initial checkin -- mostly imported from Opus

src/_kiss_fft_guts.h

+/*Copyright (c) 2003-2004, Mark Borgerding
+
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+  POSSIBILITY OF SUCH DAMAGE.*/
+
+#ifndef KISS_FFT_GUTS_H
+#define KISS_FFT_GUTS_H
+
+#define MIN(a,b) ((a)<(b) ? (a):(b))
+#define MAX(a,b) ((a)>(b) ? (a):(b))
+
+/* kiss_fft.h
+   defines kiss_fft_scalar as either short or a float type
+   and defines
+   typedef struct { kiss_fft_scalar r; kiss_fft_scalar i; }kiss_fft_cpx; */
+#include "kiss_fft.h"
+
+/*
+  Explanation of macros dealing with complex math:
+
+   C_MUL(m,a,b)         : m = a*b
+   C_FIXDIV( c , div )  : if a fixed point impl., c /= div. noop otherwise
+   C_SUB( res, a,b)     : res = a - b
+   C_SUBFROM( res , a)  : res -= a
+   C_ADDTO( res , a)    : res += a
+ * */
+#ifdef FIXED_POINT
+#include "arch.h"
+
+
+#define SAMP_MAX 2147483647
+#define TWID_MAX 32767
+#define TRIG_UPSCALE 1
+
+#define SAMP_MIN -SAMP_MAX
+
+
+#   define S_MUL(a,b) MULT16_32_Q15(b, a)
+
+#   define C_MUL(m,a,b) \
+      do{ (m).r = SUB32_ovflw(S_MUL((a).r,(b).r) , S_MUL((a).i,(b).i)); \
+          (m).i = ADD32_ovflw(S_MUL((a).r,(b).i) , S_MUL((a).i,(b).r)); }while(0)
+
+#   define C_MULC(m,a,b) \
+      do{ (m).r = ADD32_ovflw(S_MUL((a).r,(b).r) , S_MUL((a).i,(b).i)); \
+          (m).i = SUB32_ovflw(S_MUL((a).i,(b).r) , S_MUL((a).r,(b).i)); }while(0)
+
+#   define C_MULBYSCALAR( c, s ) \
+      do{ (c).r =  S_MUL( (c).r , s ) ;\
+          (c).i =  S_MUL( (c).i , s ) ; }while(0)
+
+#   define DIVSCALAR(x,k) \
+        (x) = S_MUL(  x, (TWID_MAX-((k)>>1))/(k)+1 )
+
+#   define C_FIXDIV(c,div) \
+        do {    DIVSCALAR( (c).r , div);  \
+                DIVSCALAR( (c).i  , div); }while (0)
+
+#define  C_ADD( res, a,b)\
+    do {(res).r=ADD32_ovflw((a).r,(b).r);  (res).i=ADD32_ovflw((a).i,(b).i); \
+    }while(0)
+#define  C_SUB( res, a,b)\
+    do {(res).r=SUB32_ovflw((a).r,(b).r);  (res).i=SUB32_ovflw((a).i,(b).i); \
+    }while(0)
+#define C_ADDTO( res , a)\
+    do {(res).r = ADD32_ovflw((res).r, (a).r);  (res).i = ADD32_ovflw((res).i,(a).i);\
+    }while(0)
+
+#define C_SUBFROM( res , a)\
+    do {(res).r = ADD32_ovflw((res).r,(a).r);  (res).i = SUB32_ovflw((res).i,(a).i); \
+    }while(0)
+
+#if defined(OPUS_ARM_INLINE_ASM)
+#include "arm/kiss_fft_armv4.h"
+#endif
+
+#if defined(OPUS_ARM_INLINE_EDSP)
+#include "arm/kiss_fft_armv5e.h"
+#endif
+#if defined(MIPSr1_ASM)
+#include "mips/kiss_fft_mipsr1.h"
+#endif
+
+#else  /* not FIXED_POINT*/
+
+#   define S_MUL(a,b) ( (a)*(b) )
+#define C_MUL(m,a,b) \
+    do{ (m).r = (a).r*(b).r - (a).i*(b).i;\
+        (m).i = (a).r*(b).i + (a).i*(b).r; }while(0)
+#define C_MULC(m,a,b) \
+    do{ (m).r = (a).r*(b).r + (a).i*(b).i;\
+        (m).i = (a).i*(b).r - (a).r*(b).i; }while(0)
+
+#define C_MUL4(m,a,b) C_MUL(m,a,b)
+
+#   define C_FIXDIV(c,div) /* NOOP */
+#   define C_MULBYSCALAR( c, s ) \
+    do{ (c).r *= (s);\
+        (c).i *= (s); }while(0)
