GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/jfdctint_template.c Lines: 83 114 72.8 %
Date: 2019-11-18 18:00:01 Branches: 4 6 66.7 %

Line Branch Exec Source
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) 1991-1996, 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 a slow-but-accurate integer implementation of the
40
 * forward DCT (Discrete Cosine Transform).
41
 *
42
 * A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT
43
 * on each column.  Direct algorithms are also available, but they are
44
 * much more complex and seem not to be any faster when reduced to code.
45
 *
46
 * This implementation is based on an algorithm described in
47
 *   C. Loeffler, A. Ligtenberg and G. Moschytz, "Practical Fast 1-D DCT
48
 *   Algorithms with 11 Multiplications", Proc. Int'l. Conf. on Acoustics,
49
 *   Speech, and Signal Processing 1989 (ICASSP '89), pp. 988-991.
50
 * The primary algorithm described there uses 11 multiplies and 29 adds.
51
 * We use their alternate method with 12 multiplies and 32 adds.
52
 * The advantage of this method is that no data path contains more than one
53
 * multiplication; this allows a very simple and accurate implementation in
54
 * scaled fixed-point arithmetic, with a minimal number of shifts.
55
 */
56
57
/**
58
 * @file
59
 * Independent JPEG Group's slow & accurate dct.
60
 */
61
62
#include "libavutil/common.h"
63
#include "dct.h"
64
65
#include "bit_depth_template.c"
66
67
#define DCTSIZE 8
68
#define BITS_IN_JSAMPLE BIT_DEPTH
69
#define GLOBAL(x) x
70
#define RIGHT_SHIFT(x, n) ((x) >> (n))
71
#define MULTIPLY16C16(var,const) ((var)*(const))
72
#define DESCALE(x,n)  RIGHT_SHIFT((x) + (1 << ((n) - 1)), n)
73
74
75
/*
76
 * This module is specialized to the case DCTSIZE = 8.
77
 */
78
79
#if DCTSIZE != 8
80
#error  "Sorry, this code only copes with 8x8 DCTs."
81
#endif
82
83
84
/*
85
 * The poop on this scaling stuff is as follows:
86
 *
87
 * Each 1-D DCT step produces outputs which are a factor of sqrt(N)
88
 * larger than the true DCT outputs.  The final outputs are therefore
89
 * a factor of N larger than desired; since N=8 this can be cured by
90
 * a simple right shift at the end of the algorithm.  The advantage of
91
 * this arrangement is that we save two multiplications per 1-D DCT,
92
 * because the y0 and y4 outputs need not be divided by sqrt(N).
93
 * In the IJG code, this factor of 8 is removed by the quantization step
94
 * (in jcdctmgr.c), NOT in this module.
95
 *
96
 * We have to do addition and subtraction of the integer inputs, which
97
 * is no problem, and multiplication by fractional constants, which is
98
 * a problem to do in integer arithmetic.  We multiply all the constants
99
 * by CONST_SCALE and convert them to integer constants (thus retaining
100
 * CONST_BITS bits of precision in the constants).  After doing a
101
 * multiplication we have to divide the product by CONST_SCALE, with proper
102
 * rounding, to produce the correct output.  This division can be done
103
 * cheaply as a right shift of CONST_BITS bits.  We postpone shifting
104
 * as long as possible so that partial sums can be added together with
105
 * full fractional precision.
106
 *
107
 * The outputs of the first pass are scaled up by PASS1_BITS bits so that
108
 * they are represented to better-than-integral precision.  These outputs
109
 * require BITS_IN_JSAMPLE + PASS1_BITS + 3 bits; this fits in a 16-bit word
110
 * with the recommended scaling.  (For 12-bit sample data, the intermediate
111
 * array is int32_t anyway.)
112
 *
113
 * To avoid overflow of the 32-bit intermediate results in pass 2, we must
114
 * have BITS_IN_JSAMPLE + CONST_BITS + PASS1_BITS <= 26.  Error analysis
115
 * shows that the values given below are the most effective.
