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webrtc / src / c136b0632621675f2dd7e8939c617ff2ceeaf3e6 / . / common_audio / signal_processing / include / signal_processing_library.h
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/*
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
*
* 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.
*/
/*
* This header file includes all of the fix point signal processing library
* (SPL) function descriptions and declarations. For specific function calls,
* see bottom of file.
*/
#ifndef COMMON_AUDIO_SIGNAL_PROCESSING_INCLUDE_SIGNAL_PROCESSING_LIBRARY_H_
#define COMMON_AUDIO_SIGNAL_PROCESSING_INCLUDE_SIGNAL_PROCESSING_LIBRARY_H_
#include <string.h>
#include "common_audio/signal_processing/dot_product_with_scale.h"
// Macros specific for the fixed point implementation
#define WEBRTC_SPL_WORD16_MAX 32767
#define WEBRTC_SPL_WORD16_MIN -32768
#define WEBRTC_SPL_WORD32_MAX (int32_t)0x7fffffff
#define WEBRTC_SPL_WORD32_MIN (int32_t)0x80000000
#define WEBRTC_SPL_MAX_LPC_ORDER 14
#define WEBRTC_SPL_MIN(A, B) (A < B ? A : B) // Get min value
#define WEBRTC_SPL_MAX(A, B) (A > B ? A : B) // Get max value
// TODO(kma/bjorn): For the next two macros, investigate how to correct the code
// for inputs of a = WEBRTC_SPL_WORD16_MIN or WEBRTC_SPL_WORD32_MIN.
#define WEBRTC_SPL_ABS_W16(a) (((int16_t)a >= 0) ? ((int16_t)a) : -((int16_t)a))
#define WEBRTC_SPL_ABS_W32(a) (((int32_t)a >= 0) ? ((int32_t)a) : -((int32_t)a))
#define WEBRTC_SPL_MUL(a, b) ((int32_t)((int32_t)(a) * (int32_t)(b)))
#define WEBRTC_SPL_UMUL(a, b) ((uint32_t)((uint32_t)(a) * (uint32_t)(b)))
#define WEBRTC_SPL_UMUL_32_16(a, b) ((uint32_t)((uint32_t)(a) * (uint16_t)(b)))
#define WEBRTC_SPL_MUL_16_U16(a, b) ((int32_t)(int16_t)(a) * (uint16_t)(b))
// clang-format off
// clang-format would choose some identation
// leading to presubmit error (cpplint.py)
#ifndef WEBRTC_ARCH_ARM_V7
// For ARMv7 platforms, these are inline functions in spl_inl_armv7.h
#ifndef MIPS32_LE
// For MIPS platforms, these are inline functions in spl_inl_mips.h
#define WEBRTC_SPL_MUL_16_16(a, b) ((int32_t)(((int16_t)(a)) * ((int16_t)(b))))
#define WEBRTC_SPL_MUL_16_32_RSFT16(a, b) \
(WEBRTC_SPL_MUL_16_16(a, b >> 16) + \
((WEBRTC_SPL_MUL_16_16(a, (b & 0xffff) >> 1) + 0x4000) >> 15))
#endif
#endif
#define WEBRTC_SPL_MUL_16_32_RSFT11(a, b) \
(WEBRTC_SPL_MUL_16_16(a, (b) >> 16) * (1 << 5) + \
(((WEBRTC_SPL_MUL_16_U16(a, (uint16_t)(b)) >> 1) + 0x0200) >> 10))
#define WEBRTC_SPL_MUL_16_32_RSFT14(a, b) \
(WEBRTC_SPL_MUL_16_16(a, (b) >> 16) * (1 << 2) + \
(((WEBRTC_SPL_MUL_16_U16(a, (uint16_t)(b)) >> 1) + 0x1000) >> 13))
#define WEBRTC_SPL_MUL_16_32_RSFT15(a, b) \
((WEBRTC_SPL_MUL_16_16(a, (b) >> 16) * (1 << 1)) + \
(((WEBRTC_SPL_MUL_16_U16(a, (uint16_t)(b)) >> 1) + 0x2000) >> 14))
// clang-format on
#define WEBRTC_SPL_MUL_16_16_RSFT(a, b, c) (WEBRTC_SPL_MUL_16_16(a, b) >> (c))
#define WEBRTC_SPL_MUL_16_16_RSFT_WITH_ROUND(a, b, c) \
((WEBRTC_SPL_MUL_16_16(a, b) + ((int32_t)(((int32_t)1) << ((c)-1)))) >> (c))
// C + the 32 most significant bits of A * B
#define WEBRTC_SPL_SCALEDIFF32(A, B, C) \
(C + (B >> 16) * A + (((uint32_t)(B & 0x0000FFFF) * A) >> 16))
#define WEBRTC_SPL_SAT(a, b, c) (b > a ? a : b < c ? c : b)
// Shifting with negative numbers allowed
// Positive means left shift
#define WEBRTC_SPL_SHIFT_W32(x, c) ((c) >= 0 ? (x) * (1 << (c)) : (x) >> -(c))
// Shifting with negative numbers not allowed
// We cannot do casting here due to signed/unsigned problem
#define WEBRTC_SPL_LSHIFT_W32(x, c) ((x) << (c))
#define WEBRTC_SPL_RSHIFT_U32(x, c) ((uint32_t)(x) >> (c))
#define WEBRTC_SPL_RAND(a) ((int16_t)((((int16_t)a * 18816) >> 7) & 0x00007fff))
#ifdef __cplusplus
extern "C" {
#endif
#define WEBRTC_SPL_MEMCPY_W16(v1, v2, length) \
memcpy(v1, v2, (length) * sizeof(int16_t))
// inline functions:
#include "common_audio/signal_processing/include/spl_inl.h"
// third party math functions
#include "common_audio/third_party/spl_sqrt_floor/spl_sqrt_floor.h"
// Initialize SPL. Currently it contains only function pointer initialization.
// If the underlying platform is known to be ARM-Neon (WEBRTC_HAS_NEON defined),
// the pointers will be assigned to code optimized for Neon; otherwise, generic
// C code will be assigned.
// Note that this function MUST be called in any application that uses SPL
// functions.
void WebRtcSpl_Init(void);
int16_t WebRtcSpl_GetScalingSquare(int16_t* in_vector,
size_t in_vector_length,
size_t times);
// Copy and set operations. Implementation in copy_set_operations.c.