+#endif
+
+#ifndef CHECK_OVERFLOW_OP
+#  define CHECK_OVERFLOW_OP(a,op,b) /* noop */
+#endif
+
+#ifndef C_ADD
+#define  C_ADD( res, a,b)\
+    do { \
+            CHECK_OVERFLOW_OP((a).r,+,(b).r)\
+            CHECK_OVERFLOW_OP((a).i,+,(b).i)\
+            (res).r=(a).r+(b).r;  (res).i=(a).i+(b).i; \
+    }while(0)
+#define  C_SUB( res, a,b)\
+    do { \
+            CHECK_OVERFLOW_OP((a).r,-,(b).r)\
+            CHECK_OVERFLOW_OP((a).i,-,(b).i)\
+            (res).r=(a).r-(b).r;  (res).i=(a).i-(b).i; \
+    }while(0)
+#define C_ADDTO( res , a)\
+    do { \
+            CHECK_OVERFLOW_OP((res).r,+,(a).r)\
+            CHECK_OVERFLOW_OP((res).i,+,(a).i)\
+            (res).r += (a).r;  (res).i += (a).i;\
+    }while(0)
+
+#define C_SUBFROM( res , a)\
+    do {\
+            CHECK_OVERFLOW_OP((res).r,-,(a).r)\
+            CHECK_OVERFLOW_OP((res).i,-,(a).i)\
+            (res).r -= (a).r;  (res).i -= (a).i; \
+    }while(0)
+#endif /* C_ADD defined */
+
+#ifdef FIXED_POINT
+/*#  define KISS_FFT_COS(phase)  TRIG_UPSCALE*floor(MIN(32767,MAX(-32767,.5+32768 * cos (phase))))
+#  define KISS_FFT_SIN(phase)  TRIG_UPSCALE*floor(MIN(32767,MAX(-32767,.5+32768 * sin (phase))))*/
+#  define KISS_FFT_COS(phase)  floor(.5+TWID_MAX*cos (phase))
+#  define KISS_FFT_SIN(phase)  floor(.5+TWID_MAX*sin (phase))
+#  define HALF_OF(x) ((x)>>1)
+#elif defined(USE_SIMD)
+#  define KISS_FFT_COS(phase) _mm_set1_ps( cos(phase) )
+#  define KISS_FFT_SIN(phase) _mm_set1_ps( sin(phase) )
+#  define HALF_OF(x) ((x)*_mm_set1_ps(.5f))
+#else
+#  define KISS_FFT_COS(phase) (kiss_fft_scalar) cos(phase)
+#  define KISS_FFT_SIN(phase) (kiss_fft_scalar) sin(phase)
+#  define HALF_OF(x) ((x)*.5f)
+#endif
+
+#define  kf_cexp(x,phase) \
+        do{ \
+                (x)->r = KISS_FFT_COS(phase);\
+                (x)->i = KISS_FFT_SIN(phase);\
+        }while(0)
+
+#define  kf_cexp2(x,phase) \
+   do{ \
+      (x)->r = TRIG_UPSCALE*celt_cos_norm((phase));\
+      (x)->i = TRIG_UPSCALE*celt_cos_norm((phase)-32768);\
+}while(0)
+
+#endif /* KISS_FFT_GUTS_H */

src/arch.h

+/* Copyright (c) 2003-2008 Jean-Marc Valin
+   Copyright (c) 2007-2008 CSIRO
+   Copyright (c) 2007-2009 Xiph.Org Foundation
+   Written by Jean-Marc Valin */
+/**
+   @file arch.h
+   @brief Various architecture definitions for CELT
+*/
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef ARCH_H
+#define ARCH_H
+
+#include "opus_types.h"
+#include "common.h"
+
+# if !defined(__GNUC_PREREQ)
+#  if defined(__GNUC__)&&defined(__GNUC_MINOR__)
+#   define __GNUC_PREREQ(_maj,_min) \
+ ((__GNUC__<<16)+__GNUC_MINOR__>=((_maj)<<16)+(_min))
+#  else
+#   define __GNUC_PREREQ(_maj,_min) 0
+#  endif
+# endif
+
+#define CELT_SIG_SCALE 32768.f
+
+#define celt_fatal(str) _celt_fatal(str, __FILE__, __LINE__);
+#ifdef ENABLE_ASSERTIONS
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef __GNUC__
+__attribute__((noreturn))
+#endif
