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jrevdct.c
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1 /*
2  * This file is part of the Independent JPEG Group's software.
3  *
4  * The authors make NO WARRANTY or representation, either express or implied,
5  * with respect to this software, its quality, accuracy, merchantability, or
6  * fitness for a particular purpose. This software is provided "AS IS", and
7  * you, its user, assume the entire risk as to its quality and accuracy.
8  *
9  * This software is copyright (C) 1991, 1992, Thomas G. Lane.
10  * All Rights Reserved except as specified below.
11  *
12  * Permission is hereby granted to use, copy, modify, and distribute this
13  * software (or portions thereof) for any purpose, without fee, subject to
14  * these conditions:
15  * (1) If any part of the source code for this software is distributed, then
16  * this README file must be included, with this copyright and no-warranty
17  * notice unaltered; and any additions, deletions, or changes to the original
18  * files must be clearly indicated in accompanying documentation.
19  * (2) If only executable code is distributed, then the accompanying
20  * documentation must state that "this software is based in part on the work
21  * of the Independent JPEG Group".
22  * (3) Permission for use of this software is granted only if the user accepts
23  * full responsibility for any undesirable consequences; the authors accept
24  * NO LIABILITY for damages of any kind.
25  *
26  * These conditions apply to any software derived from or based on the IJG
27  * code, not just to the unmodified library. If you use our work, you ought
28  * to acknowledge us.
29  *
30  * Permission is NOT granted for the use of any IJG author's name or company
31  * name in advertising or publicity relating to this software or products
32  * derived from it. This software may be referred to only as "the Independent
33  * JPEG Group's software".
34  *
35  * We specifically permit and encourage the use of this software as the basis
36  * of commercial products, provided that all warranty or liability claims are
37  * assumed by the product vendor.
38  *
39  * This file contains the basic inverse-DCT transformation subroutine.
40  *
41  * This implementation is based on an algorithm described in
42  * C. Loeffler, A. Ligtenberg and G. Moschytz, "Practical Fast 1-D DCT
43  * Algorithms with 11 Multiplications", Proc. Int'l. Conf. on Acoustics,
44  * Speech, and Signal Processing 1989 (ICASSP '89), pp. 988-991.
45  * The primary algorithm described there uses 11 multiplies and 29 adds.
46  * We use their alternate method with 12 multiplies and 32 adds.
47  * The advantage of this method is that no data path contains more than one
48  * multiplication; this allows a very simple and accurate implementation in
49  * scaled fixed-point arithmetic, with a minimal number of shifts.
50  *
51  * I've made lots of modifications to attempt to take advantage of the
52  * sparse nature of the DCT matrices we're getting. Although the logic
53  * is cumbersome, it's straightforward and the resulting code is much
54  * faster.
55  *
56  * A better way to do this would be to pass in the DCT block as a sparse
57  * matrix, perhaps with the difference cases encoded.
58  */
59 
60 /**
61  * @file
62  * Independent JPEG Group's LLM idct.
63  */
64 
65 #include "libavutil/common.h"
66 
67 #include "dct.h"
68 #include "idctdsp.h"
69 
70 #define EIGHT_BIT_SAMPLES
71 
72 #define DCTSIZE 8
73 #define DCTSIZE2 64
74 
75 #define GLOBAL
76 
77 #define RIGHT_SHIFT(x, n) ((x) >> (n))
78 
79 typedef int16_t DCTBLOCK[DCTSIZE2];
80 
81 #define CONST_BITS 13
82 
83 /*
84  * This routine is specialized to the case DCTSIZE = 8.
85  */
86 
87 #if DCTSIZE != 8
88  Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */
89 #endif
90 
91 
92 /*
93  * A 2-D IDCT can be done by 1-D IDCT on each row followed by 1-D IDCT
94  * on each column. Direct algorithms are also available, but they are
95  * much more complex and seem not to be any faster when reduced to code.
96  *
97  * The poop on this scaling stuff is as follows:
98  *
99  * Each 1-D IDCT step produces outputs which are a factor of sqrt(N)
100  * larger than the true IDCT outputs. The final outputs are therefore
101  * a factor of N larger than desired; since N=8 this can be cured by
102  * a simple right shift at the end of the algorithm. The advantage of
103  * this arrangement is that we save two multiplications per 1-D IDCT,
104  * because the y0 and y4 inputs need not be divided by sqrt(N).
105  *
106  * We have to do addition and subtraction of the integer inputs, which
107  * is no problem, and multiplication by fractional constants, which is
108  * a problem to do in integer arithmetic. We multiply all the constants
109  * by CONST_SCALE and convert them to integer constants (thus retaining
110  * CONST_BITS bits of precision in the constants). After doing a
111  * multiplication we have to divide the product by CONST_SCALE, with proper
112  * rounding, to produce the correct output. This division can be done
113  * cheaply as a right shift of CONST_BITS bits. We postpone shifting
114  * as long as possible so that partial sums can be added together with
115  * full fractional precision.
116  *
117  * The outputs of the first pass are scaled up by PASS1_BITS bits so that
118  * they are represented to better-than-integral precision. These outputs
119  * require BITS_IN_JSAMPLE + PASS1_BITS + 3 bits; this fits in a 16-bit word
120  * with the recommended scaling. (To scale up 12-bit sample data further, an
121  * intermediate int32 array would be needed.)
122  *
123  * To avoid overflow of the 32-bit intermediate results in pass 2, we must
124  * have BITS_IN_JSAMPLE + CONST_BITS + PASS1_BITS <= 26. Error analysis
125  * shows that the values given below are the most effective.
126  */
127 
128 #ifdef EIGHT_BIT_SAMPLES
129 #define PASS1_BITS 2
130 #else
131 #define PASS1_BITS 1 /* lose a little precision to avoid overflow */
132 #endif
133 
134 #define ONE ((int32_t) 1)
135 
136 #define CONST_SCALE (ONE << CONST_BITS)
137 
138 /* Convert a positive real constant to an integer scaled by CONST_SCALE.
139  * IMPORTANT: if your compiler doesn't do this arithmetic at compile time,
140  * you will pay a significant penalty in run time. In that case, figure
141  * the correct integer constant values and insert them by hand.
142  */
143 
144 /* Actually FIX is no longer used, we precomputed them all */
145 #define FIX(x) ((int32_t) ((x) * CONST_SCALE + 0.5))
146 
147 /* Descale and correctly round an int32_t value that's scaled by N bits.