// Descriptions at bottom of file.
void WebRtcSpl_MemSetW16(int16_t* vector,
int16_t set_value,
size_t vector_length);
void WebRtcSpl_MemSetW32(int32_t* vector,
int32_t set_value,
size_t vector_length);
void WebRtcSpl_MemCpyReversedOrder(int16_t* out_vector,
int16_t* in_vector,
size_t vector_length);
void WebRtcSpl_CopyFromEndW16(const int16_t* in_vector,
size_t in_vector_length,
size_t samples,
int16_t* out_vector);
void WebRtcSpl_ZerosArrayW16(int16_t* vector, size_t vector_length);
void WebRtcSpl_ZerosArrayW32(int32_t* vector, size_t vector_length);
// End: Copy and set operations.
// Minimum and maximum operation functions and their pointers.
// Implementation in min_max_operations.c.
// Returns the largest absolute value in a signed 16-bit vector.
//
// Input:
// - vector : 16-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Maximum absolute value in vector.
typedef int16_t (*MaxAbsValueW16)(const int16_t* vector, size_t length);
extern MaxAbsValueW16 WebRtcSpl_MaxAbsValueW16;
int16_t WebRtcSpl_MaxAbsValueW16C(const int16_t* vector, size_t length);
#if defined(WEBRTC_HAS_NEON)
int16_t WebRtcSpl_MaxAbsValueW16Neon(const int16_t* vector, size_t length);
#endif
#if defined(MIPS32_LE)
int16_t WebRtcSpl_MaxAbsValueW16_mips(const int16_t* vector, size_t length);
#endif
// Returns the largest absolute value in a signed 32-bit vector.
//
// Input:
// - vector : 32-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Maximum absolute value in vector.
typedef int32_t (*MaxAbsValueW32)(const int32_t* vector, size_t length);
extern MaxAbsValueW32 WebRtcSpl_MaxAbsValueW32;
int32_t WebRtcSpl_MaxAbsValueW32C(const int32_t* vector, size_t length);
#if defined(WEBRTC_HAS_NEON)
int32_t WebRtcSpl_MaxAbsValueW32Neon(const int32_t* vector, size_t length);
#endif
#if defined(MIPS_DSP_R1_LE)
int32_t WebRtcSpl_MaxAbsValueW32_mips(const int32_t* vector, size_t length);
#endif
// Returns the maximum value of a 16-bit vector.
//
// Input:
// - vector : 16-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Maximum sample value in |vector|.
typedef int16_t (*MaxValueW16)(const int16_t* vector, size_t length);
extern MaxValueW16 WebRtcSpl_MaxValueW16;
int16_t WebRtcSpl_MaxValueW16C(const int16_t* vector, size_t length);
#if defined(WEBRTC_HAS_NEON)
int16_t WebRtcSpl_MaxValueW16Neon(const int16_t* vector, size_t length);
#endif
#if defined(MIPS32_LE)
int16_t WebRtcSpl_MaxValueW16_mips(const int16_t* vector, size_t length);
#endif
// Returns the maximum value of a 32-bit vector.
//
// Input:
// - vector : 32-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Maximum sample value in |vector|.
typedef int32_t (*MaxValueW32)(const int32_t* vector, size_t length);
extern MaxValueW32 WebRtcSpl_MaxValueW32;
int32_t WebRtcSpl_MaxValueW32C(const int32_t* vector, size_t length);
#if defined(WEBRTC_HAS_NEON)
int32_t WebRtcSpl_MaxValueW32Neon(const int32_t* vector, size_t length);
#endif
#if defined(MIPS32_LE)
int32_t WebRtcSpl_MaxValueW32_mips(const int32_t* vector, size_t length);
#endif
// Returns the minimum value of a 16-bit vector.
//
// Input:
// - vector : 16-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Minimum sample value in |vector|.
typedef int16_t (*MinValueW16)(const int16_t* vector, size_t length);
extern MinValueW16 WebRtcSpl_MinValueW16;
int16_t WebRtcSpl_MinValueW16C(const int16_t* vector, size_t length);
#if defined(WEBRTC_HAS_NEON)
int16_t WebRtcSpl_MinValueW16Neon(const int16_t* vector, size_t length);
#endif
#if defined(MIPS32_LE)
int16_t WebRtcSpl_MinValueW16_mips(const int16_t* vector, size_t length);
#endif
// Returns the minimum value of a 32-bit vector.
//
// Input:
// - vector : 32-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Minimum sample value in |vector|.
typedef int32_t (*MinValueW32)(const int32_t* vector, size_t length);
extern MinValueW32 WebRtcSpl_MinValueW32;
int32_t WebRtcSpl_MinValueW32C(const int32_t* vector, size_t length);
#if defined(WEBRTC_HAS_NEON)
int32_t WebRtcSpl_MinValueW32Neon(const int32_t* vector, size_t length);
#endif
#if defined(MIPS32_LE)
int32_t WebRtcSpl_MinValueW32_mips(const int32_t* vector, size_t length);
#endif
// Returns the vector index to the largest absolute value of a 16-bit vector.
//
// Input:
// - vector : 16-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Index to the maximum absolute value in vector.
// If there are multiple equal maxima, return the index of the
// first. -32768 will always have precedence over 32767 (despite
// -32768 presenting an int16 absolute value of 32767).
size_t WebRtcSpl_MaxAbsIndexW16(const int16_t* vector, size_t length);
// Returns the vector index to the maximum sample value of a 16-bit vector.
//
// Input:
// - vector : 16-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Index to the maximum value in vector (if multiple
// indexes have the maximum, return the first).
size_t WebRtcSpl_MaxIndexW16(const int16_t* vector, size_t length);
// Returns the vector index to the maximum sample value of a 32-bit vector.
//
// Input:
// - vector : 32-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Index to the maximum value in vector (if multiple
// indexes have the maximum, return the first).
size_t WebRtcSpl_MaxIndexW32(const int32_t* vector, size_t length);
// Returns the vector index to the minimum sample value of a 16-bit vector.
//
// Input:
// - vector : 16-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Index to the mimimum value in vector (if multiple
// indexes have the minimum, return the first).
size_t WebRtcSpl_MinIndexW16(const int16_t* vector, size_t length);
// Returns the vector index to the minimum sample value of a 32-bit vector.
//
// Input:
// - vector : 32-bit input vector.
// - length : Number of samples in vector.
//
// Return value : Index to the mimimum value in vector (if multiple
// indexes have the minimum, return the first).
size_t WebRtcSpl_MinIndexW32(const int32_t* vector, size_t length);
// End: Minimum and maximum operations.
// Vector scaling operations. Implementation in vector_scaling_operations.c.
