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      1 /*
      2  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 
     12 /*
     13  * This header file includes all of the fix point signal processing library (SPL) function
     14  * descriptions and declarations.
     15  * For specific function calls, see bottom of file.
     16  */
     17 
     18 #ifndef WEBRTC_SPL_SIGNAL_PROCESSING_LIBRARY_H_
     19 #define WEBRTC_SPL_SIGNAL_PROCESSING_LIBRARY_H_
     20 
     21 #include <string.h>
     22 #include "typedefs.h"
     23 
     24 #ifdef ARM_WINM
     25 #include <Armintr.h> // intrinsic file for windows mobile
     26 #endif
     27 
     28 // Macros specific for the fixed point implementation
     29 #define WEBRTC_SPL_WORD16_MAX       32767
     30 #define WEBRTC_SPL_WORD16_MIN       -32768
     31 #define WEBRTC_SPL_WORD32_MAX       (WebRtc_Word32)0x7fffffff
     32 #define WEBRTC_SPL_WORD32_MIN       (WebRtc_Word32)0x80000000
     33 #define WEBRTC_SPL_MAX_LPC_ORDER    14
     34 #define WEBRTC_SPL_MAX_SEED_USED    0x80000000L
     35 #define WEBRTC_SPL_MIN(A, B)        (A < B ? A : B) // Get min value
     36 #define WEBRTC_SPL_MAX(A, B)        (A > B ? A : B) // Get max value
     37 #define WEBRTC_SPL_ABS_W16(a) \
     38     (((WebRtc_Word16)a >= 0) ? ((WebRtc_Word16)a) : -((WebRtc_Word16)a))
     39 #define WEBRTC_SPL_ABS_W32(a) \
     40     (((WebRtc_Word32)a >= 0) ? ((WebRtc_Word32)a) : -((WebRtc_Word32)a))
     41 
     42 #if (defined WEBRTC_TARGET_PC)||(defined __TARGET_XSCALE)
     43 #define WEBRTC_SPL_GET_BYTE(a, nr)  (((WebRtc_Word8 *)a)[nr])
     44 #define WEBRTC_SPL_SET_BYTE(d_ptr, val, index) \
     45     (((WebRtc_Word8 *)d_ptr)[index] = (val))
     46 #elif defined WEBRTC_BIG_ENDIAN
     47 #define WEBRTC_SPL_GET_BYTE(a, nr) \
     48     ((((WebRtc_Word16 *)a)[nr >> 1]) >> (((nr + 1) & 0x1) * 8) & 0x00ff)
     49 #define WEBRTC_SPL_SET_BYTE(d_ptr, val, index) \
     50     ((WebRtc_Word16 *)d_ptr)[index >> 1] = \
     51     ((((WebRtc_Word16 *)d_ptr)[index >> 1]) \
     52     & (0x00ff << (8 * ((index) & 0x1)))) | (val << (8 * ((index + 1) & 0x1)))
     53 #else
     54 #define WEBRTC_SPL_GET_BYTE(a,nr) \
     55     ((((WebRtc_Word16 *)(a))[(nr) >> 1]) >> (((nr) & 0x1) * 8) & 0x00ff)
     56 #define WEBRTC_SPL_SET_BYTE(d_ptr, val, index) \
     57     ((WebRtc_Word16 *)(d_ptr))[(index) >> 1] = \
     58     ((((WebRtc_Word16 *)(d_ptr))[(index) >> 1]) \
     59     & (0x00ff << (8 * (((index) + 1) & 0x1)))) | \
     60     ((val) << (8 * ((index) & 0x1)))
     61 #endif
     62 
     63 #define WEBRTC_SPL_MUL(a, b) \
     64     ((WebRtc_Word32) ((WebRtc_Word32)(a) * (WebRtc_Word32)(b)))
     65 #define WEBRTC_SPL_UMUL(a, b) \
     66     ((WebRtc_UWord32) ((WebRtc_UWord32)(a) * (WebRtc_UWord32)(b)))
     67 #define WEBRTC_SPL_UMUL_RSFT16(a, b) \
     68     ((WebRtc_UWord32) ((WebRtc_UWord32)(a) * (WebRtc_UWord32)(b)) >> 16)
     69 #define WEBRTC_SPL_UMUL_16_16(a, b) \
     70     ((WebRtc_UWord32) (WebRtc_UWord16)(a) * (WebRtc_UWord16)(b))
     71 #define WEBRTC_SPL_UMUL_16_16_RSFT16(a, b) \
     72     (((WebRtc_UWord32) (WebRtc_UWord16)(a) * (WebRtc_UWord16)(b)) >> 16)
     73 #define WEBRTC_SPL_UMUL_32_16(a, b) \
     74     ((WebRtc_UWord32) ((WebRtc_UWord32)(a) * (WebRtc_UWord16)(b)))
     75 #define WEBRTC_SPL_UMUL_32_16_RSFT16(a, b) \
     76     ((WebRtc_UWord32) ((WebRtc_UWord32)(a) * (WebRtc_UWord16)(b)) >> 16)
     77 #define WEBRTC_SPL_MUL_16_U16(a, b) \
     78     ((WebRtc_Word32)(WebRtc_Word16)(a) * (WebRtc_UWord16)(b))
     79 #define WEBRTC_SPL_DIV(a, b) \
     80     ((WebRtc_Word32) ((WebRtc_Word32)(a) / (WebRtc_Word32)(b)))
     81 #define WEBRTC_SPL_UDIV(a, b) \
     82     ((WebRtc_UWord32) ((WebRtc_UWord32)(a) / (WebRtc_UWord32)(b)))
     83 
     84 #ifndef WEBRTC_ARCH_ARM_V7A
     85 // For ARMv7 platforms, these are inline functions in spl_inl_armv7.h
     86 #define WEBRTC_SPL_MUL_16_16(a, b) \
     87     ((WebRtc_Word32) (((WebRtc_Word16)(a)) * ((WebRtc_Word16)(b))))
     88 #define WEBRTC_SPL_MUL_16_32_RSFT16(a, b) \
     89     (WEBRTC_SPL_MUL_16_16(a, b >> 16) \
     90      + ((WEBRTC_SPL_MUL_16_16(a, (b & 0xffff) >> 1) + 0x4000) >> 15))
     91 #define WEBRTC_SPL_MUL_32_32_RSFT32(a32a, a32b, b32) \
     92     ((WebRtc_Word32)(WEBRTC_SPL_MUL_16_32_RSFT16(a32a, b32) \
     93     + (WEBRTC_SPL_MUL_16_32_RSFT16(a32b, b32) >> 16)))
     94 #define WEBRTC_SPL_MUL_32_32_RSFT32BI(a32, b32) \
     95     ((WebRtc_Word32)(WEBRTC_SPL_MUL_16_32_RSFT16(( \
     96     (WebRtc_Word16)(a32 >> 16)), b32) + \
     97     (WEBRTC_SPL_MUL_16_32_RSFT16(( \
     98     (WebRtc_Word16)((a32 & 0x0000FFFF) >> 1)), b32) >> 15)))
     99 #endif
    100 
    101 #define WEBRTC_SPL_MUL_16_32_RSFT11(a, b) \
    102     ((WEBRTC_SPL_MUL_16_16(a, (b) >> 16) << 5) \
    103     + (((WEBRTC_SPL_MUL_16_U16(a, (WebRtc_UWord16)(b)) >> 1) + 0x0200) >> 10))
    104 #define WEBRTC_SPL_MUL_16_32_RSFT14(a, b) \
    105     ((WEBRTC_SPL_MUL_16_16(a, (b) >> 16) << 2) \
    106     + (((WEBRTC_SPL_MUL_16_U16(a, (WebRtc_UWord16)(b)) >> 1) + 0x1000) >> 13))
    107 #define WEBRTC_SPL_MUL_16_32_RSFT15(a, b) \
    108     ((WEBRTC_SPL_MUL_16_16(a, (b) >> 16) << 1) \
    109     + (((WEBRTC_SPL_MUL_16_U16(a, (WebRtc_UWord16)(b)) >> 1) + 0x2000) >> 14))
    110 
    111 #ifdef ARM_WINM
    112 #define WEBRTC_SPL_MUL_16_16(a, b) \
    113     _SmulLo_SW_SL((WebRtc_Word16)(a), (WebRtc_Word16)(b))
    114 #endif
    115 
    116 #define WEBRTC_SPL_MUL_16_16_RSFT(a, b, c) \
    117     (WEBRTC_SPL_MUL_16_16(a, b) >> (c))
    118 
    119 #define WEBRTC_SPL_MUL_16_16_RSFT_WITH_ROUND(a, b, c) \
    120     ((WEBRTC_SPL_MUL_16_16(a, b) + ((WebRtc_Word32) \
    121                                   (((WebRtc_Word32)1) << ((c) - 1)))) >> (c))
    122 #define WEBRTC_SPL_MUL_16_16_RSFT_WITH_FIXROUND(a, b) \
    123     ((WEBRTC_SPL_MUL_16_16(a, b) + ((WebRtc_Word32) (1 << 14))) >> 15)
    124 
    125 // C + the 32 most significant bits of A * B
    126 #define WEBRTC_SPL_SCALEDIFF32(A, B, C) \
    127     (C + (B >> 16) * A + (((WebRtc_UWord32)(0x0000FFFF & B) * A) >> 16))
    128 
    129 #define WEBRTC_SPL_ADD_SAT_W32(a, b)    WebRtcSpl_AddSatW32(a, b)
    130 #define WEBRTC_SPL_SAT(a, b, c)         (b > a ? a : b < c ? c : b)
    131 #define WEBRTC_SPL_MUL_32_16(a, b)      ((a) * (b))
    132 
    133 #define WEBRTC_SPL_SUB_SAT_W32(a, b)    WebRtcSpl_SubSatW32(a, b)
    134 #define WEBRTC_SPL_ADD_SAT_W16(a, b)    WebRtcSpl_AddSatW16(a, b)
    135 #define WEBRTC_SPL_SUB_SAT_W16(a, b)    WebRtcSpl_SubSatW16(a, b)
    136 
    137 // We cannot do casting here due to signed/unsigned problem
    138 #define WEBRTC_SPL_IS_NEG(a)            ((a) & 0x80000000)
    139 // Shifting with negative numbers allowed
    140 // Positive means left shift
    141 #define WEBRTC_SPL_SHIFT_W16(x, c) \
    142     (((c) >= 0) ? ((x) << (c)) : ((x) >> (-(c))))
    143 #define WEBRTC_SPL_SHIFT_W32(x, c) \
    144     (((c) >= 0) ? ((x) << (c)) : ((x) >> (-(c))))
    145 
    146 // Shifting with negative numbers not allowed
    147 // We cannot do casting here due to signed/unsigned problem
    148 #define WEBRTC_SPL_RSHIFT_W16(x, c)     ((x) >> (c))
    149 #define WEBRTC_SPL_LSHIFT_W16(x, c)     ((x) << (c))
