mpegvideo_altivec.c
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1 /*
2  * Copyright (c) 2002 Dieter Shirley
3  *
4  * dct_unquantize_h263_altivec:
5  * Copyright (c) 2003 Romain Dolbeau <romain@dolbeau.org>
6  *
7  * This file is part of Libav.
8  *
9  * Libav is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * Libav is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with Libav; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include <stdlib.h>
25 #include <stdio.h>
26 #include "libavutil/cpu.h"
27 #include "libavcodec/dsputil.h"
28 #include "libavcodec/mpegvideo.h"
29 
30 #include "util_altivec.h"
31 #include "types_altivec.h"
32 #include "dsputil_altivec.h"
33 
34 // Swaps two variables (used for altivec registers)
35 #define SWAP(a,b) \
36 do { \
37  __typeof__(a) swap_temp=a; \
38  a=b; \
39  b=swap_temp; \
40 } while (0)
41 
42 // transposes a matrix consisting of four vectors with four elements each
43 #define TRANSPOSE4(a,b,c,d) \
44 do { \
45  __typeof__(a) _trans_ach = vec_mergeh(a, c); \
46  __typeof__(a) _trans_acl = vec_mergel(a, c); \
47  __typeof__(a) _trans_bdh = vec_mergeh(b, d); \
48  __typeof__(a) _trans_bdl = vec_mergel(b, d); \
49  \
50  a = vec_mergeh(_trans_ach, _trans_bdh); \
51  b = vec_mergel(_trans_ach, _trans_bdh); \
52  c = vec_mergeh(_trans_acl, _trans_bdl); \
53  d = vec_mergel(_trans_acl, _trans_bdl); \
54 } while (0)
55 
56 
57 // Loads a four-byte value (int or float) from the target address
58 // into every element in the target vector. Only works if the
59 // target address is four-byte aligned (which should be always).
60 #define LOAD4(vec, address) \
61 { \
62  __typeof__(vec)* _load_addr = (__typeof__(vec)*)(address); \
63  vector unsigned char _perm_vec = vec_lvsl(0,(address)); \
64  vec = vec_ld(0, _load_addr); \
65  vec = vec_perm(vec, vec, _perm_vec); \
66  vec = vec_splat(vec, 0); \
67 }
68 
69 
70 #define FOUROF(a) {a,a,a,a}
71 
73  DCTELEM* data, int n,
74  int qscale, int* overflow)
75 {
76  int lastNonZero;
77  vector float row0, row1, row2, row3, row4, row5, row6, row7;
78  vector float alt0, alt1, alt2, alt3, alt4, alt5, alt6, alt7;
79  const vector float zero = (const vector float)FOUROF(0.);
80  // used after quantize step
81  int oldBaseValue = 0;
82 
83  // Load the data into the row/alt vectors
84  {
85  vector signed short data0, data1, data2, data3, data4, data5, data6, data7;
86 
87  data0 = vec_ld(0, data);
88  data1 = vec_ld(16, data);
89  data2 = vec_ld(32, data);
90  data3 = vec_ld(48, data);
91  data4 = vec_ld(64, data);
92  data5 = vec_ld(80, data);
93  data6 = vec_ld(96, data);
94  data7 = vec_ld(112, data);
95 
96  // Transpose the data before we start
97  TRANSPOSE8(data0, data1, data2, data3, data4, data5, data6, data7);
98 
99  // load the data into floating point vectors. We load
100  // the high half of each row into the main row vectors
101  // and the low half into the alt vectors.
102  row0 = vec_ctf(vec_unpackh(data0), 0);
103  alt0 = vec_ctf(vec_unpackl(data0), 0);
104  row1 = vec_ctf(vec_unpackh(data1), 0);
105  alt1 = vec_ctf(vec_unpackl(data1), 0);
106  row2 = vec_ctf(vec_unpackh(data2), 0);
107  alt2 = vec_ctf(vec_unpackl(data2), 0);
108  row3 = vec_ctf(vec_unpackh(data3), 0);
109  alt3 = vec_ctf(vec_unpackl(data3), 0);
110  row4 = vec_ctf(vec_unpackh(data4), 0);
111  alt4 = vec_ctf(vec_unpackl(data4), 0);
112  row5 = vec_ctf(vec_unpackh(data5), 0);
113  alt5 = vec_ctf(vec_unpackl(data5), 0);
114  row6 = vec_ctf(vec_unpackh(data6), 0);
115  alt6 = vec_ctf(vec_unpackl(data6), 0);
116  row7 = vec_ctf(vec_unpackh(data7), 0);
117  alt7 = vec_ctf(vec_unpackl(data7), 0);
118  }
119 
120  // The following block could exist as a separate an altivec dct
121  // function. However, if we put it inline, the DCT data can remain
122  // in the vector local variables, as floats, which we'll use during the
123  // quantize step...