// Description at bottom of file.
void WebRtcSpl_VectorBitShiftW16(int16_t* out_vector,
size_t vector_length,
const int16_t* in_vector,
int16_t right_shifts);
void WebRtcSpl_VectorBitShiftW32(int32_t* out_vector,
size_t vector_length,
const int32_t* in_vector,
int16_t right_shifts);
void WebRtcSpl_VectorBitShiftW32ToW16(int16_t* out_vector,
size_t vector_length,
const int32_t* in_vector,
int right_shifts);
void WebRtcSpl_ScaleVector(const int16_t* in_vector,
int16_t* out_vector,
int16_t gain,
size_t vector_length,
int16_t right_shifts);
void WebRtcSpl_ScaleVectorWithSat(const int16_t* in_vector,
int16_t* out_vector,
int16_t gain,
size_t vector_length,
int16_t right_shifts);
void WebRtcSpl_ScaleAndAddVectors(const int16_t* in_vector1,
int16_t gain1,
int right_shifts1,
const int16_t* in_vector2,
int16_t gain2,
int right_shifts2,
int16_t* out_vector,
size_t vector_length);
// The functions (with related pointer) perform the vector operation:
// out_vector[k] = ((scale1 * in_vector1[k]) + (scale2 * in_vector2[k])
// + round_value) >> right_shifts,
// where round_value = (1 << right_shifts) >> 1.
//
// Input:
// - in_vector1 : Input vector 1
// - in_vector1_scale : Gain to be used for vector 1
// - in_vector2 : Input vector 2
// - in_vector2_scale : Gain to be used for vector 2
// - right_shifts : Number of right bit shifts to be applied
// - length : Number of elements in the input vectors
//
// Output:
// - out_vector : Output vector
// Return value : 0 if OK, -1 if (in_vector1 == null
// || in_vector2 == null || out_vector == null
// || length <= 0 || right_shift < 0).
typedef int (*ScaleAndAddVectorsWithRound)(const int16_t* in_vector1,
int16_t in_vector1_scale,
const int16_t* in_vector2,
int16_t in_vector2_scale,
int right_shifts,
int16_t* out_vector,
size_t length);
extern ScaleAndAddVectorsWithRound WebRtcSpl_ScaleAndAddVectorsWithRound;
int WebRtcSpl_ScaleAndAddVectorsWithRoundC(const int16_t* in_vector1,
int16_t in_vector1_scale,
const int16_t* in_vector2,
int16_t in_vector2_scale,
int right_shifts,
int16_t* out_vector,
size_t length);
#if defined(MIPS_DSP_R1_LE)
int WebRtcSpl_ScaleAndAddVectorsWithRound_mips(const int16_t* in_vector1,
int16_t in_vector1_scale,
const int16_t* in_vector2,
int16_t in_vector2_scale,
int right_shifts,
int16_t* out_vector,
size_t length);
#endif
// End: Vector scaling operations.
// iLBC specific functions. Implementations in ilbc_specific_functions.c.
// Description at bottom of file.
void WebRtcSpl_ReverseOrderMultArrayElements(int16_t* out_vector,
const int16_t* in_vector,
const int16_t* window,
size_t vector_length,
int16_t right_shifts);
void WebRtcSpl_ElementwiseVectorMult(int16_t* out_vector,
const int16_t* in_vector,
const int16_t* window,
size_t vector_length,
int16_t right_shifts);
void WebRtcSpl_AddVectorsAndShift(int16_t* out_vector,
const int16_t* in_vector1,
const int16_t* in_vector2,
size_t vector_length,
int16_t right_shifts);
void WebRtcSpl_AddAffineVectorToVector(int16_t* out_vector,
const int16_t* in_vector,
int16_t gain,
int32_t add_constant,
int16_t right_shifts,
size_t vector_length);
void WebRtcSpl_AffineTransformVector(int16_t* out_vector,
const int16_t* in_vector,
int16_t gain,
int32_t add_constant,
int16_t right_shifts,
size_t vector_length);
// End: iLBC specific functions.
// Signal processing operations.
// A 32-bit fix-point implementation of auto-correlation computation
//
// Input:
// - in_vector : Vector to calculate autocorrelation upon
// - in_vector_length : Length (in samples) of |vector|
// - order : The order up to which the autocorrelation should be
// calculated
//
// Output:
// - result : auto-correlation values (values should be seen
// relative to each other since the absolute values
// might have been down shifted to avoid overflow)
//
// - scale : The number of left shifts required to obtain the
// auto-correlation in Q0
//
// Return value : Number of samples in |result|, i.e. (order+1)
size_t WebRtcSpl_AutoCorrelation(const int16_t* in_vector,
size_t in_vector_length,
size_t order,
int32_t* result,
int* scale);
// A 32-bit fix-point implementation of the Levinson-Durbin algorithm that
// does NOT use the 64 bit class
//
// Input:
// - auto_corr : Vector with autocorrelation values of length >= |order|+1
// - order : The LPC filter order (support up to order 20)
//
// Output:
// - lpc_coef : lpc_coef[0..order] LPC coefficients in Q12
// - refl_coef : refl_coef[0...order-1]| Reflection coefficients in Q15
//
// Return value : 1 for stable 0 for unstable
int16_t WebRtcSpl_LevinsonDurbin(const int32_t* auto_corr,
int16_t* lpc_coef,
int16_t* refl_coef,
size_t order);
// Converts reflection coefficients |refl_coef| to LPC coefficients |lpc_coef|.
// This version is a 16 bit operation.
//
// NOTE: The 16 bit refl_coef -> lpc_coef conversion might result in a
// "slightly unstable" filter (i.e., a pole just outside the unit circle) in
// "rare" cases even if the reflection coefficients are stable.
//
// Input:
// - refl_coef : Reflection coefficients in Q15 that should be converted
// to LPC coefficients
// - use_order : Number of coefficients in |refl_coef|
//
// Output:
// - lpc_coef : LPC coefficients in Q12
void WebRtcSpl_ReflCoefToLpc(const int16_t* refl_coef,
int use_order,
int16_t* lpc_coef);
// Converts LPC coefficients |lpc_coef| to reflection coefficients |refl_coef|.
// This version is a 16 bit operation.
// The conversion is implemented by the step-down algorithm.
//
// Input:
// - lpc_coef : LPC coefficients in Q12, that should be converted to
// reflection coefficients
// - use_order : Number of coefficients in |lpc_coef|
//
// Output:
// - refl_coef : Reflection coefficients in Q15.
void WebRtcSpl_LpcToReflCoef(int16_t* lpc_coef,
int use_order,
int16_t* refl_coef);
// Calculates reflection coefficients (16 bit) from auto-correlation values
//
// Input:
// - auto_corr : Auto-correlation values
// - use_order : Number of coefficients wanted be calculated
//
// Output:
// - refl_coef : Reflection coefficients in Q15.
void WebRtcSpl_AutoCorrToReflCoef(const int32_t* auto_corr,
int use_order,
int16_t* refl_coef);
// The functions (with related pointer) calculate the cross-correlation between
// two sequences |seq1| and |seq2|.