    150 #define WEBRTC_SPL_RSHIFT_W32(x, c)     ((x) >> (c))
    151 #define WEBRTC_SPL_LSHIFT_W32(x, c)     ((x) << (c))
    152 
    153 #define WEBRTC_SPL_RSHIFT_U16(x, c)     ((WebRtc_UWord16)(x) >> (c))
    154 #define WEBRTC_SPL_LSHIFT_U16(x, c)     ((WebRtc_UWord16)(x) << (c))
    155 #define WEBRTC_SPL_RSHIFT_U32(x, c)     ((WebRtc_UWord32)(x) >> (c))
    156 #define WEBRTC_SPL_LSHIFT_U32(x, c)     ((WebRtc_UWord32)(x) << (c))
    157 
    158 #define WEBRTC_SPL_VNEW(t, n)           (t *) malloc (sizeof (t) * (n))
    159 #define WEBRTC_SPL_FREE                 free
    160 
    161 #define WEBRTC_SPL_RAND(a) \
    162     ((WebRtc_Word16)(WEBRTC_SPL_MUL_16_16_RSFT((a), 18816, 7) & 0x00007fff))
    163 
    164 #ifdef __cplusplus
    165 extern "C"
    166 {
    167 #endif
    168 
    169 #define WEBRTC_SPL_MEMCPY_W8(v1, v2, length) \
    170    memcpy(v1, v2, (length) * sizeof(char))
    171 #define WEBRTC_SPL_MEMCPY_W16(v1, v2, length) \
    172    memcpy(v1, v2, (length) * sizeof(WebRtc_Word16))
    173 
    174 #define WEBRTC_SPL_MEMMOVE_W16(v1, v2, length) \
    175    memmove(v1, v2, (length) * sizeof(WebRtc_Word16))
    176 
    177 // inline functions:
    178 #include "spl_inl.h"
    179 
    180 // Get SPL Version
    181 WebRtc_Word16 WebRtcSpl_get_version(char* version,
    182                                     WebRtc_Word16 length_in_bytes);
    183 
    184 int WebRtcSpl_GetScalingSquare(WebRtc_Word16* in_vector,
    185                                int in_vector_length,
    186                                int times);
    187 
    188 // Copy and set operations. Implementation in copy_set_operations.c.
    189 // Descriptions at bottom of file.
    190 void WebRtcSpl_MemSetW16(WebRtc_Word16* vector,
    191                          WebRtc_Word16 set_value,
    192                          int vector_length);
    193 void WebRtcSpl_MemSetW32(WebRtc_Word32* vector,
    194                          WebRtc_Word32 set_value,
    195                          int vector_length);
    196 void WebRtcSpl_MemCpyReversedOrder(WebRtc_Word16* out_vector,
    197                                    WebRtc_Word16* in_vector,
    198                                    int vector_length);
    199 WebRtc_Word16 WebRtcSpl_CopyFromEndW16(G_CONST WebRtc_Word16* in_vector,
    200                                        WebRtc_Word16 in_vector_length,
    201                                        WebRtc_Word16 samples,
    202                                        WebRtc_Word16* out_vector);
    203 WebRtc_Word16 WebRtcSpl_ZerosArrayW16(WebRtc_Word16* vector,
    204                                       WebRtc_Word16 vector_length);
    205 WebRtc_Word16 WebRtcSpl_ZerosArrayW32(WebRtc_Word32* vector,
    206                                       WebRtc_Word16 vector_length);
    207 WebRtc_Word16 WebRtcSpl_OnesArrayW16(WebRtc_Word16* vector,
    208                                      WebRtc_Word16 vector_length);
    209 WebRtc_Word16 WebRtcSpl_OnesArrayW32(WebRtc_Word32* vector,
    210                                      WebRtc_Word16 vector_length);
    211 // End: Copy and set operations.
    212 
    213 // Minimum and maximum operations. Implementation in min_max_operations.c.
    214 // Descriptions at bottom of file.
    215 WebRtc_Word16 WebRtcSpl_MaxAbsValueW16(const WebRtc_Word16* vector,
    216                                        WebRtc_Word16 length);
    217 WebRtc_Word32 WebRtcSpl_MaxAbsValueW32(G_CONST WebRtc_Word32* vector,
    218                                        WebRtc_Word16 length);
    219 WebRtc_Word16 WebRtcSpl_MinValueW16(G_CONST WebRtc_Word16* vector,
    220                                     WebRtc_Word16 length);
    221 WebRtc_Word32 WebRtcSpl_MinValueW32(G_CONST WebRtc_Word32* vector,
    222                                     WebRtc_Word16 length);
    223 WebRtc_Word16 WebRtcSpl_MaxValueW16(G_CONST WebRtc_Word16* vector,
    224                                     WebRtc_Word16 length);
    225 
    226 WebRtc_Word16 WebRtcSpl_MaxAbsIndexW16(G_CONST WebRtc_Word16* vector,
    227                                        WebRtc_Word16 length);
    228 WebRtc_Word32 WebRtcSpl_MaxValueW32(G_CONST WebRtc_Word32* vector,
    229                                     WebRtc_Word16 length);
    230 WebRtc_Word16 WebRtcSpl_MinIndexW16(G_CONST WebRtc_Word16* vector,
    231                                     WebRtc_Word16 length);
    232 WebRtc_Word16 WebRtcSpl_MinIndexW32(G_CONST WebRtc_Word32* vector,
    233                                     WebRtc_Word16 length);
    234 WebRtc_Word16 WebRtcSpl_MaxIndexW16(G_CONST WebRtc_Word16* vector,
    235                                     WebRtc_Word16 length);
    236 WebRtc_Word16 WebRtcSpl_MaxIndexW32(G_CONST WebRtc_Word32* vector,
    237                                     WebRtc_Word16 length);
    238 // End: Minimum and maximum operations.
    239 
    240 // Vector scaling operations. Implementation in vector_scaling_operations.c.
    241 // Description at bottom of file.
    242 void WebRtcSpl_VectorBitShiftW16(WebRtc_Word16* out_vector,
    243                                  WebRtc_Word16 vector_length,
    244                                  G_CONST WebRtc_Word16* in_vector,
    245                                  WebRtc_Word16 right_shifts);
    246 void WebRtcSpl_VectorBitShiftW32(WebRtc_Word32* out_vector,
    247                                  WebRtc_Word16 vector_length,
    248                                  G_CONST WebRtc_Word32* in_vector,
    249                                  WebRtc_Word16 right_shifts);
    250 void WebRtcSpl_VectorBitShiftW32ToW16(WebRtc_Word16* out_vector,
    251                                       WebRtc_Word16 vector_length,
    252                                       G_CONST WebRtc_Word32* in_vector,
    253                                       WebRtc_Word16 right_shifts);
    254 
    255 void WebRtcSpl_ScaleVector(G_CONST WebRtc_Word16* in_vector,
    256                            WebRtc_Word16* out_vector,
    257                            WebRtc_Word16 gain,
    258                            WebRtc_Word16 vector_length,
    259                            WebRtc_Word16 right_shifts);
    260 void WebRtcSpl_ScaleVectorWithSat(G_CONST WebRtc_Word16* in_vector,
    261                                   WebRtc_Word16* out_vector,
    262                                   WebRtc_Word16 gain,
    263                                   WebRtc_Word16 vector_length,
    264                                   WebRtc_Word16 right_shifts);
    265 void WebRtcSpl_ScaleAndAddVectors(G_CONST WebRtc_Word16* in_vector1,
    266                                   WebRtc_Word16 gain1, int right_shifts1,
    267                                   G_CONST WebRtc_Word16* in_vector2,
    268                                   WebRtc_Word16 gain2, int right_shifts2,
    269                                   WebRtc_Word16* out_vector,
    270                                   int vector_length);
    271 // End: Vector scaling operations.
    272 
    273 // iLBC specific functions. Implementations in ilbc_specific_functions.c.
    274 // Description at bottom of file.