116
 */
117
118
#undef CONST_BITS
119
#undef PASS1_BITS
120
#undef OUT_SHIFT
121
122
#if BITS_IN_JSAMPLE == 8
123
#define CONST_BITS  13
124
#define PASS1_BITS  4   /* set this to 2 if 16x16 multiplies are faster */
125
#define OUT_SHIFT   PASS1_BITS
126
#else
127
#define CONST_BITS  13
128
#define PASS1_BITS  1   /* lose a little precision to avoid overflow */
129
#define OUT_SHIFT   (PASS1_BITS + 1)
130
#endif
131
132
/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
133
 * causing a lot of useless floating-point operations at run time.
134
 * To get around this we use the following pre-calculated constants.
135
 * If you change CONST_BITS you may want to add appropriate values.
136
 * (With a reasonable C compiler, you can just rely on the FIX() macro...)
137
 */
138
139
#if CONST_BITS == 13
140
#define FIX_0_298631336  ((int32_t)  2446)      /* FIX(0.298631336) */
141
#define FIX_0_390180644  ((int32_t)  3196)      /* FIX(0.390180644) */
142
#define FIX_0_541196100  ((int32_t)  4433)      /* FIX(0.541196100) */
143
#define FIX_0_765366865  ((int32_t)  6270)      /* FIX(0.765366865) */
144
#define FIX_0_899976223  ((int32_t)  7373)      /* FIX(0.899976223) */
145
#define FIX_1_175875602  ((int32_t)  9633)      /* FIX(1.175875602) */
146
#define FIX_1_501321110  ((int32_t)  12299)     /* FIX(1.501321110) */
147
#define FIX_1_847759065  ((int32_t)  15137)     /* FIX(1.847759065) */
148
#define FIX_1_961570560  ((int32_t)  16069)     /* FIX(1.961570560) */
149
#define FIX_2_053119869  ((int32_t)  16819)     /* FIX(2.053119869) */
150
#define FIX_2_562915447  ((int32_t)  20995)     /* FIX(2.562915447) */
151
#define FIX_3_072711026  ((int32_t)  25172)     /* FIX(3.072711026) */
152
#else
153
#define FIX_0_298631336  FIX(0.298631336)
154
#define FIX_0_390180644  FIX(0.390180644)
155
#define FIX_0_541196100  FIX(0.541196100)
156
#define FIX_0_765366865  FIX(0.765366865)
157
#define FIX_0_899976223  FIX(0.899976223)
158
#define FIX_1_175875602  FIX(1.175875602)
159
#define FIX_1_501321110  FIX(1.501321110)
160
#define FIX_1_847759065  FIX(1.847759065)
161
#define FIX_1_961570560  FIX(1.961570560)
162
#define FIX_2_053119869  FIX(2.053119869)
163
#define FIX_2_562915447  FIX(2.562915447)
164
#define FIX_3_072711026  FIX(3.072711026)
165
#endif
166
167
168
/* Multiply an int32_t variable by an int32_t constant to yield an int32_t result.
169
 * For 8-bit samples with the recommended scaling, all the variable
170
 * and constant values involved are no more than 16 bits wide, so a
171
 * 16x16->32 bit multiply can be used instead of a full 32x32 multiply.
172
 * For 12-bit samples, a full 32-bit multiplication will be needed.
