modules/audio_processing/utility/ooura_fft.cc - src/webrtc - Git at Google

 /*
  * http://www.kurims.kyoto-u.ac.jp/~ooura/fft.html
  * Copyright Takuya OOURA, 1996-2001
  *
  * You may use, copy, modify and distribute this code for any purpose (include
  * commercial use) and without fee. Please refer to this package when you modify
  * this code.
  *
  * Changes by the WebRTC authors:
  *    - Trivial type modifications.
  *    - Minimal code subset to do rdft of length 128.
  *    - Optimizations because of known length.
  *    - Removed the global variables by moving the code in to a class in order
  *      to make it thread safe.
  *
  *  All changes are covered by the WebRTC license and IP grant:
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "webrtc/modules/audio_processing//utility/ooura_fft.h"

 #include <math.h>

 #include "webrtc/modules/audio_processing/utility/ooura_fft_tables_common.h"
 #include "webrtc/system_wrappers/include/cpu_features_wrapper.h"
 #include "webrtc/typedefs.h"

 namespace webrtc {

 namespace {

 #if !(defined(MIPS_FPU_LE) || defined(WEBRTC_HAS_NEON))
 static void cft1st_128_C(float* a) {
   const int n = 128;
   int j, k1, k2;
   float wk1r, wk1i, wk2r, wk2i, wk3r, wk3i;
   float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

   // The processing of the first set of elements was simplified in C to avoid
   // some operations (multiplication by zero or one, addition of two elements
   // multiplied by the same weight, ...).
   x0r = a[0] + a[2];
   x0i = a[1] + a[3];
   x1r = a[0] - a[2];
   x1i = a[1] - a[3];
   x2r = a[4] + a[6];
   x2i = a[5] + a[7];
   x3r = a[4] - a[6];
   x3i = a[5] - a[7];
   a[0] = x0r + x2r;
   a[1] = x0i + x2i;
   a[4] = x0r - x2r;
   a[5] = x0i - x2i;
   a[2] = x1r - x3i;
   a[3] = x1i + x3r;
   a[6] = x1r + x3i;
   a[7] = x1i - x3r;
   wk1r = rdft_w[2];
   x0r = a[8] + a[10];
   x0i = a[9] + a[11];
   x1r = a[8] - a[10];
   x1i = a[9] - a[11];
   x2r = a[12] + a[14];
   x2i = a[13] + a[15];
   x3r = a[12] - a[14];
   x3i = a[13] - a[15];
   a[8] = x0r + x2r;
   a[9] = x0i + x2i;
   a[12] = x2i - x0i;
   a[13] = x0r - x2r;
   x0r = x1r - x3i;
   x0i = x1i + x3r;
   a[10] = wk1r * (x0r - x0i);
   a[11] = wk1r * (x0r + x0i);
   x0r = x3i + x1r;
   x0i = x3r - x1i;
   a[14] = wk1r * (x0i - x0r);
   a[15] = wk1r * (x0i + x0r);
   k1 = 0;
   for (j = 16; j < n; j += 16) {
     k1 += 2;
     k2 = 2 * k1;
     wk2r = rdft_w[k1 + 0];
     wk2i = rdft_w[k1 + 1];
     wk1r = rdft_w[k2 + 0];
     wk1i = rdft_w[k2 + 1];
     wk3r = rdft_wk3ri_first[k1 + 0];
     wk3i = rdft_wk3ri_first[k1 + 1];
     x0r = a[j + 0] + a[j + 2];
     x0i = a[j + 1] + a[j + 3];
     x1r = a[j + 0] - a[j + 2];
     x1i = a[j + 1] - a[j + 3];
     x2r = a[j + 4] + a[j + 6];
     x2i = a[j + 5] + a[j + 7];
     x3r = a[j + 4] - a[j + 6];
     x3i = a[j + 5] - a[j + 7];
     a[j + 0] = x0r + x2r;
     a[j + 1] = x0i + x2i;
     x0r -= x2r;
     x0i -= x2i;
     a[j + 4] = wk2r * x0r - wk2i * x0i;
     a[j + 5] = wk2r * x0i + wk2i * x0r;
     x0r = x1r - x3i;
     x0i = x1i + x3r;
     a[j + 2] = wk1r * x0r - wk1i * x0i;
     a[j + 3] = wk1r * x0i + wk1i * x0r;
     x0r = x1r + x3i;
     x0i = x1i - x3r;
     a[j + 6] = wk3r * x0r - wk3i * x0i;
     a[j + 7] = wk3r * x0i + wk3i * x0r;
     wk1r = rdft_w[k2 + 2];
     wk1i = rdft_w[k2 + 3];
     wk3r = rdft_wk3ri_second[k1 + 0];
     wk3i = rdft_wk3ri_second[k1 + 1];
     x0r = a[j + 8] + a[j + 10];
     x0i = a[j + 9] + a[j + 11];
     x1r = a[j + 8] - a[j + 10];
     x1i = a[j + 9] - a[j + 11];
     x2r = a[j + 12] + a[j + 14];
     x2i = a[j + 13] + a[j + 15];
     x3r = a[j + 12] - a[j + 14];
     x3i = a[j + 13] - a[j + 15];
     a[j + 8] = x0r + x2r;
     a[j + 9] = x0i + x2i;
     x0r -= x2r;
     x0i -= x2i;
     a[j + 12] = -wk2i * x0r - wk2r * x0i;
     a[j + 13] = -wk2i * x0i + wk2r * x0r;
     x0r = x1r - x3i;
     x0i = x1i + x3r;
     a[j + 10] = wk1r * x0r - wk1i * x0i;
     a[j + 11] = wk1r * x0i + wk1i * x0r;
     x0r = x1r + x3i;
     x0i = x1i - x3r;
     a[j + 14] = wk3r * x0r - wk3i * x0i;
     a[j + 15] = wk3r * x0i + wk3i * x0r;
   }
 }

