1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
|
/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include <assert.h>
#include <stdlib.h>
#include "config/aom_dsp_rtcd.h"
#include "aom_ports/mem.h"
void aom_minmax_8x8_c(const uint8_t *s, int p, const uint8_t *d, int dp,
int *min, int *max) {
int i, j;
*min = 255;
*max = 0;
for (i = 0; i < 8; ++i, s += p, d += dp) {
for (j = 0; j < 8; ++j) {
int diff = abs(s[j] - d[j]);
*min = diff < *min ? diff : *min;
*max = diff > *max ? diff : *max;
}
}
}
unsigned int aom_avg_4x4_c(const uint8_t *s, int p) {
int i, j;
int sum = 0;
for (i = 0; i < 4; ++i, s += p)
for (j = 0; j < 4; sum += s[j], ++j) {
}
return (sum + 8) >> 4;
}
unsigned int aom_avg_8x8_c(const uint8_t *s, int p) {
int i, j;
int sum = 0;
for (i = 0; i < 8; ++i, s += p)
for (j = 0; j < 8; sum += s[j], ++j) {
}
return (sum + 32) >> 6;
}
void aom_avg_8x8_quad_c(const uint8_t *s, int p, int x16_idx, int y16_idx,
int *avg) {
for (int k = 0; k < 4; k++) {
const int x8_idx = x16_idx + ((k & 1) << 3);
const int y8_idx = y16_idx + ((k >> 1) << 3);
const uint8_t *s_tmp = s + y8_idx * p + x8_idx;
avg[k] = aom_avg_8x8_c(s_tmp, p);
}
}
#if CONFIG_AV1_HIGHBITDEPTH
unsigned int aom_highbd_avg_8x8_c(const uint8_t *s8, int p) {
int i, j;
int sum = 0;
const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
for (i = 0; i < 8; ++i, s += p)
for (j = 0; j < 8; sum += s[j], ++j) {
}
return (sum + 32) >> 6;
}
unsigned int aom_highbd_avg_4x4_c(const uint8_t *s8, int p) {
int i, j;
int sum = 0;
const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
for (i = 0; i < 4; ++i, s += p)
for (j = 0; j < 4; sum += s[j], ++j) {
}
return (sum + 8) >> 4;
}
void aom_highbd_minmax_8x8_c(const uint8_t *s8, int p, const uint8_t *d8,
int dp, int *min, int *max) {
int i, j;
const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
const uint16_t *d = CONVERT_TO_SHORTPTR(d8);
*min = 65535;
*max = 0;
for (i = 0; i < 8; ++i, s += p, d += dp) {
for (j = 0; j < 8; ++j) {
int diff = abs(s[j] - d[j]);
*min = diff < *min ? diff : *min;
*max = diff > *max ? diff : *max;
}
}
}
#endif // CONFIG_AV1_HIGHBITDEPTH
static void hadamard_col4(const int16_t *src_diff, ptrdiff_t src_stride,
int16_t *coeff) {
int16_t b0 = (src_diff[0 * src_stride] + src_diff[1 * src_stride]) >> 1;
int16_t b1 = (src_diff[0 * src_stride] - src_diff[1 * src_stride]) >> 1;
int16_t b2 = (src_diff[2 * src_stride] + src_diff[3 * src_stride]) >> 1;
int16_t b3 = (src_diff[2 * src_stride] - src_diff[3 * src_stride]) >> 1;
coeff[0] = b0 + b2;
coeff[1] = b1 + b3;
coeff[2] = b0 - b2;
coeff[3] = b1 - b3;
}
void aom_hadamard_4x4_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
int16_t buffer[16];
int16_t buffer2[16];
int16_t *tmp_buf = &buffer[0];
for (idx = 0; idx < 4; ++idx) {
hadamard_col4(src_diff, src_stride, tmp_buf); // src_diff: 9 bit
// dynamic range [-255, 255]
tmp_buf += 4;
++src_diff;
}
tmp_buf = &buffer[0];
for (idx = 0; idx < 4; ++idx) {
hadamard_col4(tmp_buf, 4, buffer2 + 4 * idx); // tmp_buf: 12 bit
// dynamic range [-2040, 2040]
// buffer2: 15 bit
// dynamic range [-16320, 16320]
++tmp_buf;
}
// Extra transpose to match SSE2 behavior(i.e., aom_hadamard_4x4_sse2).