+static OPUS_INLINE void _celt_fatal(const char *str, const char *file, int line)
+{
+   fprintf (stderr, "Fatal (internal) error in %s, line %d: %s\n", file, line, str);
+   abort();
+}
+#define celt_assert(cond) {if (!(cond)) {celt_fatal("assertion failed: " #cond);}}
+#define celt_assert2(cond, message) {if (!(cond)) {celt_fatal("assertion failed: " #cond "\n" message);}}
+#else
+#define celt_assert(cond)
+#define celt_assert2(cond, message)
+#endif
+
+#define IMUL32(a,b) ((a)*(b))
+
+#define MIN16(a,b) ((a) < (b) ? (a) : (b))   /**< Minimum 16-bit value.   */
+#define MAX16(a,b) ((a) > (b) ? (a) : (b))   /**< Maximum 16-bit value.   */
+#define MIN32(a,b) ((a) < (b) ? (a) : (b))   /**< Minimum 32-bit value.   */
+#define MAX32(a,b) ((a) > (b) ? (a) : (b))   /**< Maximum 32-bit value.   */
+#define IMIN(a,b) ((a) < (b) ? (a) : (b))   /**< Minimum int value.   */
+#define IMAX(a,b) ((a) > (b) ? (a) : (b))   /**< Maximum int value.   */
+#define UADD32(a,b) ((a)+(b))
+#define USUB32(a,b) ((a)-(b))
+
+/* Set this if opus_int64 is a native type of the CPU. */
+/* Assume that all LP64 architectures have fast 64-bit types; also x86_64
+   (which can be ILP32 for x32) and Win64 (which is LLP64). */
+#if defined(__x86_64__) || defined(__LP64__) || defined(_WIN64)
+#define OPUS_FAST_INT64 1
+#else
+#define OPUS_FAST_INT64 0
+#endif
+
+#define PRINT_MIPS(file)
+
+#ifdef FIXED_POINT
+
+typedef opus_int16 opus_val16;
+typedef opus_int32 opus_val32;
+typedef opus_int64 opus_val64;
+
+typedef opus_val32 celt_sig;
+typedef opus_val16 celt_norm;
+typedef opus_val32 celt_ener;
+
+#define Q15ONE 32767
+
+#define SIG_SHIFT 12
+/* Safe saturation value for 32-bit signals. Should be less than
+   2^31*(1-0.85) to avoid blowing up on DC at deemphasis.*/
+#define SIG_SAT (300000000)
+
+#define NORM_SCALING 16384
+
+#define DB_SHIFT 10
+
+#define EPSILON 1
+#define VERY_SMALL 0
+#define VERY_LARGE16 ((opus_val16)32767)
+#define Q15_ONE ((opus_val16)32767)
+
+#define SCALEIN(a)      (a)
+#define SCALEOUT(a)     (a)
+
+#define ABS16(x) ((x) < 0 ? (-(x)) : (x))
+#define ABS32(x) ((x) < 0 ? (-(x)) : (x))
+
+static OPUS_INLINE opus_int16 SAT16(opus_int32 x) {
+   return x > 32767 ? 32767 : x < -32768 ? -32768 : (opus_int16)x;
+}
+
+#ifdef FIXED_DEBUG
+#include "fixed_debug.h"
+#else
+
+#include "fixed_generic.h"
+
+#ifdef OPUS_ARM_PRESUME_AARCH64_NEON_INTR
+#include "arm/fixed_arm64.h"
+#elif OPUS_ARM_INLINE_EDSP
+#include "arm/fixed_armv5e.h"
+#elif defined (OPUS_ARM_INLINE_ASM)
+#include "arm/fixed_armv4.h"
+#elif defined (BFIN_ASM)
+#include "fixed_bfin.h"
+#elif defined (TI_C5X_ASM)
+#include "fixed_c5x.h"
+#elif defined (TI_C6X_ASM)
+#include "fixed_c6x.h"
+#endif
+
+#endif
+
+#else /* FIXED_POINT */
+
+typedef float opus_val16;
+typedef float opus_val32;
+typedef float opus_val64;
+
+typedef float celt_sig;
+typedef float celt_norm;
+typedef float celt_ener;
+
+#ifdef FLOAT_APPROX
+/* This code should reliably detect NaN/inf even when -ffast-math is used.