// |seq1| is fixed and |seq2| slides as the pointer is increased with the
// amount |step_seq2|. Note the arguments should obey the relationship:
// |dim_seq| - 1 + |step_seq2| * (|dim_cross_correlation| - 1) <
// buffer size of |seq2|
//
// Input:
// - seq1 : First sequence (fixed throughout the correlation)
// - seq2 : Second sequence (slides |step_vector2| for each
// new correlation)
// - dim_seq : Number of samples to use in the cross-correlation
// - dim_cross_correlation : Number of cross-correlations to calculate (the
// start position for |vector2| is updated for each
// new one)
// - right_shifts : Number of right bit shifts to use. This will
// become the output Q-domain.
// - step_seq2 : How many (positive or negative) steps the
// |vector2| pointer should be updated for each new
// cross-correlation value.
//
// Output:
// - cross_correlation : The cross-correlation in Q(-right_shifts)
typedef void (*CrossCorrelation)(int32_t* cross_correlation,
const int16_t* seq1,
const int16_t* seq2,
size_t dim_seq,
size_t dim_cross_correlation,
int right_shifts,
int step_seq2);
extern CrossCorrelation WebRtcSpl_CrossCorrelation;
void WebRtcSpl_CrossCorrelationC(int32_t* cross_correlation,
const int16_t* seq1,
const int16_t* seq2,
size_t dim_seq,
size_t dim_cross_correlation,
int right_shifts,
int step_seq2);
#if defined(WEBRTC_HAS_NEON)
void WebRtcSpl_CrossCorrelationNeon(int32_t* cross_correlation,
const int16_t* seq1,
const int16_t* seq2,
size_t dim_seq,
size_t dim_cross_correlation,
int right_shifts,
int step_seq2);
#endif
#if defined(MIPS32_LE)
void WebRtcSpl_CrossCorrelation_mips(int32_t* cross_correlation,
const int16_t* seq1,
const int16_t* seq2,
size_t dim_seq,
size_t dim_cross_correlation,
int right_shifts,
int step_seq2);
#endif
// Creates (the first half of) a Hanning window. Size must be at least 1 and
// at most 512.
//
// Input:
// - size : Length of the requested Hanning window (1 to 512)
//
// Output:
// - window : Hanning vector in Q14.
void WebRtcSpl_GetHanningWindow(int16_t* window, size_t size);
// Calculates y[k] = sqrt(1 - x[k]^2) for each element of the input vector
// |in_vector|. Input and output values are in Q15.
//
// Inputs:
// - in_vector : Values to calculate sqrt(1 - x^2) of
// - vector_length : Length of vector |in_vector|
//
// Output:
// - out_vector : Output values in Q15
void WebRtcSpl_SqrtOfOneMinusXSquared(int16_t* in_vector,
size_t vector_length,
int16_t* out_vector);
// End: Signal processing operations.
// Randomization functions. Implementations collected in
// randomization_functions.c and descriptions at bottom of this file.
int16_t WebRtcSpl_RandU(uint32_t* seed);
int16_t WebRtcSpl_RandN(uint32_t* seed);
int16_t WebRtcSpl_RandUArray(int16_t* vector,
int16_t vector_length,
uint32_t* seed);
// End: Randomization functions.
// Math functions
int32_t WebRtcSpl_Sqrt(int32_t value);
// Divisions. Implementations collected in division_operations.c and
// descriptions at bottom of this file.
uint32_t WebRtcSpl_DivU32U16(uint32_t num, uint16_t den);
int32_t WebRtcSpl_DivW32W16(int32_t num, int16_t den);
int16_t WebRtcSpl_DivW32W16ResW16(int32_t num, int16_t den);
int32_t WebRtcSpl_DivResultInQ31(int32_t num, int32_t den);
int32_t WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low);
// End: Divisions.
int32_t WebRtcSpl_Energy(int16_t* vector,
size_t vector_length,
int* scale_factor);
// Filter operations.
size_t WebRtcSpl_FilterAR(const int16_t* ar_coef,
size_t ar_coef_length,
const int16_t* in_vector,
size_t in_vector_length,
int16_t* filter_state,
size_t filter_state_length,
int16_t* filter_state_low,
size_t filter_state_low_length,
int16_t* out_vector,
int16_t* out_vector_low,
size_t out_vector_low_length);
// WebRtcSpl_FilterMAFastQ12(...)
//
// Performs a MA filtering on a vector in Q12
//
// Input:
// - in_vector : Input samples (state in positions
// in_vector[-order] .. in_vector[-1])
// - ma_coef : Filter coefficients (in Q12)
// - ma_coef_length : Number of B coefficients (order+1)
// - vector_length : Number of samples to be filtered
//
// Output:
// - out_vector : Filtered samples
//
void WebRtcSpl_FilterMAFastQ12(const int16_t* in_vector,
int16_t* out_vector,
const int16_t* ma_coef,
size_t ma_coef_length,
size_t vector_length);
// Performs a AR filtering on a vector in Q12
// Input:
// - data_in : Input samples
// - data_out : State information in positions
// data_out[-order] .. data_out[-1]
// - coefficients : Filter coefficients (in Q12)
// - coefficients_length: Number of coefficients (order+1)
// - data_length : Number of samples to be filtered
// Output:
// - data_out : Filtered samples
void WebRtcSpl_FilterARFastQ12(const int16_t* data_in,
int16_t* data_out,
const int16_t* __restrict coefficients,
size_t coefficients_length,
size_t data_length);
// The functions (with related pointer) perform a MA down sampling filter
// on a vector.
// Input:
// - data_in : Input samples (state in positions
// data_in[-order] .. data_in[-1])
// - data_in_length : Number of samples in |data_in| to be filtered.
// This must be at least
// |delay| + |factor|*(|out_vector_length|-1) + 1)
// - data_out_length : Number of down sampled samples desired
// - coefficients : Filter coefficients (in Q12)
// - coefficients_length: Number of coefficients (order+1)
// - factor : Decimation factor
// - delay : Delay of filter (compensated for in out_vector)
// Output:
// - data_out : Filtered samples
// Return value : 0 if OK, -1 if |in_vector| is too short
typedef int (*DownsampleFast)(const int16_t* data_in,
size_t data_in_length,
int16_t* data_out,
size_t data_out_length,
const int16_t* __restrict coefficients,
size_t coefficients_length,
int factor,
size_t delay);
extern DownsampleFast WebRtcSpl_DownsampleFast;
int WebRtcSpl_DownsampleFastC(const int16_t* data_in,
size_t data_in_length,
int16_t* data_out,
size_t data_out_length,
const int16_t* __restrict coefficients,
size_t coefficients_length,
int factor,
size_t delay);
#if defined(WEBRTC_HAS_NEON)
int WebRtcSpl_DownsampleFastNeon(const int16_t* data_in,
size_t data_in_length,
int16_t* data_out,
size_t data_out_length,
const int16_t* __restrict coefficients,
size_t coefficients_length,
int factor,
size_t delay);
#endif
#if defined(MIPS32_LE)
int WebRtcSpl_DownsampleFast_mips(const int16_t* data_in,
size_t data_in_length,
int16_t* data_out,
size_t data_out_length,
const int16_t* __restrict coefficients,
size_t coefficients_length,
int factor,
size_t delay);
#endif
// End: Filter operations.