 static void cftmdl_128_C(float* a) {
   const int l = 8;
   const int n = 128;
   const int m = 32;
   int j0, j1, j2, j3, k, k1, k2, m2;
   float wk1r, wk1i, wk2r, wk2i, wk3r, wk3i;
   float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

   for (j0 = 0; j0 < l; j0 += 2) {
     j1 = j0 + 8;
     j2 = j0 + 16;
     j3 = j0 + 24;
     x0r = a[j0 + 0] + a[j1 + 0];
     x0i = a[j0 + 1] + a[j1 + 1];
     x1r = a[j0 + 0] - a[j1 + 0];
     x1i = a[j0 + 1] - a[j1 + 1];
     x2r = a[j2 + 0] + a[j3 + 0];
     x2i = a[j2 + 1] + a[j3 + 1];
     x3r = a[j2 + 0] - a[j3 + 0];
     x3i = a[j2 + 1] - a[j3 + 1];
     a[j0 + 0] = x0r + x2r;
     a[j0 + 1] = x0i + x2i;
     a[j2 + 0] = x0r - x2r;
     a[j2 + 1] = x0i - x2i;
     a[j1 + 0] = x1r - x3i;
     a[j1 + 1] = x1i + x3r;
     a[j3 + 0] = x1r + x3i;
     a[j3 + 1] = x1i - x3r;
   }
   wk1r = rdft_w[2];
   for (j0 = m; j0 < l + m; j0 += 2) {
     j1 = j0 + 8;
     j2 = j0 + 16;
     j3 = j0 + 24;
     x0r = a[j0 + 0] + a[j1 + 0];
     x0i = a[j0 + 1] + a[j1 + 1];
     x1r = a[j0 + 0] - a[j1 + 0];
     x1i = a[j0 + 1] - a[j1 + 1];
     x2r = a[j2 + 0] + a[j3 + 0];
     x2i = a[j2 + 1] + a[j3 + 1];
     x3r = a[j2 + 0] - a[j3 + 0];
     x3i = a[j2 + 1] - a[j3 + 1];
     a[j0 + 0] = x0r + x2r;
     a[j0 + 1] = x0i + x2i;
     a[j2 + 0] = x2i - x0i;
     a[j2 + 1] = x0r - x2r;
     x0r = x1r - x3i;
     x0i = x1i + x3r;
     a[j1 + 0] = wk1r * (x0r - x0i);
     a[j1 + 1] = wk1r * (x0r + x0i);
     x0r = x3i + x1r;
     x0i = x3r - x1i;
     a[j3 + 0] = wk1r * (x0i - x0r);
     a[j3 + 1] = wk1r * (x0i + x0r);
   }
   k1 = 0;
   m2 = 2 * m;
   for (k = m2; k < n; k += m2) {
     k1 += 2;
     k2 = 2 * k1;
     wk2r = rdft_w[k1 + 0];
     wk2i = rdft_w[k1 + 1];
     wk1r = rdft_w[k2 + 0];
     wk1i = rdft_w[k2 + 1];
     wk3r = rdft_wk3ri_first[k1 + 0];
     wk3i = rdft_wk3ri_first[k1 + 1];
     for (j0 = k; j0 < l + k; j0 += 2) {
       j1 = j0 + 8;
       j2 = j0 + 16;
       j3 = j0 + 24;
       x0r = a[j0 + 0] + a[j1 + 0];
       x0i = a[j0 + 1] + a[j1 + 1];
       x1r = a[j0 + 0] - a[j1 + 0];
       x1i = a[j0 + 1] - a[j1 + 1];
       x2r = a[j2 + 0] + a[j3 + 0];
       x2i = a[j2 + 1] + a[j3 + 1];
       x3r = a[j2 + 0] - a[j3 + 0];
       x3i = a[j2 + 1] - a[j3 + 1];
       a[j0 + 0] = x0r + x2r;
       a[j0 + 1] = x0i + x2i;
       x0r -= x2r;
       x0i -= x2i;
       a[j2 + 0] = wk2r * x0r - wk2i * x0i;
       a[j2 + 1] = wk2r * x0i + wk2i * x0r;
       x0r = x1r - x3i;
       x0i = x1i + x3r;
       a[j1 + 0] = wk1r * x0r - wk1i * x0i;
       a[j1 + 1] = wk1r * x0i + wk1i * x0r;
       x0r = x1r + x3i;
       x0i = x1i - x3r;
       a[j3 + 0] = wk3r * x0r - wk3i * x0i;
       a[j3 + 1] = wk3r * x0i + wk3i * x0r;
     }
     wk1r = rdft_w[k2 + 2];
     wk1i = rdft_w[k2 + 3];
     wk3r = rdft_wk3ri_second[k1 + 0];
     wk3i = rdft_wk3ri_second[k1 + 1];
     for (j0 = k + m; j0 < l + (k + m); j0 += 2) {
       j1 = j0 + 8;
       j2 = j0 + 16;
       j3 = j0 + 24;
       x0r = a[j0 + 0] + a[j1 + 0];
       x0i = a[j0 + 1] + a[j1 + 1];
       x1r = a[j0 + 0] - a[j1 + 0];
       x1i = a[j0 + 1] - a[j1 + 1];
       x2r = a[j2 + 0] + a[j3 + 0];
       x2i = a[j2 + 1] + a[j3 + 1];
       x3r = a[j2 + 0] - a[j3 + 0];
       x3i = a[j2 + 1] - a[j3 + 1];
       a[j0 + 0] = x0r + x2r;
       a[j0 + 1] = x0i + x2i;
       x0r -= x2r;
       x0i -= x2i;
       a[j2 + 0] = -wk2i * x0r - wk2r * x0i;
       a[j2 + 1] = -wk2i * x0i + wk2r * x0r;
       x0r = x1r - x3i;
       x0i = x1i + x3r;
       a[j1 + 0] = wk1r * x0r - wk1i * x0i;
       a[j1 + 1] = wk1r * x0i + wk1i * x0r;
       x0r = x1r + x3i;
       x0i = x1i - x3r;
       a[j3 + 0] = wk3r * x0r - wk3i * x0i;
       a[j3 + 1] = wk3r * x0i + wk3i * x0r;
     }
   }
 }