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
coeff[i * 4 + j] = (tran_low_t)buffer2[j * 4 + i];
}
}
}
// src_diff: first pass, 9 bit, dynamic range [-255, 255]
// second pass, 12 bit, dynamic range [-2040, 2040]
static void hadamard_col8(const int16_t *src_diff, ptrdiff_t src_stride,
int16_t *coeff) {
int16_t b0 = src_diff[0 * src_stride] + src_diff[1 * src_stride];
int16_t b1 = src_diff[0 * src_stride] - src_diff[1 * src_stride];
int16_t b2 = src_diff[2 * src_stride] + src_diff[3 * src_stride];
int16_t b3 = src_diff[2 * src_stride] - src_diff[3 * src_stride];
int16_t b4 = src_diff[4 * src_stride] + src_diff[5 * src_stride];
int16_t b5 = src_diff[4 * src_stride] - src_diff[5 * src_stride];
int16_t b6 = src_diff[6 * src_stride] + src_diff[7 * src_stride];
int16_t b7 = src_diff[6 * src_stride] - src_diff[7 * src_stride];
int16_t c0 = b0 + b2;
int16_t c1 = b1 + b3;
int16_t c2 = b0 - b2;
int16_t c3 = b1 - b3;
int16_t c4 = b4 + b6;
int16_t c5 = b5 + b7;
int16_t c6 = b4 - b6;
int16_t c7 = b5 - b7;
coeff[0] = c0 + c4;
coeff[7] = c1 + c5;
coeff[3] = c2 + c6;
coeff[4] = c3 + c7;
coeff[2] = c0 - c4;
coeff[6] = c1 - c5;
coeff[1] = c2 - c6;
coeff[5] = c3 - c7;
}
void aom_hadamard_8x8_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
int16_t buffer[64];
int16_t buffer2[64];
int16_t *tmp_buf = &buffer[0];
for (idx = 0; idx < 8; ++idx) {
hadamard_col8(src_diff, src_stride, tmp_buf); // src_diff: 9 bit
// dynamic range [-255, 255]
tmp_buf += 8;
++src_diff;
}
tmp_buf = &buffer[0];
for (idx = 0; idx < 8; ++idx) {
hadamard_col8(tmp_buf, 8, buffer2 + 8 * idx); // tmp_buf: 12 bit
// dynamic range [-2040, 2040]
// buffer2: 15 bit
// dynamic range [-16320, 16320]
++tmp_buf;
}
// Extra transpose to match SSE2 behavior(i.e., aom_hadamard_8x8_sse2).
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
coeff[i * 8 + j] = (tran_low_t)buffer2[j * 8 + i];
}
}
}
void aom_hadamard_lp_8x8_c(const int16_t *src_diff, ptrdiff_t src_stride,
int16_t *coeff) {
int16_t buffer[64];
int16_t buffer2[64];
int16_t *tmp_buf = &buffer[0];
for (int idx = 0; idx < 8; ++idx) {
hadamard_col8(src_diff, src_stride, tmp_buf); // src_diff: 9 bit
// dynamic range [-255, 255]
tmp_buf += 8;
++src_diff;
}
tmp_buf = &buffer[0];
for (int idx = 0; idx < 8; ++idx) {
hadamard_col8(tmp_buf, 8, buffer2 + 8 * idx); // tmp_buf: 12 bit
// dynamic range [-2040, 2040]
// buffer2: 15 bit
// dynamic range [-16320, 16320]
++tmp_buf;
}
for (int idx = 0; idx < 64; ++idx) coeff[idx] = buffer2[idx];
// Extra transpose to match SSE2 behavior(i.e., aom_hadamard_lp_8x8_sse2).