148  * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
149  * the fudge factor is correct for either sign of X.
150  */
151 
152 #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
153 
154 /* Multiply an int32_t variable by an int32_t constant to yield an int32_t result.
155  * For 8-bit samples with the recommended scaling, all the variable
156  * and constant values involved are no more than 16 bits wide, so a
157  * 16x16->32 bit multiply can be used instead of a full 32x32 multiply;
158  * this provides a useful speedup on many machines.
159  * There is no way to specify a 16x16->32 multiply in portable C, but
160  * some C compilers will do the right thing if you provide the correct
161  * combination of casts.
162  * NB: for 12-bit samples, a full 32-bit multiplication will be needed.
163  */
164 
165 #ifdef EIGHT_BIT_SAMPLES
166 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
167 #define MULTIPLY(var,const) (((int16_t) (var)) * ((int16_t) (const)))
168 #endif
169 #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
170 #define MULTIPLY(var,const) (((int16_t) (var)) * ((int32_t) (const)))
171 #endif
172 #endif
173 
174 #ifndef MULTIPLY /* default definition */
175 #define MULTIPLY(var,const) ((var) * (const))
176 #endif
177 
178 
179 /*
180  Unlike our decoder where we approximate the FIXes, we need to use exact
181 ones here or successive P-frames will drift too much with Reference frame coding
182 */
183 #define FIX_0_211164243 1730
184 #define FIX_0_275899380 2260
185 #define FIX_0_298631336 2446
186 #define FIX_0_390180644 3196
187 #define FIX_0_509795579 4176
188 #define FIX_0_541196100 4433
189 #define FIX_0_601344887 4926
190 #define FIX_0_765366865 6270
191 #define FIX_0_785694958 6436
192 #define FIX_0_899976223 7373
193 #define FIX_1_061594337 8697
194 #define FIX_1_111140466 9102
195 #define FIX_1_175875602 9633
196 #define FIX_1_306562965 10703
197 #define FIX_1_387039845 11363
198 #define FIX_1_451774981 11893
199 #define FIX_1_501321110 12299
200 #define FIX_1_662939225 13623
201 #define FIX_1_847759065 15137
202 #define FIX_1_961570560 16069
203 #define FIX_2_053119869 16819
204 #define FIX_2_172734803 17799
205 #define FIX_2_562915447 20995
206 #define FIX_3_072711026 25172
207 
208 /*
209  * Perform the inverse DCT on one block of coefficients.
210  */
211 
212 void ff_j_rev_dct(DCTBLOCK data)
213 {
214  int32_t tmp0, tmp1, tmp2, tmp3;
215  int32_t tmp10, tmp11, tmp12, tmp13;
216  int32_t z1, z2, z3, z4, z5;
217  int32_t d0, d1, d2, d3, d4, d5, d6, d7;
218  register int16_t *dataptr;
219  int rowctr;
220 
221  /* Pass 1: process rows. */
222  /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
223  /* furthermore, we scale the results by 2**PASS1_BITS. */
224 
225  dataptr = data;
226 
227  for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
228  /* Due to quantization, we will usually find that many of the input
229  * coefficients are zero, especially the AC terms. We can exploit this
230  * by short-circuiting the IDCT calculation for any row in which all
231  * the AC terms are zero. In that case each output is equal to the
232  * DC coefficient (with scale factor as needed).
233  * With typical images and quantization tables, half or more of the
234  * row DCT calculations can be simplified this way.
235  */
236 
237  register int *idataptr = (int*)dataptr;
238 
239  /* WARNING: we do the same permutation as MMX idct to simplify the
240  video core */
241  d0 = dataptr[0];
242  d2 = dataptr[1];
243  d4 = dataptr[2];
244  d6 = dataptr[3];
245  d1 = dataptr[4];
246  d3 = dataptr[5];
247  d5 = dataptr[6];
248  d7 = dataptr[7];
249 
250  if ((d1 | d2 | d3 | d4 | d5 | d6 | d7) == 0) {
251  /* AC terms all zero */
252  if (d0) {
253  /* Compute a 32 bit value to assign. */
254  int16_t dcval = (int16_t) (d0 * (1 << PASS1_BITS));
255  register int v = (dcval & 0xffff) | ((dcval * (1 << 16)) & 0xffff0000);
256 
257  idataptr[0] = v;
258  idataptr[1] = v;
259  idataptr[2] = v;
260  idataptr[3] = v;
261  }
262 
263  dataptr += DCTSIZE; /* advance pointer to next row */
264  continue;
265  }
266 
267  /* Even part: reverse the even part of the forward DCT. */
268  /* The rotator is sqrt(2)*c(-6). */
269 {
270  if (d6) {
271  if (d2) {
272  /* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
273  z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
274  tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
275  tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
276 
277  tmp0 = (d0 + d4) * CONST_SCALE;
278  tmp1 = (d0 - d4) * CONST_SCALE;
279 
280  tmp10 = tmp0 + tmp3;
281  tmp13 = tmp0 - tmp3;
282  tmp11 = tmp1 + tmp2;
283  tmp12 = tmp1 - tmp2;
284  } else {
285  /* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
286  tmp2 = MULTIPLY(-d6, FIX_1_306562965);
287  tmp3 = MULTIPLY(d6, FIX_0_541196100);
288 
289  tmp0 = (d0 + d4) * CONST_SCALE;
290  tmp1 = (d0 - d4) * CONST_SCALE;
291 
292  tmp10 = tmp0 + tmp3;
293  tmp13 = tmp0 - tmp3;
294  tmp11 = tmp1 + tmp2;
295  tmp12 = tmp1 - tmp2;
296  }
297  } else {
298  if (d2) {
299  /* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
300  tmp2 = MULTIPLY(d2, FIX_0_541196100);
301  tmp3 = MULTIPLY(d2, FIX_1_306562965);
302 
303  tmp0 = (d0 + d4) * CONST_SCALE;
304  tmp1 = (d0 - d4) * CONST_SCALE;
305 
306  tmp10 = tmp0 + tmp3;
307  tmp13 = tmp0 - tmp3;
308  tmp11 = tmp1 + tmp2;
309  tmp12 = tmp1 - tmp2;
310  } else {
311  /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
312  tmp10 = tmp13 = (d0 + d4) * CONST_SCALE;
313  tmp11 = tmp12 = (d0 - d4) * CONST_SCALE;
314  }
315  }
316 
317  /* Odd part per figure 8; the matrix is unitary and hence its
318  * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively.