 static void rftfsub_128_C(float* a) {
   const float* c = rdft_w + 32;
   int j1, j2, k1, k2;
   float wkr, wki, xr, xi, yr, yi;

   for (j1 = 1, j2 = 2; j2 < 64; j1 += 1, j2 += 2) {
     k2 = 128 - j2;
     k1 = 32 - j1;
     wkr = 0.5f - c[k1];
     wki = c[j1];
     xr = a[j2 + 0] - a[k2 + 0];
     xi = a[j2 + 1] + a[k2 + 1];
     yr = wkr * xr - wki * xi;
     yi = wkr * xi + wki * xr;
     a[j2 + 0] -= yr;
     a[j2 + 1] -= yi;
     a[k2 + 0] += yr;
     a[k2 + 1] -= yi;
   }
 }

 static void rftbsub_128_C(float* a) {
   const float* c = rdft_w + 32;
   int j1, j2, k1, k2;
   float wkr, wki, xr, xi, yr, yi;

   a[1] = -a[1];
   for (j1 = 1, j2 = 2; j2 < 64; j1 += 1, j2 += 2) {
     k2 = 128 - j2;
     k1 = 32 - j1;
     wkr = 0.5f - c[k1];
     wki = c[j1];
     xr = a[j2 + 0] - a[k2 + 0];
     xi = a[j2 + 1] + a[k2 + 1];
     yr = wkr * xr + wki * xi;
     yi = wkr * xi - wki * xr;
     a[j2 + 0] = a[j2 + 0] - yr;
     a[j2 + 1] = yi - a[j2 + 1];
     a[k2 + 0] = yr + a[k2 + 0];
     a[k2 + 1] = yi - a[k2 + 1];
   }
   a[65] = -a[65];
 }
 #endif


 }  // namespace

 OouraFft::OouraFft() {
 #if defined(WEBRTC_ARCH_X86_FAMILY)
   use_sse2_ = (WebRtc_GetCPUInfo(kSSE2) != 0);
 #else
   use_sse2_ = false;
 #endif
 }

 OouraFft::~OouraFft() = default;

 void OouraFft::Fft(float* a) const {
   float xi;
   bitrv2_128(a);
   cftfsub_128(a);
   rftfsub_128(a);
   xi = a[0] - a[1];
   a[0] += a[1];
   a[1] = xi;
 }
 void OouraFft::InverseFft(float* a) const {
   a[1] = 0.5f * (a[0] - a[1]);
   a[0] -= a[1];
   rftbsub_128(a);
   bitrv2_128(a);
   cftbsub_128(a);
 }

 void OouraFft::cft1st_128(float* a) const {
 #if defined(MIPS_FPU_LE)
   cft1st_128_mips(a);
 #elif defined(WEBRTC_HAS_NEON)
   cft1st_128_neon(a);
 #elif defined(WEBRTC_ARCH_X86_FAMILY)
   if (use_sse2_) {
     cft1st_128_SSE2(a);
   } else {
     cft1st_128_C(a);
   }
 #else
   cft1st_128_C(a);
 #endif
 }
 void OouraFft::cftmdl_128(float* a) const {
 #if defined(MIPS_FPU_LE)
   cftmdl_128_mips(a);
 #elif defined(WEBRTC_HAS_NEON)
   cftmdl_128_neon(a);
 #elif defined(WEBRTC_ARCH_X86_FAMILY)
   if (use_sse2_) {
     cftmdl_128_SSE2(a);
   } else {
     cftmdl_128_C(a);
   }
 #else
   cftmdl_128_C(a);
 #endif
 }
 void OouraFft::rftfsub_128(float* a) const {
 #if defined(MIPS_FPU_LE)
   rftfsub_128_mips(a);
 #elif defined(WEBRTC_HAS_NEON)
   rftfsub_128_neon(a);
 #elif defined(WEBRTC_ARCH_X86_FAMILY)
   if (use_sse2_) {
     rftfsub_128_SSE2(a);
   } else {
     rftfsub_128_C(a);
   }
 #else
   rftfsub_128_C(a);
 #endif
 }

