Home | History | Annotate | Download | only in aec
      1 /*
      2  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #include "webrtc/modules/audio_processing/aec/aec_rdft.h"
     12 
     13 #include <emmintrin.h>
     14 
     15 static const ALIGN16_BEG float ALIGN16_END
     16     k_swap_sign[4] = {-1.f, 1.f, -1.f, 1.f};
     17 
     18 static void cft1st_128_SSE2(float* a) {
     19   const __m128 mm_swap_sign = _mm_load_ps(k_swap_sign);
     20   int j, k2;
     21 
     22   for (k2 = 0, j = 0; j < 128; j += 16, k2 += 4) {
     23     __m128 a00v = _mm_loadu_ps(&a[j + 0]);
     24     __m128 a04v = _mm_loadu_ps(&a[j + 4]);
     25     __m128 a08v = _mm_loadu_ps(&a[j + 8]);
     26     __m128 a12v = _mm_loadu_ps(&a[j + 12]);
     27     __m128 a01v = _mm_shuffle_ps(a00v, a08v, _MM_SHUFFLE(1, 0, 1, 0));
     28     __m128 a23v = _mm_shuffle_ps(a00v, a08v, _MM_SHUFFLE(3, 2, 3, 2));
     29     __m128 a45v = _mm_shuffle_ps(a04v, a12v, _MM_SHUFFLE(1, 0, 1, 0));
     30     __m128 a67v = _mm_shuffle_ps(a04v, a12v, _MM_SHUFFLE(3, 2, 3, 2));
     31 
     32     const __m128 wk1rv = _mm_load_ps(&rdft_wk1r[k2]);
     33     const __m128 wk1iv = _mm_load_ps(&rdft_wk1i[k2]);
     34     const __m128 wk2rv = _mm_load_ps(&rdft_wk2r[k2]);
     35     const __m128 wk2iv = _mm_load_ps(&rdft_wk2i[k2]);
     36     const __m128 wk3rv = _mm_load_ps(&rdft_wk3r[k2]);
     37     const __m128 wk3iv = _mm_load_ps(&rdft_wk3i[k2]);
     38     __m128 x0v = _mm_add_ps(a01v, a23v);
     39     const __m128 x1v = _mm_sub_ps(a01v, a23v);
     40     const __m128 x2v = _mm_add_ps(a45v, a67v);
     41     const __m128 x3v = _mm_sub_ps(a45v, a67v);
     42     __m128 x0w;
     43     a01v = _mm_add_ps(x0v, x2v);
     44     x0v = _mm_sub_ps(x0v, x2v);
     45     x0w = _mm_shuffle_ps(x0v, x0v, _MM_SHUFFLE(2, 3, 0, 1));
     46     {
     47       const __m128 a45_0v = _mm_mul_ps(wk2rv, x0v);
     48       const __m128 a45_1v = _mm_mul_ps(wk2iv, x0w);
     49       a45v = _mm_add_ps(a45_0v, a45_1v);
     50     }
     51     {
     52       __m128 a23_0v, a23_1v;
     53       const __m128 x3w = _mm_shuffle_ps(x3v, x3v, _MM_SHUFFLE(2, 3, 0, 1));
     54       const __m128 x3s = _mm_mul_ps(mm_swap_sign, x3w);
     55       x0v = _mm_add_ps(x1v, x3s);
     56       x0w = _mm_shuffle_ps(x0v, x0v, _MM_SHUFFLE(2, 3, 0, 1));
     57       a23_0v = _mm_mul_ps(wk1rv, x0v);
     58       a23_1v = _mm_mul_ps(wk1iv, x0w);
     59       a23v = _mm_add_ps(a23_0v, a23_1v);
     60 
     61       x0v = _mm_sub_ps(x1v, x3s);
     62       x0w = _mm_shuffle_ps(x0v, x0v, _MM_SHUFFLE(2, 3, 0, 1));
     63     }
     64     {
     65       const __m128 a67_0v = _mm_mul_ps(wk3rv, x0v);
     66       const __m128 a67_1v = _mm_mul_ps(wk3iv, x0w);
     67       a67v = _mm_add_ps(a67_0v, a67_1v);
     68     }
     69 