    275 void WebRtcSpl_ScaleAndAddVectorsWithRound(WebRtc_Word16* in_vector1,
    276                                            WebRtc_Word16 scale1,
    277                                            WebRtc_Word16* in_vector2,
    278                                            WebRtc_Word16 scale2,
    279                                            WebRtc_Word16 right_shifts,
    280                                            WebRtc_Word16* out_vector,
    281                                            WebRtc_Word16 vector_length);
    282 void WebRtcSpl_ReverseOrderMultArrayElements(WebRtc_Word16* out_vector,
    283                                              G_CONST WebRtc_Word16* in_vector,
    284                                              G_CONST WebRtc_Word16* window,
    285                                              WebRtc_Word16 vector_length,
    286                                              WebRtc_Word16 right_shifts);
    287 void WebRtcSpl_ElementwiseVectorMult(WebRtc_Word16* out_vector,
    288                                      G_CONST WebRtc_Word16* in_vector,
    289                                      G_CONST WebRtc_Word16* window,
    290                                      WebRtc_Word16 vector_length,
    291                                      WebRtc_Word16 right_shifts);
    292 void WebRtcSpl_AddVectorsAndShift(WebRtc_Word16* out_vector,
    293                                   G_CONST WebRtc_Word16* in_vector1,
    294                                   G_CONST WebRtc_Word16* in_vector2,
    295                                   WebRtc_Word16 vector_length,
    296                                   WebRtc_Word16 right_shifts);
    297 void WebRtcSpl_AddAffineVectorToVector(WebRtc_Word16* out_vector,
    298                                        WebRtc_Word16* in_vector,
    299                                        WebRtc_Word16 gain,
    300                                        WebRtc_Word32 add_constant,
    301                                        WebRtc_Word16 right_shifts,
    302                                        int vector_length);
    303 void WebRtcSpl_AffineTransformVector(WebRtc_Word16* out_vector,
    304                                      WebRtc_Word16* in_vector,
    305                                      WebRtc_Word16 gain,
    306                                      WebRtc_Word32 add_constant,
    307                                      WebRtc_Word16 right_shifts,
    308                                      int vector_length);
    309 // End: iLBC specific functions.
    310 
    311 // Signal processing operations. Descriptions at bottom of this file.
    312 int WebRtcSpl_AutoCorrelation(G_CONST WebRtc_Word16* vector,
    313                               int vector_length, int order,
    314                               WebRtc_Word32* result_vector,
    315                               int* scale);
    316 WebRtc_Word16 WebRtcSpl_LevinsonDurbin(WebRtc_Word32* auto_corr,
    317                                        WebRtc_Word16* lpc_coef,
    318                                        WebRtc_Word16* refl_coef,
    319                                        WebRtc_Word16 order);
    320 void WebRtcSpl_ReflCoefToLpc(G_CONST WebRtc_Word16* refl_coef,
    321                              int use_order,
    322                              WebRtc_Word16* lpc_coef);
    323 void WebRtcSpl_LpcToReflCoef(WebRtc_Word16* lpc_coef,
    324                              int use_order,
    325                              WebRtc_Word16* refl_coef);
    326 void WebRtcSpl_AutoCorrToReflCoef(G_CONST WebRtc_Word32* auto_corr,
    327                                   int use_order,
    328                                   WebRtc_Word16* refl_coef);
    329 void WebRtcSpl_CrossCorrelation(WebRtc_Word32* cross_corr,
    330                                 WebRtc_Word16* vector1,
    331                                 WebRtc_Word16* vector2,
    332                                 WebRtc_Word16 dim_vector,
    333                                 WebRtc_Word16 dim_cross_corr,
    334                                 WebRtc_Word16 right_shifts,
    335                                 WebRtc_Word16 step_vector2);
    336 void WebRtcSpl_GetHanningWindow(WebRtc_Word16* window, WebRtc_Word16 size);
    337 void WebRtcSpl_SqrtOfOneMinusXSquared(WebRtc_Word16* in_vector,
    338                                       int vector_length,
    339                                       WebRtc_Word16* out_vector);
    340 // End: Signal processing operations.
    341 
    342 // Randomization functions. Implementations collected in randomization_functions.c and
    343 // descriptions at bottom of this file.
    344 WebRtc_UWord32 WebRtcSpl_IncreaseSeed(WebRtc_UWord32* seed);
    345 WebRtc_Word16 WebRtcSpl_RandU(WebRtc_UWord32* seed);
    346 WebRtc_Word16 WebRtcSpl_RandN(WebRtc_UWord32* seed);
    347 WebRtc_Word16 WebRtcSpl_RandUArray(WebRtc_Word16* vector,
    348                                    WebRtc_Word16 vector_length,
    349                                    WebRtc_UWord32* seed);
    350 // End: Randomization functions.
    351 
    352 // Math functions
    353 WebRtc_Word32 WebRtcSpl_Sqrt(WebRtc_Word32 value);
    354 WebRtc_Word32 WebRtcSpl_SqrtFloor(WebRtc_Word32 value);
    355 
    356 // Divisions. Implementations collected in division_operations.c and
    357 // descriptions at bottom of this file.
    358 WebRtc_UWord32 WebRtcSpl_DivU32U16(WebRtc_UWord32 num, WebRtc_UWord16 den);
    359 WebRtc_Word32 WebRtcSpl_DivW32W16(WebRtc_Word32 num, WebRtc_Word16 den);
    360 WebRtc_Word16 WebRtcSpl_DivW32W16ResW16(WebRtc_Word32 num, WebRtc_Word16 den);
    361 WebRtc_Word32 WebRtcSpl_DivResultInQ31(WebRtc_Word32 num, WebRtc_Word32 den);
    362 WebRtc_Word32 WebRtcSpl_DivW32HiLow(WebRtc_Word32 num, WebRtc_Word16 den_hi,
    363                                     WebRtc_Word16 den_low);
    364 // End: Divisions.
    365 
    366 WebRtc_Word32 WebRtcSpl_Energy(WebRtc_Word16* vector,
    367                                int vector_length,
    368                                int* scale_factor);
    369 
    370 WebRtc_Word32 WebRtcSpl_DotProductWithScale(WebRtc_Word16* vector1,
    371                                             WebRtc_Word16* vector2,
    372                                             int vector_length,
    373                                             int scaling);
    374 
    375 // Filter operations.
    376 int WebRtcSpl_FilterAR(G_CONST WebRtc_Word16* ar_coef, int ar_coef_length,
    377                        G_CONST WebRtc_Word16* in_vector, int in_vector_length,
    378                        WebRtc_Word16* filter_state, int filter_state_length,
    379                        WebRtc_Word16* filter_state_low,
    380                        int filter_state_low_length, WebRtc_Word16* out_vector,
    381                        WebRtc_Word16* out_vector_low, int out_vector_low_length);
    382 
    383 void WebRtcSpl_FilterMAFastQ12(WebRtc_Word16* in_vector,
    384                                WebRtc_Word16* out_vector,
    385                                WebRtc_Word16* ma_coef,
    386                                WebRtc_Word16 ma_coef_length,
    387                                WebRtc_Word16 vector_length);
    388 void WebRtcSpl_FilterARFastQ12(WebRtc_Word16* in_vector,
    389                                WebRtc_Word16* out_vector,
    390                                WebRtc_Word16* ar_coef,
    391                                WebRtc_Word16 ar_coef_length,
    392                                WebRtc_Word16 vector_length);
    393 int WebRtcSpl_DownsampleFast(WebRtc_Word16* in_vector,
    394                              WebRtc_Word16 in_vector_length,
    395                              WebRtc_Word16* out_vector,
    396                              WebRtc_Word16 out_vector_length,
    397                              WebRtc_Word16* ma_coef,
    398                              WebRtc_Word16 ma_coef_length,
    399                              WebRtc_Word16 factor,
    400                              WebRtc_Word16 delay);
    401 // End: Filter operations.