 void OouraFft::rftbsub_128(float* a) const {
 #if defined(MIPS_FPU_LE)
   rftbsub_128_mips(a);
 #elif defined(WEBRTC_HAS_NEON)
   rftbsub_128_neon(a);
 #elif defined(WEBRTC_ARCH_X86_FAMILY)
   if (use_sse2_) {
     rftbsub_128_SSE2(a);
   } else {
     rftbsub_128_C(a);
   }
 #else
   rftbsub_128_C(a);
 #endif
 }

 void OouraFft::cftbsub_128(float* a) const {
   int j, j1, j2, j3, l;
   float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

   cft1st_128(a);
   cftmdl_128(a);
   l = 32;

   for (j = 0; j < l; j += 2) {
     j1 = j + l;
     j2 = j1 + l;
     j3 = j2 + l;
     x0r = a[j] + a[j1];
     x0i = -a[j + 1] - a[j1 + 1];
     x1r = a[j] - a[j1];
     x1i = -a[j + 1] + a[j1 + 1];
     x2r = a[j2] + a[j3];
     x2i = a[j2 + 1] + a[j3 + 1];
     x3r = a[j2] - a[j3];
     x3i = a[j2 + 1] - a[j3 + 1];
     a[j] = x0r + x2r;
     a[j + 1] = x0i - x2i;
     a[j2] = x0r - x2r;
     a[j2 + 1] = x0i + x2i;
     a[j1] = x1r - x3i;
     a[j1 + 1] = x1i - x3r;
     a[j3] = x1r + x3i;
     a[j3 + 1] = x1i + x3r;
   }
 }

 void OouraFft::cftfsub_128(float* a) const {
   int j, j1, j2, j3, l;
   float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

   cft1st_128(a);
   cftmdl_128(a);
   l = 32;
   for (j = 0; j < l; j += 2) {
     j1 = j + l;
     j2 = j1 + l;
     j3 = j2 + l;
     x0r = a[j] + a[j1];
     x0i = a[j + 1] + a[j1 + 1];
     x1r = a[j] - a[j1];
     x1i = a[j + 1] - a[j1 + 1];
     x2r = a[j2] + a[j3];
     x2i = a[j2 + 1] + a[j3 + 1];
     x3r = a[j2] - a[j3];
     x3i = a[j2 + 1] - a[j3 + 1];
     a[j] = x0r + x2r;
     a[j + 1] = x0i + x2i;
     a[j2] = x0r - x2r;
     a[j2 + 1] = x0i - x2i;
     a[j1] = x1r - x3i;
     a[j1 + 1] = x1i + x3r;
     a[j3] = x1r + x3i;
     a[j3 + 1] = x1i - x3r;
   }
 }

 void OouraFft::bitrv2_128(float* a) const {
   /*
       Following things have been attempted but are no faster:
       (a) Storing the swap indexes in a LUT (index calculations are done
           for 'free' while waiting on memory/L1).
       (b) Consolidate the load/store of two consecutive floats by a 64 bit
           integer (execution is memory/L1 bound).
       (c) Do a mix of floats and 64 bit integer to maximize register
           utilization (execution is memory/L1 bound).
       (d) Replacing ip[i] by ((k<<31)>>25) + ((k >> 1)<<5).
       (e) Hard-coding of the offsets to completely eliminates index
           calculations.
   */

   unsigned int j, j1, k, k1;
   float xr, xi, yr, yi;

   const int ip[4] = {0, 64, 32, 96};
   for (k = 0; k < 4; k++) {
     for (j = 0; j < k; j++) {
       j1 = 2 * j + ip[k];
       k1 = 2 * k + ip[j];
       xr = a[j1 + 0];
       xi = a[j1 + 1];
       yr = a[k1 + 0];
       yi = a[k1 + 1];
       a[j1 + 0] = yr;
       a[j1 + 1] = yi;
       a[k1 + 0] = xr;
       a[k1 + 1] = xi;
       j1 += 8;
       k1 += 16;
       xr = a[j1 + 0];
       xi = a[j1 + 1];
       yr = a[k1 + 0];
       yi = a[k1 + 1];
       a[j1 + 0] = yr;
       a[j1 + 1] = yi;
       a[k1 + 0] = xr;
       a[k1 + 1] = xi;
       j1 += 8;
       k1 -= 8;
       xr = a[j1 + 0];
       xi = a[j1 + 1];
       yr = a[k1 + 0];
       yi = a[k1 + 1];
       a[j1 + 0] = yr;
       a[j1 + 1] = yi;
       a[k1 + 0] = xr;
       a[k1 + 1] = xi;
       j1 += 8;
       k1 += 16;
       xr = a[j1 + 0];
       xi = a[j1 + 1];
       yr = a[k1 + 0];
       yi = a[k1 + 1];
       a[j1 + 0] = yr;
       a[j1 + 1] = yi;
       a[k1 + 0] = xr;
       a[k1 + 1] = xi;
     }
     j1 = 2 * k + 8 + ip[k];
     k1 = j1 + 8;
     xr = a[j1 + 0];
     xi = a[j1 + 1];
     yr = a[k1 + 0];
     yi = a[k1 + 1];
     a[j1 + 0] = yr;
     a[j1 + 1] = yi;
     a[k1 + 0] = xr;
     a[k1 + 1] = xi;
   }
 }