     70     a00v = _mm_shuffle_ps(a01v, a23v, _MM_SHUFFLE(1, 0, 1, 0));
     71     a04v = _mm_shuffle_ps(a45v, a67v, _MM_SHUFFLE(1, 0, 1, 0));
     72     a08v = _mm_shuffle_ps(a01v, a23v, _MM_SHUFFLE(3, 2, 3, 2));
     73     a12v = _mm_shuffle_ps(a45v, a67v, _MM_SHUFFLE(3, 2, 3, 2));
     74     _mm_storeu_ps(&a[j + 0], a00v);
     75     _mm_storeu_ps(&a[j + 4], a04v);
     76     _mm_storeu_ps(&a[j + 8], a08v);
     77     _mm_storeu_ps(&a[j + 12], a12v);
     78   }
     79 }
     80 
     81 static void cftmdl_128_SSE2(float* a) {
     82   const int l = 8;
     83   const __m128 mm_swap_sign = _mm_load_ps(k_swap_sign);
     84   int j0;
     85 
     86   __m128 wk1rv = _mm_load_ps(cftmdl_wk1r);
     87   for (j0 = 0; j0 < l; j0 += 2) {
     88     const __m128i a_00 = _mm_loadl_epi64((__m128i*)&a[j0 + 0]);
     89     const __m128i a_08 = _mm_loadl_epi64((__m128i*)&a[j0 + 8]);
     90     const __m128i a_32 = _mm_loadl_epi64((__m128i*)&a[j0 + 32]);
     91     const __m128i a_40 = _mm_loadl_epi64((__m128i*)&a[j0 + 40]);
     92     const __m128 a_00_32 = _mm_shuffle_ps(_mm_castsi128_ps(a_00),
     93                                           _mm_castsi128_ps(a_32),
     94                                           _MM_SHUFFLE(1, 0, 1, 0));
     95     const __m128 a_08_40 = _mm_shuffle_ps(_mm_castsi128_ps(a_08),
     96                                           _mm_castsi128_ps(a_40),
     97                                           _MM_SHUFFLE(1, 0, 1, 0));
     98     __m128 x0r0_0i0_0r1_x0i1 = _mm_add_ps(a_00_32, a_08_40);
     99     const __m128 x1r0_1i0_1r1_x1i1 = _mm_sub_ps(a_00_32, a_08_40);
    100 
    101     const __m128i a_16 = _mm_loadl_epi64((__m128i*)&a[j0 + 16]);
    102     const __m128i a_24 = _mm_loadl_epi64((__m128i*)&a[j0 + 24]);
    103     const __m128i a_48 = _mm_loadl_epi64((__m128i*)&a[j0 + 48]);
    104     const __m128i a_56 = _mm_loadl_epi64((__m128i*)&a[j0 + 56]);
    105     const __m128 a_16_48 = _mm_shuffle_ps(_mm_castsi128_ps(a_16),
    106                                           _mm_castsi128_ps(a_48),
    107                                           _MM_SHUFFLE(1, 0, 1, 0));
    108     const __m128 a_24_56 = _mm_shuffle_ps(_mm_castsi128_ps(a_24),
    109                                           _mm_castsi128_ps(a_56),
    110                                           _MM_SHUFFLE(1, 0, 1, 0));
    111     const __m128 x2r0_2i0_2r1_x2i1 = _mm_add_ps(a_16_48, a_24_56);
    112     const __m128 x3r0_3i0_3r1_x3i1 = _mm_sub_ps(a_16_48, a_24_56);
    113 
    114     const __m128 xx0 = _mm_add_ps(x0r0_0i0_0r1_x0i1, x2r0_2i0_2r1_x2i1);
    115     const __m128 xx1 = _mm_sub_ps(x0r0_0i0_0r1_x0i1, x2r0_2i0_2r1_x2i1);
    116 
    117     const __m128 x3i0_3r0_3i1_x3r1 = _mm_castsi128_ps(_mm_shuffle_epi32(
    118         _mm_castps_si128(x3r0_3i0_3r1_x3i1), _MM_SHUFFLE(2, 3, 0, 1)));
