1 /*
2 * jdpred.c
3 *
4 * Copyright (C) 1998, 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 sample undifferencing (reconstruction) for lossless JPEG.
9 *
10 * In order to avoid paying the performance penalty of having to check the
11 * predictor being used and the row being processed for each call of the
12 * undifferencer, and to promote optimization, we have separate undifferencing
13 * functions for each case.
14 *
15 * We are able to avoid duplicating source code by implementing the predictors
16 * and undifferencers as macros. Each of the undifferencing functions are
17 * simply wrappers around an UNDIFFERENCE macro with the appropriate PREDICTOR
18 * macro passed as an argument.
19 */
20
21 #define JPEG_INTERNALS
22 #include "jinclude.h"
23 #include "jpeglib.h"
24 #include "jlossls.h" /* Private declarations for lossless codec */
25
26
27 #ifdef D_LOSSLESS_SUPPORTED
28
29 /* Predictor for the first column of the first row: 2^(P-Pt-1) */
30 #define INITIAL_PREDICTORx (1 << (cinfo->data_precision - cinfo->Al - 1))
31
32 /* Predictor for the first column of the remaining rows: Rb */
33 #define INITIAL_PREDICTOR2 GETJSAMPLE(prev_row[0])
34
35
36 /*
37 * 1-Dimensional undifferencer routine.
38 *
39 * This macro implements the 1-D horizontal predictor (1). INITIAL_PREDICTOR
40 * is used as the special case predictor for the first column, which must be
41 * either INITIAL_PREDICTOR2 or INITIAL_PREDICTORx. The remaining samples
42 * use PREDICTOR1.
43 *
44 * The reconstructed sample is supposed to be calculated modulo 2^16, so we
45 * logically AND the result with 0xFFFF.
46 */
47
48 #define UNDIFFERENCE_1D(INITIAL_PREDICTOR) \
49 unsigned int xindex; \
50 int Ra; \
51 \
52 Ra = (diff_buf[0] + INITIAL_PREDICTOR) & 0xFFFF; \
53 undiff_buf[0] = Ra; \
54 \
55 for (xindex = 1; xindex < width; xindex++) { \
56 Ra = (diff_buf[xindex] + PREDICTOR1) & 0xFFFF; \
57 undiff_buf[xindex] = Ra; \
58 }
59
60 /*
61 * 2-Dimensional undifferencer routine.
62 *
63 * This macro implements the 2-D horizontal predictors (#2-7). PREDICTOR2 is
64 * used as the special case predictor for the first column. The remaining
65 * samples use PREDICTOR, which is a function of Ra, Rb, Rc.
66 *
67 * Because prev_row and output_buf may point to the same storage area (in an
68 * interleaved image with Vi=1, for example), we must take care to buffer Rb/Rc
69 * before writing the current reconstructed sample value into output_buf.
70 *
71 * The reconstructed sample is supposed to be calculated modulo 2^16, so we
72 * logically AND the result with 0xFFFF.
73 */
74
75 #define UNDIFFERENCE_2D_BUG(PREDICTOR) \
76 Rb = GETJSAMPLE(prev_row[0]); \
77 Ra = (diff_buf[0] + PREDICTOR2) & 0xFFFF; \
78 undiff_buf[0] = Ra; \
79 \
80 for (xindex = 1; xindex < width; xindex++) { \
81 Rc = Rb; \
82 Rb = GETJSAMPLE(prev_row[xindex]); \
83 Ra = (diff_buf[xindex] + PREDICTOR) & 0xFFFF; \
84 undiff_buf[xindex] = Ra; \
85 }
86
87 #define UNDIFFERENCE_2D(PREDICTOR) \
88 unsigned int xindex; \
89 int Ra, Rb, Rc; \
90 \
91 Rb = GETJSAMPLE(prev_row[0]); \
92 Ra = (diff_buf[0] + PREDICTOR2) & 0xFFFF; \
93 undiff_buf[0] = Ra; \
94 \
95 for (xindex = 1; xindex < width; xindex++) { \
96 Rc = Rb; \
97 Rb = GETJSAMPLE(prev_row[xindex]); \
98 Ra = (diff_buf[xindex] + PREDICTOR) & 0xFFFF; \
99 undiff_buf[xindex] = Ra; \
100 }
101
102
103 /*
104 * Undifferencers for the all rows but the first in a scan or restart interval.