    402 
    403 // FFT operations
    404 int WebRtcSpl_ComplexFFT(WebRtc_Word16 vector[], int stages, int mode);
    405 int WebRtcSpl_ComplexIFFT(WebRtc_Word16 vector[], int stages, int mode);
    406 void WebRtcSpl_ComplexBitReverse(WebRtc_Word16 vector[], int stages);
    407 // End: FFT operations
    408 
    409 /************************************************************
    410  *
    411  * RESAMPLING FUNCTIONS AND THEIR STRUCTS ARE DEFINED BELOW
    412  *
    413  ************************************************************/
    414 
    415 /*******************************************************************
    416  * resample.c
    417  *
    418  * Includes the following resampling combinations
    419  * 22 kHz -> 16 kHz
    420  * 16 kHz -> 22 kHz
    421  * 22 kHz ->  8 kHz
    422  *  8 kHz -> 22 kHz
    423  *
    424  ******************************************************************/
    425 
    426 // state structure for 22 -> 16 resampler
    427 typedef struct
    428 {
    429     WebRtc_Word32 S_22_44[8];
    430     WebRtc_Word32 S_44_32[8];
    431     WebRtc_Word32 S_32_16[8];
    432 } WebRtcSpl_State22khzTo16khz;
    433 
    434 void WebRtcSpl_Resample22khzTo16khz(const WebRtc_Word16* in,
    435                                     WebRtc_Word16* out,
    436                                     WebRtcSpl_State22khzTo16khz* state,
    437                                     WebRtc_Word32* tmpmem);
    438 
    439 void WebRtcSpl_ResetResample22khzTo16khz(WebRtcSpl_State22khzTo16khz* state);
    440 
    441 // state structure for 16 -> 22 resampler
    442 typedef struct
    443 {
    444     WebRtc_Word32 S_16_32[8];
    445     WebRtc_Word32 S_32_22[8];
    446 } WebRtcSpl_State16khzTo22khz;
    447 
    448 void WebRtcSpl_Resample16khzTo22khz(const WebRtc_Word16* in,
    449                                     WebRtc_Word16* out,
    450                                     WebRtcSpl_State16khzTo22khz* state,
    451                                     WebRtc_Word32* tmpmem);
    452 
    453 void WebRtcSpl_ResetResample16khzTo22khz(WebRtcSpl_State16khzTo22khz* state);
    454 
    455 // state structure for 22 -> 8 resampler
    456 typedef struct
    457 {
    458     WebRtc_Word32 S_22_22[16];
    459     WebRtc_Word32 S_22_16[8];
    460     WebRtc_Word32 S_16_8[8];
    461 } WebRtcSpl_State22khzTo8khz;
    462 
    463 void WebRtcSpl_Resample22khzTo8khz(const WebRtc_Word16* in, WebRtc_Word16* out,
    464                                    WebRtcSpl_State22khzTo8khz* state,
    465                                    WebRtc_Word32* tmpmem);
    466 
    467 void WebRtcSpl_ResetResample22khzTo8khz(WebRtcSpl_State22khzTo8khz* state);
    468 
    469 // state structure for 8 -> 22 resampler
    470 typedef struct
    471 {
    472     WebRtc_Word32 S_8_16[8];
    473     WebRtc_Word32 S_16_11[8];
    474     WebRtc_Word32 S_11_22[8];
    475 } WebRtcSpl_State8khzTo22khz;
    476 
    477 void WebRtcSpl_Resample8khzTo22khz(const WebRtc_Word16* in, WebRtc_Word16* out,
    478                                    WebRtcSpl_State8khzTo22khz* state,
    479                                    WebRtc_Word32* tmpmem);
    480 
    481 void WebRtcSpl_ResetResample8khzTo22khz(WebRtcSpl_State8khzTo22khz* state);
    482 
    483 /*******************************************************************
    484  * resample_fractional.c
    485  * Functions for internal use in the other resample functions
    486  *
    487  * Includes the following resampling combinations
    488  * 48 kHz -> 32 kHz
    489  * 32 kHz -> 24 kHz
    490  * 44 kHz -> 32 kHz
    491  *
    492  ******************************************************************/
    493 
    494 void WebRtcSpl_Resample48khzTo32khz(const WebRtc_Word32* In, WebRtc_Word32* Out,
    495                                     const WebRtc_Word32 K);
    496 
    497 void WebRtcSpl_Resample32khzTo24khz(const WebRtc_Word32* In, WebRtc_Word32* Out,
    498                                     const WebRtc_Word32 K);
    499 
    500 void WebRtcSpl_Resample44khzTo32khz(const WebRtc_Word32* In, WebRtc_Word32* Out,
    501                                     const WebRtc_Word32 K);
    502 
    503 /*******************************************************************
    504  * resample_48khz.c
    505  *
    506  * Includes the following resampling combinations
    507  * 48 kHz -> 16 kHz
    508  * 16 kHz -> 48 kHz
    509  * 48 kHz ->  8 kHz
    510  *  8 kHz -> 48 kHz
    511  *
    512  ******************************************************************/
    513 
    514 typedef struct
    515 {
    516     WebRtc_Word32 S_48_48[16];
    517     WebRtc_Word32 S_48_32[8];
    518     WebRtc_Word32 S_32_16[8];
    519 } WebRtcSpl_State48khzTo16khz;
    520 
    521 void WebRtcSpl_Resample48khzTo16khz(const WebRtc_Word16* in, WebRtc_Word16* out,
    522                                     WebRtcSpl_State48khzTo16khz* state,
    523                                     WebRtc_Word32* tmpmem);
    524 
    525 void WebRtcSpl_ResetResample48khzTo16khz(WebRtcSpl_State48khzTo16khz* state);
    526 
    527 typedef struct
    528 {
    529     WebRtc_Word32 S_16_32[8];
    530     WebRtc_Word32 S_32_24[8];
    531     WebRtc_Word32 S_24_48[8];
    532 } WebRtcSpl_State16khzTo48khz;
    533 
    534 void WebRtcSpl_Resample16khzTo48khz(const WebRtc_Word16* in, WebRtc_Word16* out,
    535                                     WebRtcSpl_State16khzTo48khz* state,
    536                                     WebRtc_Word32* tmpmem);
    537 
    538 void WebRtcSpl_ResetResample16khzTo48khz(WebRtcSpl_State16khzTo48khz* state);
    539 
    540 typedef struct
    541 {
    542     WebRtc_Word32 S_48_24[8];
    543     WebRtc_Word32 S_24_24[16];
    544     WebRtc_Word32 S_24_16[8];
    545     WebRtc_Word32 S_16_8[8];
    546 } WebRtcSpl_State48khzTo8khz;
    547 
    548 void WebRtcSpl_Resample48khzTo8khz(const WebRtc_Word16* in, WebRtc_Word16* out,
    549                                    WebRtcSpl_State48khzTo8khz* state,
    550                                    WebRtc_Word32* tmpmem);
    551 
    552 void WebRtcSpl_ResetResample48khzTo8khz(WebRtcSpl_State48khzTo8khz* state);
    553 
    554 typedef struct
    555 {
    556     WebRtc_Word32 S_8_16[8];
    557     WebRtc_Word32 S_16_12[8];
    558     WebRtc_Word32 S_12_24[8];
    559     WebRtc_Word32 S_24_48[8];
    560 } WebRtcSpl_State8khzTo48khz;
    561 
    562 void WebRtcSpl_Resample8khzTo48khz(const WebRtc_Word16* in, WebRtc_Word16* out,
    563                                    WebRtcSpl_State8khzTo48khz* state,
    564                                    WebRtc_Word32* tmpmem);
    565 
    566 void WebRtcSpl_ResetResample8khzTo48khz(WebRtcSpl_State8khzTo48khz* state);
    567 
    568 /*******************************************************************
    569  * resample_by_2.c
    570  *
    571  * Includes down and up sampling by a factor of two.
    572  *
    573  ******************************************************************/
    574 
    575 void WebRtcSpl_DownsampleBy2(const WebRtc_Word16* in, const WebRtc_Word16 len,
    576                              WebRtc_Word16* out, WebRtc_Word32* filtState);
    577 
    578 void WebRtcSpl_UpsampleBy2(const WebRtc_Word16* in, WebRtc_Word16 len, WebRtc_Word16* out,
    579                            WebRtc_Word32* filtState);
    580 
    581 /************************************************************
    582  * END OF RESAMPLING FUNCTIONS
    583  ************************************************************/
    584 void WebRtcSpl_AnalysisQMF(const WebRtc_Word16* in_data,
    585                            WebRtc_Word16* low_band,
    586                            WebRtc_Word16* high_band,
    587                            WebRtc_Word32* filter_state1,
    588                            WebRtc_Word32* filter_state2);
    589 void WebRtcSpl_SynthesisQMF(const WebRtc_Word16* low_band,
    590                             const WebRtc_Word16* high_band,
    591                             WebRtc_Word16* out_data,
    592                             WebRtc_Word32* filter_state1,
    593                             WebRtc_Word32* filter_state2);
    594 
    595 #ifdef __cplusplus
    596 }
    597 #endif // __cplusplus
    598 #endif // WEBRTC_SPL_SIGNAL_PROCESSING_LIBRARY_H_
    599 
    600 //
    601 // WebRtcSpl_AddSatW16(...)
    602 // WebRtcSpl_AddSatW32(...)
    603 //
    604 // Returns the result of a saturated 16-bit, respectively 32-bit, addition of
    605 // the numbers specified by the |var1| and |var2| parameters.
    606 //
    607 // Input:
    608 //      - var1      : Input variable 1
    609 //      - var2      : Input variable 2
    610 //
    611 // Return value     : Added and saturated value
    612 //
    613 
    614 //
    615 // WebRtcSpl_SubSatW16(...)
    616 // WebRtcSpl_SubSatW32(...)
    617 //
    618 // Returns the result of a saturated 16-bit, respectively 32-bit, subtraction
    619 // of the numbers specified by the |var1| and |var2| parameters.
    620 //
    621 // Input:
    622 //      - var1      : Input variable 1
    623 //      - var2      : Input variable 2
    624 //
    625 // Returned value   : Subtracted and saturated value
    626 //
    627 
    628 //
    629 // WebRtcSpl_GetSizeInBits(...)
    630 //
    631 // Returns the # of bits that are needed at the most to represent the number
    632 // specified by the |value| parameter.
    633 //
    634 // Input:
    635 //      - value     : Input value
    636 //
    637 // Return value     : Number of bits needed to represent |value|
    638 //
    639 
    640 //
    641 // WebRtcSpl_NormW32(...)
    642 //
    643 // Norm returns the # of left shifts required to 32-bit normalize the 32-bit
    644 // signed number specified by the |value| parameter.
    645 //
    646 // Input:
    647 //      - value     : Input value
    648 //
    649 // Return value     : Number of bit shifts needed to 32-bit normalize |value|
    650 //
    651 
    652 //
    653 // WebRtcSpl_NormW16(...)
    654 //
    655 // Norm returns the # of left shifts required to 16-bit normalize the 16-bit
    656 // signed number specified by the |value| parameter.
    657 //
    658 // Input:
    659 //      - value     : Input value
    660 //
    661 // Return value     : Number of bit shifts needed to 32-bit normalize |value|
    662 //
    663 
    664 //
    665 // WebRtcSpl_NormU32(...)
    666 //
    667 // Norm returns the # of left shifts required to 32-bit normalize the unsigned
    668 // 32-bit number specified by the |value| parameter.
    669 //
    670 // Input:
    671 //      - value     : Input value
    672 //
    673 // Return value     : Number of bit shifts needed to 32-bit normalize |value|
    674 //
    675 
    676 //
    677 // WebRtcSpl_GetScalingSquare(...)
    678 //
    679 // Returns the # of bits required to scale the samples specified in the
    680 // |in_vector| parameter so that, if the squares of the samples are added the
    681 // # of times specified by the |times| parameter, the 32-bit addition will not
    682 // overflow (result in WebRtc_Word32).
    683 //
    684 // Input:
    685 //      - in_vector         : Input vector to check scaling on
    686 //      - in_vector_length  : Samples in |in_vector|
    687 //      - times             : Number of additions to be performed
    688 //
    689 // Return value             : Number of right bit shifts needed to avoid
    690 //                            overflow in the addition calculation
    691 //
    692 
    693 //
    694 // WebRtcSpl_MemSetW16(...)