319  */
320 
321  if (d7) {
322  if (d5) {
323  if (d3) {
324  if (d1) {
325  /* d1 != 0, d3 != 0, d5 != 0, d7 != 0 */
326  z1 = d7 + d1;
327  z2 = d5 + d3;
328  z3 = d7 + d3;
329  z4 = d5 + d1;
330  z5 = MULTIPLY(z3 + z4, FIX_1_175875602);
331 
332  tmp0 = MULTIPLY(d7, FIX_0_298631336);
333  tmp1 = MULTIPLY(d5, FIX_2_053119869);
334  tmp2 = MULTIPLY(d3, FIX_3_072711026);
335  tmp3 = MULTIPLY(d1, FIX_1_501321110);
336  z1 = MULTIPLY(-z1, FIX_0_899976223);
337  z2 = MULTIPLY(-z2, FIX_2_562915447);
338  z3 = MULTIPLY(-z3, FIX_1_961570560);
339  z4 = MULTIPLY(-z4, FIX_0_390180644);
340 
341  z3 += z5;
342  z4 += z5;
343 
344  tmp0 += z1 + z3;
345  tmp1 += z2 + z4;
346  tmp2 += z2 + z3;
347  tmp3 += z1 + z4;
348  } else {
349  /* d1 == 0, d3 != 0, d5 != 0, d7 != 0 */
350  z2 = d5 + d3;
351  z3 = d7 + d3;
352  z5 = MULTIPLY(z3 + d5, FIX_1_175875602);
353 
354  tmp0 = MULTIPLY(d7, FIX_0_298631336);
355  tmp1 = MULTIPLY(d5, FIX_2_053119869);
356  tmp2 = MULTIPLY(d3, FIX_3_072711026);
357  z1 = MULTIPLY(-d7, FIX_0_899976223);
358  z2 = MULTIPLY(-z2, FIX_2_562915447);
359  z3 = MULTIPLY(-z3, FIX_1_961570560);
360  z4 = MULTIPLY(-d5, FIX_0_390180644);
361 
362  z3 += z5;
363  z4 += z5;
364 
365  tmp0 += z1 + z3;
366  tmp1 += z2 + z4;
367  tmp2 += z2 + z3;
368  tmp3 = z1 + z4;
369  }
370  } else {
371  if (d1) {
372  /* d1 != 0, d3 == 0, d5 != 0, d7 != 0 */
373  z1 = d7 + d1;
374  z4 = d5 + d1;
375  z5 = MULTIPLY(d7 + z4, FIX_1_175875602);
376 
377  tmp0 = MULTIPLY(d7, FIX_0_298631336);
378  tmp1 = MULTIPLY(d5, FIX_2_053119869);
379  tmp3 = MULTIPLY(d1, FIX_1_501321110);
380  z1 = MULTIPLY(-z1, FIX_0_899976223);
381  z2 = MULTIPLY(-d5, FIX_2_562915447);
382  z3 = MULTIPLY(-d7, FIX_1_961570560);
383  z4 = MULTIPLY(-z4, FIX_0_390180644);
384 
385  z3 += z5;
386  z4 += z5;
387 
388  tmp0 += z1 + z3;
389  tmp1 += z2 + z4;
390  tmp2 = z2 + z3;
391  tmp3 += z1 + z4;
392  } else {
393  /* d1 == 0, d3 == 0, d5 != 0, d7 != 0 */
394  tmp0 = MULTIPLY(-d7, FIX_0_601344887);
395  z1 = MULTIPLY(-d7, FIX_0_899976223);
396  z3 = MULTIPLY(-d7, FIX_1_961570560);
397  tmp1 = MULTIPLY(-d5, FIX_0_509795579);
398  z2 = MULTIPLY(-d5, FIX_2_562915447);
399  z4 = MULTIPLY(-d5, FIX_0_390180644);
400  z5 = MULTIPLY(d5 + d7, FIX_1_175875602);
401 
402  z3 += z5;
403  z4 += z5;
404 
405  tmp0 += z3;
406  tmp1 += z4;
407  tmp2 = z2 + z3;
408  tmp3 = z1 + z4;
409  }
410  }
411  } else {
412  if (d3) {
413  if (d1) {
414  /* d1 != 0, d3 != 0, d5 == 0, d7 != 0 */
415  z1 = d7 + d1;
416  z3 = d7 + d3;
417  z5 = MULTIPLY(z3 + d1, FIX_1_175875602);
418 
419  tmp0 = MULTIPLY(d7, FIX_0_298631336);
420  tmp2 = MULTIPLY(d3, FIX_3_072711026);
421  tmp3 = MULTIPLY(d1, FIX_1_501321110);
422  z1 = MULTIPLY(-z1, FIX_0_899976223);
423  z2 = MULTIPLY(-d3, FIX_2_562915447);
424  z3 = MULTIPLY(-z3, FIX_1_961570560);
425  z4 = MULTIPLY(-d1, FIX_0_390180644);
426 
427  z3 += z5;
428  z4 += z5;
429 
430  tmp0 += z1 + z3;
431  tmp1 = z2 + z4;
432  tmp2 += z2 + z3;
433  tmp3 += z1 + z4;
434  } else {
435  /* d1 == 0, d3 != 0, d5 == 0, d7 != 0 */
436  z3 = d7 + d3;
437 
438  tmp0 = MULTIPLY(-d7, FIX_0_601344887);
439  z1 = MULTIPLY(-d7, FIX_0_899976223);
440  tmp2 = MULTIPLY(d3, FIX_0_509795579);
441  z2 = MULTIPLY(-d3, FIX_2_562915447);
442  z5 = MULTIPLY(z3, FIX_1_175875602);
443  z3 = MULTIPLY(-z3, FIX_0_785694958);
444 
445  tmp0 += z3;
446  tmp1 = z2 + z5;
447  tmp2 += z3;
448  tmp3 = z1 + z5;
449  }
450  } else {
451  if (d1) {
452  /* d1 != 0, d3 == 0, d5 == 0, d7 != 0 */
453  z1 = d7 + d1;
454  z5 = MULTIPLY(z1, FIX_1_175875602);
455 
456  z1 = MULTIPLY(z1, FIX_0_275899380);
457  z3 = MULTIPLY(-d7, FIX_1_961570560);
458  tmp0 = MULTIPLY(-d7, FIX_1_662939225);
459  z4 = MULTIPLY(-d1, FIX_0_390180644);
460  tmp3 = MULTIPLY(d1, FIX_1_111140466);
461 
462  tmp0 += z1;
463  tmp1 = z4 + z5;
464  tmp2 = z3 + z5;
465  tmp3 += z1;
466  } else {
467  /* d1 == 0, d3 == 0, d5 == 0, d7 != 0 */
468  tmp0 = MULTIPLY(-d7, FIX_1_387039845);
469  tmp1 = MULTIPLY(d7, FIX_1_175875602);
470  tmp2 = MULTIPLY(-d7, FIX_0_785694958);