// FFT operations
int WebRtcSpl_ComplexFFT(int16_t vector[], int stages, int mode);
int WebRtcSpl_ComplexIFFT(int16_t vector[], int stages, int mode);
// Treat a 16-bit complex data buffer |complex_data| as an array of 32-bit
// values, and swap elements whose indexes are bit-reverses of each other.
//
// Input:
// - complex_data : Complex data buffer containing 2^|stages| real
// elements interleaved with 2^|stages| imaginary
// elements: [Re Im Re Im Re Im....]
// - stages : Number of FFT stages. Must be at least 3 and at most
// 10, since the table WebRtcSpl_kSinTable1024[] is 1024
// elements long.
//
// Output:
// - complex_data : The complex data buffer.
void WebRtcSpl_ComplexBitReverse(int16_t* __restrict complex_data, int stages);
// End: FFT operations
/************************************************************
*
* RESAMPLING FUNCTIONS AND THEIR STRUCTS ARE DEFINED BELOW
*
************************************************************/
/*******************************************************************
* resample.c
*
* Includes the following resampling combinations
* 22 kHz -> 16 kHz
* 16 kHz -> 22 kHz
* 22 kHz -> 8 kHz
* 8 kHz -> 22 kHz
*
******************************************************************/
// state structure for 22 -> 16 resampler
typedef struct {
int32_t S_22_44[8];
int32_t S_44_32[8];
int32_t S_32_16[8];
} WebRtcSpl_State22khzTo16khz;
void WebRtcSpl_Resample22khzTo16khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State22khzTo16khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample22khzTo16khz(WebRtcSpl_State22khzTo16khz* state);
// state structure for 16 -> 22 resampler
typedef struct {
int32_t S_16_32[8];
int32_t S_32_22[8];
} WebRtcSpl_State16khzTo22khz;
void WebRtcSpl_Resample16khzTo22khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State16khzTo22khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample16khzTo22khz(WebRtcSpl_State16khzTo22khz* state);
// state structure for 22 -> 8 resampler
typedef struct {
int32_t S_22_22[16];
int32_t S_22_16[8];
int32_t S_16_8[8];
} WebRtcSpl_State22khzTo8khz;
void WebRtcSpl_Resample22khzTo8khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State22khzTo8khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample22khzTo8khz(WebRtcSpl_State22khzTo8khz* state);
// state structure for 8 -> 22 resampler
typedef struct {
int32_t S_8_16[8];
int32_t S_16_11[8];
int32_t S_11_22[8];
} WebRtcSpl_State8khzTo22khz;
void WebRtcSpl_Resample8khzTo22khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State8khzTo22khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample8khzTo22khz(WebRtcSpl_State8khzTo22khz* state);
/*******************************************************************
* resample_fractional.c
* Functions for internal use in the other resample functions
*
* Includes the following resampling combinations
* 48 kHz -> 32 kHz
* 32 kHz -> 24 kHz
* 44 kHz -> 32 kHz
*
******************************************************************/
void WebRtcSpl_Resample48khzTo32khz(const int32_t* In, int32_t* Out, size_t K);
void WebRtcSpl_Resample32khzTo24khz(const int32_t* In, int32_t* Out, size_t K);
void WebRtcSpl_Resample44khzTo32khz(const int32_t* In, int32_t* Out, size_t K);
/*******************************************************************
* resample_48khz.c
*
* Includes the following resampling combinations
* 48 kHz -> 16 kHz
* 16 kHz -> 48 kHz
* 48 kHz -> 8 kHz
* 8 kHz -> 48 kHz
*
******************************************************************/
typedef struct {
int32_t S_48_48[16];
int32_t S_48_32[8];
int32_t S_32_16[8];
} WebRtcSpl_State48khzTo16khz;
void WebRtcSpl_Resample48khzTo16khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State48khzTo16khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample48khzTo16khz(WebRtcSpl_State48khzTo16khz* state);
typedef struct {
int32_t S_16_32[8];
int32_t S_32_24[8];
int32_t S_24_48[8];
} WebRtcSpl_State16khzTo48khz;
void WebRtcSpl_Resample16khzTo48khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State16khzTo48khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample16khzTo48khz(WebRtcSpl_State16khzTo48khz* state);
typedef struct {
int32_t S_48_24[8];
int32_t S_24_24[16];
int32_t S_24_16[8];
int32_t S_16_8[8];
} WebRtcSpl_State48khzTo8khz;
void WebRtcSpl_Resample48khzTo8khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State48khzTo8khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample48khzTo8khz(WebRtcSpl_State48khzTo8khz* state);
typedef struct {
int32_t S_8_16[8];
int32_t S_16_12[8];
int32_t S_12_24[8];
int32_t S_24_48[8];
} WebRtcSpl_State8khzTo48khz;
void WebRtcSpl_Resample8khzTo48khz(const int16_t* in,
int16_t* out,
WebRtcSpl_State8khzTo48khz* state,
int32_t* tmpmem);
void WebRtcSpl_ResetResample8khzTo48khz(WebRtcSpl_State8khzTo48khz* state);
/*******************************************************************
* resample_by_2.c
*
* Includes down and up sampling by a factor of two.
*
******************************************************************/
void WebRtcSpl_DownsampleBy2(const int16_t* in,
size_t len,
int16_t* out,
int32_t* filtState);
void WebRtcSpl_UpsampleBy2(const int16_t* in,
size_t len,
int16_t* out,
int32_t* filtState);
/************************************************************
* END OF RESAMPLING FUNCTIONS
************************************************************/
void WebRtcSpl_AnalysisQMF(const int16_t* in_data,
size_t in_data_length,
int16_t* low_band,
int16_t* high_band,
int32_t* filter_state1,
int32_t* filter_state2);
void WebRtcSpl_SynthesisQMF(const int16_t* low_band,
const int16_t* high_band,
size_t band_length,
int16_t* out_data,
int32_t* filter_state1,
int32_t* filter_state2);
#ifdef __cplusplus
}
#endif // __cplusplus
#endif // COMMON_AUDIO_SIGNAL_PROCESSING_INCLUDE_SIGNAL_PROCESSING_LIBRARY_H_
//
// WebRtcSpl_AddSatW16(...)
