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