSTATE_SCANNING ||
259       cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
260    /* Terminate this pass. */
261    /* We do not require the whole pass to have been completed. */
262    (*cinfo->master->finish_output_pass) (cinfo);
263    cinfo->global_state = DSTATE_BUFPOST;
264  } else if (cinfo->global_state != DSTATE_BUFPOST) {
265    /* BUFPOST = repeat call after a suspension, anything else is error */
266    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
267  }
268  /* Read markers looking for SOS or EOI */
269  while (cinfo->input_scan_number <= cinfo->output_scan_number &&
270	 ! cinfo->inputctl->eoi_reached) {
271    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
272      return FALSE;		/* Suspend, come back later */
273  }
274  cinfo->global_state = DSTATE_BUFIMAGE;
275  return TRUE;
276}
277
278#endif /* D_MULTISCAN_FILES_SUPPORTED */
279