1 /*
2  * jdtrans.c
3  *
4  * Copyright (C) 1995-1997, 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 library routines for transcoding decompression,
9  * that is, reading raw DCT coefficient arrays from an input JPEG file.
10  * The routines in jdapimin.c will also be needed by a transcoder.
11  */
12 
13 #define JPEG_INTERNALS
14 #include "jinclude.h"
15 #include "jpeglib.h"
16 
17 
18 /* Forward declarations */
19 LOCAL(void) transdecode_master_selection JPP((j_decompress_ptr cinfo));
20 
21 
22 /*
23  * Read the coefficient arrays from a JPEG file.
24  * jpeg_read_header must be completed before calling this.
25  *
26  * The entire image is read into a set of virtual coefficient-block arrays,
27  * one per component.  The return value is a pointer to the array of
28  * virtual-array descriptors.  These can be manipulated directly via the
29  * JPEG memory manager, or handed off to jpeg_write_coefficients().
30  * To release the memory occupied by the virtual arrays, call
31  * jpeg_finish_decompress() when done with the data.
32  *
33  * An alternative usage is to simply obtain access to the coefficient arrays
34  * during a buffered-image-mode decompression operation.  This is allowed
35  * after any jpeg_finish_output() call.  The arrays can be accessed until
36  * jpeg_finish_decompress() is called.  (Note that any call to the library
37  * may reposition the arrays, so don't rely on access_virt_barray() results
38  * to stay valid across library calls.)
39  *
40  * Returns NULL if suspended.  This case need be checked only if
41  * a suspending data source is used.
42  */
43 
44 GLOBAL(jvirt_barray_ptr *)
jpeg_read_coefficients(j_decompress_ptr cinfo)45 jpeg_read_coefficients (j_decompress_ptr cinfo)
46 {
47   if (cinfo->global_state == DSTATE_READY) {
48     /* First call: initialize active modules */
49     transdecode_master_selection(cinfo);
50     cinfo->global_state = DSTATE_RDCOEFS;
51   }
52   if (cinfo->global_state == DSTATE_RDCOEFS) {
53     /* Absorb whole file into the coef buffer */
54     for (;;) {
55       int retcode;
56       /* Call progress monitor hook if present */
57       if (cinfo->progress != NULL)
58         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
59       /* Absorb some more input */
60       retcode = (*cinfo->inputctl->consume_input) (cinfo);
61       if (retcode == JPEG_SUSPENDED)
62         return NULL;
63       if (retcode == JPEG_REACHED_EOI)
64         break;
65       /* Advance progress counter if appropriate */
66       if (cinfo->progress != NULL &&
67 	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
68         if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
69 	  /* startup underestimated number of scans; ratchet up one scan */
70         cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
71         }
72       }
73     }
74     /* Set state so that jpeg_finish_decompress does the right thing */
75     cinfo->global_state = DSTATE_STOPPING;
76   }
77   /* At this point we should be in state DSTATE_STOPPING if being used
78    * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
79    * to the coefficients during a full buffered-image-mode decompression.
80    */
81   if ((cinfo->global_state == DSTATE_STOPPING ||
82        cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
83     return cinfo->coef->coef_arrays;
84   }
85   /* Oops, improper usage */
86   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
87   return NULL;			/* keep compiler happy */
88 }
89 
90 LOCAL(boolean)
jpeg_build_huffman_index_progressive(j_decompress_ptr cinfo,huffman_index * index)91 jpeg_build_huffman_index_progressive(j_decompress_ptr cinfo,
92         huffman_index *index)
93 {
94   if (cinfo->global_state == DSTATE_READY) {
95     printf("Progressive Mode\n");
96     /* First call: initialize active modules */
97     transdecode_master_selection(cinfo);
98     cinfo->global_state = DSTATE_RDCOEFS;
99   }
100   if (cinfo->global_state == DSTATE_RDCOEFS) {
101     int mcu, i;
102     cinfo->marker->get_sos_marker_position(cinfo, index);
103 
104     /* Absorb whole file into the coef buffer */
105     for (mcu = 0; mcu < cinfo->total_iMCU_rows; mcu++) {
106       int retcode = 0;
107       /* Call progress monitor hook if present */
108       if (cinfo->progress != NULL)
109         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
110       /* Absorb some more input */
111       jinit_phuff_decoder(cinfo);
112       for (i = 0; i < index->scan_count; i++) {
113         (*cinfo->inputctl->finish_input_pass) (cinfo);
114         jset_input_stream_position(cinfo, index->scan[i].bitstream_offset);
115         cinfo->unread_marker = 0;
116         retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
117                     (cinfo, index, i);
118         if (retcode == JPEG_REACHED_EOI)
119           break;
120         cinfo->input_iMCU_row = mcu;
121         if (mcu != 0)
122           (*cinfo->entropy->configure_huffman_decoder)
123                 (cinfo, index->scan[i].prev_MCU_offset);
124         cinfo->input_scan_number = i;
125         retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
126                     (cinfo, index, i);
127       }
128       if (retcode == JPEG_SUSPENDED)
129         return FALSE;
130       if (retcode == JPEG_REACHED_EOI)
131         break;
132       /* Advance progress counter if appropriate */
133       if (cinfo->progress != NULL &&
134 	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
135         if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
136 	  /* startup underestimated number of scans; ratchet up one scan */
137           cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
138         }
139       }
140     }
141     cinfo->global_state = DSTATE_STOPPING;
142   }
143   /* At this point we should be in state DSTATE_STOPPING if being used
144    * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
145    * to the coefficients during a full buffered-image-mode decompression.