// WebRtcSpl_AddSatW32(...)
//
// Returns the result of a saturated 16-bit, respectively 32-bit, addition of
// the numbers specified by the |var1| and |var2| parameters.
//
// Input:
// - var1 : Input variable 1
// - var2 : Input variable 2
//
// Return value : Added and saturated value
//
//
// WebRtcSpl_SubSatW16(...)
// WebRtcSpl_SubSatW32(...)
//
// Returns the result of a saturated 16-bit, respectively 32-bit, subtraction
// of the numbers specified by the |var1| and |var2| parameters.
//
// Input:
// - var1 : Input variable 1
// - var2 : Input variable 2
//
// Returned value : Subtracted and saturated value
//
//
// WebRtcSpl_GetSizeInBits(...)
//
// Returns the # of bits that are needed at the most to represent the number
// specified by the |value| parameter.
//
// Input:
// - value : Input value
//
// Return value : Number of bits needed to represent |value|
//
//
// WebRtcSpl_NormW32(...)
//
// Norm returns the # of left shifts required to 32-bit normalize the 32-bit
// signed number specified by the |value| parameter.
//
// Input:
// - value : Input value
//
// Return value : Number of bit shifts needed to 32-bit normalize |value|
//
//
// WebRtcSpl_NormW16(...)
//
// Norm returns the # of left shifts required to 16-bit normalize the 16-bit
// signed number specified by the |value| parameter.
//
// Input:
// - value : Input value
//
// Return value : Number of bit shifts needed to 32-bit normalize |value|
//
//
// WebRtcSpl_NormU32(...)
//
// Norm returns the # of left shifts required to 32-bit normalize the unsigned
// 32-bit number specified by the |value| parameter.
//
// Input:
// - value : Input value
//
// Return value : Number of bit shifts needed to 32-bit normalize |value|
//
//
// WebRtcSpl_GetScalingSquare(...)
//
// Returns the # of bits required to scale the samples specified in the
// |in_vector| parameter so that, if the squares of the samples are added the
// # of times specified by the |times| parameter, the 32-bit addition will not
// overflow (result in int32_t).
//
// Input:
// - in_vector : Input vector to check scaling on
// - in_vector_length : Samples in |in_vector|
// - times : Number of additions to be performed
//
// Return value : Number of right bit shifts needed to avoid
// overflow in the addition calculation
//
//
// WebRtcSpl_MemSetW16(...)
//
// Sets all the values in the int16_t vector |vector| of length
// |vector_length| to the specified value |set_value|
//
// Input:
// - vector : Pointer to the int16_t vector
// - set_value : Value specified
// - vector_length : Length of vector
//
//
// WebRtcSpl_MemSetW32(...)
//
// Sets all the values in the int32_t vector |vector| of length
// |vector_length| to the specified value |set_value|
//
// Input:
// - vector : Pointer to the int16_t vector
// - set_value : Value specified
// - vector_length : Length of vector
//
//
// WebRtcSpl_MemCpyReversedOrder(...)
//
// Copies all the values from the source int16_t vector |in_vector| to a
// destination int16_t vector |out_vector|. It is done in reversed order,
// meaning that the first sample of |in_vector| is copied to the last sample of
// the |out_vector|. The procedure continues until the last sample of
// |in_vector| has been copied to the first sample of |out_vector|. This
// creates a reversed vector. Used in e.g. prediction in iLBC.
//
// Input:
// - in_vector : Pointer to the first sample in a int16_t vector
// of length |length|
// - vector_length : Number of elements to copy
//
// Output:
// - out_vector : Pointer to the last sample in a int16_t vector
// of length |length|
//
//
// WebRtcSpl_CopyFromEndW16(...)
//
// Copies the rightmost |samples| of |in_vector| (of length |in_vector_length|)
// to the vector |out_vector|.
//
// Input:
// - in_vector : Input vector
// - in_vector_length : Number of samples in |in_vector|
// - samples : Number of samples to extract (from right side)
// from |in_vector|
//
// Output:
// - out_vector : Vector with the requested samples
//
//
// WebRtcSpl_ZerosArrayW16(...)
// WebRtcSpl_ZerosArrayW32(...)
//
// Inserts the value "zero" in all positions of a w16 and a w32 vector
// respectively.
//
// Input:
// - vector_length : Number of samples in vector
//
// Output:
// - vector : Vector containing all zeros
//
//
// WebRtcSpl_VectorBitShiftW16(...)
// WebRtcSpl_VectorBitShiftW32(...)
//
// Bit shifts all the values in a vector up or downwards. Different calls for
// int16_t and int32_t vectors respectively.
//
// Input:
// - vector_length : Length of vector
// - in_vector : Pointer to the vector that should be bit shifted
// - right_shifts : Number of right bit shifts (negative value gives left
// shifts)
//
// Output:
// - out_vector : Pointer to the result vector (can be the same as
// |in_vector|)
//
//
// WebRtcSpl_VectorBitShiftW32ToW16(...)
//
// Bit shifts all the values in a int32_t vector up or downwards and
// stores the result as an int16_t vector. The function will saturate the
// signal if needed, before storing in the output vector.
//
// Input:
// - vector_length : Length of vector
// - in_vector : Pointer to the vector that should be bit shifted
// - right_shifts : Number of right bit shifts (negative value gives left
// shifts)
//
// Output:
// - out_vector : Pointer to the result vector (can be the same as
// |in_vector|)
//
//
// WebRtcSpl_ScaleVector(...)
//
// Performs the vector operation:
// out_vector[k] = (gain*in_vector[k])>>right_shifts
//
// Input:
// - in_vector : Input vector
// - gain : Scaling gain
// - vector_length : Elements in the |in_vector|
// - right_shifts : Number of right bit shifts applied
//
// Output:
// - out_vector : Output vector (can be the same as |in_vector|)
//
//
// WebRtcSpl_ScaleVectorWithSat(...)
//
// Performs the vector operation:
// out_vector[k] = SATURATE( (gain*in_vector[k])>>right_shifts )
//
// Input:
// - in_vector : Input vector
// - gain : Scaling gain
// - vector_length : Elements in the |in_vector|
// - right_shifts : Number of right bit shifts applied
//
// Output:
// - out_vector : Output vector (can be the same as |in_vector|)
//
//
// WebRtcSpl_ScaleAndAddVectors(...)
//
// Performs the vector operation:
// out_vector[k] = (gain1*in_vector1[k])>>right_shifts1
// + (gain2*in_vector2[k])>>right_shifts2
//
// Input:
// - in_vector1 : Input vector 1
// - gain1 : Gain to be used for vector 1
// - right_shifts1 : Right bit shift to be used for vector 1
// - in_vector2 : Input vector 2
// - gain2 : Gain to be used for vector 2
// - right_shifts2 : Right bit shift to be used for vector 2
// - vector_length : Elements in the input vectors
//
// Output:
// - out_vector : Output vector
//
//
// WebRtcSpl_ReverseOrderMultArrayElements(...)