471  tmp3 = MULTIPLY(d7, FIX_0_275899380);
472  }
473  }
474  }
475  } else {
476  if (d5) {
477  if (d3) {
478  if (d1) {
479  /* d1 != 0, d3 != 0, d5 != 0, d7 == 0 */
480  z2 = d5 + d3;
481  z4 = d5 + d1;
482  z5 = MULTIPLY(d3 + z4, FIX_1_175875602);
483 
484  tmp1 = MULTIPLY(d5, FIX_2_053119869);
485  tmp2 = MULTIPLY(d3, FIX_3_072711026);
486  tmp3 = MULTIPLY(d1, FIX_1_501321110);
487  z1 = MULTIPLY(-d1, FIX_0_899976223);
488  z2 = MULTIPLY(-z2, FIX_2_562915447);
489  z3 = MULTIPLY(-d3, FIX_1_961570560);
490  z4 = MULTIPLY(-z4, FIX_0_390180644);
491 
492  z3 += z5;
493  z4 += z5;
494 
495  tmp0 = z1 + z3;
496  tmp1 += z2 + z4;
497  tmp2 += z2 + z3;
498  tmp3 += z1 + z4;
499  } else {
500  /* d1 == 0, d3 != 0, d5 != 0, d7 == 0 */
501  z2 = d5 + d3;
502 
503  z5 = MULTIPLY(z2, FIX_1_175875602);
504  tmp1 = MULTIPLY(d5, FIX_1_662939225);
505  z4 = MULTIPLY(-d5, FIX_0_390180644);
506  z2 = MULTIPLY(-z2, FIX_1_387039845);
507  tmp2 = MULTIPLY(d3, FIX_1_111140466);
508  z3 = MULTIPLY(-d3, FIX_1_961570560);
509 
510  tmp0 = z3 + z5;
511  tmp1 += z2;
512  tmp2 += z2;
513  tmp3 = z4 + z5;
514  }
515  } else {
516  if (d1) {
517  /* d1 != 0, d3 == 0, d5 != 0, d7 == 0 */
518  z4 = d5 + d1;
519 
520  z5 = MULTIPLY(z4, FIX_1_175875602);
521  z1 = MULTIPLY(-d1, FIX_0_899976223);
522  tmp3 = MULTIPLY(d1, FIX_0_601344887);
523  tmp1 = MULTIPLY(-d5, FIX_0_509795579);
524  z2 = MULTIPLY(-d5, FIX_2_562915447);
525  z4 = MULTIPLY(z4, FIX_0_785694958);
526 
527  tmp0 = z1 + z5;
528  tmp1 += z4;
529  tmp2 = z2 + z5;
530  tmp3 += z4;
531  } else {
532  /* d1 == 0, d3 == 0, d5 != 0, d7 == 0 */
533  tmp0 = MULTIPLY(d5, FIX_1_175875602);
534  tmp1 = MULTIPLY(d5, FIX_0_275899380);
535  tmp2 = MULTIPLY(-d5, FIX_1_387039845);
536  tmp3 = MULTIPLY(d5, FIX_0_785694958);
537  }
538  }
539  } else {
540  if (d3) {
541  if (d1) {
542  /* d1 != 0, d3 != 0, d5 == 0, d7 == 0 */
543  z5 = d1 + d3;
544  tmp3 = MULTIPLY(d1, FIX_0_211164243);
545  tmp2 = MULTIPLY(-d3, FIX_1_451774981);
546  z1 = MULTIPLY(d1, FIX_1_061594337);
547  z2 = MULTIPLY(-d3, FIX_2_172734803);
548  z4 = MULTIPLY(z5, FIX_0_785694958);
549  z5 = MULTIPLY(z5, FIX_1_175875602);
550 
551  tmp0 = z1 - z4;
552  tmp1 = z2 + z4;
553  tmp2 += z5;
554  tmp3 += z5;
555  } else {
556  /* d1 == 0, d3 != 0, d5 == 0, d7 == 0 */
557  tmp0 = MULTIPLY(-d3, FIX_0_785694958);
558  tmp1 = MULTIPLY(-d3, FIX_1_387039845);
559  tmp2 = MULTIPLY(-d3, FIX_0_275899380);
560  tmp3 = MULTIPLY(d3, FIX_1_175875602);
561  }
562  } else {
563  if (d1) {
564  /* d1 != 0, d3 == 0, d5 == 0, d7 == 0 */
565  tmp0 = MULTIPLY(d1, FIX_0_275899380);
566  tmp1 = MULTIPLY(d1, FIX_0_785694958);
567  tmp2 = MULTIPLY(d1, FIX_1_175875602);
568  tmp3 = MULTIPLY(d1, FIX_1_387039845);
569  } else {
570  /* d1 == 0, d3 == 0, d5 == 0, d7 == 0 */
571  tmp0 = tmp1 = tmp2 = tmp3 = 0;
572  }
573  }
574  }
575  }
576 }
577  /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
578 
579  dataptr[0] = (int16_t) DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS);
580  dataptr[7] = (int16_t) DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS);
581  dataptr[1] = (int16_t) DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS);
582  dataptr[6] = (int16_t) DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS);
583  dataptr[2] = (int16_t) DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS);
584  dataptr[5] = (int16_t) DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS);
585  dataptr[3] = (int16_t) DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS);
586  dataptr[4] = (int16_t) DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS);
587 
588  dataptr += DCTSIZE; /* advance pointer to next row */
589  }
590 
591  /* Pass 2: process columns. */
592  /* Note that we must descale the results by a factor of 8 == 2**3, */
593  /* and also undo the PASS1_BITS scaling. */
594 
595  dataptr = data;
596  for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
597  /* Columns of zeroes can be exploited in the same way as we did with rows.