+   Assumes IEEE 754 format. */
+static OPUS_INLINE int celt_isnan(float x)
+{
+   union {float f; opus_uint32 i;} in;
+   in.f = x;
+   return ((in.i>>23)&0xFF)==0xFF && (in.i&0x007FFFFF)!=0;
+}
+#else
+#ifdef __FAST_MATH__
+#error Cannot build libopus with -ffast-math unless FLOAT_APPROX is defined. This could result in crashes on extreme (e.g. NaN) input
+#endif
+#define celt_isnan(x) ((x)!=(x))
+#endif
+
+#define Q15ONE 1.0f
+
+#define NORM_SCALING 1.f
+
+#define EPSILON 1e-15f
+#define VERY_SMALL 1e-30f
+#define VERY_LARGE16 1e15f
+#define Q15_ONE ((opus_val16)1.f)
+
+/* This appears to be the same speed as C99's fabsf() but it's more portable. */
+#define ABS16(x) ((float)fabs(x))
+#define ABS32(x) ((float)fabs(x))
+
+#define QCONST16(x,bits) (x)
+#define QCONST32(x,bits) (x)
+
+#define NEG16(x) (-(x))
+#define NEG32(x) (-(x))
+#define NEG32_ovflw(x) (-(x))
+#define EXTRACT16(x) (x)
+#define EXTEND32(x) (x)
+#define SHR16(a,shift) (a)
+#define SHL16(a,shift) (a)
+#define SHR32(a,shift) (a)
+#define SHL32(a,shift) (a)
+#define PSHR32(a,shift) (a)
+#define VSHR32(a,shift) (a)
+
+#define PSHR(a,shift)   (a)
+#define SHR(a,shift)    (a)
+#define SHL(a,shift)    (a)
+#define SATURATE(x,a)   (x)
+#define SATURATE16(x)   (x)
+
+#define ROUND16(a,shift)  (a)
+#define SROUND16(a,shift) (a)
+#define HALF16(x)       (.5f*(x))
+#define HALF32(x)       (.5f*(x))
+
+#define ADD16(a,b) ((a)+(b))
+#define SUB16(a,b) ((a)-(b))
+#define ADD32(a,b) ((a)+(b))
+#define SUB32(a,b) ((a)-(b))
+#define ADD32_ovflw(a,b) ((a)+(b))
+#define SUB32_ovflw(a,b) ((a)-(b))
+#define MULT16_16_16(a,b)     ((a)*(b))
+#define MULT16_16(a,b)     ((opus_val32)(a)*(opus_val32)(b))
+#define MAC16_16(c,a,b)     ((c)+(opus_val32)(a)*(opus_val32)(b))
+
+#define MULT16_32_Q15(a,b)     ((a)*(b))
+#define MULT16_32_Q16(a,b)     ((a)*(b))
+
+#define MULT32_32_Q31(a,b)     ((a)*(b))
+
+#define MAC16_32_Q15(c,a,b)     ((c)+(a)*(b))
+#define MAC16_32_Q16(c,a,b)     ((c)+(a)*(b))
+
+#define MULT16_16_Q11_32(a,b)     ((a)*(b))
+#define MULT16_16_Q11(a,b)     ((a)*(b))
+#define MULT16_16_Q13(a,b)     ((a)*(b))
+#define MULT16_16_Q14(a,b)     ((a)*(b))
+#define MULT16_16_Q15(a,b)     ((a)*(b))
+#define MULT16_16_P15(a,b)     ((a)*(b))
+#define MULT16_16_P13(a,b)     ((a)*(b))
+#define MULT16_16_P14(a,b)     ((a)*(b))
+#define MULT16_32_P16(a,b)     ((a)*(b))
+
+#define DIV32_16(a,b)     (((opus_val32)(a))/(opus_val16)(b))