//
// Performs the vector operation:
// out_vector[n] = (in_vector[n]*window[-n])>>right_shifts
//
// Input:
// - in_vector : Input vector
// - window : Window vector (should be reversed). The pointer
// should be set to the last value in the vector
// - right_shifts : Number of right bit shift to be applied after the
// multiplication
// - vector_length : Number of elements in |in_vector|
//
// Output:
// - out_vector : Output vector (can be same as |in_vector|)
//
//
// WebRtcSpl_ElementwiseVectorMult(...)
//
// Performs the vector operation:
// out_vector[n] = (in_vector[n]*window[n])>>right_shifts
//
// Input:
// - in_vector : Input vector
// - window : Window vector.
// - right_shifts : Number of right bit shift to be applied after the
// multiplication
// - vector_length : Number of elements in |in_vector|
//
// Output:
// - out_vector : Output vector (can be same as |in_vector|)
//
//
// WebRtcSpl_AddVectorsAndShift(...)
//
// Performs the vector operation:
// out_vector[k] = (in_vector1[k] + in_vector2[k])>>right_shifts
//
// Input:
// - in_vector1 : Input vector 1
// - in_vector2 : Input vector 2
// - right_shifts : Number of right bit shift to be applied after the
// multiplication
// - vector_length : Number of elements in |in_vector1| and |in_vector2|
//
// Output:
// - out_vector : Output vector (can be same as |in_vector1|)
//
//
// WebRtcSpl_AddAffineVectorToVector(...)
//
// Adds an affine transformed vector to another vector |out_vector|, i.e,
// performs
// out_vector[k] += (in_vector[k]*gain+add_constant)>>right_shifts
//
// Input:
// - in_vector : Input vector
// - gain : Gain value, used to multiply the in vector with
// - add_constant : Constant value to add (usually 1<<(right_shifts-1),
// but others can be used as well
// - right_shifts : Number of right bit shifts (0-16)
// - vector_length : Number of samples in |in_vector| and |out_vector|
//
// Output:
// - out_vector : Vector with the output
//
//
// WebRtcSpl_AffineTransformVector(...)
//
// Affine transforms a vector, i.e, performs
// out_vector[k] = (in_vector[k]*gain+add_constant)>>right_shifts
//
// Input:
// - in_vector : Input vector
// - gain : Gain value, used to multiply the in vector with
// - add_constant : Constant value to add (usually 1<<(right_shifts-1),
// but others can be used as well
// - right_shifts : Number of right bit shifts (0-16)
// - vector_length : Number of samples in |in_vector| and |out_vector|
//
// Output:
// - out_vector : Vector with the output
//
//
// WebRtcSpl_IncreaseSeed(...)
//
// Increases the seed (and returns the new value)
//
// Input:
// - seed : Seed for random calculation
//
// Output:
// - seed : Updated seed value
//
// Return value : The new seed value
//
//
// WebRtcSpl_RandU(...)
//
// Produces a uniformly distributed value in the int16_t range
//
// Input:
// - seed : Seed for random calculation
//
// Output:
// - seed : Updated seed value
//
// Return value : Uniformly distributed value in the range
// [Word16_MIN...Word16_MAX]
//
//
// WebRtcSpl_RandN(...)
//
// Produces a normal distributed value in the int16_t range
//
// Input:
// - seed : Seed for random calculation
//
// Output:
// - seed : Updated seed value
//
// Return value : N(0,1) value in the Q13 domain
//
//
// WebRtcSpl_RandUArray(...)
//
// Produces a uniformly distributed vector with elements in the int16_t
// range
//
// Input:
// - vector_length : Samples wanted in the vector
// - seed : Seed for random calculation
//
// Output:
// - vector : Vector with the uniform values
// - seed : Updated seed value
//
// Return value : Number of samples in vector, i.e., |vector_length|
//
//
// WebRtcSpl_Sqrt(...)
//
// Returns the square root of the input value |value|. The precision of this
// function is integer precision, i.e., sqrt(8) gives 2 as answer.
// If |value| is a negative number then 0 is returned.
//
// Algorithm:
//
// A sixth order Taylor Series expansion is used here to compute the square
// root of a number y^0.5 = (1+x)^0.5
// where
// x = y-1
// = 1+(x/2)-0.5*((x/2)^2+0.5*((x/2)^3-0.625*((x/2)^4+0.875*((x/2)^5)
// 0.5 <= x < 1
//
// Input:
// - value : Value to calculate sqrt of
//
// Return value : Result of the sqrt calculation
//
//
// WebRtcSpl_DivU32U16(...)
//
// Divides a uint32_t |num| by a uint16_t |den|.
//
// If |den|==0, (uint32_t)0xFFFFFFFF is returned.
//
// Input:
// - num : Numerator
// - den : Denominator
//
// Return value : Result of the division (as a uint32_t), i.e., the
// integer part of num/den.
//
//
// WebRtcSpl_DivW32W16(...)
//
// Divides a int32_t |num| by a int16_t |den|.
//
// If |den|==0, (int32_t)0x7FFFFFFF is returned.
//
// Input:
// - num : Numerator
// - den : Denominator
//
// Return value : Result of the division (as a int32_t), i.e., the
// integer part of num/den.
//
//
// WebRtcSpl_DivW32W16ResW16(...)
//
// Divides a int32_t |num| by a int16_t |den|, assuming that the
// result is less than 32768, otherwise an unpredictable result will occur.
//
// If |den|==0, (int16_t)0x7FFF is returned.
//
// Input:
// - num : Numerator
// - den : Denominator
//
// Return value : Result of the division (as a int16_t), i.e., the
// integer part of num/den.
//
//
// WebRtcSpl_DivResultInQ31(...)
//
// Divides a int32_t |num| by a int16_t |den|, assuming that the
// absolute value of the denominator is larger than the numerator, otherwise
// an unpredictable result will occur.
//
// Input:
// - num : Numerator
// - den : Denominator
//
// Return value : Result of the division in Q31.
//
//
// WebRtcSpl_DivW32HiLow(...)
//
// Divides a int32_t |num| by a denominator in hi, low format. The
// absolute value of the denominator has to be larger (or equal to) the
// numerator.
//
// Input:
// - num : Numerator
// - den_hi : High part of denominator
// - den_low : Low part of denominator
//
// Return value : Divided value in Q31
//
//
// WebRtcSpl_Energy(...)