 }  // namespace webrtc
	/*
	* http://www.kurims.kyoto-u.ac.jp/~ooura/fft.html
	* Copyright Takuya OOURA, 1996-2001
	*
	* You may use, copy, modify and distribute this code for any purpose (include
	* commercial use) and without fee. Please refer to this package when you modify
	* this code.
	*
	* Changes by the WebRTC authors:
	* - Trivial type modifications.
	* - Minimal code subset to do rdft of length 128.
	* - Optimizations because of known length.
	* - Removed the global variables by moving the code in to a class in order
	* to make it thread safe.
	*
	* All changes are covered by the WebRTC license and IP grant:
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "webrtc/modules/audio_processing//utility/ooura_fft.h"

	#include <math.h>

	#include "webrtc/modules/audio_processing/utility/ooura_fft_tables_common.h"
	#include "webrtc/system_wrappers/include/cpu_features_wrapper.h"
	#include "webrtc/typedefs.h"

	namespace webrtc {

	namespace {

	#if !(defined(MIPS_FPU_LE) \|\| defined(WEBRTC_HAS_NEON))
	static void cft1st_128_C(float* a) {
	const int n = 128;
	int j, k1, k2;
	float wk1r, wk1i, wk2r, wk2i, wk3r, wk3i;
	float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

	// The processing of the first set of elements was simplified in C to avoid
	// some operations (multiplication by zero or one, addition of two elements
	// multiplied by the same weight, ...).
	x0r = a[0] + a[2];
	x0i = a[1] + a[3];
	x1r = a[0] - a[2];
	x1i = a[1] - a[3];
	x2r = a[4] + a[6];
	x2i = a[5] + a[7];
	x3r = a[4] - a[6];
	x3i = a[5] - a[7];
	a[0] = x0r + x2r;
	a[1] = x0i + x2i;
	a[4] = x0r - x2r;
	a[5] = x0i - x2i;
	a[2] = x1r - x3i;
	a[3] = x1i + x3r;
	a[6] = x1r + x3i;
	a[7] = x1i - x3r;
	wk1r = rdft_w[2];
	x0r = a[8] + a[10];
	x0i = a[9] + a[11];
	x1r = a[8] - a[10];
	x1i = a[9] - a[11];
	x2r = a[12] + a[14];
	x2i = a[13] + a[15];
	x3r = a[12] - a[14];
	x3i = a[13] - a[15];
	a[8] = x0r + x2r;
	a[9] = x0i + x2i;
	a[12] = x2i - x0i;
	a[13] = x0r - x2r;
	x0r = x1r - x3i;
	x0i = x1i + x3r;
	a[10] = wk1r * (x0r - x0i);
	a[11] = wk1r * (x0r + x0i);
	x0r = x3i + x1r;
	x0i = x3r - x1i;
	a[14] = wk1r * (x0i - x0r);
	a[15] = wk1r * (x0i + x0r);
	k1 = 0;
	for (j = 16; j < n; j += 16) {
	k1 += 2;
	k2 = 2 * k1;
	wk2r = rdft_w[k1 + 0];
	wk2i = rdft_w[k1 + 1];
	wk1r = rdft_w[k2 + 0];
	wk1i = rdft_w[k2 + 1];
	wk3r = rdft_wk3ri_first[k1 + 0];
	wk3i = rdft_wk3ri_first[k1 + 1];
	x0r = a[j + 0] + a[j + 2];
	x0i = a[j + 1] + a[j + 3];
	x1r = a[j + 0] - a[j + 2];
	x1i = a[j + 1] - a[j + 3];
	x2r = a[j + 4] + a[j + 6];
	x2i = a[j + 5] + a[j + 7];
	x3r = a[j + 4] - a[j + 6];
	x3i = a[j + 5] - a[j + 7];
	a[j + 0] = x0r + x2r;
	a[j + 1] = x0i + x2i;
	x0r -= x2r;
	x0i -= x2i;
	a[j + 4] = wk2r * x0r - wk2i * x0i;
	a[j + 5] = wk2r * x0i + wk2i * x0r;
	x0r = x1r - x3i;
	x0i = x1i + x3r;
	a[j + 2] = wk1r * x0r - wk1i * x0i;
	a[j + 3] = wk1r * x0i + wk1i * x0r;
	x0r = x1r + x3i;
	x0i = x1i - x3r;
	a[j + 6] = wk3r * x0r - wk3i * x0i;
	a[j + 7] = wk3r * x0i + wk3i * x0r;
	wk1r = rdft_w[k2 + 2];
	wk1i = rdft_w[k2 + 3];
	wk3r = rdft_wk3ri_second[k1 + 0];
	wk3i = rdft_wk3ri_second[k1 + 1];
	x0r = a[j + 8] + a[j + 10];
	x0i = a[j + 9] + a[j + 11];
	x1r = a[j + 8] - a[j + 10];
	x1i = a[j + 9] - a[j + 11];
	x2r = a[j + 12] + a[j + 14];
	x2i = a[j + 13] + a[j + 15];
	x3r = a[j + 12] - a[j + 14];
	x3i = a[j + 13] - a[j + 15];
	a[j + 8] = x0r + x2r;
	a[j + 9] = x0i + x2i;
	x0r -= x2r;
	x0i -= x2i;
	a[j + 12] = -wk2i * x0r - wk2r * x0i;
	a[j + 13] = -wk2i * x0i + wk2r * x0r;
	x0r = x1r - x3i;
	x0i = x1i + x3r;
	a[j + 10] = wk1r * x0r - wk1i * x0i;
	a[j + 11] = wk1r * x0i + wk1i * x0r;
	x0r = x1r + x3i;
	x0i = x1i - x3r;
	a[j + 14] = wk3r * x0r - wk3i * x0i;
	a[j + 15] = wk3r * x0i + wk3i * x0r;
	}
	}