173
 */
174
175
#if BITS_IN_JSAMPLE == 8 && CONST_BITS<=13 && PASS1_BITS<=2
176
#define MULTIPLY(var,const)  MULTIPLY16C16(var,const)
177
#else
178
#define MULTIPLY(var,const)  ((var) * (const))
179
#endif
180
181
182
19278466
static av_always_inline void FUNC(row_fdct)(int16_t *data)
183
{
184
  int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
185
  int tmp10, tmp11, tmp12, tmp13;
186
  int z1, z2, z3, z4, z5;
187
  int16_t *dataptr;
188
  int ctr;
189
190
  /* Pass 1: process rows. */
191
  /* Note results are scaled up by sqrt(8) compared to a true DCT; */
192
  /* furthermore, we scale the results by 2**PASS1_BITS. */
193
194
19278466
  dataptr = data;
195
173506194
  for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
196
154227728
    tmp0 = dataptr[0] + dataptr[7];
197
154227728
    tmp7 = dataptr[0] - dataptr[7];
198
154227728
    tmp1 = dataptr[1] + dataptr[6];
199
154227728
    tmp6 = dataptr[1] - dataptr[6];
200
154227728
    tmp2 = dataptr[2] + dataptr[5];
201
154227728
    tmp5 = dataptr[2] - dataptr[5];
202
154227728
    tmp3 = dataptr[3] + dataptr[4];
203
154227728
    tmp4 = dataptr[3] - dataptr[4];
204
205
    /* Even part per LL&M figure 1 --- note that published figure is faulty;
206
     * rotator "sqrt(2)*c1" should be "sqrt(2)*c6".
207
     */
208
209
154227728
    tmp10 = tmp0 + tmp3;
210
154227728
    tmp13 = tmp0 - tmp3;
211
154227728
    tmp11 = tmp1 + tmp2;
212
154227728
    tmp12 = tmp1 - tmp2;
213
214
154227728
    dataptr[0] = (int16_t) ((tmp10 + tmp11) * (1 << PASS1_BITS));
215
154227728
    dataptr[4] = (int16_t) ((tmp10 - tmp11) * (1 << PASS1_BITS));
216
217
154227728
    z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
218
154227728
    dataptr[2] = (int16_t) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
219
                                   CONST_BITS-PASS1_BITS);
220
154227728
    dataptr[6] = (int16_t) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
221
                                   CONST_BITS-PASS1_BITS);
222
223
    /* Odd part per figure 8 --- note paper omits factor of sqrt(2).
224
     * cK represents cos(K*pi/16).
225
     * i0..i3 in the paper are tmp4..tmp7 here.
226
     */
227
228
154227728
    z1 = tmp4 + tmp7;
229
154227728
    z2 = tmp5 + tmp6;
230
154227728
    z3 = tmp4 + tmp6;
231
154227728
    z4 = tmp5 + tmp7;
232
154227728
    z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
233
234
154227728
    tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
235
154227728
    tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
236
154227728
    tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
237
154227728
    tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
238
154227728
    z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
239
154227728
    z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
240
154227728
    z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
241
154227728
    z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
242
243
154227728
    z3 += z5;
244
154227728
    z4 += z5;
245
246
154227728
    dataptr[7] = (int16_t) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS);
247
154227728
    dataptr[5] = (int16_t) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS);
248
154227728
    dataptr[3] = (int16_t) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS);
249
154227728
    dataptr[1] = (int16_t) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS);
250
251
154227728
    dataptr += DCTSIZE;         /* advance pointer to next row */
252
  }
253
19278466
}
254
255
/*
256
 * Perform the forward DCT on one block of samples.
257
 */
258
259
GLOBAL(void)
260
19278466
FUNC(ff_jpeg_fdct_islow)(int16_t *data)
261
{
262
  int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
263
  int tmp10, tmp11, tmp12, tmp13;
264
  int z1, z2, z3, z4, z5;
265
  int16_t *dataptr;
266
  int ctr;
267
268
19278466
  FUNC(row_fdct)(data);
269
270
  /* Pass 2: process columns.
271
   * We remove the PASS1_BITS scaling, but leave the results scaled up
272
   * by an overall factor of 8.
273
   */
274
275
19278466
  dataptr = data;
276
173506194
  for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
277
154227728
    tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7];
278
154227728
    tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7];
279
154227728
    tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6];
280
154227728
    tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6];
281
154227728
    tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5];
282
154227728
    tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5];
283
154227728
    tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4];
284
154227728
    tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4];
285
286
    /* Even part per LL&M figure 1 --- note that published figure is faulty;
287
     * rotator "sqrt(2)*c1" should be "sqrt(2)*c6".
