1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * jdinput.c
7 *
8 * Copyright (C) 1991-1997, Thomas G. Lane.
9 * This file is part of the Independent JPEG Group's software.
10 * For conditions of distribution and use, see the accompanying README file.
11 *
12 * This file contains input control logic for the JPEG decompressor.
13 * These routines are concerned with controlling the decompressor's input
14 * processing (marker reading and coefficient decoding). The actual input
15 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
16 */
17
18#define JPEG_INTERNALS
19#include "jinclude.h"
20#include "jpeglib.h"
21
22
23/* Private state */
24
25typedef struct {
26 struct jpeg_input_controller pub; /* public fields */
27
28 boolean inheaders; /* TRUE until first SOS is reached */
29} my_input_controller;
30
31typedef my_input_controller * my_inputctl_ptr;
32
33
34/* Forward declarations */
35METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
36
37
38/*
39 * Routines to calculate various quantities related to the size of the image.
40 */
41
42LOCAL(void)
43initial_setup (j_decompress_ptr cinfo)
44/* Called once, when first SOS marker is reached */
45{
46 int ci;
47 jpeg_component_info *compptr;
48
49 /* Make sure image isn't bigger than I can handle */
50 if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
51 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
52 ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
53
54 /* For now, precision must match compiled-in value... */
55 if (cinfo->data_precision != BITS_IN_JSAMPLE)
56 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
57
58 /* Check that number of components won't exceed internal array sizes */
59 if (cinfo->num_components > MAX_COMPONENTS)
60 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
61 MAX_COMPONENTS);
62
63 /* Compute maximum sampling factors; check factor validity */
64 cinfo->max_h_samp_factor = 1;
65 cinfo->max_v_samp_factor = 1;
66 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
67 ci++, compptr++) {
68 if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
69 compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
70 ERREXIT(cinfo, JERR_BAD_SAMPLING);
71 cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
72 compptr->h_samp_factor);
73 cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
74 compptr->v_samp_factor);
75 }
76
77 /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
78 * In the full decompressor, this will be overridden by jdmaster.c;
79 * but in the transcoder, jdmaster.c is not used, so we must do it here.
80 */
81 cinfo->min_DCT_scaled_size = DCTSIZE;
82
83 /* Compute dimensions of components */
84 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
85 ci++, compptr++) {
86 compptr->DCT_scaled_size = DCTSIZE;
87 /* Size in DCT blocks */
88 compptr->width_in_blocks = (JDIMENSION)
89 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
90 (long) (cinfo->max_h_samp_factor * DCTSIZE));
91 compptr->height_in_blocks = (JDIMENSION)
92 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
93 (long) (cinfo->max_v_samp_factor * DCTSIZE));
94 /* downsampled_width and downsampled_height will also be overridden by
95 * jdmaster.c if we are doing full decompression. The transcoder library
96 * doesn't use these values, but the calling application might.
97 */
98 /* Size in samples */
99 compptr->downsampled_width = (JDIMENSION)
100 jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
101 (long) cinfo->max_h_samp_factor);
102 compptr->downsampled_height = (JDIMENSION)
103 jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
104 (long) cinfo->max_v_samp_factor);
105 /* Mark component needed, until color conversion says otherwise */
106 compptr->component_needed = TRUE;
107 /* Mark no quantization table yet saved for component */
108 compptr->quant_table = NULL;
109 }
110
111 /* Compute number of fully interleaved MCU rows. */
112 cinfo->total_iMCU_rows = (JDIMENSION)
113 jdiv_round_up((long) cinfo->image_height,
114 (long) (cinfo->max_v_samp_factor*DCTSIZE));
115
116 /* Decide whether file contains multiple scans */
117 if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
118 cinfo->inputctl->has_multiple_scans = TRUE;
119 else
120 cinfo->inputctl->has_multiple_scans = FALSE;
121}
122
123
124LOCAL(void)
125per_scan_setup (j_decompress_ptr cinfo)
126/* Do computations that are needed before processing a JPEG scan */
127/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
128{
129 int ci, mcublks, tmp;
130 jpeg_component_info *compptr;
131
132 if (cinfo->comps_in_scan == 1) {
133
134 /* Noninterleaved (single-component) scan */
135 compptr = cinfo->cur_comp_info[0];
136
137 /* Overall image size in MCUs */
138 cinfo->MCUs_per_row = compptr->width_in_blocks;
139 cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
140
141 /* For noninterleaved scan, always one block per MCU */
142 compptr->MCU_width = 1;
143 compptr->MCU_height = 1;
144 compptr->MCU_blocks = 1;
145 compptr->MCU_sample_width = compptr->DCT_scaled_size;
146 compptr->last_col_width = 1;
147 /* For noninterleaved scans, it is convenient to define last_row_height
148 * as the number of block rows present in the last iMCU row.