124  {
125  const vector float vec_0_298631336 = (vector float)FOUROF(0.298631336f);
126  const vector float vec_0_390180644 = (vector float)FOUROF(-0.390180644f);
127  const vector float vec_0_541196100 = (vector float)FOUROF(0.541196100f);
128  const vector float vec_0_765366865 = (vector float)FOUROF(0.765366865f);
129  const vector float vec_0_899976223 = (vector float)FOUROF(-0.899976223f);
130  const vector float vec_1_175875602 = (vector float)FOUROF(1.175875602f);
131  const vector float vec_1_501321110 = (vector float)FOUROF(1.501321110f);
132  const vector float vec_1_847759065 = (vector float)FOUROF(-1.847759065f);
133  const vector float vec_1_961570560 = (vector float)FOUROF(-1.961570560f);
134  const vector float vec_2_053119869 = (vector float)FOUROF(2.053119869f);
135  const vector float vec_2_562915447 = (vector float)FOUROF(-2.562915447f);
136  const vector float vec_3_072711026 = (vector float)FOUROF(3.072711026f);
137 
138 
139  int whichPass, whichHalf;
140 
141  for(whichPass = 1; whichPass<=2; whichPass++) {
142  for(whichHalf = 1; whichHalf<=2; whichHalf++) {
143  vector float tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
144  vector float tmp10, tmp11, tmp12, tmp13;
145  vector float z1, z2, z3, z4, z5;
146 
147  tmp0 = vec_add(row0, row7); // tmp0 = dataptr[0] + dataptr[7];
148  tmp7 = vec_sub(row0, row7); // tmp7 = dataptr[0] - dataptr[7];
149  tmp3 = vec_add(row3, row4); // tmp3 = dataptr[3] + dataptr[4];
150  tmp4 = vec_sub(row3, row4); // tmp4 = dataptr[3] - dataptr[4];
151  tmp1 = vec_add(row1, row6); // tmp1 = dataptr[1] + dataptr[6];
152  tmp6 = vec_sub(row1, row6); // tmp6 = dataptr[1] - dataptr[6];
153  tmp2 = vec_add(row2, row5); // tmp2 = dataptr[2] + dataptr[5];
154  tmp5 = vec_sub(row2, row5); // tmp5 = dataptr[2] - dataptr[5];
155 
156  tmp10 = vec_add(tmp0, tmp3); // tmp10 = tmp0 + tmp3;
157  tmp13 = vec_sub(tmp0, tmp3); // tmp13 = tmp0 - tmp3;
158  tmp11 = vec_add(tmp1, tmp2); // tmp11 = tmp1 + tmp2;
159  tmp12 = vec_sub(tmp1, tmp2); // tmp12 = tmp1 - tmp2;
160 
161 
162  // dataptr[0] = (DCTELEM) ((tmp10 + tmp11) << PASS1_BITS);
163  row0 = vec_add(tmp10, tmp11);
164 
165  // dataptr[4] = (DCTELEM) ((tmp10 - tmp11) << PASS1_BITS);
166  row4 = vec_sub(tmp10, tmp11);
167 
168 
169  // z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
170  z1 = vec_madd(vec_add(tmp12, tmp13), vec_0_541196100, (vector float)zero);
171 
172  // dataptr[2] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
173  // CONST_BITS-PASS1_BITS);
174  row2 = vec_madd(tmp13, vec_0_765366865, z1);
175 
176  // dataptr[6] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
177  // CONST_BITS-PASS1_BITS);
178  row6 = vec_madd(tmp12, vec_1_847759065, z1);
179 
180  z1 = vec_add(tmp4, tmp7); // z1 = tmp4 + tmp7;
181  z2 = vec_add(tmp5, tmp6); // z2 = tmp5 + tmp6;
182  z3 = vec_add(tmp4, tmp6); // z3 = tmp4 + tmp6;
183  z4 = vec_add(tmp5, tmp7); // z4 = tmp5 + tmp7;
184 
185  // z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
186  z5 = vec_madd(vec_add(z3, z4), vec_1_175875602, (vector float)zero);
187 
188  // z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
189  z3 = vec_madd(z3, vec_1_961570560, z5);
190 
191  // z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
192  z4 = vec_madd(z4, vec_0_390180644, z5);
193 
194  // The following adds are rolled into the multiplies above
195  // z3 = vec_add(z3, z5); // z3 += z5;
196  // z4 = vec_add(z4, z5); // z4 += z5;
197 
198  // z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
199  // Wow! It's actually more efficient to roll this multiply
200  // into the adds below, even thought the multiply gets done twice!