	static void cftmdl_128_C(float* a) {
	const int l = 8;
	const int n = 128;
	const int m = 32;
	int j0, j1, j2, j3, k, k1, k2, m2;
	float wk1r, wk1i, wk2r, wk2i, wk3r, wk3i;
	float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

	for (j0 = 0; j0 < l; j0 += 2) {
	j1 = j0 + 8;
	j2 = j0 + 16;
	j3 = j0 + 24;
	x0r = a[j0 + 0] + a[j1 + 0];
	x0i = a[j0 + 1] + a[j1 + 1];
	x1r = a[j0 + 0] - a[j1 + 0];
	x1i = a[j0 + 1] - a[j1 + 1];
	x2r = a[j2 + 0] + a[j3 + 0];
	x2i = a[j2 + 1] + a[j3 + 1];
	x3r = a[j2 + 0] - a[j3 + 0];
	x3i = a[j2 + 1] - a[j3 + 1];
	a[j0 + 0] = x0r + x2r;
	a[j0 + 1] = x0i + x2i;
	a[j2 + 0] = x0r - x2r;
	a[j2 + 1] = x0i - x2i;
	a[j1 + 0] = x1r - x3i;
	a[j1 + 1] = x1i + x3r;
	a[j3 + 0] = x1r + x3i;
	a[j3 + 1] = x1i - x3r;
	}
	wk1r = rdft_w[2];
	for (j0 = m; j0 < l + m; j0 += 2) {
	j1 = j0 + 8;
	j2 = j0 + 16;
	j3 = j0 + 24;
	x0r = a[j0 + 0] + a[j1 + 0];
	x0i = a[j0 + 1] + a[j1 + 1];
	x1r = a[j0 + 0] - a[j1 + 0];
	x1i = a[j0 + 1] - a[j1 + 1];
	x2r = a[j2 + 0] + a[j3 + 0];
	x2i = a[j2 + 1] + a[j3 + 1];
	x3r = a[j2 + 0] - a[j3 + 0];
	x3i = a[j2 + 1] - a[j3 + 1];
	a[j0 + 0] = x0r + x2r;
	a[j0 + 1] = x0i + x2i;
	a[j2 + 0] = x2i - x0i;
	a[j2 + 1] = x0r - x2r;
	x0r = x1r - x3i;
	x0i = x1i + x3r;
	a[j1 + 0] = wk1r * (x0r - x0i);
	a[j1 + 1] = wk1r * (x0r + x0i);
	x0r = x3i + x1r;
	x0i = x3r - x1i;
	a[j3 + 0] = wk1r * (x0i - x0r);
	a[j3 + 1] = wk1r * (x0i + x0r);
	}
	k1 = 0;
	m2 = 2 * m;
	for (k = m2; k < n; k += m2) {
	k1 += 2;
	k2 = 2 * k1;
	wk2r = rdft_w[k1 + 0];
	wk2i = rdft_w[k1 + 1];
	wk1r = rdft_w[k2 + 0];
	wk1i = rdft_w[k2 + 1];
	wk3r = rdft_wk3ri_first[k1 + 0];
	wk3i = rdft_wk3ri_first[k1 + 1];
	for (j0 = k; j0 < l + k; j0 += 2) {
	j1 = j0 + 8;
	j2 = j0 + 16;
	j3 = j0 + 24;
	x0r = a[j0 + 0] + a[j1 + 0];
	x0i = a[j0 + 1] + a[j1 + 1];
	x1r = a[j0 + 0] - a[j1 + 0];
	x1i = a[j0 + 1] - a[j1 + 1];
	x2r = a[j2 + 0] + a[j3 + 0];
	x2i = a[j2 + 1] + a[j3 + 1];
	x3r = a[j2 + 0] - a[j3 + 0];
	x3i = a[j2 + 1] - a[j3 + 1];
	a[j0 + 0] = x0r + x2r;
	a[j0 + 1] = x0i + x2i;
	x0r -= x2r;
	x0i -= x2i;
	a[j2 + 0] = wk2r * x0r - wk2i * x0i;
	a[j2 + 1] = wk2r * x0i + wk2i * x0r;
	x0r = x1r - x3i;
	x0i = x1i + x3r;
	a[j1 + 0] = wk1r * x0r - wk1i * x0i;
	a[j1 + 1] = wk1r * x0i + wk1i * x0r;
	x0r = x1r + x3i;
	x0i = x1i - x3r;
	a[j3 + 0] = wk3r * x0r - wk3i * x0i;
	a[j3 + 1] = wk3r * x0i + wk3i * x0r;
	}
	wk1r = rdft_w[k2 + 2];
	wk1i = rdft_w[k2 + 3];
	wk3r = rdft_wk3ri_second[k1 + 0];
	wk3i = rdft_wk3ri_second[k1 + 1];
	for (j0 = k + m; j0 < l + (k + m); j0 += 2) {
	j1 = j0 + 8;
	j2 = j0 + 16;
	j3 = j0 + 24;
	x0r = a[j0 + 0] + a[j1 + 0];
	x0i = a[j0 + 1] + a[j1 + 1];
	x1r = a[j0 + 0] - a[j1 + 0];
	x1i = a[j0 + 1] - a[j1 + 1];
	x2r = a[j2 + 0] + a[j3 + 0];
	x2i = a[j2 + 1] + a[j3 + 1];
	x3r = a[j2 + 0] - a[j3 + 0];
	x3i = a[j2 + 1] - a[j3 + 1];
	a[j0 + 0] = x0r + x2r;
	a[j0 + 1] = x0i + x2i;
	x0r -= x2r;
	x0i -= x2i;
	a[j2 + 0] = -wk2i * x0r - wk2r * x0i;
	a[j2 + 1] = -wk2i * x0i + wk2r * x0r;
	x0r = x1r - x3i;
	x0i = x1i + x3r;
	a[j1 + 0] = wk1r * x0r - wk1i * x0i;
	a[j1 + 1] = wk1r * x0i + wk1i * x0r;
	x0r = x1r + x3i;
	x0i = x1i - x3r;
	a[j3 + 0] = wk3r * x0r - wk3i * x0i;
	a[j3 + 1] = wk3r * x0i + wk3i * x0r;
	}
	}
	}