    119     const __m128 x3_swapped = _mm_mul_ps(mm_swap_sign, x3i0_3r0_3i1_x3r1);
    120     const __m128 x1_x3_add = _mm_add_ps(x1r0_1i0_1r1_x1i1, x3_swapped);
    121     const __m128 x1_x3_sub = _mm_sub_ps(x1r0_1i0_1r1_x1i1, x3_swapped);
    122 
    123     const __m128 yy0 =
    124         _mm_shuffle_ps(x1_x3_add, x1_x3_sub, _MM_SHUFFLE(2, 2, 2, 2));
    125     const __m128 yy1 =
    126         _mm_shuffle_ps(x1_x3_add, x1_x3_sub, _MM_SHUFFLE(3, 3, 3, 3));
    127     const __m128 yy2 = _mm_mul_ps(mm_swap_sign, yy1);
    128     const __m128 yy3 = _mm_add_ps(yy0, yy2);
    129     const __m128 yy4 = _mm_mul_ps(wk1rv, yy3);
    130 
    131     _mm_storel_epi64((__m128i*)&a[j0 + 0], _mm_castps_si128(xx0));
    132     _mm_storel_epi64(
    133         (__m128i*)&a[j0 + 32],
    134         _mm_shuffle_epi32(_mm_castps_si128(xx0), _MM_SHUFFLE(3, 2, 3, 2)));
    135 
    136     _mm_storel_epi64((__m128i*)&a[j0 + 16], _mm_castps_si128(xx1));
    137     _mm_storel_epi64(
    138         (__m128i*)&a[j0 + 48],
    139         _mm_shuffle_epi32(_mm_castps_si128(xx1), _MM_SHUFFLE(2, 3, 2, 3)));
    140     a[j0 + 48] = -a[j0 + 48];
    141 
    142     _mm_storel_epi64((__m128i*)&a[j0 + 8], _mm_castps_si128(x1_x3_add));
    143     _mm_storel_epi64((__m128i*)&a[j0 + 24], _mm_castps_si128(x1_x3_sub));
    144 
    145     _mm_storel_epi64((__m128i*)&a[j0 + 40], _mm_castps_si128(yy4));
    146     _mm_storel_epi64(
    147         (__m128i*)&a[j0 + 56],
    148         _mm_shuffle_epi32(_mm_castps_si128(yy4), _MM_SHUFFLE(2, 3, 2, 3)));
    149   }
    150 
    151   {
    152     int k = 64;
    153     int k1 = 2;
    154     int k2 = 2 * k1;
    155     const __m128 wk2rv = _mm_load_ps(&rdft_wk2r[k2 + 0]);
    156     const __m128 wk2iv = _mm_load_ps(&rdft_wk2i[k2 + 0]);
    157     const __m128 wk1iv = _mm_load_ps(&rdft_wk1i[k2 + 0]);
    158     const __m128 wk3rv = _mm_load_ps(&rdft_wk3r[k2 + 0]);
    159     const __m128 wk3iv = _mm_load_ps(&rdft_wk3i[k2 + 0]);
    160     wk1rv = _mm_load_ps(&rdft_wk1r[k2 + 0]);
    161     for (j0 = k; j0 < l + k; j0 += 2) {
    162       const __m128i a_00 = _mm_loadl_epi64((__m128i*)&a[j0 + 0]);
    163       const __m128i a_08 = _mm_loadl_epi64((__m128i*)&a[j0 + 8]);
    164       const __m128i a_32 = _mm_loadl_epi64((__m128i*)&a[j0 + 32]);
    165       const __m128i a_40 = _mm_loadl_epi64((__m128i*)&a[j0 + 40]);
    166       const __m128 a_00_32 = _mm_shuffle_ps(_mm_castsi128_ps(a_00),
    167                                             _mm_castsi128_ps(a_32),
    168                                             _MM_SHUFFLE(1, 0, 1, 0));
    169       const __m128 a_08_40 = _mm_shuffle_ps(_mm_castsi128_ps(a_08),
    170                                             _mm_castsi128_ps(a_40),
    171                                             _MM_SHUFFLE(1, 0, 1, 0));