146    */
147   if ((cinfo->global_state == DSTATE_STOPPING ||
148        cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
149     return TRUE;
150   }
151   /* Oops, improper usage */
152   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
153   return FALSE;			/* keep compiler happy */
154 }
155 
156 LOCAL(boolean)
jpeg_build_huffman_index_baseline(j_decompress_ptr cinfo,huffman_index * index)157 jpeg_build_huffman_index_baseline(j_decompress_ptr cinfo, huffman_index *index)
158 {
159   if (cinfo->global_state == DSTATE_READY) {
160     printf("Baseline Mode\n");
161     /* First call: initialize active modules */
162     transdecode_master_selection(cinfo);
163     cinfo->global_state = DSTATE_RDCOEFS;
164   }
165   if (cinfo->global_state == DSTATE_RDCOEFS) {
166     /* Absorb whole file into the coef buffer */
167     for (;;) {
168       int retcode;
169       /* Call progress monitor hook if present */
170       if (cinfo->progress != NULL)
171         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
172       /* Absorb some more input */
173       retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
174                     (cinfo, index, 0);
175       if (retcode == JPEG_SUSPENDED)
176         return FALSE;
177       if (retcode == JPEG_REACHED_EOI)
178         break;
179       if (retcode == JPEG_SCAN_COMPLETED)
180         break;
181 
182       /* Advance progress counter if appropriate */
183       if (cinfo->progress != NULL &&
184 	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
185         if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
186 	  /* startup underestimated number of scans; ratchet up one scan */
187         cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
188         }
189       }
190     }
191     /* Set state so that jpeg_finish_decompress does the right thing */
192     cinfo->global_state = DSTATE_STOPPING;
193   }
194   /* At this point we should be in state DSTATE_STOPPING if being used
195    * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
196    * to the coefficients during a full buffered-image-mode decompression.
197    */
198   if ((cinfo->global_state == DSTATE_STOPPING ||
199        cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
200     return TRUE;
201   }
202   /* Oops, improper usage */
203   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
204   return FALSE;			/* keep compiler happy */
205 }
206 
207 GLOBAL(boolean)
jpeg_build_huffman_index(j_decompress_ptr cinfo,huffman_index * index)208 jpeg_build_huffman_index(j_decompress_ptr cinfo, huffman_index *index)
209 {
210     cinfo->tile_decode = TRUE;
211     if (cinfo->progressive_mode)
212       return jpeg_build_huffman_index_progressive(cinfo, index);
213     else
214       return jpeg_build_huffman_index_baseline(cinfo, index);
215 }
216 
217 /*
218  * Master selection of decompression modules for transcoding.
219  * This substitutes for jdmaster.c's initialization of the full decompressor.
220  */
221 
222 LOCAL(void)
transdecode_master_selection(j_decompress_ptr cinfo)223 transdecode_master_selection (j_decompress_ptr cinfo)
224 {
225   /* This is effectively a buffered-image operation. */
226   cinfo->buffered_image = TRUE;
227 
228   /* Entropy decoding: either Huffman or arithmetic coding. */
229   if (cinfo->arith_code) {
230     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
231   } else {
232     if (cinfo->progressive_mode) {
233 #ifdef D_PROGRESSIVE_SUPPORTED
234       jinit_phuff_decoder(cinfo);
235 #else
236       ERREXIT(cinfo, JERR_NOT_COMPILED);
237 #endif
238     } else {
239       jinit_huff_decoder(cinfo);
240     }
241   }
242 
243   /* Always get a full-image coefficient buffer. */
244   jinit_d_coef_controller(cinfo, TRUE);
245 
246   /* We can now tell the memory manager to allocate virtual arrays. */
247   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
248 
249   /* Initialize input side of decompressor to consume first scan. */
250   (*cinfo->inputctl->start_input_pass) (cinfo);
251 
252   /* Initialize progress monitoring. */
253   if (cinfo->progress != NULL) {
254     int nscans;
255     /* Estimate number of scans to set pass_limit. */
256     if (cinfo->progressive_mode) {
257       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
258       nscans = 2 + 3 * cinfo->num_components;
259     } else if (cinfo->inputctl->has_multiple_scans) {
260       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
261       nscans = cinfo->num_components;
262     } else {
263       nscans = 1;
264     }
265     cinfo->progress->pass_counter = 0L;
266     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
267     cinfo->progress->completed_passes = 0;
268     cinfo->progress->total_passes = 1;
269   }
270 }
271