201  // z2 = vec_madd(z2, vec_2_562915447, (vector float)zero);
202 
203  // z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
204  // Same with this one...
205  // z1 = vec_madd(z1, vec_0_899976223, (vector float)zero);
206 
207  // tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
208  // dataptr[7] = (DCTELEM) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS);
209  row7 = vec_madd(tmp4, vec_0_298631336, vec_madd(z1, vec_0_899976223, z3));
210 
211  // tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
212  // dataptr[5] = (DCTELEM) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS);
213  row5 = vec_madd(tmp5, vec_2_053119869, vec_madd(z2, vec_2_562915447, z4));
214 
215  // tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
216  // dataptr[3] = (DCTELEM) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS);
217  row3 = vec_madd(tmp6, vec_3_072711026, vec_madd(z2, vec_2_562915447, z3));
218 
219  // tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
220  // dataptr[1] = (DCTELEM) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS);
221  row1 = vec_madd(z1, vec_0_899976223, vec_madd(tmp7, vec_1_501321110, z4));
222 
223  // Swap the row values with the alts. If this is the first half,
224  // this sets up the low values to be acted on in the second half.
225  // If this is the second half, it puts the high values back in
226  // the row values where they are expected to be when we're done.
227  SWAP(row0, alt0);
228  SWAP(row1, alt1);
229  SWAP(row2, alt2);
230  SWAP(row3, alt3);
231  SWAP(row4, alt4);
232  SWAP(row5, alt5);
233  SWAP(row6, alt6);
234  SWAP(row7, alt7);
235  }
236 
237  if (whichPass == 1) {
238  // transpose the data for the second pass
239 
240  // First, block transpose the upper right with lower left.
241  SWAP(row4, alt0);
242  SWAP(row5, alt1);
243  SWAP(row6, alt2);
244  SWAP(row7, alt3);
245 
246  // Now, transpose each block of four
247  TRANSPOSE4(row0, row1, row2, row3);
248  TRANSPOSE4(row4, row5, row6, row7);
249  TRANSPOSE4(alt0, alt1, alt2, alt3);
250  TRANSPOSE4(alt4, alt5, alt6, alt7);
251  }
252  }
253  }
254 
255  // perform the quantize step, using the floating point data
256  // still in the row/alt registers
257  {
258  const int* biasAddr;
259  const vector signed int* qmat;
260  vector float bias, negBias;
261 
262  if (s->mb_intra) {
263  vector signed int baseVector;
264 
265  // We must cache element 0 in the intra case
266  // (it needs special handling).
267  baseVector = vec_cts(vec_splat(row0, 0), 0);
268  vec_ste(baseVector, 0, &oldBaseValue);
269 
270  qmat = (vector signed int*)s->q_intra_matrix[qscale];
271  biasAddr = &s->intra_quant_bias;
272  } else {
273  qmat = (vector signed int*)s->q_inter_matrix[qscale];
274  biasAddr = &s->inter_quant_bias;
275  }
276 
277  // Load the bias vector (We add 0.5 to the bias so that we're
278  // rounding when we convert to int, instead of flooring.)