598  * However, the row calculation has created many nonzero AC terms, so the
599  * simplification applies less often (typically 5% to 10% of the time).
600  * On machines with very fast multiplication, it's possible that the
601  * test takes more time than it's worth. In that case this section
602  * may be commented out.
603  */
604 
605  d0 = dataptr[DCTSIZE*0];
606  d1 = dataptr[DCTSIZE*1];
607  d2 = dataptr[DCTSIZE*2];
608  d3 = dataptr[DCTSIZE*3];
609  d4 = dataptr[DCTSIZE*4];
610  d5 = dataptr[DCTSIZE*5];
611  d6 = dataptr[DCTSIZE*6];
612  d7 = dataptr[DCTSIZE*7];
613 
614  /* Even part: reverse the even part of the forward DCT. */
615  /* The rotator is sqrt(2)*c(-6). */
616  if (d6) {
617  if (d2) {
618  /* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
619  z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
620  tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
621  tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
622 
623  tmp0 = (d0 + d4) * CONST_SCALE;
624  tmp1 = (d0 - d4) * CONST_SCALE;
625 
626  tmp10 = tmp0 + tmp3;
627  tmp13 = tmp0 - tmp3;
628  tmp11 = tmp1 + tmp2;
629  tmp12 = tmp1 - tmp2;
630  } else {
631  /* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
632  tmp2 = MULTIPLY(-d6, FIX_1_306562965);
633  tmp3 = MULTIPLY(d6, FIX_0_541196100);
634 
635  tmp0 = (d0 + d4) * CONST_SCALE;
636  tmp1 = (d0 - d4) * CONST_SCALE;
637 
638  tmp10 = tmp0 + tmp3;
639  tmp13 = tmp0 - tmp3;
640  tmp11 = tmp1 + tmp2;
641  tmp12 = tmp1 - tmp2;
642  }
643  } else {
644  if (d2) {
645  /* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
646  tmp2 = MULTIPLY(d2, FIX_0_541196100);
647  tmp3 = MULTIPLY(d2, FIX_1_306562965);
648 
649  tmp0 = (d0 + d4) * CONST_SCALE;
650  tmp1 = (d0 - d4) * CONST_SCALE;
651 
652  tmp10 = tmp0 + tmp3;
653  tmp13 = tmp0 - tmp3;
654  tmp11 = tmp1 + tmp2;
655  tmp12 = tmp1 - tmp2;
656  } else {
657  /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
658  tmp10 = tmp13 = (d0 + d4) * CONST_SCALE;
659  tmp11 = tmp12 = (d0 - d4) * CONST_SCALE;
660  }
661  }
662 
663  /* Odd part per figure 8; the matrix is unitary and hence its
664  * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively.
665  */
666  if (d7) {
667  if (d5) {
668  if (d3) {
669  if (d1) {
670  /* d1 != 0, d3 != 0, d5 != 0, d7 != 0 */
671  z1 = d7 + d1;
672  z2 = d5 + d3;
673  z3 = d7 + d3;
674  z4 = d5 + d1;
675  z5 = MULTIPLY(z3 + z4, FIX_1_175875602);
676 
677  tmp0 = MULTIPLY(d7, FIX_0_298631336);
678  tmp1 = MULTIPLY(d5, FIX_2_053119869);
679  tmp2 = MULTIPLY(d3, FIX_3_072711026);
680  tmp3 = MULTIPLY(d1, FIX_1_501321110);
681  z1 = MULTIPLY(-z1, FIX_0_899976223);
682  z2 = MULTIPLY(-z2, FIX_2_562915447);
683  z3 = MULTIPLY(-z3, FIX_1_961570560);
684  z4 = MULTIPLY(-z4, FIX_0_390180644);
685 
686  z3 += z5;
687  z4 += z5;
688 
689  tmp0 += z1 + z3;
690  tmp1 += z2 + z4;
691  tmp2 += z2 + z3;
692  tmp3 += z1 + z4;
693  } else {
694  /* d1 == 0, d3 != 0, d5 != 0, d7 != 0 */
695  z2 = d5 + d3;
696  z3 = d7 + d3;
697  z5 = MULTIPLY(z3 + d5, FIX_1_175875602);
698 
699  tmp0 = MULTIPLY(d7, FIX_0_298631336);
700  tmp1 = MULTIPLY(d5, FIX_2_053119869);
701  tmp2 = MULTIPLY(d3, FIX_3_072711026);
702  z1 = MULTIPLY(-d7, FIX_0_899976223);
703  z2 = MULTIPLY(-z2, FIX_2_562915447);
704  z3 = MULTIPLY(-z3, FIX_1_961570560);
705  z4 = MULTIPLY(-d5, FIX_0_390180644);
706 
707  z3 += z5;
708  z4 += z5;
709 
710  tmp0 += z1 + z3;
711  tmp1 += z2 + z4;
712  tmp2 += z2 + z3;
713  tmp3 = z1 + z4;
714  }
715  } else {
716  if (d1) {
717  /* d1 != 0, d3 == 0, d5 != 0, d7 != 0 */
718  z1 = d7 + d1;
719  z3 = d7;
720  z4 = d5 + d1;
721  z5 = MULTIPLY(z3 + z4, FIX_1_175875602);
722 
723  tmp0 = MULTIPLY(d7, FIX_0_298631336);
724  tmp1 = MULTIPLY(d5, FIX_2_053119869);
725  tmp3 = MULTIPLY(d1, FIX_1_501321110);
726  z1 = MULTIPLY(-z1, FIX_0_899976223);
727  z2 = MULTIPLY(-d5, FIX_2_562915447);
728  z3 = MULTIPLY(-d7, FIX_1_961570560);
729  z4 = MULTIPLY(-z4, FIX_0_390180644);
730 
731  z3 += z5;
732  z4 += z5;
733 
734  tmp0 += z1 + z3;
735  tmp1 += z2 + z4;
736  tmp2 = z2 + z3;
737  tmp3 += z1 + z4;
738  } else {
739  /* d1 == 0, d3 == 0, d5 != 0, d7 != 0 */
740  tmp0 = MULTIPLY(-d7, FIX_0_601344887);
741  z1 = MULTIPLY(-d7, FIX_0_899976223);
742  z3 = MULTIPLY(-d7, FIX_1_961570560);
743  tmp1 = MULTIPLY(-d5, FIX_0_509795579);
744  z2 = MULTIPLY(-d5, FIX_2_562915447);
745  z4 = MULTIPLY(-d5, FIX_0_390180644);
746  z5 = MULTIPLY(d5 + d7, FIX_1_175875602);
747 
748  z3 += z5;
749  z4 += z5;
750 
751  tmp0 += z3;
752  tmp1 += z4;
753  tmp2 = z2 + z3;
754  tmp3 = z1 + z4;
755  }
756  }
757  } else {
758  if (d3) {