149 */
150 tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
151 if (tmp == 0) tmp = compptr->v_samp_factor;
152 compptr->last_row_height = tmp;
153
154 /* Prepare array describing MCU composition */
155 cinfo->blocks_in_MCU = 1;
156 cinfo->MCU_membership[0] = 0;
157
158 } else {
159
160 /* Interleaved (multi-component) scan */
161 if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
162 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
163 MAX_COMPS_IN_SCAN);
164
165 /* Overall image size in MCUs */
166 cinfo->MCUs_per_row = (JDIMENSION)
167 jdiv_round_up((long) cinfo->image_width,
168 (long) (cinfo->max_h_samp_factor*DCTSIZE));
169 cinfo->MCU_rows_in_scan = (JDIMENSION)
170 jdiv_round_up((long) cinfo->image_height,
171 (long) (cinfo->max_v_samp_factor*DCTSIZE));
172
173 cinfo->blocks_in_MCU = 0;
174
175 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
176 compptr = cinfo->cur_comp_info[ci];
177 /* Sampling factors give # of blocks of component in each MCU */
178 compptr->MCU_width = compptr->h_samp_factor;
179 compptr->MCU_height = compptr->v_samp_factor;
180 compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
181 compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
182 /* Figure number of non-dummy blocks in last MCU column & row */
183 tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
184 if (tmp == 0) tmp = compptr->MCU_width;
185 compptr->last_col_width = tmp;
186 tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
187 if (tmp == 0) tmp = compptr->MCU_height;
188 compptr->last_row_height = tmp;
189 /* Prepare array describing MCU composition */
190 mcublks = compptr->MCU_blocks;
191 if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
192 ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
193 while (mcublks-- > 0) {
194 cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
195 }
196 }
197
198 }
199}
200
201
202/*
203 * Save away a copy of the Q-table referenced by each component present
204 * in the current scan, unless already saved during a prior scan.
205 *
206 * In a multiple-scan JPEG file, the encoder could assign different components
207 * the same Q-table slot number, but change table definitions between scans
208 * so that each component uses a different Q-table. (The IJG encoder is not
209 * currently capable of doing this, but other encoders might.) Since we want
210 * to be able to dequantize all the components at the end of the file, this
211 * means that we have to save away the table actually used for each component.
212 * We do this by copying the table at the start of the first scan containing
213 * the component.
214 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
215 * slot between scans of a component using that slot. If the encoder does so
216 * anyway, this decoder will simply use the Q-table values that were current
217 * at the start of the first scan for the component.
218 *
219 * The decompressor output side looks only at the saved quant tables,
220 * not at the current Q-table slots.
221 */
222
223LOCAL(void)
224latch_quant_tables (j_decompress_ptr cinfo)
225{
226 int ci, qtblno;
227 jpeg_component_info *compptr;
228 JQUANT_TBL * qtbl;
229
230 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
231 compptr = cinfo->cur_comp_info[ci];
232 /* No work if we already saved Q-table for this component */
233 if (compptr->quant_table != NULL)
234 continue;
235 /* Make sure specified quantization table is present */
236 qtblno = compptr->quant_tbl_no;
237 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
238 cinfo->quant_tbl_ptrs[qtblno] == NULL)
239 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
240 /* OK, save away the quantization table */
241 qtbl = (JQUANT_TBL *)
242 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
243 SIZEOF(JQUANT_TBL));
244 MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
245 compptr->quant_table = qtbl;
246 }
247}
248
249
250/*
251 * Initialize the input modules to read a scan of compressed data.
252 * The first call to this is done by jdmaster.c after initializing
253 * the entire decompressor (during jpeg_start_decompress).