    695 //
    696 // Sets all the values in the WebRtc_Word16 vector |vector| of length
    697 // |vector_length| to the specified value |set_value|
    698 //
    699 // Input:
    700 //      - vector        : Pointer to the WebRtc_Word16 vector
    701 //      - set_value     : Value specified
    702 //      - vector_length : Length of vector
    703 //
    704 
    705 //
    706 // WebRtcSpl_MemSetW32(...)
    707 //
    708 // Sets all the values in the WebRtc_Word32 vector |vector| of length
    709 // |vector_length| to the specified value |set_value|
    710 //
    711 // Input:
    712 //      - vector        : Pointer to the WebRtc_Word16 vector
    713 //      - set_value     : Value specified
    714 //      - vector_length : Length of vector
    715 //
    716 
    717 //
    718 // WebRtcSpl_MemCpyReversedOrder(...)
    719 //
    720 // Copies all the values from the source WebRtc_Word16 vector |in_vector| to a
    721 // destination WebRtc_Word16 vector |out_vector|. It is done in reversed order,
    722 // meaning that the first sample of |in_vector| is copied to the last sample of
    723 // the |out_vector|. The procedure continues until the last sample of
    724 // |in_vector| has been copied to the first sample of |out_vector|. This
    725 // creates a reversed vector. Used in e.g. prediction in iLBC.
    726 //
    727 // Input:
    728 //      - in_vector     : Pointer to the first sample in a WebRtc_Word16 vector
    729 //                        of length |length|
    730 //      - vector_length : Number of elements to copy
    731 //
    732 // Output:
    733 //      - out_vector    : Pointer to the last sample in a WebRtc_Word16 vector
    734 //                        of length |length|
    735 //
    736 
    737 //
    738 // WebRtcSpl_CopyFromEndW16(...)
    739 //
    740 // Copies the rightmost |samples| of |in_vector| (of length |in_vector_length|)
    741 // to the vector |out_vector|.
    742 //
    743 // Input:
    744 //      - in_vector         : Input vector
    745 //      - in_vector_length  : Number of samples in |in_vector|
    746 //      - samples           : Number of samples to extract (from right side)
    747 //                            from |in_vector|
    748 //
    749 // Output:
    750 //      - out_vector        : Vector with the requested samples
    751 //
    752 // Return value             : Number of copied samples in |out_vector|
    753 //
    754 
    755 //
    756 // WebRtcSpl_ZerosArrayW16(...)
    757 // WebRtcSpl_ZerosArrayW32(...)
    758 //
    759 // Inserts the value "zero" in all positions of a w16 and a w32 vector
    760 // respectively.
    761 //
    762 // Input:
    763 //      - vector_length : Number of samples in vector
    764 //
    765 // Output:
    766 //      - vector        : Vector containing all zeros
    767 //
    768 // Return value         : Number of samples in vector
    769 //
    770 
    771 //
    772 // WebRtcSpl_OnesArrayW16(...)
    773 // WebRtcSpl_OnesArrayW32(...)
    774 //
    775 // Inserts the value "one" in all positions of a w16 and a w32 vector
    776 // respectively.
    777 //
    778 // Input:
    779 //      - vector_length : Number of samples in vector
    780 //
    781 // Output:
    782 //      - vector        : Vector containing all ones
    783 //
    784 // Return value         : Number of samples in vector
    785 //
    786 
    787 //
    788 // WebRtcSpl_MinValueW16(...)
    789 // WebRtcSpl_MinValueW32(...)
    790 //
    791 // Returns the minimum value of a vector
    792 //
    793 // Input:
    794 //      - vector        : Input vector
    795 //      - vector_length : Number of samples in vector
    796 //
    797 // Return value         : Minimum sample value in vector
    798 //
    799 
    800 //
    801 // WebRtcSpl_MaxValueW16(...)
    802 // WebRtcSpl_MaxValueW32(...)
    803 //
    804 // Returns the maximum value of a vector
    805 //
    806 // Input:
    807 //      - vector        : Input vector
    808 //      - vector_length : Number of samples in vector
    809 //
    810 // Return value         : Maximum sample value in vector
    811 //
    812 
    813 //
    814 // WebRtcSpl_MaxAbsValueW16(...)
    815 // WebRtcSpl_MaxAbsValueW32(...)
    816 //
    817 // Returns the largest absolute value of a vector
    818 //
    819 // Input:
    820 //      - vector        : Input vector
    821 //      - vector_length : Number of samples in vector
    822 //
    823 // Return value         : Maximum absolute value in vector
    824 //
    825 
    826 //
    827 // WebRtcSpl_MaxAbsIndexW16(...)
    828 //
    829 // Returns the vector index to the largest absolute value of a vector
    830 //
    831 // Input:
    832 //      - vector        : Input vector
    833 //      - vector_length : Number of samples in vector
    834 //
    835 // Return value         : Index to maximum absolute value in vector
    836 //
    837 
    838 //
    839 // WebRtcSpl_MinIndexW16(...)
    840 // WebRtcSpl_MinIndexW32(...)
    841 //
    842 // Returns the vector index to the minimum sample value of a vector
    843 //
    844 // Input:
    845 //      - vector        : Input vector
    846 //      - vector_length : Number of samples in vector
    847 //
    848 // Return value         : Index to minimum sample value in vector
    849 //
    850 
    851 //
    852 // WebRtcSpl_MaxIndexW16(...)
    853 // WebRtcSpl_MaxIndexW32(...)
    854 //
    855 // Returns the vector index to the maximum sample value of a vector
    856 //
    857 // Input:
    858 //      - vector        : Input vector
    859 //      - vector_length : Number of samples in vector
    860 //
    861 // Return value         : Index to maximum sample value in vector
    862 //
    863 
    864 //
    865 // WebRtcSpl_VectorBitShiftW16(...)
    866 // WebRtcSpl_VectorBitShiftW32(...)
    867 //
    868 // Bit shifts all the values in a vector up or downwards. Different calls for
    869 // WebRtc_Word16 and WebRtc_Word32 vectors respectively.
    870 //
    871 // Input:
    872 //      - vector_length : Length of vector
    873 //      - in_vector     : Pointer to the vector that should be bit shifted
    874 //      - right_shifts  : Number of right bit shifts (negative value gives left
    875 //                        shifts)
    876 //
    877 // Output:
    878 //      - out_vector    : Pointer to the result vector (can be the same as
    879 //                        |in_vector|)
    880 //
    881 
    882 //
    883 // WebRtcSpl_VectorBitShiftW32ToW16(...)
    884 //
    885 // Bit shifts all the values in a WebRtc_Word32 vector up or downwards and
    886 // stores the result as a WebRtc_Word16 vector
    887 //
    888 // Input:
    889 //      - vector_length : Length of vector
    890 //      - in_vector     : Pointer to the vector that should be bit shifted
    891 //      - right_shifts  : Number of right bit shifts (negative value gives left
    892 //                        shifts)
    893 //
    894 // Output:
    895 //      - out_vector    : Pointer to the result vector (can be the same as
    896 //                        |in_vector|)
    897 //
    898 
    899 //
    900 // WebRtcSpl_ScaleVector(...)
    901 //
    902 // Performs the vector operation:
    903 //  out_vector[k] = (gain*in_vector[k])>>right_shifts
    904 //
    905 // Input:
    906 //      - in_vector     : Input vector
    907 //      - gain          : Scaling gain
    908 //      - vector_length : Elements in the |in_vector|
    909 //      - right_shifts  : Number of right bit shifts applied
    910 //
    911 // Output:
    912 //      - out_vector    : Output vector (can be the same as |in_vector|)
    913 //
    914 
    915 //
    916 // WebRtcSpl_ScaleVectorWithSat(...)
    917 //
    918 // Performs the vector operation:
    919 //  out_vector[k] = SATURATE( (gain*in_vector[k])>>right_shifts )
    920 //
    921 // Input:
    922 //      - in_vector     : Input vector
    923 //      - gain          : Scaling gain
    924 //      - vector_length : Elements in the |in_vector|
    925 //      - right_shifts  : Number of right bit shifts applied
    926 //
    927 // Output:
    928 //      - out_vector    : Output vector (can be the same as |in_vector|)
    929 //
    930 
    931 //
    932 // WebRtcSpl_ScaleAndAddVectors(...)
    933 //
    934 // Performs the vector operation:
    935 //  out_vector[k] = (gain1*in_vector1[k])>>right_shifts1
    936 //                  + (gain2*in_vector2[k])>>right_shifts2
    937 //
    938 // Input:
    939 //      - in_vector1    : Input vector 1
    940 //      - gain1         : Gain to be used for vector 1
    941 //      - right_shifts1 : Right bit shift to be used for vector 1
    942 //      - in_vector2    : Input vector 2
    943 //      - gain2         : Gain to be used for vector 2
    944 //      - right_shifts2 : Right bit shift to be used for vector 2
    945 //      - vector_length : Elements in the input vectors
    946 //
    947 // Output:
    948 //      - out_vector    : Output vector
    949 //
    950 
    951 //
    952 // WebRtcSpl_ScaleAndAddVectorsWithRound(...)
    953 //
    954 // Performs the vector operation:
    955 //
    956 //  out_vector[k] = ((scale1*in_vector1[k]) + (scale2*in_vector2[k])
    957 //                      + round_value) >> right_shifts
    958 //
    959 //      where:
    960 //
    961 //  round_value = (1<<right_shifts)>>1
    962 //
    963 // Input:
    964 //      - in_vector1    : Input vector 1
    965 //      - scale1        : Gain to be used for vector 1
    966 //      - in_vector2    : Input vector 2
    967 //      - scale2        : Gain to be used for vector 2
    968 //      - right_shifts  : Number of right bit shifts to be applied
    969 //      - vector_length : Number of elements in the input vectors
    970 //
    971 // Output:
    972 //      - out_vector    : Output vector
    973 //
    974 
    975 //
    976 // WebRtcSpl_ReverseOrderMultArrayElements(...)