105 * The first sample in the row is undifferenced using the vertical
106 * predictor (2). The rest of the samples are undifferenced using the
107 * predictor specified in the scan header.
108 */
109
110 METHODDEF(void)
jpeg_undifference1(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)111 jpeg_undifference1(j_decompress_ptr cinfo, int comp_index,
112 JDIFFROW diff_buf, JDIFFROW prev_row,
113 JDIFFROW undiff_buf, JDIMENSION width)
114 {
115 UNDIFFERENCE_1D(INITIAL_PREDICTOR2);
116 (void)cinfo;(void)comp_index;(void)diff_buf;(void)prev_row;(void)undiff_buf;(void)width;
117 }
118
119 METHODDEF(void)
jpeg_undifference2(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)120 jpeg_undifference2(j_decompress_ptr cinfo, int comp_index,
121 JDIFFROW diff_buf, JDIFFROW prev_row,
122 JDIFFROW undiff_buf, JDIMENSION width)
123 {
124 UNDIFFERENCE_2D(PREDICTOR2);
125 (void)cinfo;(void)comp_index;(void)diff_buf;(void)prev_row;(void)undiff_buf;(void)width;
126 }
127
128 METHODDEF(void)
jpeg_undifference3(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)129 jpeg_undifference3(j_decompress_ptr cinfo, int comp_index,
130 JDIFFROW diff_buf, JDIFFROW prev_row,
131 JDIFFROW undiff_buf, JDIMENSION width)
132 {
133 UNDIFFERENCE_2D(PREDICTOR3);
134 (void)cinfo;(void)comp_index;(void)diff_buf;(void)prev_row;(void)undiff_buf;(void)width;
135 }
136
137 METHODDEF(void)
jpeg_undifference4(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)138 jpeg_undifference4(j_decompress_ptr cinfo, int comp_index,
139 JDIFFROW diff_buf, JDIFFROW prev_row,
140 JDIFFROW undiff_buf, JDIMENSION width)
141 {
142 UNDIFFERENCE_2D(PREDICTOR4);
143 (void)cinfo;(void)comp_index;(void)diff_buf;(void)prev_row;(void)undiff_buf;(void)width;
144 }
145
146 METHODDEF(void)
jpeg_undifference5(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)147 jpeg_undifference5(j_decompress_ptr cinfo, int comp_index,
148 JDIFFROW diff_buf, JDIFFROW prev_row,
149 JDIFFROW undiff_buf, JDIMENSION width)
150 {
151 SHIFT_TEMPS
152 UNDIFFERENCE_2D(PREDICTOR5);
153 (void)cinfo;(void)comp_index;(void)diff_buf;(void)prev_row;(void)undiff_buf;(void)width;
154 }
155
156 #ifdef SUPPORT_DICOMOBJECTS_BUG
157 /* uninitialized */
158 static int dicomobjectsbug = -1; /* 0 == nobug, 1 == bug */
159 #endif
160
161 METHODDEF(void)
jpeg_undifference6(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)162 jpeg_undifference6(j_decompress_ptr cinfo, int comp_index,
163 JDIFFROW diff_buf, JDIFFROW prev_row,
164 JDIFFROW undiff_buf, JDIMENSION width)
165 {
166 #ifdef SUPPORT_DICOMOBJECTS_BUG
167 unsigned int xindex;
168 int Ra, Rb, Rc;
169 int min, max, temp;
170 SHIFT_TEMPS
171 if( dicomobjectsbug == -1 )
172 {
173 dicomobjectsbug = 0; /* no bug by default */
174
175 Rb = GETJSAMPLE(prev_row[0]);
176 Ra = (diff_buf[0] + PREDICTOR2) & 0xFFFF;
177 undiff_buf[0] = Ra;
178 temp = min = max = undiff_buf[0];
179
180 for (xindex = 1; xindex < width; xindex++) {
181 Rc = Rb;
182 Rb = GETJSAMPLE(prev_row[xindex]);
183 Ra = (diff_buf[xindex] + PREDICTOR6) & 0xFFFF;
184 temp = Ra;
185 min = temp < min ? temp : min;
186 max = temp > max ? temp : max;
187 }
188 if( (max - min) > 50000) /* magic number */
189 {
190 dicomobjectsbug = 1;
191 WARNMS(cinfo, JWRN_SIGNED_ARITH);
192 }
193 }
194 if(dicomobjectsbug)
195 {
196 UNDIFFERENCE_2D_BUG(PREDICTOR6_BUG);
197 }
198 else
199 {
200 UNDIFFERENCE_2D_BUG(PREDICTOR6);
201 }
202 #else
203 SHIFT_TEMPS
204 UNDIFFERENCE_2D(PREDICTOR6);
205 #endif
206 (void)comp_index;(void)cinfo;
207 }
208
209 METHODDEF(void)
jpeg_undifference7(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)210 jpeg_undifference7(j_decompress_ptr cinfo, int comp_index,
211 JDIFFROW diff_buf, JDIFFROW prev_row,
212 JDIFFROW undiff_buf, JDIMENSION width)
213 {
214 SHIFT_TEMPS
215 UNDIFFERENCE_2D(PREDICTOR7);
216 (void)cinfo;(void)comp_index;(void)diff_buf;(void)prev_row;(void)undiff_buf;(void)width;
217 }
218
219
220 /*
221 * Undifferencer for the first row in a scan or restart interval. The first
222 * sample in the row is undifferenced using the special predictor constant
223 * x=2^(P-Pt-1). The rest of the samples are undifferenced using the
224 * 1-D horizontal predictor (1).