254 * Subsequent calls come from consume_markers, below.
255 */
256
257METHODDEF(void)
258start_input_pass (j_decompress_ptr cinfo)
259{
260 per_scan_setup(cinfo);
261 latch_quant_tables(cinfo);
262 (*cinfo->entropy->start_pass) (cinfo);
263 (*cinfo->coef->start_input_pass) (cinfo);
264 cinfo->inputctl->consume_input = cinfo->coef->consume_data;
265}
266
267
268/*
269 * Finish up after inputting a compressed-data scan.
270 * This is called by the coefficient controller after it's read all
271 * the expected data of the scan.
272 */
273
274METHODDEF(void)
275finish_input_pass (j_decompress_ptr cinfo)
276{
277 cinfo->inputctl->consume_input = consume_markers;
278}
279
280
281/*
282 * Read JPEG markers before, between, or after compressed-data scans.
283 * Change state as necessary when a new scan is reached.
284 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
285 *
286 * The consume_input method pointer points either here or to the
287 * coefficient controller's consume_data routine, depending on whether
288 * we are reading a compressed data segment or inter-segment markers.
289 */
290
291METHODDEF(int)
292consume_markers (j_decompress_ptr cinfo)
293{
294 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
295 int val;
296
297 if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
298 return JPEG_REACHED_EOI;
299
300 val = (*cinfo->marker->read_markers) (cinfo);
301
302 switch (val) {
303 case JPEG_REACHED_SOS: /* Found SOS */
304 if (inputctl->inheaders) { /* 1st SOS */
305 initial_setup(cinfo);
306 inputctl->inheaders = FALSE;
307 /* Note: start_input_pass must be called by jdmaster.c
308 * before any more input can be consumed. jdapimin.c is
309 * responsible for enforcing this sequencing.
310 */
311 } else { /* 2nd or later SOS marker */
312 if (! inputctl->pub.has_multiple_scans)
313 ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
314 start_input_pass(cinfo);
315 }
316 break;
317 case JPEG_REACHED_EOI: /* Found EOI */
318 inputctl->pub.eoi_reached = TRUE;
319 if (inputctl->inheaders) { /* Tables-only datastream, apparently */
320 if (cinfo->marker->saw_SOF)
321 ERREXIT(cinfo, JERR_SOF_NO_SOS);
322 } else {
323 /* Prevent infinite loop in coef ctlr's decompress_data routine
324 * if user set output_scan_number larger than number of scans.
325 */
326 if (cinfo->output_scan_number > cinfo->input_scan_number)
327 cinfo->output_scan_number = cinfo->input_scan_number;
328 }
329 break;
330 case JPEG_SUSPENDED:
331 break;
332 }
333
334 return val;
335}
336
337
338/*
339 * Reset state to begin a fresh datastream.
340 */
341
342METHODDEF(void)
343reset_input_controller (j_decompress_ptr cinfo)
344{
345 my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
346
347 inputctl->pub.consume_input = consume_markers;
348 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
349 inputctl->pub.eoi_reached = FALSE;
350 inputctl->inheaders = TRUE;
351 /* Reset other modules */
352 (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
353 (*cinfo->marker->reset_marker_reader) (cinfo);
354 /* Reset progression state -- would be cleaner if entropy decoder did this */
355 cinfo->coef_bits = NULL;
356}
357
358
359/*
360 * Initialize the input controller module.
361 * This is called only once, when the decompression object is created.
362 */
363
364GLOBAL(void)
365jinit_input_controller (j_decompress_ptr cinfo)
366{
367 my_inputctl_ptr inputctl;
368
369 /* Create subobject in permanent pool */
370 inputctl = (my_inputctl_ptr)
371 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
372 SIZEOF(my_input_controller));
373 cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
374 /* Initialize method pointers */
375 inputctl->pub.consume_input = consume_markers;
376 inputctl->pub.reset_input_controller = reset_input_controller;
377 inputctl->pub.start_input_pass = start_input_pass;
378 inputctl->pub.finish_input_pass = finish_input_pass;
379 /* Initialize state: can't use reset_input_controller since we don't
380 * want to try to reset other modules yet.
381 */
382 inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
383 inputctl->pub.eoi_reached = FALSE;
384 inputctl->inheaders = TRUE;
385}
386