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
coeff[i * 8 + j] = buffer2[j * 8 + i];
}
}
}
void aom_hadamard_lp_8x8_dual_c(const int16_t *src_diff, ptrdiff_t src_stride,
int16_t *coeff) {
for (int i = 0; i < 2; i++) {
aom_hadamard_lp_8x8_c(src_diff + (i * 8), src_stride,
(int16_t *)coeff + (i * 64));
}
}
// In place 16x16 2D Hadamard transform
void aom_hadamard_16x16_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
for (idx = 0; idx < 4; ++idx) {
// src_diff: 9 bit, dynamic range [-255, 255]
const int16_t *src_ptr =
src_diff + (idx >> 1) * 8 * src_stride + (idx & 0x01) * 8;
aom_hadamard_8x8_c(src_ptr, src_stride, coeff + idx * 64);
}
// coeff: 15 bit, dynamic range [-16320, 16320]
for (idx = 0; idx < 64; ++idx) {
tran_low_t a0 = coeff[0];
tran_low_t a1 = coeff[64];
tran_low_t a2 = coeff[128];
tran_low_t a3 = coeff[192];
tran_low_t b0 = (a0 + a1) >> 1; // (a0 + a1): 16 bit, [-32640, 32640]
tran_low_t b1 = (a0 - a1) >> 1; // b0-b3: 15 bit, dynamic range
tran_low_t b2 = (a2 + a3) >> 1; // [-16320, 16320]
tran_low_t b3 = (a2 - a3) >> 1;
coeff[0] = b0 + b2; // 16 bit, [-32640, 32640]
coeff[64] = b1 + b3;
coeff[128] = b0 - b2;
coeff[192] = b1 - b3;
++coeff;
}
coeff -= 64;
// Extra shift to match AVX2 output (i.e., aom_hadamard_16x16_avx2).
// Note that to match SSE2 output, it does not need this step.
for (int i = 0; i < 16; i++) {
for (int j = 0; j < 4; j++) {
tran_low_t temp = coeff[i * 16 + 4 + j];
coeff[i * 16 + 4 + j] = coeff[i * 16 + 8 + j];
coeff[i * 16 + 8 + j] = temp;
}
}
}
void aom_hadamard_lp_16x16_c(const int16_t *src_diff, ptrdiff_t src_stride,
int16_t *coeff) {
for (int idx = 0; idx < 4; ++idx) {
// src_diff: 9 bit, dynamic range [-255, 255]
const int16_t *src_ptr =
src_diff + (idx >> 1) * 8 * src_stride + (idx & 0x01) * 8;
aom_hadamard_lp_8x8_c(src_ptr, src_stride, coeff + idx * 64);
}
for (int idx = 0; idx < 64; ++idx) {
int16_t a0 = coeff[0];
int16_t a1 = coeff[64];
int16_t a2 = coeff[128];
int16_t a3 = coeff[192];
int16_t b0 = (a0 + a1) >> 1; // (a0 + a1): 16 bit, [-32640, 32640]
int16_t b1 = (a0 - a1) >> 1; // b0-b3: 15 bit, dynamic range
int16_t b2 = (a2 + a3) >> 1; // [-16320, 16320]
int16_t b3 = (a2 - a3) >> 1;
coeff[0] = b0 + b2; // 16 bit, [-32640, 32640]
coeff[64] = b1 + b3;
coeff[128] = b0 - b2;
coeff[192] = b1 - b3;
++coeff;
}
}
void aom_hadamard_32x32_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
for (idx = 0; idx < 4; ++idx) {
// src_diff: 9 bit, dynamic range [-255, 255]
const int16_t *src_ptr =
src_diff + (idx >> 1) * 16 * src_stride + (idx & 0x01) * 16;
aom_hadamard_16x16_c(src_ptr, src_stride, coeff + idx * 256);
}
// coeff: 16 bit, dynamic range [-32768, 32767]
for (idx = 0; idx < 256; ++idx) {
tran_low_t a0 = coeff[0];
tran_low_t a1 = coeff[256];
tran_low_t a2 = coeff[512];
tran_low_t a3 = coeff[768];
tran_low_t b0 = (a0 + a1) >> 2; // (a0 + a1): 17 bit, [-65536, 65535]
tran_low_t b1 = (a0 - a1) >> 2; // b0-b3: 15 bit, dynamic range
tran_low_t b2 = (a2 + a3) >> 2; // [-16384, 16383]
tran_low_t b3 = (a2 - a3) >> 2;
coeff[0] = b0 + b2; // 16 bit, [-32768, 32767]
coeff[256] = b1 + b3;
coeff[512] = b0 - b2;
coeff[768] = b1 - b3;
++coeff;
}
}
#if CONFIG_AV1_HIGHBITDEPTH
static void hadamard_highbd_col8_first_pass(const int16_t *src_diff,