225 */
226
227 METHODDEF(void)
jpeg_undifference_first_row(j_decompress_ptr cinfo,int comp_index,JDIFFROW diff_buf,JDIFFROW prev_row,JDIFFROW undiff_buf,JDIMENSION width)228 jpeg_undifference_first_row(j_decompress_ptr cinfo, int comp_index,
229 JDIFFROW diff_buf, JDIFFROW prev_row,
230 JDIFFROW undiff_buf, JDIMENSION width)
231 {
232 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
233
234 UNDIFFERENCE_1D(INITIAL_PREDICTORx);
235 (void)prev_row;
236
237 /*
238 * Now that we have undifferenced the first row, we want to use the
239 * undifferencer which corresponds to the predictor specified in the
240 * scan header.
241 */
242 switch (cinfo->Ss) {
243 case 1:
244 losslsd->predict_undifference[comp_index] = jpeg_undifference1;
245 break;
246 case 2:
247 losslsd->predict_undifference[comp_index] = jpeg_undifference2;
248 break;
249 case 3:
250 losslsd->predict_undifference[comp_index] = jpeg_undifference3;
251 break;
252 case 4:
253 losslsd->predict_undifference[comp_index] = jpeg_undifference4;
254 break;
255 case 5:
256 losslsd->predict_undifference[comp_index] = jpeg_undifference5;
257 break;
258 case 6:
259 losslsd->predict_undifference[comp_index] = jpeg_undifference6;
260 break;
261 case 7:
262 losslsd->predict_undifference[comp_index] = jpeg_undifference7;
263 break;
264 }
265 }
266
267
268 /*
269 * Initialize for an input processing pass.
270 */
271
272 METHODDEF(void)
predict_start_pass(j_decompress_ptr cinfo)273 predict_start_pass (j_decompress_ptr cinfo)
274 {
275 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
276 int ci;
277
278 /* Check that the scan parameters Ss, Se, Ah, Al are OK for lossless JPEG.
279 *
280 * Ss is the predictor selection value (psv). Legal values for sequential
281 * lossless JPEG are: 1 <= psv <= 7.
282 *
283 * Se and Ah are not used and should be zero.
284 *
285 * Al specifies the point transform (Pt). Legal values are: 0 <= Pt <= 15.
286 */
287 if (cinfo->Ss < 1 || cinfo->Ss > 7 ||
288 cinfo->Se != 0 || cinfo->Ah != 0 ||
289 cinfo->Al > 15) /* need not check for < 0 */
290 ERREXIT4(cinfo, JERR_BAD_LOSSLESS,
291 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
292
293 /* Set undifference functions to first row function */
294 for (ci = 0; ci < cinfo->num_components; ci++)
295 losslsd->predict_undifference[ci] = jpeg_undifference_first_row;
296 }
297
298
299 /*
300 * Module initialization routine for the undifferencer.
301 */
302
303 GLOBAL(void)
jinit_undifferencer(j_decompress_ptr cinfo)304 jinit_undifferencer (j_decompress_ptr cinfo)
305 {
306 j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
307
308 losslsd->predict_start_pass = predict_start_pass;
309 losslsd->predict_process_restart = predict_start_pass;
310 }
311
312 #endif /* D_LOSSLESS_SUPPORTED */
313