    172       __m128 x0r0_0i0_0r1_x0i1 = _mm_add_ps(a_00_32, a_08_40);
    173       const __m128 x1r0_1i0_1r1_x1i1 = _mm_sub_ps(a_00_32, a_08_40);
    174 
    175       const __m128i a_16 = _mm_loadl_epi64((__m128i*)&a[j0 + 16]);
    176       const __m128i a_24 = _mm_loadl_epi64((__m128i*)&a[j0 + 24]);
    177       const __m128i a_48 = _mm_loadl_epi64((__m128i*)&a[j0 + 48]);
    178       const __m128i a_56 = _mm_loadl_epi64((__m128i*)&a[j0 + 56]);
    179       const __m128 a_16_48 = _mm_shuffle_ps(_mm_castsi128_ps(a_16),
    180                                             _mm_castsi128_ps(a_48),
    181                                             _MM_SHUFFLE(1, 0, 1, 0));
    182       const __m128 a_24_56 = _mm_shuffle_ps(_mm_castsi128_ps(a_24),
    183                                             _mm_castsi128_ps(a_56),
    184                                             _MM_SHUFFLE(1, 0, 1, 0));
    185       const __m128 x2r0_2i0_2r1_x2i1 = _mm_add_ps(a_16_48, a_24_56);
    186       const __m128 x3r0_3i0_3r1_x3i1 = _mm_sub_ps(a_16_48, a_24_56);
    187 
    188       const __m128 xx = _mm_add_ps(x0r0_0i0_0r1_x0i1, x2r0_2i0_2r1_x2i1);
    189       const __m128 xx1 = _mm_sub_ps(x0r0_0i0_0r1_x0i1, x2r0_2i0_2r1_x2i1);
    190       const __m128 xx2 = _mm_mul_ps(xx1, wk2rv);
    191       const __m128 xx3 =
    192           _mm_mul_ps(wk2iv,
    193                      _mm_castsi128_ps(_mm_shuffle_epi32(
    194                          _mm_castps_si128(xx1), _MM_SHUFFLE(2, 3, 0, 1))));
    195       const __m128 xx4 = _mm_add_ps(xx2, xx3);
    196 
    197       const __m128 x3i0_3r0_3i1_x3r1 = _mm_castsi128_ps(_mm_shuffle_epi32(
    198           _mm_castps_si128(x3r0_3i0_3r1_x3i1), _MM_SHUFFLE(2, 3, 0, 1)));
    199       const __m128 x3_swapped = _mm_mul_ps(mm_swap_sign, x3i0_3r0_3i1_x3r1);
    200       const __m128 x1_x3_add = _mm_add_ps(x1r0_1i0_1r1_x1i1, x3_swapped);
    201       const __m128 x1_x3_sub = _mm_sub_ps(x1r0_1i0_1r1_x1i1, x3_swapped);
    202 
    203       const __m128 xx10 = _mm_mul_ps(x1_x3_add, wk1rv);
    204       const __m128 xx11 = _mm_mul_ps(
    205           wk1iv,
    206           _mm_castsi128_ps(_mm_shuffle_epi32(_mm_castps_si128(x1_x3_add),
    207                                              _MM_SHUFFLE(2, 3, 0, 1))));
    208       const __m128 xx12 = _mm_add_ps(xx10, xx11);
    209 
    210       const __m128 xx20 = _mm_mul_ps(x1_x3_sub, wk3rv);
    211       const __m128 xx21 = _mm_mul_ps(
    212           wk3iv,
    213           _mm_castsi128_ps(_mm_shuffle_epi32(_mm_castps_si128(x1_x3_sub),
    214                                              _MM_SHUFFLE(2, 3, 0, 1))));
    215       const __m128 xx22 = _mm_add_ps(xx20, xx21);
    216 
    217       _mm_storel_epi64((__m128i*)&a[j0 + 0], _mm_castps_si128(xx));
    218       _mm_storel_epi64(