    977 //
    978 // Performs the vector operation:
    979 //  out_vector[n] = (in_vector[n]*window[-n])>>right_shifts
    980 //
    981 // Input:
    982 //      - in_vector     : Input vector
    983 //      - window        : Window vector (should be reversed). The pointer
    984 //                        should be set to the last value in the vector
    985 //      - right_shifts  : Number of right bit shift to be applied after the
    986 //                        multiplication
    987 //      - vector_length : Number of elements in |in_vector|
    988 //
    989 // Output:
    990 //      - out_vector    : Output vector (can be same as |in_vector|)
    991 //
    992 
    993 //
    994 // WebRtcSpl_ElementwiseVectorMult(...)
    995 //
    996 // Performs the vector operation:
    997 //  out_vector[n] = (in_vector[n]*window[n])>>right_shifts
    998 //
    999 // Input:
   1000 //      - in_vector     : Input vector
   1001 //      - window        : Window vector.
   1002 //      - right_shifts  : Number of right bit shift to be applied after the
   1003 //                        multiplication
   1004 //      - vector_length : Number of elements in |in_vector|
   1005 //
   1006 // Output:
   1007 //      - out_vector    : Output vector (can be same as |in_vector|)
   1008 //
   1009 
   1010 //
   1011 // WebRtcSpl_AddVectorsAndShift(...)
   1012 //
   1013 // Performs the vector operation:
   1014 //  out_vector[k] = (in_vector1[k] + in_vector2[k])>>right_shifts
   1015 //
   1016 // Input:
   1017 //      - in_vector1    : Input vector 1
   1018 //      - in_vector2    : Input vector 2
   1019 //      - right_shifts  : Number of right bit shift to be applied after the
   1020 //                        multiplication
   1021 //      - vector_length : Number of elements in |in_vector1| and |in_vector2|
   1022 //
   1023 // Output:
   1024 //      - out_vector    : Output vector (can be same as |in_vector1|)
   1025 //
   1026 
   1027 //
   1028 // WebRtcSpl_AddAffineVectorToVector(...)
   1029 //
   1030 // Adds an affine transformed vector to another vector |out_vector|, i.e,
   1031 // performs
   1032 //  out_vector[k] += (in_vector[k]*gain+add_constant)>>right_shifts
   1033 //
   1034 // Input:
   1035 //      - in_vector     : Input vector
   1036 //      - gain          : Gain value, used to multiply the in vector with
   1037 //      - add_constant  : Constant value to add (usually 1<<(right_shifts-1),
   1038 //                        but others can be used as well
   1039 //      - right_shifts  : Number of right bit shifts (0-16)
   1040 //      - vector_length : Number of samples in |in_vector| and |out_vector|
   1041 //
   1042 // Output:
   1043 //      - out_vector    : Vector with the output
   1044 //
   1045 
   1046 //
   1047 // WebRtcSpl_AffineTransformVector(...)
   1048 //
   1049 // Affine transforms a vector, i.e, performs
   1050 //  out_vector[k] = (in_vector[k]*gain+add_constant)>>right_shifts
   1051 //
   1052 // Input:
   1053 //      - in_vector     : Input vector
   1054 //      - gain          : Gain value, used to multiply the in vector with
   1055 //      - add_constant  : Constant value to add (usually 1<<(right_shifts-1),
   1056 //                        but others can be used as well
   1057 //      - right_shifts  : Number of right bit shifts (0-16)
   1058 //      - vector_length : Number of samples in |in_vector| and |out_vector|
   1059 //
   1060 // Output:
   1061 //      - out_vector    : Vector with the output
   1062 //
   1063 
   1064 //
   1065 // WebRtcSpl_AutoCorrelation(...)
   1066 //
   1067 // A 32-bit fix-point implementation of auto-correlation computation
   1068 //
   1069 // Input:
   1070 //      - vector        : Vector to calculate autocorrelation upon
   1071 //      - vector_length : Length (in samples) of |vector|
   1072 //      - order         : The order up to which the autocorrelation should be
   1073 //                        calculated
   1074 //
   1075 // Output:
   1076 //      - result_vector : auto-correlation values (values should be seen
   1077 //                        relative to each other since the absolute values
   1078 //                        might have been down shifted to avoid overflow)
   1079 //
   1080 //      - scale         : The number of left shifts required to obtain the
   1081 //                        auto-correlation in Q0
   1082 //
   1083 // Return value         : Number of samples in |result_vector|, i.e., (order+1)
   1084 //
   1085 
   1086 //
   1087 // WebRtcSpl_LevinsonDurbin(...)
   1088 //
   1089 // A 32-bit fix-point implementation of the Levinson-Durbin algorithm that
   1090 // does NOT use the 64 bit class
   1091 //
   1092 // Input:
   1093 //      - auto_corr : Vector with autocorrelation values of length >=
   1094 //                    |use_order|+1
   1095 //      - use_order : The LPC filter order (support up to order 20)
   1096 //
   1097 // Output:
   1098 //      - lpc_coef  : lpc_coef[0..use_order] LPC coefficients in Q12
   1099 //      - refl_coef : refl_coef[0...use_order-1]| Reflection coefficients in
   1100 //                    Q15
   1101 //
   1102 // Return value     : 1 for stable 0 for unstable
   1103 //
   1104 
   1105 //
   1106 // WebRtcSpl_ReflCoefToLpc(...)
   1107 //
   1108 // Converts reflection coefficients |refl_coef| to LPC coefficients |lpc_coef|.
   1109 // This version is a 16 bit operation.
   1110 //
   1111 // NOTE: The 16 bit refl_coef -> lpc_coef conversion might result in a
   1112 // "slightly unstable" filter (i.e., a pole just outside the unit circle) in
   1113 // "rare" cases even if the reflection coefficients are stable.
   1114 //
   1115 // Input:
   1116 //      - refl_coef : Reflection coefficients in Q15 that should be converted
   1117 //                    to LPC coefficients
   1118 //      - use_order : Number of coefficients in |refl_coef|
   1119 //
   1120 // Output:
   1121 //      - lpc_coef  : LPC coefficients in Q12
   1122 //
   1123 
   1124 //
   1125 // WebRtcSpl_LpcToReflCoef(...)
   1126 //
   1127 // Converts LPC coefficients |lpc_coef| to reflection coefficients |refl_coef|.
   1128 // This version is a 16 bit operation.
   1129 // The conversion is implemented by the step-down algorithm.
   1130 //
   1131 // Input:
   1132 //      - lpc_coef  : LPC coefficients in Q12, that should be converted to
   1133 //                    reflection coefficients
   1134 //      - use_order : Number of coefficients in |lpc_coef|
   1135 //
   1136 // Output:
   1137 //      - refl_coef : Reflection coefficients in Q15.
   1138 //
   1139 
   1140 //
   1141 // WebRtcSpl_AutoCorrToReflCoef(...)
   1142 //
   1143 // Calculates reflection coefficients (16 bit) from auto-correlation values
   1144 //
   1145 // Input:
   1146 //      - auto_corr : Auto-correlation values
   1147 //      - use_order : Number of coefficients wanted be calculated
   1148 //
   1149 // Output:
   1150 //      - refl_coef : Reflection coefficients in Q15.
   1151 //
   1152 
   1153 //
   1154 // WebRtcSpl_CrossCorrelation(...)
   1155 //
   1156 // Calculates the cross-correlation between two sequences |vector1| and
   1157 // |vector2|. |vector1| is fixed and |vector2| slides as the pointer is
   1158 // increased with the amount |step_vector2|
   1159 //
   1160 // Input:
   1161 //      - vector1           : First sequence (fixed throughout the correlation)
   1162 //      - vector2           : Second sequence (slides |step_vector2| for each
   1163 //                            new correlation)
   1164 //      - dim_vector        : Number of samples to use in the cross-correlation
   1165 //      - dim_cross_corr    : Number of cross-correlations to calculate (the
   1166 //                            start position for |vector2| is updated for each
   1167 //                            new one)
   1168 //      - right_shifts      : Number of right bit shifts to use. This will
   1169 //                            become the output Q-domain.
   1170 //      - step_vector2      : How many (positive or negative) steps the
   1171 //                            |vector2| pointer should be updated for each new
   1172 //                            cross-correlation value.
   1173 //
   1174 // Output:
   1175 //      - cross_corr        : The cross-correlation in Q(-right_shifts)
   1176 //
   1177 
   1178 //
   1179 // WebRtcSpl_GetHanningWindow(...)
   1180 //
   1181 // Creates (the first half of) a Hanning window. Size must be at least 1 and
   1182 // at most 512.
   1183 //
   1184 // Input:
   1185 //      - size      : Length of the requested Hanning window (1 to 512)
   1186 //
   1187 // Output:
   1188 //      - window    : Hanning vector in Q14.
   1189 //
   1190 
   1191 //
   1192 // WebRtcSpl_SqrtOfOneMinusXSquared(...)
   1193 //
   1194 // Calculates y[k] = sqrt(1 - x[k]^2) for each element of the input vector
   1195 // |in_vector|. Input and output values are in Q15.
   1196 //
   1197 // Inputs:
   1198 //      - in_vector     : Values to calculate sqrt(1 - x^2) of
   1199 //      - vector_length : Length of vector |in_vector|
   1200 //
   1201 // Output:
   1202 //      - out_vector    : Output values in Q15
   1203 //
   1204 
   1205 //
   1206 // WebRtcSpl_IncreaseSeed(...)
   1207 //
   1208 // Increases the seed (and returns the new value)
   1209 //
   1210 // Input:
   1211 //      - seed      : Seed for random calculation
   1212 //
   1213 // Output:
   1214 //      - seed      : Updated seed value
   1215 //
   1216 // Return value     : The new seed value
   1217 //
   1218 
   1219 //
   1220 // WebRtcSpl_RandU(...)