	static void rftfsub_128_C(float* a) {
	const float* c = rdft_w + 32;
	int j1, j2, k1, k2;
	float wkr, wki, xr, xi, yr, yi;

	for (j1 = 1, j2 = 2; j2 < 64; j1 += 1, j2 += 2) {
	k2 = 128 - j2;
	k1 = 32 - j1;
	wkr = 0.5f - c[k1];
	wki = c[j1];
	xr = a[j2 + 0] - a[k2 + 0];
	xi = a[j2 + 1] + a[k2 + 1];
	yr = wkr * xr - wki * xi;
	yi = wkr * xi + wki * xr;
	a[j2 + 0] -= yr;
	a[j2 + 1] -= yi;
	a[k2 + 0] += yr;
	a[k2 + 1] -= yi;
	}
	}

	static void rftbsub_128_C(float* a) {
	const float* c = rdft_w + 32;
	int j1, j2, k1, k2;
	float wkr, wki, xr, xi, yr, yi;

	a[1] = -a[1];
	for (j1 = 1, j2 = 2; j2 < 64; j1 += 1, j2 += 2) {
	k2 = 128 - j2;
	k1 = 32 - j1;
	wkr = 0.5f - c[k1];
	wki = c[j1];
	xr = a[j2 + 0] - a[k2 + 0];
	xi = a[j2 + 1] + a[k2 + 1];
	yr = wkr * xr + wki * xi;
	yi = wkr * xi - wki * xr;
	a[j2 + 0] = a[j2 + 0] - yr;
	a[j2 + 1] = yi - a[j2 + 1];
	a[k2 + 0] = yr + a[k2 + 0];
	a[k2 + 1] = yi - a[k2 + 1];
	}
	a[65] = -a[65];
	}
	#endif


	} // namespace

	OouraFft::OouraFft() {
	#if defined(WEBRTC_ARCH_X86_FAMILY)
	use_sse2_ = (WebRtc_GetCPUInfo(kSSE2) != 0);
	#else
	use_sse2_ = false;
	#endif
	}

	OouraFft::~OouraFft() = default;

	void OouraFft::Fft(float* a) const {
	float xi;
	bitrv2_128(a);
	cftfsub_128(a);
	rftfsub_128(a);
	xi = a[0] - a[1];
	a[0] += a[1];
	a[1] = xi;
	}
	void OouraFft::InverseFft(float* a) const {
	a[1] = 0.5f * (a[0] - a[1]);
	a[0] -= a[1];
	rftbsub_128(a);
	bitrv2_128(a);
	cftbsub_128(a);
	}

	void OouraFft::cft1st_128(float* a) const {
	#if defined(MIPS_FPU_LE)
	cft1st_128_mips(a);
	#elif defined(WEBRTC_HAS_NEON)
	cft1st_128_neon(a);
	#elif defined(WEBRTC_ARCH_X86_FAMILY)
	if (use_sse2_) {
	cft1st_128_SSE2(a);
	} else {
	cft1st_128_C(a);
	}
	#else
	cft1st_128_C(a);
	#endif
	}
	void OouraFft::cftmdl_128(float* a) const {
	#if defined(MIPS_FPU_LE)
	cftmdl_128_mips(a);
	#elif defined(WEBRTC_HAS_NEON)
	cftmdl_128_neon(a);
	#elif defined(WEBRTC_ARCH_X86_FAMILY)
	if (use_sse2_) {
	cftmdl_128_SSE2(a);
	} else {
	cftmdl_128_C(a);
	}
	#else
	cftmdl_128_C(a);
	#endif
	}
	void OouraFft::rftfsub_128(float* a) const {
	#if defined(MIPS_FPU_LE)
	rftfsub_128_mips(a);
	#elif defined(WEBRTC_HAS_NEON)
	rftfsub_128_neon(a);
	#elif defined(WEBRTC_ARCH_X86_FAMILY)
	if (use_sse2_) {
	rftfsub_128_SSE2(a);
	} else {
	rftfsub_128_C(a);
	}
	#else
	rftfsub_128_C(a);
	#endif
	}