    219           (__m128i*)&a[j0 + 32],
    220           _mm_shuffle_epi32(_mm_castps_si128(xx), _MM_SHUFFLE(3, 2, 3, 2)));
    221 
    222       _mm_storel_epi64((__m128i*)&a[j0 + 16], _mm_castps_si128(xx4));
    223       _mm_storel_epi64(
    224           (__m128i*)&a[j0 + 48],
    225           _mm_shuffle_epi32(_mm_castps_si128(xx4), _MM_SHUFFLE(3, 2, 3, 2)));
    226 
    227       _mm_storel_epi64((__m128i*)&a[j0 + 8], _mm_castps_si128(xx12));
    228       _mm_storel_epi64(
    229           (__m128i*)&a[j0 + 40],
    230           _mm_shuffle_epi32(_mm_castps_si128(xx12), _MM_SHUFFLE(3, 2, 3, 2)));
    231 
    232       _mm_storel_epi64((__m128i*)&a[j0 + 24], _mm_castps_si128(xx22));
    233       _mm_storel_epi64(
    234           (__m128i*)&a[j0 + 56],
    235           _mm_shuffle_epi32(_mm_castps_si128(xx22), _MM_SHUFFLE(3, 2, 3, 2)));
    236     }
    237   }
    238 }
    239 
    240 static void rftfsub_128_SSE2(float* a) {
    241   const float* c = rdft_w + 32;
    242   int j1, j2, k1, k2;
    243   float wkr, wki, xr, xi, yr, yi;
    244 
    245   static const ALIGN16_BEG float ALIGN16_END
    246       k_half[4] = {0.5f, 0.5f, 0.5f, 0.5f};
    247   const __m128 mm_half = _mm_load_ps(k_half);
    248 
    249   // Vectorized code (four at once).
    250   //    Note: commented number are indexes for the first iteration of the loop.
    251   for (j1 = 1, j2 = 2; j2 + 7 < 64; j1 += 4, j2 += 8) {
    252     // Load 'wk'.
    253     const __m128 c_j1 = _mm_loadu_ps(&c[j1]);       //  1,  2,  3,  4,
    254     const __m128 c_k1 = _mm_loadu_ps(&c[29 - j1]);  // 28, 29, 30, 31,
    255     const __m128 wkrt = _mm_sub_ps(mm_half, c_k1);  // 28, 29, 30, 31,
    256     const __m128 wkr_ =
    257         _mm_shuffle_ps(wkrt, wkrt, _MM_SHUFFLE(0, 1, 2, 3));  // 31, 30, 29, 28,
    258     const __m128 wki_ = c_j1;                                 //  1,  2,  3,  4,
    259     // Load and shuffle 'a'.
    260     const __m128 a_j2_0 = _mm_loadu_ps(&a[0 + j2]);    //   2,   3,   4,   5,
    261     const __m128 a_j2_4 = _mm_loadu_ps(&a[4 + j2]);    //   6,   7,   8,   9,
    262     const __m128 a_k2_0 = _mm_loadu_ps(&a[122 - j2]);  // 120, 121, 122, 123,
    263     const __m128 a_k2_4 = _mm_loadu_ps(&a[126 - j2]);  // 124, 125, 126, 127,
    264     const __m128 a_j2_p0 = _mm_shuffle_ps(
    265         a_j2_0, a_j2_4, _MM_SHUFFLE(2, 0, 2, 0));  //   2,   4,   6,   8,
    266     const __m128 a_j2_p1 = _mm_shuffle_ps(
    267         a_j2_0, a_j2_4, _MM_SHUFFLE(3, 1, 3, 1));  //   3,   5,   7,   9,
    268     const __m128 a_k2_p0 = _mm_shuffle_ps(
    269         a_k2_4, a_k2_0, _MM_SHUFFLE(0, 2, 0, 2));  // 126, 124, 122, 120,
    270     const __m128 a_k2_p1 = _mm_shuffle_ps(
    271         a_k2_4, a_k2_0, _MM_SHUFFLE(1, 3, 1, 3));  // 127, 125, 123, 121,
    272     // Calculate 'x'.