279  {
280  vector signed int biasInt;
281  const vector float negOneFloat = (vector float)FOUROF(-1.0f);
282  LOAD4(biasInt, biasAddr);
283  bias = vec_ctf(biasInt, QUANT_BIAS_SHIFT);
284  negBias = vec_madd(bias, negOneFloat, zero);
285  }
286 
287  {
288  vector float q0, q1, q2, q3, q4, q5, q6, q7;
289 
290  q0 = vec_ctf(qmat[0], QMAT_SHIFT);
291  q1 = vec_ctf(qmat[2], QMAT_SHIFT);
292  q2 = vec_ctf(qmat[4], QMAT_SHIFT);
293  q3 = vec_ctf(qmat[6], QMAT_SHIFT);
294  q4 = vec_ctf(qmat[8], QMAT_SHIFT);
295  q5 = vec_ctf(qmat[10], QMAT_SHIFT);
296  q6 = vec_ctf(qmat[12], QMAT_SHIFT);
297  q7 = vec_ctf(qmat[14], QMAT_SHIFT);
298 
299  row0 = vec_sel(vec_madd(row0, q0, negBias), vec_madd(row0, q0, bias),
300  vec_cmpgt(row0, zero));
301  row1 = vec_sel(vec_madd(row1, q1, negBias), vec_madd(row1, q1, bias),
302  vec_cmpgt(row1, zero));
303  row2 = vec_sel(vec_madd(row2, q2, negBias), vec_madd(row2, q2, bias),
304  vec_cmpgt(row2, zero));
305  row3 = vec_sel(vec_madd(row3, q3, negBias), vec_madd(row3, q3, bias),
306  vec_cmpgt(row3, zero));
307  row4 = vec_sel(vec_madd(row4, q4, negBias), vec_madd(row4, q4, bias),
308  vec_cmpgt(row4, zero));
309  row5 = vec_sel(vec_madd(row5, q5, negBias), vec_madd(row5, q5, bias),
310  vec_cmpgt(row5, zero));
311  row6 = vec_sel(vec_madd(row6, q6, negBias), vec_madd(row6, q6, bias),
312  vec_cmpgt(row6, zero));
313  row7 = vec_sel(vec_madd(row7, q7, negBias), vec_madd(row7, q7, bias),
314  vec_cmpgt(row7, zero));
315 
316  q0 = vec_ctf(qmat[1], QMAT_SHIFT);
317  q1 = vec_ctf(qmat[3], QMAT_SHIFT);
318  q2 = vec_ctf(qmat[5], QMAT_SHIFT);
319  q3 = vec_ctf(qmat[7], QMAT_SHIFT);
320  q4 = vec_ctf(qmat[9], QMAT_SHIFT);
321  q5 = vec_ctf(qmat[11], QMAT_SHIFT);
322  q6 = vec_ctf(qmat[13], QMAT_SHIFT);
323  q7 = vec_ctf(qmat[15], QMAT_SHIFT);
324 
325  alt0 = vec_sel(vec_madd(alt0, q0, negBias), vec_madd(alt0, q0, bias),
326  vec_cmpgt(alt0, zero));
327  alt1 = vec_sel(vec_madd(alt1, q1, negBias), vec_madd(alt1, q1, bias),
328  vec_cmpgt(alt1, zero));
329  alt2 = vec_sel(vec_madd(alt2, q2, negBias), vec_madd(alt2, q2, bias),
330  vec_cmpgt(alt2, zero));
331  alt3 = vec_sel(vec_madd(alt3, q3, negBias), vec_madd(alt3, q3, bias),
332  vec_cmpgt(alt3, zero));
333  alt4 = vec_sel(vec_madd(alt4, q4, negBias), vec_madd(alt4, q4, bias),
334  vec_cmpgt(alt4, zero));
335  alt5 = vec_sel(vec_madd(alt5, q5, negBias), vec_madd(alt5, q5, bias),
336  vec_cmpgt(alt5, zero));
337  alt6 = vec_sel(vec_madd(alt6, q6, negBias), vec_madd(alt6, q6, bias),
338  vec_cmpgt(alt6, zero));
339  alt7 = vec_sel(vec_madd(alt7, q7, negBias), vec_madd(alt7, q7, bias),
340  vec_cmpgt(alt7, zero));
341  }
342 
343 
344  }
345 
346  // Store the data back into the original block
347  {
348  vector signed short data0, data1, data2, data3, data4, data5, data6, data7;
349 
350  data0 = vec_pack(vec_cts(row0, 0), vec_cts(alt0, 0));
351  data1 = vec_pack(vec_cts(row1, 0), vec_cts(alt1, 0));
352  data2 = vec_pack(vec_cts(row2, 0), vec_cts(alt2, 0));
353  data3 = vec_pack(vec_cts(row3, 0), vec_cts(alt3, 0));
354  data4 = vec_pack(vec_cts(row4, 0), vec_cts(alt4, 0));
355  data5 = vec_pack(vec_cts(row5, 0), vec_cts(alt5, 0));
356  data6 = vec_pack(vec_cts(row6, 0), vec_cts(alt6, 0));
357  data7 = vec_pack(vec_cts(row7, 0), vec_cts(alt7, 0));
358 
359  {
360  // Clamp for overflow
361  vector signed int max_q_int, min_q_int;
362  vector signed short max_q, min_q;
363 
364  LOAD4(max_q_int, &s->max_qcoeff);
365  LOAD4(min_q_int, &s->min_qcoeff);
366 
367  max_q = vec_pack(max_q_int, max_q_int);
368  min_q = vec_pack(min_q_int, min_q_int);
369 
370  data0 = vec_max(vec_min(data0, max_q), min_q);
371  data1 = vec_max(vec_min(data1, max_q), min_q);
372  data2 = vec_max(vec_min(data2, max_q), min_q);
373  data4 = vec_max(vec_min(data4, max_q), min_q);
374  data5 = vec_max(vec_min(data5, max_q), min_q);
375  data6 = vec_max(vec_min(data6, max_q), min_q);
376  data7 = vec_max(vec_min(data7, max_q), min_q);
377  }
378 
379  {
380  vector bool char zero_01, zero_23, zero_45, zero_67;
381  vector signed char scanIndexes_01, scanIndexes_23, scanIndexes_45, scanIndexes_67;
382  vector signed char negOne = vec_splat_s8(-1);
383  vector signed char* scanPtr =
384  (vector signed char*)(s->intra_scantable.inverse);
385  signed char lastNonZeroChar;
386 
387  // Determine the largest non-zero index.