+#define DIV32(a,b)     (((opus_val32)(a))/(opus_val32)(b))
+
+#define SCALEIN(a)      ((a)*CELT_SIG_SCALE)
+#define SCALEOUT(a)     ((a)*(1/CELT_SIG_SCALE))
+
+#define SIG2WORD16(x) (x)
+
+#endif /* !FIXED_POINT */
+
+#ifndef GLOBAL_STACK_SIZE
+#ifdef FIXED_POINT
+#define GLOBAL_STACK_SIZE 120000
+#else
+#define GLOBAL_STACK_SIZE 120000
+#endif
+#endif
+
+#endif /* ARCH_H */

src/common.h

+
+
+#ifndef COMMON_H
+#define COMMON_H
+
+#define OPUS_INLINE inline
+
+#endif

src/denoise.c

+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "kiss_fft.h"
+
+#define FRAME_SIZE_SHIFT 2
+#define FRAME_SIZE (120<<FRAME_SIZE_SHIFT)
+#define WINDOW_SIZE (2*FRAME_SIZE)
+#define FREQ_SIZE (FRAME_SIZE + 1)
+
+#define NB_BANDS 21
+
+#define SQUARE(x) ((x)*(x))
+
+static const opus_int16 eband5ms[] = {
+/*0  200 400 600 800  1k 1.2 1.4 1.6  2k 2.4 2.8 3.2  4k 4.8 5.6 6.8  8k 9.6 12k 15.6 20k*/
+  0,  1,  2,  3,  4,  5,  6,  7,  8, 10, 12, 14, 16, 20, 24, 28, 34, 40, 48, 60, 78, 100
+};
+
+
+typedef struct {
+  int init;
+  kiss_fft_state *kfft;
+} CommonState;
+
+typedef struct {
+  float analysis_mem[FRAME_SIZE];
+  float synthesis_mem[FRAME_SIZE];
+  
+} DenoiseState;
+
+void compute_band_energy(float *bandE, const kiss_fft_cpx *X) {
+  int i;
+  for (i=0;i<NB_BANDS;i++)
+  {
+    int j;
+    opus_val32 sum = 1e-27;
+    for (j=0;j<(eband5ms[i+1]-eband5ms[i])<<FRAME_SIZE_SHIFT;j++) {
+      sum += SQUARE(X[(eband5ms[i]<<FRAME_SIZE_SHIFT) + j].r);
+      sum += SQUARE(X[(eband5ms[i]<<FRAME_SIZE_SHIFT) + j].i);
+    }
+    bandE[i] = sqrt(sum);
+  }
+}
+
+void interp_band_gain(float *g, const float *bandE) {
+  int i;
+  for (i=0;i<NB_BANDS;i++)
+  {
+    int j;
+    for (j=0;j<(eband5ms[i+1]-eband5ms[i])<<FRAME_SIZE_SHIFT;j++)
+      g[(eband5ms[i]<<FRAME_SIZE_SHIFT) + j] = bandE[i];
+  }
+}
+
+CommonState common;
+
+static void check_init() {
+  if (common.init) return;
+  common.kfft = opus_fft_alloc_twiddles(2*FRAME_SIZE, NULL, NULL, NULL, 0);
+  common.init = 1;
+}
+
+
+void forward_transform(kiss_fft_cpx *out, const float *in) {
+  int i;
+  kiss_fft_cpx x[WINDOW_SIZE];
+  kiss_fft_cpx y[WINDOW_SIZE];
+  check_init();
+  for (i=0;i<WINDOW_SIZE;i++) {
+    x[i].r = in[i];
+    x[i].i = 0;
+  }
+  opus_fft(common.kfft, x, y, 0);
+  for (i=0;i<FREQ_SIZE;i++) {
+    out[i] = y[i];
+  }
+}
+
+void inverse_transform(float *out, const kiss_fft_cpx *in) {