    273     const __m128 xr_ = _mm_sub_ps(a_j2_p0, a_k2_p0);
    274     // 2-126, 4-124, 6-122, 8-120,
    275     const __m128 xi_ = _mm_add_ps(a_j2_p1, a_k2_p1);
    276     // 3-127, 5-125, 7-123, 9-121,
    277     // Calculate product into 'y'.
    278     //    yr = wkr * xr - wki * xi;
    279     //    yi = wkr * xi + wki * xr;
    280     const __m128 a_ = _mm_mul_ps(wkr_, xr_);
    281     const __m128 b_ = _mm_mul_ps(wki_, xi_);
    282     const __m128 c_ = _mm_mul_ps(wkr_, xi_);
    283     const __m128 d_ = _mm_mul_ps(wki_, xr_);
    284     const __m128 yr_ = _mm_sub_ps(a_, b_);  // 2-126, 4-124, 6-122, 8-120,
    285     const __m128 yi_ = _mm_add_ps(c_, d_);  // 3-127, 5-125, 7-123, 9-121,
    286                                             // Update 'a'.
    287                                             //    a[j2 + 0] -= yr;
    288                                             //    a[j2 + 1] -= yi;
    289                                             //    a[k2 + 0] += yr;
    290     //    a[k2 + 1] -= yi;
    291     const __m128 a_j2_p0n = _mm_sub_ps(a_j2_p0, yr_);  //   2,   4,   6,   8,
    292     const __m128 a_j2_p1n = _mm_sub_ps(a_j2_p1, yi_);  //   3,   5,   7,   9,
    293     const __m128 a_k2_p0n = _mm_add_ps(a_k2_p0, yr_);  // 126, 124, 122, 120,
    294     const __m128 a_k2_p1n = _mm_sub_ps(a_k2_p1, yi_);  // 127, 125, 123, 121,
    295     // Shuffle in right order and store.
    296     const __m128 a_j2_0n = _mm_unpacklo_ps(a_j2_p0n, a_j2_p1n);
    297     //   2,   3,   4,   5,
    298     const __m128 a_j2_4n = _mm_unpackhi_ps(a_j2_p0n, a_j2_p1n);
    299     //   6,   7,   8,   9,
    300     const __m128 a_k2_0nt = _mm_unpackhi_ps(a_k2_p0n, a_k2_p1n);
    301     // 122, 123, 120, 121,
    302     const __m128 a_k2_4nt = _mm_unpacklo_ps(a_k2_p0n, a_k2_p1n);
    303     // 126, 127, 124, 125,
    304     const __m128 a_k2_0n = _mm_shuffle_ps(
    305         a_k2_0nt, a_k2_0nt, _MM_SHUFFLE(1, 0, 3, 2));  // 120, 121, 122, 123,
    306     const __m128 a_k2_4n = _mm_shuffle_ps(
    307         a_k2_4nt, a_k2_4nt, _MM_SHUFFLE(1, 0, 3, 2));  // 124, 125, 126, 127,
    308     _mm_storeu_ps(&a[0 + j2], a_j2_0n);
    309     _mm_storeu_ps(&a[4 + j2], a_j2_4n);
    310     _mm_storeu_ps(&a[122 - j2], a_k2_0n);
    311     _mm_storeu_ps(&a[126 - j2], a_k2_4n);
    312   }
    313   // Scalar code for the remaining items.