288
     */
289
290
154227728
    tmp10 = tmp0 + tmp3;
291
154227728
    tmp13 = tmp0 - tmp3;
292
154227728
    tmp11 = tmp1 + tmp2;
293
154227728
    tmp12 = tmp1 - tmp2;
294
295
154227728
    dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT);
296
154227728
    dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT);
297
298
154227728
    z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
299
154227728
    dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
300
                                 CONST_BITS + OUT_SHIFT);
301
154227728
    dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
302
                                 CONST_BITS + OUT_SHIFT);
303
304
    /* Odd part per figure 8 --- note paper omits factor of sqrt(2).
305
     * cK represents cos(K*pi/16).
306
     * i0..i3 in the paper are tmp4..tmp7 here.
307
     */
308
309
154227728
    z1 = tmp4 + tmp7;
310
154227728
    z2 = tmp5 + tmp6;
311
154227728
    z3 = tmp4 + tmp6;
312
154227728
    z4 = tmp5 + tmp7;
313
154227728
    z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
314
315
154227728
    tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
316
154227728
    tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
317
154227728
    tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
318
154227728
    tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
319
154227728
    z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
320
154227728
    z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
321
154227728
    z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
322
154227728
    z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
323
324
154227728
    z3 += z5;
325
154227728
    z4 += z5;
326
327
154227728
    dataptr[DCTSIZE*7] = DESCALE(tmp4 + z1 + z3, CONST_BITS + OUT_SHIFT);
328
154227728
    dataptr[DCTSIZE*5] = DESCALE(tmp5 + z2 + z4, CONST_BITS + OUT_SHIFT);
329
154227728
    dataptr[DCTSIZE*3] = DESCALE(tmp6 + z2 + z3, CONST_BITS + OUT_SHIFT);
330
154227728
    dataptr[DCTSIZE*1] = DESCALE(tmp7 + z1 + z4, CONST_BITS + OUT_SHIFT);
331
332
154227728
    dataptr++;                  /* advance pointer to next column */
333
  }
334
19278466
}
335
336
/*
337
 * The secret of DCT2-4-8 is really simple -- you do the usual 1-DCT
338
 * on the rows and then, instead of doing even and odd, part on the columns
339
 * you do even part two times.
340
 */
341
GLOBAL(void)
342
FUNC(ff_fdct248_islow)(int16_t *data)
343
{
344
  int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
345
  int tmp10, tmp11, tmp12, tmp13;
346
  int z1;
347
  int16_t *dataptr;
348
  int ctr;
349
350
  FUNC(row_fdct)(data);
351
352
  /* Pass 2: process columns.
353
   * We remove the PASS1_BITS scaling, but leave the results scaled up
354
   * by an overall factor of 8.
355
   */
356
357
  dataptr = data;
358
  for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
359
     tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1];
360
     tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3];
361
     tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5];
362
     tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7];
363
     tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1];
364
     tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3];
365
     tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5];
366
     tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7];
367
368
     tmp10 = tmp0 + tmp3;
369
     tmp11 = tmp1 + tmp2;
370
     tmp12 = tmp1 - tmp2;
371
     tmp13 = tmp0 - tmp3;
372
373
     dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT);
374
     dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT);
375
376
     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
377
     dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
378
                                  CONST_BITS+OUT_SHIFT);
379
     dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
380
                                  CONST_BITS+OUT_SHIFT);
381
382
     tmp10 = tmp4 + tmp7;
383
     tmp11 = tmp5 + tmp6;
384
     tmp12 = tmp5 - tmp6;
385
     tmp13 = tmp4 - tmp7;
386
387
     dataptr[DCTSIZE*1] = DESCALE(tmp10 + tmp11, OUT_SHIFT);
388
     dataptr[DCTSIZE*5] = DESCALE(tmp10 - tmp11, OUT_SHIFT);
389
390
     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
391
     dataptr[DCTSIZE*3] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
392
                                  CONST_BITS + OUT_SHIFT);
393
     dataptr[DCTSIZE*7] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
394
                                  CONST_BITS + OUT_SHIFT);
395
396
     dataptr++;                 /* advance pointer to next column */
397
  }
398
}