388  zero_01 = vec_pack(vec_cmpeq(data0, (vector signed short)zero),
389  vec_cmpeq(data1, (vector signed short)zero));
390  zero_23 = vec_pack(vec_cmpeq(data2, (vector signed short)zero),
391  vec_cmpeq(data3, (vector signed short)zero));
392  zero_45 = vec_pack(vec_cmpeq(data4, (vector signed short)zero),
393  vec_cmpeq(data5, (vector signed short)zero));
394  zero_67 = vec_pack(vec_cmpeq(data6, (vector signed short)zero),
395  vec_cmpeq(data7, (vector signed short)zero));
396 
397  // 64 biggest values
398  scanIndexes_01 = vec_sel(scanPtr[0], negOne, zero_01);
399  scanIndexes_23 = vec_sel(scanPtr[1], negOne, zero_23);
400  scanIndexes_45 = vec_sel(scanPtr[2], negOne, zero_45);
401  scanIndexes_67 = vec_sel(scanPtr[3], negOne, zero_67);
402 
403  // 32 largest values
404  scanIndexes_01 = vec_max(scanIndexes_01, scanIndexes_23);
405  scanIndexes_45 = vec_max(scanIndexes_45, scanIndexes_67);
406 
407  // 16 largest values
408  scanIndexes_01 = vec_max(scanIndexes_01, scanIndexes_45);
409 
410  // 8 largest values
411  scanIndexes_01 = vec_max(vec_mergeh(scanIndexes_01, negOne),
412  vec_mergel(scanIndexes_01, negOne));
413 
414  // 4 largest values
415  scanIndexes_01 = vec_max(vec_mergeh(scanIndexes_01, negOne),
416  vec_mergel(scanIndexes_01, negOne));
417 
418  // 2 largest values
419  scanIndexes_01 = vec_max(vec_mergeh(scanIndexes_01, negOne),
420  vec_mergel(scanIndexes_01, negOne));
421 
422  // largest value
423  scanIndexes_01 = vec_max(vec_mergeh(scanIndexes_01, negOne),
424  vec_mergel(scanIndexes_01, negOne));
425 
426  scanIndexes_01 = vec_splat(scanIndexes_01, 0);
427 
428 
429  vec_ste(scanIndexes_01, 0, &lastNonZeroChar);
430 
431  lastNonZero = lastNonZeroChar;
432 
433  // While the data is still in vectors we check for the transpose IDCT permute
434  // and handle it using the vector unit if we can. This is the permute used
435  // by the altivec idct, so it is common when using the altivec dct.
436 
437  if ((lastNonZero > 0) && (s->dsp.idct_permutation_type == FF_TRANSPOSE_IDCT_PERM)) {
438  TRANSPOSE8(data0, data1, data2, data3, data4, data5, data6, data7);
439  }
440 
441  vec_st(data0, 0, data);
442  vec_st(data1, 16, data);
443  vec_st(data2, 32, data);
444  vec_st(data3, 48, data);
445  vec_st(data4, 64, data);
446  vec_st(data5, 80, data);
447  vec_st(data6, 96, data);
448  vec_st(data7, 112, data);
449  }
450  }
451 
452  // special handling of block[0]
453  if (s->mb_intra) {
454  if (!s->h263_aic) {
455  if (n < 4)
456  oldBaseValue /= s->y_dc_scale;
457  else
458  oldBaseValue /= s->c_dc_scale;
459  }
460 
461  // Divide by 8, rounding the result
462  data[0] = (oldBaseValue + 4) >> 3;
463  }
464 
465  // We handled the transpose permutation above and we don't
466  // need to permute the "no" permutation case.