ptrdiff_t src_stride,
int16_t *coeff) {
int16_t b0 = src_diff[0 * src_stride] + src_diff[1 * src_stride];
int16_t b1 = src_diff[0 * src_stride] - src_diff[1 * src_stride];
int16_t b2 = src_diff[2 * src_stride] + src_diff[3 * src_stride];
int16_t b3 = src_diff[2 * src_stride] - src_diff[3 * src_stride];
int16_t b4 = src_diff[4 * src_stride] + src_diff[5 * src_stride];
int16_t b5 = src_diff[4 * src_stride] - src_diff[5 * src_stride];
int16_t b6 = src_diff[6 * src_stride] + src_diff[7 * src_stride];
int16_t b7 = src_diff[6 * src_stride] - src_diff[7 * src_stride];
int16_t c0 = b0 + b2;
int16_t c1 = b1 + b3;
int16_t c2 = b0 - b2;
int16_t c3 = b1 - b3;
int16_t c4 = b4 + b6;
int16_t c5 = b5 + b7;
int16_t c6 = b4 - b6;
int16_t c7 = b5 - b7;
coeff[0] = c0 + c4;
coeff[7] = c1 + c5;
coeff[3] = c2 + c6;
coeff[4] = c3 + c7;
coeff[2] = c0 - c4;
coeff[6] = c1 - c5;
coeff[1] = c2 - c6;
coeff[5] = c3 - c7;
}
// src_diff: 16 bit, dynamic range [-32760, 32760]
// coeff: 19 bit
static void hadamard_highbd_col8_second_pass(const int16_t *src_diff,
ptrdiff_t src_stride,
int32_t *coeff) {
int32_t b0 = src_diff[0 * src_stride] + src_diff[1 * src_stride];
int32_t b1 = src_diff[0 * src_stride] - src_diff[1 * src_stride];
int32_t b2 = src_diff[2 * src_stride] + src_diff[3 * src_stride];
int32_t b3 = src_diff[2 * src_stride] - src_diff[3 * src_stride];
int32_t b4 = src_diff[4 * src_stride] + src_diff[5 * src_stride];
int32_t b5 = src_diff[4 * src_stride] - src_diff[5 * src_stride];
int32_t b6 = src_diff[6 * src_stride] + src_diff[7 * src_stride];
int32_t b7 = src_diff[6 * src_stride] - src_diff[7 * src_stride];
int32_t c0 = b0 + b2;
int32_t c1 = b1 + b3;
int32_t c2 = b0 - b2;
int32_t c3 = b1 - b3;
int32_t c4 = b4 + b6;
int32_t c5 = b5 + b7;
int32_t c6 = b4 - b6;
int32_t c7 = b5 - b7;
coeff[0] = c0 + c4;
coeff[7] = c1 + c5;
coeff[3] = c2 + c6;
coeff[4] = c3 + c7;
coeff[2] = c0 - c4;
coeff[6] = c1 - c5;
coeff[1] = c2 - c6;
coeff[5] = c3 - c7;
}
// The order of the output coeff of the hadamard is not important. For
// optimization purposes the final transpose may be skipped.
void aom_highbd_hadamard_8x8_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
int16_t buffer[64];
int32_t buffer2[64];
int16_t *tmp_buf = &buffer[0];
for (idx = 0; idx < 8; ++idx) {
// src_diff: 13 bit
// buffer: 16 bit, dynamic range [-32760, 32760]
hadamard_highbd_col8_first_pass(src_diff, src_stride, tmp_buf);
tmp_buf += 8;
++src_diff;
}
tmp_buf = &buffer[0];
for (idx = 0; idx < 8; ++idx) {
// buffer: 16 bit
// buffer2: 19 bit, dynamic range [-262080, 262080]
hadamard_highbd_col8_second_pass(tmp_buf, 8, buffer2 + 8 * idx);
++tmp_buf;
}
for (idx = 0; idx < 64; ++idx) coeff[idx] = (tran_low_t)buffer2[idx];
}
// In place 16x16 2D Hadamard transform
void aom_highbd_hadamard_16x16_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
for (idx = 0; idx < 4; ++idx) {
// src_diff: 13 bit, dynamic range [-4095, 4095]
const int16_t *src_ptr =
src_diff + (idx >> 1) * 8 * src_stride + (idx & 0x01) * 8;
aom_highbd_hadamard_8x8_c(src_ptr, src_stride, coeff + idx * 64);
}
// coeff: 19 bit, dynamic range [-262080, 262080]
for (idx = 0; idx < 64; ++idx) {
tran_low_t a0 = coeff[0];