    314   for (; j2 < 64; j1 += 1, j2 += 2) {
    315     k2 = 128 - j2;
    316     k1 = 32 - j1;
    317     wkr = 0.5f - c[k1];
    318     wki = c[j1];
    319     xr = a[j2 + 0] - a[k2 + 0];
    320     xi = a[j2 + 1] + a[k2 + 1];
    321     yr = wkr * xr - wki * xi;
    322     yi = wkr * xi + wki * xr;
    323     a[j2 + 0] -= yr;
    324     a[j2 + 1] -= yi;
    325     a[k2 + 0] += yr;
    326     a[k2 + 1] -= yi;
    327   }
    328 }
    329 
    330 static void rftbsub_128_SSE2(float* a) {
    331   const float* c = rdft_w + 32;
    332   int j1, j2, k1, k2;
    333   float wkr, wki, xr, xi, yr, yi;
    334 
    335   static const ALIGN16_BEG float ALIGN16_END
    336       k_half[4] = {0.5f, 0.5f, 0.5f, 0.5f};
    337   const __m128 mm_half = _mm_load_ps(k_half);
    338 
    339   a[1] = -a[1];
    340   // Vectorized code (four at once).
    341   //    Note: commented number are indexes for the first iteration of the loop.
    342   for (j1 = 1, j2 = 2; j2 + 7 < 64; j1 += 4, j2 += 8) {
    343     // Load 'wk'.
    344     const __m128 c_j1 = _mm_loadu_ps(&c[j1]);       //  1,  2,  3,  4,
    345     const __m128 c_k1 = _mm_loadu_ps(&c[29 - j1]);  // 28, 29, 30, 31,
    346     const __m128 wkrt = _mm_sub_ps(mm_half, c_k1);  // 28, 29, 30, 31,
    347     const __m128 wkr_ =
    348         _mm_shuffle_ps(wkrt, wkrt, _MM_SHUFFLE(0, 1, 2, 3));  // 31, 30, 29, 28,
    349     const __m128 wki_ = c_j1;                                 //  1,  2,  3,  4,
    350     // Load and shuffle 'a'.
    351     const __m128 a_j2_0 = _mm_loadu_ps(&a[0 + j2]);    //   2,   3,   4,   5,
    352     const __m128 a_j2_4 = _mm_loadu_ps(&a[4 + j2]);    //   6,   7,   8,   9,
    353     const __m128 a_k2_0 = _mm_loadu_ps(&a[122 - j2]);  // 120, 121, 122, 123,
    354     const __m128 a_k2_4 = _mm_loadu_ps(&a[126 - j2]);  // 124, 125, 126, 127,
    355     const __m128 a_j2_p0 = _mm_shuffle_ps(
    356         a_j2_0, a_j2_4, _MM_SHUFFLE(2, 0, 2, 0));  //   2,   4,   6,   8,
    357     const __m128 a_j2_p1 = _mm_shuffle_ps(
    358         a_j2_0, a_j2_4, _MM_SHUFFLE(3, 1, 3, 1));  //   3,   5,   7,   9,
    359     const __m128 a_k2_p0 = _mm_shuffle_ps(
    360         a_k2_4, a_k2_0, _MM_SHUFFLE(0, 2, 0, 2));  // 126, 124, 122, 120,
    361     const __m128 a_k2_p1 = _mm_shuffle_ps(
    362         a_k2_4, a_k2_0, _MM_SHUFFLE(1, 3, 1, 3));  // 127, 125, 123, 121,
    363     // Calculate 'x'.
    364     const __m128 xr_ = _mm_sub_ps(a_j2_p0, a_k2_p0);
    365     // 2-126, 4-124, 6-122, 8-120,
    366     const __m128 xi_ = _mm_add_ps(a_j2_p1, a_k2_p1);
    367     // 3-127, 5-125, 7-123, 9-121,
    368     // Calculate product into 'y'.