759  if (d1) {
760  /* d1 != 0, d3 != 0, d5 == 0, d7 != 0 */
761  z1 = d7 + d1;
762  z3 = d7 + d3;
763  z5 = MULTIPLY(z3 + d1, FIX_1_175875602);
764 
765  tmp0 = MULTIPLY(d7, FIX_0_298631336);
766  tmp2 = MULTIPLY(d3, FIX_3_072711026);
767  tmp3 = MULTIPLY(d1, FIX_1_501321110);
768  z1 = MULTIPLY(-z1, FIX_0_899976223);
769  z2 = MULTIPLY(-d3, FIX_2_562915447);
770  z3 = MULTIPLY(-z3, FIX_1_961570560);
771  z4 = MULTIPLY(-d1, FIX_0_390180644);
772 
773  z3 += z5;
774  z4 += z5;
775 
776  tmp0 += z1 + z3;
777  tmp1 = z2 + z4;
778  tmp2 += z2 + z3;
779  tmp3 += z1 + z4;
780  } else {
781  /* d1 == 0, d3 != 0, d5 == 0, d7 != 0 */
782  z3 = d7 + d3;
783 
784  tmp0 = MULTIPLY(-d7, FIX_0_601344887);
785  z1 = MULTIPLY(-d7, FIX_0_899976223);
786  tmp2 = MULTIPLY(d3, FIX_0_509795579);
787  z2 = MULTIPLY(-d3, FIX_2_562915447);
788  z5 = MULTIPLY(z3, FIX_1_175875602);
789  z3 = MULTIPLY(-z3, FIX_0_785694958);
790 
791  tmp0 += z3;
792  tmp1 = z2 + z5;
793  tmp2 += z3;
794  tmp3 = z1 + z5;
795  }
796  } else {
797  if (d1) {
798  /* d1 != 0, d3 == 0, d5 == 0, d7 != 0 */
799  z1 = d7 + d1;
800  z5 = MULTIPLY(z1, FIX_1_175875602);
801 
802  z1 = MULTIPLY(z1, FIX_0_275899380);
803  z3 = MULTIPLY(-d7, FIX_1_961570560);
804  tmp0 = MULTIPLY(-d7, FIX_1_662939225);
805  z4 = MULTIPLY(-d1, FIX_0_390180644);
806  tmp3 = MULTIPLY(d1, FIX_1_111140466);
807 
808  tmp0 += z1;
809  tmp1 = z4 + z5;
810  tmp2 = z3 + z5;
811  tmp3 += z1;
812  } else {
813  /* d1 == 0, d3 == 0, d5 == 0, d7 != 0 */
814  tmp0 = MULTIPLY(-d7, FIX_1_387039845);
815  tmp1 = MULTIPLY(d7, FIX_1_175875602);
816  tmp2 = MULTIPLY(-d7, FIX_0_785694958);
817  tmp3 = MULTIPLY(d7, FIX_0_275899380);
818  }
819  }
820  }
821  } else {
822  if (d5) {
823  if (d3) {
824  if (d1) {
825  /* d1 != 0, d3 != 0, d5 != 0, d7 == 0 */
826  z2 = d5 + d3;
827  z4 = d5 + d1;
828  z5 = MULTIPLY(d3 + z4, FIX_1_175875602);
829 
830  tmp1 = MULTIPLY(d5, FIX_2_053119869);
831  tmp2 = MULTIPLY(d3, FIX_3_072711026);
832  tmp3 = MULTIPLY(d1, FIX_1_501321110);
833  z1 = MULTIPLY(-d1, FIX_0_899976223);
834  z2 = MULTIPLY(-z2, FIX_2_562915447);
835  z3 = MULTIPLY(-d3, FIX_1_961570560);
836  z4 = MULTIPLY(-z4, FIX_0_390180644);
837 
838  z3 += z5;
839  z4 += z5;
840 
841  tmp0 = z1 + z3;
842  tmp1 += z2 + z4;
843  tmp2 += z2 + z3;
844  tmp3 += z1 + z4;
845  } else {
846  /* d1 == 0, d3 != 0, d5 != 0, d7 == 0 */
847  z2 = d5 + d3;
848 
849  z5 = MULTIPLY(z2, FIX_1_175875602);
850  tmp1 = MULTIPLY(d5, FIX_1_662939225);
851  z4 = MULTIPLY(-d5, FIX_0_390180644);
852  z2 = MULTIPLY(-z2, FIX_1_387039845);
853  tmp2 = MULTIPLY(d3, FIX_1_111140466);
854  z3 = MULTIPLY(-d3, FIX_1_961570560);
855 
856  tmp0 = z3 + z5;
857  tmp1 += z2;
858  tmp2 += z2;
859  tmp3 = z4 + z5;
860  }
861  } else {
862  if (d1) {
863  /* d1 != 0, d3 == 0, d5 != 0, d7 == 0 */
864  z4 = d5 + d1;
865 
866  z5 = MULTIPLY(z4, FIX_1_175875602);
867  z1 = MULTIPLY(-d1, FIX_0_899976223);
868  tmp3 = MULTIPLY(d1, FIX_0_601344887);
869  tmp1 = MULTIPLY(-d5, FIX_0_509795579);
870  z2 = MULTIPLY(-d5, FIX_2_562915447);
871  z4 = MULTIPLY(z4, FIX_0_785694958);
872 
873  tmp0 = z1 + z5;
874  tmp1 += z4;
875  tmp2 = z2 + z5;
876  tmp3 += z4;
877  } else {
878  /* d1 == 0, d3 == 0, d5 != 0, d7 == 0 */
879  tmp0 = MULTIPLY(d5, FIX_1_175875602);
880  tmp1 = MULTIPLY(d5, FIX_0_275899380);
881  tmp2 = MULTIPLY(-d5, FIX_1_387039845);
882  tmp3 = MULTIPLY(d5, FIX_0_785694958);
883  }
884  }
885  } else {
886  if (d3) {
887  if (d1) {
888  /* d1 != 0, d3 != 0, d5 == 0, d7 == 0 */
889  z5 = d1 + d3;
890  tmp3 = MULTIPLY(d1, FIX_0_211164243);
891  tmp2 = MULTIPLY(-d3, FIX_1_451774981);
892  z1 = MULTIPLY(d1, FIX_1_061594337);
893  z2 = MULTIPLY(-d3, FIX_2_172734803);
894  z4 = MULTIPLY(z5, FIX_0_785694958);
895  z5 = MULTIPLY(z5, FIX_1_175875602);
896 
897  tmp0 = z1 - z4;
898  tmp1 = z2 + z4;
899  tmp2 += z5;
900  tmp3 += z5;
901  } else {
902  /* d1 == 0, d3 != 0, d5 == 0, d7 == 0 */
903  tmp0 = MULTIPLY(-d3, FIX_0_785694958);
904  tmp1 = MULTIPLY(-d3, FIX_1_387039845);
905  tmp2 = MULTIPLY(-d3, FIX_0_275899380);
906  tmp3 = MULTIPLY(d3, FIX_1_175875602);
907  }
908  } else {
909  if (d1) {
910  /* d1 != 0, d3 == 0, d5 == 0, d7 == 0 */
911  tmp0 = MULTIPLY(d1, FIX_0_275899380);
912  tmp1 = MULTIPLY(d1, FIX_0_785694958);
913  tmp2 = MULTIPLY(d1, FIX_1_175875602);
914  tmp3 = MULTIPLY(d1, FIX_1_387039845);
915  } else {
916  /* d1 == 0, d3 == 0, d5 == 0, d7 == 0 */
917  tmp0 = tmp1 = tmp2 = tmp3 = 0;
918  }
919  }
920  }
921  }
922 
923  /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
924 
925  dataptr[DCTSIZE*0] = (int16_t) DESCALE(tmp10 + tmp3,