tran_low_t a1 = coeff[64];
tran_low_t a2 = coeff[128];
tran_low_t a3 = coeff[192];
tran_low_t b0 = (a0 + a1) >> 1;
tran_low_t b1 = (a0 - a1) >> 1;
tran_low_t b2 = (a2 + a3) >> 1;
tran_low_t b3 = (a2 - a3) >> 1;
// new coeff dynamic range: 20 bit
coeff[0] = b0 + b2;
coeff[64] = b1 + b3;
coeff[128] = b0 - b2;
coeff[192] = b1 - b3;
++coeff;
}
}
void aom_highbd_hadamard_32x32_c(const int16_t *src_diff, ptrdiff_t src_stride,
tran_low_t *coeff) {
int idx;
for (idx = 0; idx < 4; ++idx) {
// src_diff: 13 bit, dynamic range [-4095, 4095]
const int16_t *src_ptr =
src_diff + (idx >> 1) * 16 * src_stride + (idx & 0x01) * 16;
aom_highbd_hadamard_16x16_c(src_ptr, src_stride, coeff + idx * 256);
}
// coeff: 20 bit
for (idx = 0; idx < 256; ++idx) {
tran_low_t a0 = coeff[0];
tran_low_t a1 = coeff[256];
tran_low_t a2 = coeff[512];
tran_low_t a3 = coeff[768];
tran_low_t b0 = (a0 + a1) >> 2;
tran_low_t b1 = (a0 - a1) >> 2;
tran_low_t b2 = (a2 + a3) >> 2;
tran_low_t b3 = (a2 - a3) >> 2;
// new coeff dynamic range: 20 bit
coeff[0] = b0 + b2;
coeff[256] = b1 + b3;
coeff[512] = b0 - b2;
coeff[768] = b1 - b3;
++coeff;
}
}
#endif // CONFIG_AV1_HIGHBITDEPTH
// coeff: 20 bits, dynamic range [-524287, 524287].
// length: value range {16, 32, 64, 128, 256, 512, 1024}.
int aom_satd_c(const tran_low_t *coeff, int length) {
int i;
int satd = 0;
for (i = 0; i < length; ++i) satd += abs(coeff[i]);
// satd: 30 bits, dynamic range [-524287 * 1024, 524287 * 1024]
return satd;
}
int aom_satd_lp_c(const int16_t *coeff, int length) {
int satd = 0;
for (int i = 0; i < length; ++i) satd += abs(coeff[i]);
// satd: 26 bits, dynamic range [-32640 * 1024, 32640 * 1024]
return satd;
}
// Integer projection onto row vectors.
// height: value range {16, 32, 64, 128}.
void aom_int_pro_row_c(int16_t *hbuf, const uint8_t *ref, const int ref_stride,
const int width, const int height, int norm_factor) {
assert(height >= 2);
for (int idx = 0; idx < width; ++idx) {
hbuf[idx] = 0;
// hbuf[idx]: 14 bit, dynamic range [0, 32640].
for (int i = 0; i < height; ++i) hbuf[idx] += ref[i * ref_stride];
// hbuf[idx]: 9 bit, dynamic range [0, 1020].
hbuf[idx] >>= norm_factor;
++ref;
}
}
// width: value range {16, 32, 64, 128}.
void aom_int_pro_col_c(int16_t *vbuf, const uint8_t *ref, const int ref_stride,
const int width, const int height, int norm_factor) {
for (int ht = 0; ht < height; ++ht) {
int16_t sum = 0;
// sum: 14 bit, dynamic range [0, 32640]
for (int idx = 0; idx < width; ++idx) sum += ref[idx];
vbuf[ht] = sum >> norm_factor;
ref += ref_stride;
}
}
// ref: [0 - 510]
// src: [0 - 510]
// bwl: {2, 3, 4, 5}
int aom_vector_var_c(const int16_t *ref, const int16_t *src, int bwl) {
int i;
int width = 4 << bwl;
int sse = 0, mean = 0, var;
for (i = 0; i < width; ++i) {
int diff = ref[i] - src[i]; // diff: dynamic range [-510, 510], 10 bits.
mean += diff; // mean: dynamic range 16 bits.
sse += diff * diff; // sse: dynamic range 26 bits.
}
// (mean * mean): dynamic range 31 bits.
// If width == 128, the mean can be 510 * 128 = 65280, and log2(65280 ** 2) ~=
// 31.99, so it needs to be casted to unsigned int to compute its square.
const unsigned int mean_abs = abs(mean);
var = sse - ((mean_abs * mean_abs) >> (bwl + 2));
return var;
}
|