+  check_init();
+}
+
+int main() {
+  int i;
+  kiss_fft_state *kfft;
+  float x[2*FRAME_SIZE];
+  kiss_fft_cpx y[2*FRAME_SIZE];
+  float bandE[NB_BANDS];
+  memset(x, 0, sizeof(x));
+  x[0] = 1;
+  x[1] = 1;
+  kfft = opus_fft_alloc_twiddles(2*FRAME_SIZE, NULL, NULL, NULL, 0);
+  //opus_fft(kfft, x, y, 0);
+  forward_transform(y, x);
+  compute_band_energy(bandE, y);
+  /*for (i=0;i<2*FRAME_SIZE;i++)
+    printf("%f %f\n", y[i].r, y[i].i);*/
+  for (i=0;i<NB_BANDS;i++)
+    printf("%f\n", bandE[i]);
+  return 0;
+}

src/kiss_fft.c

+/*Copyright (c) 2003-2004, Mark Borgerding
+  Lots of modifications by Jean-Marc Valin
+  Copyright (c) 2005-2007, Xiph.Org Foundation
+  Copyright (c) 2008,      Xiph.Org Foundation, CSIRO
+
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+  POSSIBILITY OF SUCH DAMAGE.*/
+
+/* This code is originally from Mark Borgerding's KISS-FFT but has been
+   heavily modified to better suit Opus */
+
+#ifndef SKIP_CONFIG_H
+#  ifdef HAVE_CONFIG_H
+#    include "config.h"
+#  endif
+#endif
+
+#include "_kiss_fft_guts.h"
+#define CUSTOM_MODES
+
+/* The guts header contains all the multiplication and addition macros that are defined for
+   complex numbers.  It also delares the kf_ internal functions.
+*/
+
+static void kf_bfly2(
+                     kiss_fft_cpx * Fout,
+                     int m,
+                     int N
+                    )
+{
+   kiss_fft_cpx * Fout2;
+   int i;
+   (void)m;
+#ifdef CUSTOM_MODES
+   if (m==1)
+   {
+      celt_assert(m==1);
+      for (i=0;i<N;i++)
+      {
+         kiss_fft_cpx t;
+         Fout2 = Fout + 1;
+         t = *Fout2;
+         C_SUB( *Fout2 ,  *Fout , t );
+         C_ADDTO( *Fout ,  t );
+         Fout += 2;
+      }
+   } else
+#endif
+   {
+      opus_val16 tw;
+      tw = QCONST16(0.7071067812f, 15);
+      /* We know that m==4 here because the radix-2 is just after a radix-4 */
+      celt_assert(m==4);
+      for (i=0;i<N;i++)
+      {
+         kiss_fft_cpx t;
+         Fout2 = Fout + 4;
+         t = Fout2[0];
+         C_SUB( Fout2[0] ,  Fout[0] , t );
+         C_ADDTO( Fout[0] ,  t );
+
+         t.r = S_MUL(ADD32_ovflw(Fout2[1].r, Fout2[1].i), tw);
+         t.i = S_MUL(SUB32_ovflw(Fout2[1].i, Fout2[1].r), tw);
+         C_SUB( Fout2[1] ,  Fout[1] , t );
+         C_ADDTO( Fout[1] ,  t );
+
+         t.r = Fout2[2].i;
+         t.i = -Fout2[2].r;