	void OouraFft::rftbsub_128(float* a) const {
	#if defined(MIPS_FPU_LE)
	rftbsub_128_mips(a);
	#elif defined(WEBRTC_HAS_NEON)
	rftbsub_128_neon(a);
	#elif defined(WEBRTC_ARCH_X86_FAMILY)
	if (use_sse2_) {
	rftbsub_128_SSE2(a);
	} else {
	rftbsub_128_C(a);
	}
	#else
	rftbsub_128_C(a);
	#endif
	}

	void OouraFft::cftbsub_128(float* a) const {
	int j, j1, j2, j3, l;
	float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

	cft1st_128(a);
	cftmdl_128(a);
	l = 32;

	for (j = 0; j < l; j += 2) {
	j1 = j + l;
	j2 = j1 + l;
	j3 = j2 + l;
	x0r = a[j] + a[j1];
	x0i = -a[j + 1] - a[j1 + 1];
	x1r = a[j] - a[j1];
	x1i = -a[j + 1] + a[j1 + 1];
	x2r = a[j2] + a[j3];
	x2i = a[j2 + 1] + a[j3 + 1];
	x3r = a[j2] - a[j3];
	x3i = a[j2 + 1] - a[j3 + 1];
	a[j] = x0r + x2r;
	a[j + 1] = x0i - x2i;
	a[j2] = x0r - x2r;
	a[j2 + 1] = x0i + x2i;
	a[j1] = x1r - x3i;
	a[j1 + 1] = x1i - x3r;
	a[j3] = x1r + x3i;
	a[j3 + 1] = x1i + x3r;
	}
	}

	void OouraFft::cftfsub_128(float* a) const {
	int j, j1, j2, j3, l;
	float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;

	cft1st_128(a);
	cftmdl_128(a);
	l = 32;
	for (j = 0; j < l; j += 2) {
	j1 = j + l;
	j2 = j1 + l;
	j3 = j2 + l;
	x0r = a[j] + a[j1];
	x0i = a[j + 1] + a[j1 + 1];
	x1r = a[j] - a[j1];
	x1i = a[j + 1] - a[j1 + 1];
	x2r = a[j2] + a[j3];
	x2i = a[j2 + 1] + a[j3 + 1];
	x3r = a[j2] - a[j3];
	x3i = a[j2 + 1] - a[j3 + 1];
	a[j] = x0r + x2r;
	a[j + 1] = x0i + x2i;
	a[j2] = x0r - x2r;
	a[j2 + 1] = x0i - x2i;
	a[j1] = x1r - x3i;
	a[j1 + 1] = x1i + x3r;
	a[j3] = x1r + x3i;
	a[j3 + 1] = x1i - x3r;
	}
	}

	void OouraFft::bitrv2_128(float* a) const {
	/*
	Following things have been attempted but are no faster:
	(a) Storing the swap indexes in a LUT (index calculations are done
	for 'free' while waiting on memory/L1).
	(b) Consolidate the load/store of two consecutive floats by a 64 bit
	integer (execution is memory/L1 bound).
	(c) Do a mix of floats and 64 bit integer to maximize register
	utilization (execution is memory/L1 bound).
	(d) Replacing ip[i] by ((k<<31)>>25) + ((k >> 1)<<5).
	(e) Hard-coding of the offsets to completely eliminates index
	calculations.
	*/

	unsigned int j, j1, k, k1;
	float xr, xi, yr, yi;

	const int ip[4] = {0, 64, 32, 96};
	for (k = 0; k < 4; k++) {
	for (j = 0; j < k; j++) {
	j1 = 2 * j + ip[k];
	k1 = 2 * k + ip[j];
	xr = a[j1 + 0];
	xi = a[j1 + 1];
	yr = a[k1 + 0];
	yi = a[k1 + 1];
	a[j1 + 0] = yr;
	a[j1 + 1] = yi;
	a[k1 + 0] = xr;
	a[k1 + 1] = xi;
	j1 += 8;
	k1 += 16;
	xr = a[j1 + 0];
	xi = a[j1 + 1];
	yr = a[k1 + 0];
	yi = a[k1 + 1];
	a[j1 + 0] = yr;
	a[j1 + 1] = yi;
	a[k1 + 0] = xr;
	a[k1 + 1] = xi;
	j1 += 8;
	k1 -= 8;
	xr = a[j1 + 0];
	xi = a[j1 + 1];
	yr = a[k1 + 0];
	yi = a[k1 + 1];
	a[j1 + 0] = yr;
	a[j1 + 1] = yi;
	a[k1 + 0] = xr;
	a[k1 + 1] = xi;
	j1 += 8;
	k1 += 16;
	xr = a[j1 + 0];
	xi = a[j1 + 1];
	yr = a[k1 + 0];
	yi = a[k1 + 1];
	a[j1 + 0] = yr;
	a[j1 + 1] = yi;
	a[k1 + 0] = xr;
	a[k1 + 1] = xi;
	}
	j1 = 2 * k + 8 + ip[k];
	k1 = j1 + 8;
	xr = a[j1 + 0];
	xi = a[j1 + 1];
	yr = a[k1 + 0];
	yi = a[k1 + 1];
	a[j1 + 0] = yr;
	a[j1 + 1] = yi;
	a[k1 + 0] = xr;
	a[k1 + 1] = xi;
	}
	}

	} // namespace webrtc