//
// Calculates the energy of a vector
//
// Input:
// - vector : Vector which the energy should be calculated on
// - vector_length : Number of samples in vector
//
// Output:
// - scale_factor : Number of left bit shifts needed to get the physical
// energy value, i.e, to get the Q0 value
//
// Return value : Energy value in Q(-|scale_factor|)
//
//
// WebRtcSpl_FilterAR(...)
//
// Performs a 32-bit AR filtering on a vector in Q12
//
// Input:
// - ar_coef : AR-coefficient vector (values in Q12),
// ar_coef[0] must be 4096.
// - ar_coef_length : Number of coefficients in |ar_coef|.
// - in_vector : Vector to be filtered.
// - in_vector_length : Number of samples in |in_vector|.
// - filter_state : Current state (higher part) of the filter.
// - filter_state_length : Length (in samples) of |filter_state|.
// - filter_state_low : Current state (lower part) of the filter.
// - filter_state_low_length : Length (in samples) of |filter_state_low|.
// - out_vector_low_length : Maximum length (in samples) of
// |out_vector_low|.
//
// Output:
// - filter_state : Updated state (upper part) vector.
// - filter_state_low : Updated state (lower part) vector.
// - out_vector : Vector containing the upper part of the
// filtered values.
// - out_vector_low : Vector containing the lower part of the
// filtered values.
//
// Return value : Number of samples in the |out_vector|.
//
//
// WebRtcSpl_ComplexIFFT(...)
//
// Complex Inverse FFT
//
// Computes an inverse complex 2^|stages|-point FFT on the input vector, which
// is in bit-reversed order. The original content of the vector is destroyed in
// the process, since the input is overwritten by the output, normal-ordered,
// FFT vector. With X as the input complex vector, y as the output complex
// vector and with M = 2^|stages|, the following is computed:
//
// M-1
// y(k) = sum[X(i)*[cos(2*pi*i*k/M) + j*sin(2*pi*i*k/M)]]
// i=0
//
// The implementations are optimized for speed, not for code size. It uses the
// decimation-in-time algorithm with radix-2 butterfly technique.
//
// Input:
// - vector : In pointer to complex vector containing 2^|stages|
// real elements interleaved with 2^|stages| imaginary
// elements.
// [ReImReImReIm....]
// The elements are in Q(-scale) domain, see more on Return
// Value below.
//
// - stages : Number of FFT stages. Must be at least 3 and at most 10,
// since the table WebRtcSpl_kSinTable1024[] is 1024
// elements long.
//
// - mode : This parameter gives the user to choose how the FFT
// should work.
// mode==0: Low-complexity and Low-accuracy mode
// mode==1: High-complexity and High-accuracy mode
//
// Output:
// - vector : Out pointer to the FFT vector (the same as input).
//
// Return Value : The scale value that tells the number of left bit shifts
// that the elements in the |vector| should be shifted with
// in order to get Q0 values, i.e. the physically correct
// values. The scale parameter is always 0 or positive,
// except if N>1024 (|stages|>10), which returns a scale
// value of -1, indicating error.
//
//
// WebRtcSpl_ComplexFFT(...)
//
// Complex FFT
//
// Computes a complex 2^|stages|-point FFT on the input vector, which is in
// bit-reversed order. The original content of the vector is destroyed in
// the process, since the input is overwritten by the output, normal-ordered,
// FFT vector. With x as the input complex vector, Y as the output complex
// vector and with M = 2^|stages|, the following is computed:
//
// M-1
// Y(k) = 1/M * sum[x(i)*[cos(2*pi*i*k/M) + j*sin(2*pi*i*k/M)]]
// i=0
//
// The implementations are optimized for speed, not for code size. It uses the
// decimation-in-time algorithm with radix-2 butterfly technique.
//
// This routine prevents overflow by scaling by 2 before each FFT stage. This is
// a fixed scaling, for proper normalization - there will be log2(n) passes, so
// this results in an overall factor of 1/n, distributed to maximize arithmetic
// accuracy.
//
// Input:
// - vector : In pointer to complex vector containing 2^|stages| real
// elements interleaved with 2^|stages| imaginary elements.
// [ReImReImReIm....]
// The output is in the Q0 domain.
//
// - stages : Number of FFT stages. Must be at least 3 and at most 10,
// since the table WebRtcSpl_kSinTable1024[] is 1024
// elements long.
//
// - mode : This parameter gives the user to choose how the FFT
// should work.
// mode==0: Low-complexity and Low-accuracy mode
// mode==1: High-complexity and High-accuracy mode
//
// Output:
// - vector : The output FFT vector is in the Q0 domain.
//
// Return value : The scale parameter is always 0, except if N>1024,
// which returns a scale value of -1, indicating error.
//
//
// WebRtcSpl_AnalysisQMF(...)
//
// Splits a 0-2*F Hz signal into two sub bands: 0-F Hz and F-2*F Hz. The
// current version has F = 8000, therefore, a super-wideband audio signal is
// split to lower-band 0-8 kHz and upper-band 8-16 kHz.
//
// Input:
// - in_data : Wide band speech signal, 320 samples (10 ms)
//
// Input & Output:
// - filter_state1 : Filter state for first All-pass filter
// - filter_state2 : Filter state for second All-pass filter
//
// Output:
// - low_band : Lower-band signal 0-8 kHz band, 160 samples (10 ms)
// - high_band : Upper-band signal 8-16 kHz band (flipped in frequency
// domain), 160 samples (10 ms)
//
//
// WebRtcSpl_SynthesisQMF(...)
//
// Combines the two sub bands (0-F and F-2*F Hz) into a signal of 0-2*F
// Hz, (current version has F = 8000 Hz). So the filter combines lower-band
// (0-8 kHz) and upper-band (8-16 kHz) channels to obtain super-wideband 0-16
// kHz audio.
//
// Input:
// - low_band : The signal with the 0-8 kHz band, 160 samples (10 ms)
// - high_band : The signal with the 8-16 kHz band, 160 samples (10 ms)
//
// Input & Output:
// - filter_state1 : Filter state for first All-pass filter
// - filter_state2 : Filter state for second All-pass filter
//
// Output:
// - out_data : Super-wideband speech signal, 0-16 kHz
//
// int16_t WebRtcSpl_SatW32ToW16(...)
//
// This function saturates a 32-bit word into a 16-bit word.
//
// Input:
// - value32 : The value of a 32-bit word.
//
// Output:
// - out16 : the saturated 16-bit word.
//
// int32_t WebRtc_MulAccumW16(...)
//
// This function multiply a 16-bit word by a 16-bit word, and accumulate this
// value to a 32-bit integer.
//
// Input:
// - a : The value of the first 16-bit word.
// - b : The value of the second 16-bit word.
// - c : The value of an 32-bit integer.
//
// Return Value: The value of a * b + c.
//