   1221 //
   1222 // Produces a uniformly distributed value in the WebRtc_Word16 range
   1223 //
   1224 // Input:
   1225 //      - seed      : Seed for random calculation
   1226 //
   1227 // Output:
   1228 //      - seed      : Updated seed value
   1229 //
   1230 // Return value     : Uniformly distributed value in the range
   1231 //                    [Word16_MIN...Word16_MAX]
   1232 //
   1233 
   1234 //
   1235 // WebRtcSpl_RandN(...)
   1236 //
   1237 // Produces a normal distributed value in the WebRtc_Word16 range
   1238 //
   1239 // Input:
   1240 //      - seed      : Seed for random calculation
   1241 //
   1242 // Output:
   1243 //      - seed      : Updated seed value
   1244 //
   1245 // Return value     : N(0,1) value in the Q13 domain
   1246 //
   1247 
   1248 //
   1249 // WebRtcSpl_RandUArray(...)
   1250 //
   1251 // Produces a uniformly distributed vector with elements in the WebRtc_Word16
   1252 // range
   1253 //
   1254 // Input:
   1255 //      - vector_length : Samples wanted in the vector
   1256 //      - seed          : Seed for random calculation
   1257 //
   1258 // Output:
   1259 //      - vector        : Vector with the uniform values
   1260 //      - seed          : Updated seed value
   1261 //
   1262 // Return value         : Number of samples in vector, i.e., |vector_length|
   1263 //
   1264 
   1265 //
   1266 // WebRtcSpl_Sqrt(...)
   1267 //
   1268 // Returns the square root of the input value |value|. The precision of this
   1269 // function is integer precision, i.e., sqrt(8) gives 2 as answer.
   1270 // If |value| is a negative number then 0 is returned.
   1271 //
   1272 // Algorithm:
   1273 //
   1274 // A sixth order Taylor Series expansion is used here to compute the square
   1275 // root of a number y^0.5 = (1+x)^0.5
   1276 // where
   1277 // x = y-1
   1278 //   = 1+(x/2)-0.5*((x/2)^2+0.5*((x/2)^3-0.625*((x/2)^4+0.875*((x/2)^5)
   1279 // 0.5 <= x < 1
   1280 //
   1281 // Input:
   1282 //      - value     : Value to calculate sqrt of
   1283 //
   1284 // Return value     : Result of the sqrt calculation
   1285 //
   1286 
   1287 //
   1288 // WebRtcSpl_SqrtFloor(...)
   1289 //
   1290 // Returns the square root of the input value |value|. The precision of this
   1291 // function is rounding down integer precision, i.e., sqrt(8) gives 2 as answer.
   1292 // If |value| is a negative number then 0 is returned.
   1293 //
   1294 // Algorithm:
   1295 //
   1296 // An iterative 4 cylce/bit routine
   1297 //
   1298 // Input:
   1299 //      - value     : Value to calculate sqrt of
   1300 //
   1301 // Return value     : Result of the sqrt calculation
   1302 //
   1303 
   1304 //
   1305 // WebRtcSpl_DivU32U16(...)
   1306 //
   1307 // Divides a WebRtc_UWord32 |num| by a WebRtc_UWord16 |den|.
   1308 //
   1309 // If |den|==0, (WebRtc_UWord32)0xFFFFFFFF is returned.
   1310 //
   1311 // Input:
   1312 //      - num       : Numerator
   1313 //      - den       : Denominator
   1314 //
   1315 // Return value     : Result of the division (as a WebRtc_UWord32), i.e., the
   1316 //                    integer part of num/den.
   1317 //
   1318 
   1319 //
   1320 // WebRtcSpl_DivW32W16(...)
   1321 //
   1322 // Divides a WebRtc_Word32 |num| by a WebRtc_Word16 |den|.
   1323 //
   1324 // If |den|==0, (WebRtc_Word32)0x7FFFFFFF is returned.
   1325 //
   1326 // Input:
   1327 //      - num       : Numerator
   1328 //      - den       : Denominator
   1329 //
   1330 // Return value     : Result of the division (as a WebRtc_Word32), i.e., the
   1331 //                    integer part of num/den.
   1332 //
   1333 
   1334 //
   1335 // WebRtcSpl_DivW32W16ResW16(...)
   1336 //
   1337 // Divides a WebRtc_Word32 |num| by a WebRtc_Word16 |den|, assuming that the
   1338 // result is less than 32768, otherwise an unpredictable result will occur.
   1339 //
   1340 // If |den|==0, (WebRtc_Word16)0x7FFF is returned.
   1341 //
   1342 // Input:
   1343 //      - num       : Numerator
   1344 //      - den       : Denominator
   1345 //
   1346 // Return value     : Result of the division (as a WebRtc_Word16), i.e., the
   1347 //                    integer part of num/den.
   1348 //
   1349 
   1350 //
   1351 // WebRtcSpl_DivResultInQ31(...)
   1352 //
   1353 // Divides a WebRtc_Word32 |num| by a WebRtc_Word16 |den|, assuming that the
   1354 // absolute value of the denominator is larger than the numerator, otherwise
   1355 // an unpredictable result will occur.
   1356 //
   1357 // Input:
   1358 //      - num       : Numerator
   1359 //      - den       : Denominator
   1360 //
   1361 // Return value     : Result of the division in Q31.
   1362 //
   1363 
   1364 //
   1365 // WebRtcSpl_DivW32HiLow(...)
   1366 //
   1367 // Divides a WebRtc_Word32 |num| by a denominator in hi, low format. The
   1368 // absolute value of the denominator has to be larger (or equal to) the
   1369 // numerator.
   1370 //
   1371 // Input:
   1372 //      - num       : Numerator
   1373 //      - den_hi    : High part of denominator
   1374 //      - den_low   : Low part of denominator
   1375 //
   1376 // Return value     : Divided value in Q31
   1377 //
   1378 
   1379 //
   1380 // WebRtcSpl_Energy(...)
   1381 //
   1382 // Calculates the energy of a vector
   1383 //
   1384 // Input:
   1385 //      - vector        : Vector which the energy should be calculated on
   1386 //      - vector_length : Number of samples in vector
   1387 //
   1388 // Output:
   1389 //      - scale_factor  : Number of left bit shifts needed to get the physical
   1390 //                        energy value, i.e, to get the Q0 value
   1391 //
   1392 // Return value         : Energy value in Q(-|scale_factor|)
   1393 //
   1394 
   1395 //
   1396 // WebRtcSpl_FilterAR(...)
   1397 //
   1398 // Performs a 32-bit AR filtering on a vector in Q12
   1399 //
   1400 // Input:
   1401 //  - ar_coef                   : AR-coefficient vector (values in Q12),
   1402 //                                ar_coef[0] must be 4096.
   1403 //  - ar_coef_length            : Number of coefficients in |ar_coef|.
   1404 //  - in_vector                 : Vector to be filtered.
   1405 //  - in_vector_length          : Number of samples in |in_vector|.
   1406 //  - filter_state              : Current state (higher part) of the filter.
   1407 //  - filter_state_length       : Length (in samples) of |filter_state|.
   1408 //  - filter_state_low          : Current state (lower part) of the filter.
   1409 //  - filter_state_low_length   : Length (in samples) of |filter_state_low|.
   1410 //  - out_vector_low_length     : Maximum length (in samples) of
   1411 //                                |out_vector_low|.
   1412 //
   1413 // Output:
   1414 //  - filter_state              : Updated state (upper part) vector.
   1415 //  - filter_state_low          : Updated state (lower part) vector.
   1416 //  - out_vector                : Vector containing the upper part of the
   1417 //                                filtered values.
   1418 //  - out_vector_low            : Vector containing the lower part of the
   1419 //                                filtered values.
   1420 //
   1421 // Return value                 : Number of samples in the |out_vector|.
   1422 //
   1423 
   1424 //
   1425 // WebRtcSpl_FilterMAFastQ12(...)
   1426 //
   1427 // Performs a MA filtering on a vector in Q12
   1428 //
   1429 // Input:
   1430 //      - in_vector         : Input samples (state in positions
   1431 //                            in_vector[-order] .. in_vector[-1])
   1432 //      - ma_coef           : Filter coefficients (in Q12)
   1433 //      - ma_coef_length    : Number of B coefficients (order+1)
   1434 //      - vector_length     : Number of samples to be filtered
   1435 //
   1436 // Output:
   1437 //      - out_vector        : Filtered samples
   1438 //
   1439 
   1440 //
   1441 // WebRtcSpl_FilterARFastQ12(...)
   1442 //
   1443 // Performs a AR filtering on a vector in Q12
   1444 //
   1445 // Input:
   1446 //      - in_vector         : Input samples
   1447 //      - out_vector        : State information in positions
   1448 //                            out_vector[-order] .. out_vector[-1]
   1449 //      - ar_coef           : Filter coefficients (in Q12)
   1450 //      - ar_coef_length    : Number of B coefficients (order+1)
   1451 //      - vector_length     : Number of samples to be filtered
   1452 //
   1453 // Output:
   1454 //      - out_vector        : Filtered samples
   1455 //
   1456 
   1457 //
   1458 // WebRtcSpl_DownsampleFast(...)
   1459 //
   1460 // Performs a MA down sampling filter on a vector
   1461 //
   1462 // Input:
   1463 //      - in_vector         : Input samples (state in positions
   1464 //                            in_vector[-order] .. in_vector[-1])
   1465 //      - in_vector_length  : Number of samples in |in_vector| to be filtered.