467  if ((lastNonZero > 0) &&
471  s->intra_scantable.scantable, lastNonZero);
472  }
473 
474  return lastNonZero;
475 }
476 
477 /* AltiVec version of dct_unquantize_h263
478  this code assumes `block' is 16 bytes-aligned */
480  DCTELEM *block, int n, int qscale)
481 {
482  int i, level, qmul, qadd;
483  int nCoeffs;
484 
485  assert(s->block_last_index[n]>=0);
486 
487  qadd = (qscale - 1) | 1;
488  qmul = qscale << 1;
489 
490  if (s->mb_intra) {
491  if (!s->h263_aic) {
492  if (n < 4)
493  block[0] = block[0] * s->y_dc_scale;
494  else
495  block[0] = block[0] * s->c_dc_scale;
496  }else
497  qadd = 0;
498  i = 1;
499  nCoeffs= 63; //does not always use zigzag table
500  } else {
501  i = 0;
502  nCoeffs= s->intra_scantable.raster_end[ s->block_last_index[n] ];
503  }
504 
505  {
506  register const vector signed short vczero = (const vector signed short)vec_splat_s16(0);
507  DECLARE_ALIGNED(16, short, qmul8) = qmul;
508  DECLARE_ALIGNED(16, short, qadd8) = qadd;
509  register vector signed short blockv, qmulv, qaddv, nqaddv, temp1;
510  register vector bool short blockv_null, blockv_neg;
511  register short backup_0 = block[0];
512  register int j = 0;
513 
514  qmulv = vec_splat((vec_s16)vec_lde(0, &qmul8), 0);
515  qaddv = vec_splat((vec_s16)vec_lde(0, &qadd8), 0);
516  nqaddv = vec_sub(vczero, qaddv);
517 
518  // vectorize all the 16 bytes-aligned blocks
519  // of 8 elements
520  for(; (j + 7) <= nCoeffs ; j+=8) {
521  blockv = vec_ld(j << 1, block);
522  blockv_neg = vec_cmplt(blockv, vczero);
523  blockv_null = vec_cmpeq(blockv, vczero);
524  // choose between +qadd or -qadd as the third operand
525  temp1 = vec_sel(qaddv, nqaddv, blockv_neg);
526  // multiply & add (block{i,i+7} * qmul [+-] qadd)
527  temp1 = vec_mladd(blockv, qmulv, temp1);
528  // put 0 where block[{i,i+7} used to have 0
529  blockv = vec_sel(temp1, blockv, blockv_null);
530  vec_st(blockv, j << 1, block);
531  }
532 
533  // if nCoeffs isn't a multiple of 8, finish the job
534  // using good old scalar units.
535  // (we could do it using a truncated vector,
536  // but I'm not sure it's worth the hassle)
537  for(; j <= nCoeffs ; j++) {
538  level = block[j];
539  if (level) {
540  if (level < 0) {
541  level = level * qmul - qadd;
542  } else {
543  level = level * qmul + qadd;
544  }
545  block[j] = level;
546  }
547  }
548 
549  if (i == 1) {
550  // cheat. this avoid special-casing the first iteration
551  block[0] = backup_0;
552  }
553  }
554 }
555 
556 
558 {
559  if (!(av_get_cpu_flags() & AV_CPU_FLAG_ALTIVEC)) return;
560 
561  // Test to make sure that the dct required alignments are met.
562  if ((((long)(s->q_intra_matrix) & 0x0f) != 0) ||
563  (((long)(s->q_inter_matrix) & 0x0f) != 0)) {
564  av_log(s->avctx, AV_LOG_INFO, "Internal Error: q-matrix blocks must be 16-byte aligned "
565  "to use AltiVec DCT. Reverting to non-AltiVec version.\n");
566  return;
567  }
568 
569  if (((long)(s->intra_scantable.inverse) & 0x0f) != 0) {
570  av_log(s->avctx, AV_LOG_INFO, "Internal Error: scan table blocks must be 16-byte aligned "
571  "to use AltiVec DCT. Reverting to non-AltiVec version.\n");
572  return;
573  }
574 
575 
576  if ((s->avctx->dct_algo == FF_DCT_AUTO) ||
577  (s->avctx->dct_algo == FF_DCT_ALTIVEC)) {
580  }
581 }