926  CONST_BITS+PASS1_BITS+3);
927  dataptr[DCTSIZE*7] = (int16_t) DESCALE(tmp10 - tmp3,
928  CONST_BITS+PASS1_BITS+3);
929  dataptr[DCTSIZE*1] = (int16_t) DESCALE(tmp11 + tmp2,
930  CONST_BITS+PASS1_BITS+3);
931  dataptr[DCTSIZE*6] = (int16_t) DESCALE(tmp11 - tmp2,
932  CONST_BITS+PASS1_BITS+3);
933  dataptr[DCTSIZE*2] = (int16_t) DESCALE(tmp12 + tmp1,
934  CONST_BITS+PASS1_BITS+3);
935  dataptr[DCTSIZE*5] = (int16_t) DESCALE(tmp12 - tmp1,
936  CONST_BITS+PASS1_BITS+3);
937  dataptr[DCTSIZE*3] = (int16_t) DESCALE(tmp13 + tmp0,
938  CONST_BITS+PASS1_BITS+3);
939  dataptr[DCTSIZE*4] = (int16_t) DESCALE(tmp13 - tmp0,
940  CONST_BITS+PASS1_BITS+3);
941 
942  dataptr++; /* advance pointer to next column */
943  }
944 }
945 
946 #undef DCTSIZE
947 #define DCTSIZE 4
948 #define DCTSTRIDE 8
949 
950 void ff_j_rev_dct4(DCTBLOCK data)
951 {
952  int32_t tmp0, tmp1, tmp2, tmp3;
953  int32_t tmp10, tmp11, tmp12, tmp13;
954  int32_t z1;
955  int32_t d0, d2, d4, d6;
956  register int16_t *dataptr;
957  int rowctr;
958 
959  /* Pass 1: process rows. */
960  /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
961  /* furthermore, we scale the results by 2**PASS1_BITS. */
962 
963  data[0] += 4;
964 
965  dataptr = data;
966 
967  for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
968  /* Due to quantization, we will usually find that many of the input
969  * coefficients are zero, especially the AC terms. We can exploit this
970  * by short-circuiting the IDCT calculation for any row in which all
971  * the AC terms are zero. In that case each output is equal to the
972  * DC coefficient (with scale factor as needed).
973  * With typical images and quantization tables, half or more of the
974  * row DCT calculations can be simplified this way.
975  */
976 
977  register int *idataptr = (int*)dataptr;
978 
979  d0 = dataptr[0];
980  d2 = dataptr[1];
981  d4 = dataptr[2];
982  d6 = dataptr[3];
983 
984  if ((d2 | d4 | d6) == 0) {
985  /* AC terms all zero */
986  if (d0) {
987  /* Compute a 32 bit value to assign. */
988  int16_t dcval = (int16_t) (d0 << PASS1_BITS);
989  register int v = (dcval & 0xffff) | ((dcval << 16) & 0xffff0000);
990 
991  idataptr[0] = v;
992  idataptr[1] = v;
993  }
994 
995  dataptr += DCTSTRIDE; /* advance pointer to next row */
996  continue;
997  }
998 
999  /* Even part: reverse the even part of the forward DCT. */
1000  /* The rotator is sqrt(2)*c(-6). */
1001  if (d6) {
1002  if (d2) {
1003  /* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
1004  z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
1005  tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
1006  tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
1007 
1008  tmp0 = (d0 + d4) << CONST_BITS;
1009  tmp1 = (d0 - d4) << CONST_BITS;
1010 
1011  tmp10 = tmp0 + tmp3;
1012  tmp13 = tmp0 - tmp3;
1013  tmp11 = tmp1 + tmp2;
1014  tmp12 = tmp1 - tmp2;
1015  } else {
1016  /* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
1017  tmp2 = MULTIPLY(-d6, FIX_1_306562965);
1018  tmp3 = MULTIPLY(d6, FIX_0_541196100);
1019 
1020  tmp0 = (d0 + d4) << CONST_BITS;
1021  tmp1 = (d0 - d4) << CONST_BITS;
1022 
1023  tmp10 = tmp0 + tmp3;
1024  tmp13 = tmp0 - tmp3;
1025  tmp11 = tmp1 + tmp2;
1026  tmp12 = tmp1 - tmp2;
1027  }
1028  } else {
1029  if (d2) {
1030  /* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
1031  tmp2 = MULTIPLY(d2, FIX_0_541196100);
1032  tmp3 = MULTIPLY(d2, FIX_1_306562965);
1033 
1034  tmp0 = (d0 + d4) << CONST_BITS;
1035  tmp1 = (d0 - d4) << CONST_BITS;
1036 
1037  tmp10 = tmp0 + tmp3;
1038  tmp13 = tmp0 - tmp3;
1039  tmp11 = tmp1 + tmp2;
1040  tmp12 = tmp1 - tmp2;
1041  } else {
1042  /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
1043  tmp10 = tmp13 = (d0 + d4) << CONST_BITS;
1044  tmp11 = tmp12 = (d0 - d4) << CONST_BITS;
1045  }
1046  }
1047 
1048  /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
1049 
1050  dataptr[0] = (int16_t) DESCALE(tmp10, CONST_BITS-PASS1_BITS);
1051  dataptr[1] = (int16_t) DESCALE(tmp11, CONST_BITS-PASS1_BITS);
1052  dataptr[2] = (int16_t) DESCALE(tmp12, CONST_BITS-PASS1_BITS);
1053  dataptr[3] = (int16_t) DESCALE(tmp13, CONST_BITS-PASS1_BITS);
1054 
1055  dataptr += DCTSTRIDE; /* advance pointer to next row */
1056  }
1057 
1058  /* Pass 2: process columns. */
1059  /* Note that we must descale the results by a factor of 8 == 2**3, */
1060  /* and also undo the PASS1_BITS scaling. */
1061 
1062  dataptr = data;
1063  for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
1064  /* Columns of zeroes can be exploited in the same way as we did with rows.