    369     //    yr = wkr * xr + wki * xi;
    370     //    yi = wkr * xi - wki * xr;
    371     const __m128 a_ = _mm_mul_ps(wkr_, xr_);
    372     const __m128 b_ = _mm_mul_ps(wki_, xi_);
    373     const __m128 c_ = _mm_mul_ps(wkr_, xi_);
    374     const __m128 d_ = _mm_mul_ps(wki_, xr_);
    375     const __m128 yr_ = _mm_add_ps(a_, b_);  // 2-126, 4-124, 6-122, 8-120,
    376     const __m128 yi_ = _mm_sub_ps(c_, d_);  // 3-127, 5-125, 7-123, 9-121,
    377                                             // Update 'a'.
    378                                             //    a[j2 + 0] = a[j2 + 0] - yr;
    379                                             //    a[j2 + 1] = yi - a[j2 + 1];
    380                                             //    a[k2 + 0] = yr + a[k2 + 0];
    381     //    a[k2 + 1] = yi - a[k2 + 1];
    382     const __m128 a_j2_p0n = _mm_sub_ps(a_j2_p0, yr_);  //   2,   4,   6,   8,
    383     const __m128 a_j2_p1n = _mm_sub_ps(yi_, a_j2_p1);  //   3,   5,   7,   9,
    384     const __m128 a_k2_p0n = _mm_add_ps(a_k2_p0, yr_);  // 126, 124, 122, 120,
    385     const __m128 a_k2_p1n = _mm_sub_ps(yi_, a_k2_p1);  // 127, 125, 123, 121,
    386     // Shuffle in right order and store.
    387     const __m128 a_j2_0n = _mm_unpacklo_ps(a_j2_p0n, a_j2_p1n);
    388     //   2,   3,   4,   5,
    389     const __m128 a_j2_4n = _mm_unpackhi_ps(a_j2_p0n, a_j2_p1n);
    390     //   6,   7,   8,   9,
    391     const __m128 a_k2_0nt = _mm_unpackhi_ps(a_k2_p0n, a_k2_p1n);
    392     // 122, 123, 120, 121,
    393     const __m128 a_k2_4nt = _mm_unpacklo_ps(a_k2_p0n, a_k2_p1n);
    394     // 126, 127, 124, 125,
    395     const __m128 a_k2_0n = _mm_shuffle_ps(
    396         a_k2_0nt, a_k2_0nt, _MM_SHUFFLE(1, 0, 3, 2));  // 120, 121, 122, 123,
    397     const __m128 a_k2_4n = _mm_shuffle_ps(
    398         a_k2_4nt, a_k2_4nt, _MM_SHUFFLE(1, 0, 3, 2));  // 124, 125, 126, 127,
    399     _mm_storeu_ps(&a[0 + j2], a_j2_0n);
    400     _mm_storeu_ps(&a[4 + j2], a_j2_4n);
    401     _mm_storeu_ps(&a[122 - j2], a_k2_0n);
    402     _mm_storeu_ps(&a[126 - j2], a_k2_4n);
    403   }
    404   // Scalar code for the remaining items.
    405   for (; j2 < 64; j1 += 1, j2 += 2) {
    406     k2 = 128 - j2;
    407     k1 = 32 - j1;
    408     wkr = 0.5f - c[k1];
    409     wki = c[j1];
    410     xr = a[j2 + 0] - a[k2 + 0];
    411     xi = a[j2 + 1] + a[k2 + 1];
    412     yr = wkr * xr + wki * xi;
    413     yi = wkr * xi - wki * xr;
    414     a[j2 + 0] = a[j2 + 0] - yr;
    415     a[j2 + 1] = yi - a[j2 + 1];
    416     a[k2 + 0] = yr + a[k2 + 0];
    417     a[k2 + 1] = yi - a[k2 + 1];
    418   }
    419   a[65] = -a[65];
    420 }
    421 
    422 void aec_rdft_init_sse2(void) {
    423   cft1st_128 = cft1st_128_SSE2;
    424   cftmdl_128 = cftmdl_128_SSE2;
    425   rftfsub_128 = rftfsub_128_SSE2;
    426   rftbsub_128 = rftbsub_128_SSE2;
    427 }
    428