   1466 //                            This must be at least
   1467 //                            |delay| + |factor|*(|out_vector_length|-1) + 1)
   1468 //      - out_vector_length : Number of down sampled samples desired
   1469 //      - ma_coef           : Filter coefficients (in Q12)
   1470 //      - ma_coef_length    : Number of B coefficients (order+1)
   1471 //      - factor            : Decimation factor
   1472 //      - delay             : Delay of filter (compensated for in out_vector)
   1473 //
   1474 // Output:
   1475 //      - out_vector        : Filtered samples
   1476 //
   1477 // Return value             : 0 if OK, -1 if |in_vector| is too short
   1478 //
   1479 
   1480 //
   1481 // WebRtcSpl_DotProductWithScale(...)
   1482 //
   1483 // Calculates the dot product between two (WebRtc_Word16) vectors
   1484 //
   1485 // Input:
   1486 //      - vector1       : Vector 1
   1487 //      - vector2       : Vector 2
   1488 //      - vector_length : Number of samples used in the dot product
   1489 //      - scaling       : The number of right bit shifts to apply on each term
   1490 //                        during calculation to avoid overflow, i.e., the
   1491 //                        output will be in Q(-|scaling|)
   1492 //
   1493 // Return value         : The dot product in Q(-scaling)
   1494 //
   1495 
   1496 //
   1497 // WebRtcSpl_ComplexIFFT(...)
   1498 //
   1499 // Complex Inverse FFT
   1500 //
   1501 // Computes an inverse complex 2^|stages|-point FFT on the input vector, which
   1502 // is in bit-reversed order. The original content of the vector is destroyed in
   1503 // the process, since the input is overwritten by the output, normal-ordered,
   1504 // FFT vector. With X as the input complex vector, y as the output complex
   1505 // vector and with M = 2^|stages|, the following is computed:
   1506 //
   1507 //        M-1
   1508 // y(k) = sum[X(i)*[cos(2*pi*i*k/M) + j*sin(2*pi*i*k/M)]]
   1509 //        i=0
   1510 //
   1511 // The implementations are optimized for speed, not for code size. It uses the
   1512 // decimation-in-time algorithm with radix-2 butterfly technique.
   1513 //
   1514 // Input:
   1515 //      - vector    : In pointer to complex vector containing 2^|stages|
   1516 //                    real elements interleaved with 2^|stages| imaginary
   1517 //                    elements.
   1518 //                    [ReImReImReIm....]
   1519 //                    The elements are in Q(-scale) domain, see more on Return
   1520 //                    Value below.
   1521 //
   1522 //      - stages    : Number of FFT stages. Must be at least 3 and at most 10,
   1523 //                    since the table WebRtcSpl_kSinTable1024[] is 1024
   1524 //                    elements long.
   1525 //
   1526 //      - mode      : This parameter gives the user to choose how the FFT
   1527 //                    should work.
   1528 //                    mode==0: Low-complexity and Low-accuracy mode
   1529 //                    mode==1: High-complexity and High-accuracy mode
   1530 //
   1531 // Output:
   1532 //      - vector    : Out pointer to the FFT vector (the same as input).
   1533 //
   1534 // Return Value     : The scale value that tells the number of left bit shifts
   1535 //                    that the elements in the |vector| should be shifted with
   1536 //                    in order to get Q0 values, i.e. the physically correct
   1537 //                    values. The scale parameter is always 0 or positive,
   1538 //                    except if N>1024 (|stages|>10), which returns a scale
   1539 //                    value of -1, indicating error.
   1540 //
   1541 
   1542 //
   1543 // WebRtcSpl_ComplexFFT(...)
   1544 //
   1545 // Complex FFT
   1546 //
   1547 // Computes a complex 2^|stages|-point FFT on the input vector, which is in
   1548 // bit-reversed order. The original content of the vector is destroyed in
   1549 // the process, since the input is overwritten by the output, normal-ordered,
   1550 // FFT vector. With x as the input complex vector, Y as the output complex
   1551 // vector and with M = 2^|stages|, the following is computed:
   1552 //
   1553 //              M-1
   1554 // Y(k) = 1/M * sum[x(i)*[cos(2*pi*i*k/M) + j*sin(2*pi*i*k/M)]]
   1555 //              i=0
   1556 //
   1557 // The implementations are optimized for speed, not for code size. It uses the
   1558 // decimation-in-time algorithm with radix-2 butterfly technique.
   1559 //
   1560 // This routine prevents overflow by scaling by 2 before each FFT stage. This is
   1561 // a fixed scaling, for proper normalization - there will be log2(n) passes, so
   1562 // this results in an overall factor of 1/n, distributed to maximize arithmetic
   1563 // accuracy.
   1564 //
   1565 // Input:
   1566 //      - vector    : In pointer to complex vector containing 2^|stages| real
   1567 //                    elements interleaved with 2^|stages| imaginary elements.
   1568 //                    [ReImReImReIm....]
   1569 //                    The output is in the Q0 domain.
   1570 //
   1571 //      - stages    : Number of FFT stages. Must be at least 3 and at most 10,
   1572 //                    since the table WebRtcSpl_kSinTable1024[] is 1024
   1573 //                    elements long.
   1574 //
   1575 //      - mode      : This parameter gives the user to choose how the FFT
   1576 //                    should work.
   1577 //                    mode==0: Low-complexity and Low-accuracy mode
   1578 //                    mode==1: High-complexity and High-accuracy mode
   1579 //
   1580 // Output:
   1581 //      - vector    : The output FFT vector is in the Q0 domain.
   1582 //
   1583 // Return value     : The scale parameter is always 0, except if N>1024,
   1584 //                    which returns a scale value of -1, indicating error.
   1585 //
   1586 
   1587 //
   1588 // WebRtcSpl_ComplexBitReverse(...)
   1589 //
   1590 // Complex Bit Reverse
   1591 //
   1592 // This function bit-reverses the position of elements in the complex input
   1593 // vector into the output vector.
   1594 //
   1595 // If you bit-reverse a linear-order array, you obtain a bit-reversed order
   1596 // array. If you bit-reverse a bit-reversed order array, you obtain a
   1597 // linear-order array.
   1598 //
   1599 // Input:
   1600 //      - vector    : In pointer to complex vector containing 2^|stages| real
   1601 //                    elements interleaved with 2^|stages| imaginary elements.
   1602 //                    [ReImReImReIm....]
   1603 //      - stages    : Number of FFT stages. Must be at least 3 and at most 10,
   1604 //                    since the table WebRtcSpl_kSinTable1024[] is 1024
   1605 //                    elements long.
   1606 //
   1607 // Output:
   1608 //      - vector    : Out pointer to complex vector in bit-reversed order.
   1609 //                    The input vector is over written.
   1610 //
   1611 
   1612 //
   1613 // WebRtcSpl_AnalysisQMF(...)
   1614 //
   1615 // Splits a 0-2*F Hz signal into two sub bands: 0-F Hz and F-2*F Hz. The
   1616 // current version has F = 8000, therefore, a super-wideband audio signal is
   1617 // split to lower-band 0-8 kHz and upper-band 8-16 kHz.
   1618 //
   1619 // Input:
   1620 //      - in_data       : Wide band speech signal, 320 samples (10 ms)
   1621 //
   1622 // Input & Output:
   1623 //      - filter_state1 : Filter state for first All-pass filter
   1624 //      - filter_state2 : Filter state for second All-pass filter
   1625 //
   1626 // Output:
   1627 //      - low_band      : Lower-band signal 0-8 kHz band, 160 samples (10 ms)
   1628 //      - high_band     : Upper-band signal 8-16 kHz band (flipped in frequency
   1629 //                        domain), 160 samples (10 ms)
   1630 //
   1631 
   1632 //
   1633 // WebRtcSpl_SynthesisQMF(...)
   1634 //
   1635 // Combines the two sub bands (0-F and F-2*F Hz) into a signal of 0-2*F
   1636 // Hz, (current version has F = 8000 Hz). So the filter combines lower-band
   1637 // (0-8 kHz) and upper-band (8-16 kHz) channels to obtain super-wideband 0-16
   1638 // kHz audio.
   1639 //
   1640 // Input:
   1641 //      - low_band      : The signal with the 0-8 kHz band, 160 samples (10 ms)
   1642 //      - high_band     : The signal with the 8-16 kHz band, 160 samples (10 ms)
   1643 //
   1644 // Input & Output:
   1645 //      - filter_state1 : Filter state for first All-pass filter
   1646 //      - filter_state2 : Filter state for second All-pass filter
   1647 //
   1648 // Output:
   1649 //      - out_data      : Super-wideband speech signal, 0-16 kHz
   1650 //
   1651 
   1652 // WebRtc_Word16 WebRtcSpl_SatW32ToW16(...)
   1653 //
   1654 // This function saturates a 32-bit word into a 16-bit word.
   1655 //
   1656 // Input:
   1657 //      - value32   : The value of a 32-bit word.
   1658 //
   1659 // Output:
   1660 //      - out16     : the saturated 16-bit word.
   1661 //
   1662 
   1663 // int32_t WebRtc_MulAccumW16(...)
   1664 //
   1665 // This function multiply a 16-bit word by a 16-bit word, and accumulate this
   1666 // value to a 32-bit integer.
   1667 //
   1668 // Input:
   1669 //      - a    : The value of the first 16-bit word.
   1670 //      - b    : The value of the second 16-bit word.
   1671 //      - c    : The value of an 32-bit integer.
   1672 //
   1673 // Return Value: The value of a * b + c.
   1674 //
   1675 
   1676 // WebRtc_Word16 WebRtcSpl_get_version(...)
   1677 //
   1678 // This function gives the version string of the Signal Processing Library.
   1679 //
   1680 // Input:
   1681 //      - length_in_bytes   : The size of Allocated space (in Bytes) where
   1682 //                            the version number is written to (in string format).
   1683 //
   1684 // Output:
   1685 //      - version           : Pointer to a buffer where the version number is written to.
   1686 //
   1687