1065  * However, the row calculation has created many nonzero AC terms, so the
1066  * simplification applies less often (typically 5% to 10% of the time).
1067  * On machines with very fast multiplication, it's possible that the
1068  * test takes more time than it's worth. In that case this section
1069  * may be commented out.
1070  */
1071 
1072  d0 = dataptr[DCTSTRIDE*0];
1073  d2 = dataptr[DCTSTRIDE*1];
1074  d4 = dataptr[DCTSTRIDE*2];
1075  d6 = dataptr[DCTSTRIDE*3];
1076 
1077  /* Even part: reverse the even part of the forward DCT. */
1078  /* The rotator is sqrt(2)*c(-6). */
1079  if (d6) {
1080  if (d2) {
1081  /* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
1082  z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
1083  tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
1084  tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
1085 
1086  tmp0 = (d0 + d4) << CONST_BITS;
1087  tmp1 = (d0 - d4) << CONST_BITS;
1088 
1089  tmp10 = tmp0 + tmp3;
1090  tmp13 = tmp0 - tmp3;
1091  tmp11 = tmp1 + tmp2;
1092  tmp12 = tmp1 - tmp2;
1093  } else {
1094  /* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
1095  tmp2 = MULTIPLY(-d6, FIX_1_306562965);
1096  tmp3 = MULTIPLY(d6, FIX_0_541196100);
1097 
1098  tmp0 = (d0 + d4) << CONST_BITS;
1099  tmp1 = (d0 - d4) << CONST_BITS;
1100 
1101  tmp10 = tmp0 + tmp3;
1102  tmp13 = tmp0 - tmp3;
1103  tmp11 = tmp1 + tmp2;
1104  tmp12 = tmp1 - tmp2;
1105  }
1106  } else {
1107  if (d2) {
1108  /* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
1109  tmp2 = MULTIPLY(d2, FIX_0_541196100);
1110  tmp3 = MULTIPLY(d2, FIX_1_306562965);
1111 
1112  tmp0 = (d0 + d4) << CONST_BITS;
1113  tmp1 = (d0 - d4) << CONST_BITS;
1114 
1115  tmp10 = tmp0 + tmp3;
1116  tmp13 = tmp0 - tmp3;
1117  tmp11 = tmp1 + tmp2;
1118  tmp12 = tmp1 - tmp2;
1119  } else {
1120  /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
1121  tmp10 = tmp13 = (d0 + d4) << CONST_BITS;
1122  tmp11 = tmp12 = (d0 - d4) << CONST_BITS;
1123  }
1124  }
1125 
1126  /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
1127 
1128  dataptr[DCTSTRIDE*0] = tmp10 >> (CONST_BITS+PASS1_BITS+3);
1129  dataptr[DCTSTRIDE*1] = tmp11 >> (CONST_BITS+PASS1_BITS+3);
1130  dataptr[DCTSTRIDE*2] = tmp12 >> (CONST_BITS+PASS1_BITS+3);
1131  dataptr[DCTSTRIDE*3] = tmp13 >> (CONST_BITS+PASS1_BITS+3);
1132 
1133  dataptr++; /* advance pointer to next column */
1134  }
1135 }
1136 
1137 void ff_j_rev_dct2(DCTBLOCK data){
1138  int d00, d01, d10, d11;
1139 
1140  data[0] += 4;
1141  d00 = data[0+0*DCTSTRIDE] + data[1+0*DCTSTRIDE];
1142  d01 = data[0+0*DCTSTRIDE] - data[1+0*DCTSTRIDE];
1143  d10 = data[0+1*DCTSTRIDE] + data[1+1*DCTSTRIDE];
1144  d11 = data[0+1*DCTSTRIDE] - data[1+1*DCTSTRIDE];
1145 
1146  data[0+0*DCTSTRIDE]= (d00 + d10)>>3;
1147  data[1+0*DCTSTRIDE]= (d01 + d11)>>3;
1148  data[0+1*DCTSTRIDE]= (d00 - d10)>>3;
1149  data[1+1*DCTSTRIDE]= (d01 - d11)>>3;
1150 }
1151 
1152 void ff_j_rev_dct1(DCTBLOCK data){
1153  data[0] = (data[0] + 4)>>3;
1154 }
1155 
1156 #undef FIX
1157 #undef CONST_BITS
1158 
1159 void ff_jref_idct_put(uint8_t *dest, int line_size, int16_t *block)
1160 {
1161  ff_j_rev_dct(block);
1162  ff_put_pixels_clamped(block, dest, line_size);
1163 }
1164 
1165 void ff_jref_idct_add(uint8_t *dest, int line_size, int16_t *block)
1166 {
1167  ff_j_rev_dct(block);
1168  ff_add_pixels_clamped(block, dest, line_size);
1169 }
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