common_audio/signal_processing/get_hanning_window.c

/*
 *  Copyright (c) 2011 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 file contains the function WebRtcSpl_GetHanningWindow().
 * The description header can be found in signal_processing_library.h
 *
 */

#include "common_audio/signal_processing/include/signal_processing_library.h"

// Hanning table with 256 entries
static const int16_t kHanningTable[] = {
    1,     2,     6,     10,    15,    22,    30,    39,    50,    62,    75,
    89,    104,   121,   138,   157,   178,   199,   222,   246,   271,   297,
    324,   353,   383,   413,   446,   479,   513,   549,   586,   624,   663,
    703,   744,   787,   830,   875,   920,   967,   1015,  1064,  1114,  1165,
    1218,  1271,  1325,  1381,  1437,  1494,  1553,  1612,  1673,  1734,  1796,
    1859,  1924,  1989,  2055,  2122,  2190,  2259,  2329,  2399,  2471,  2543,
    2617,  2691,  2765,  2841,  2918,  2995,  3073,  3152,  3232,  3312,  3393,
    3475,  3558,  3641,  3725,  3809,  3895,  3980,  4067,  4154,  4242,  4330,
    4419,  4509,  4599,  4689,  4781,  4872,  4964,  5057,  5150,  5244,  5338,
    5432,  5527,  5622,  5718,  5814,  5910,  6007,  6104,  6202,  6299,  6397,
    6495,  6594,  6693,  6791,  6891,  6990,  7090,  7189,  7289,  7389,  7489,
    7589,  7690,  7790,  7890,  7991,  8091,  8192,  8293,  8393,  8494,  8594,
    8694,  8795,  8895,  8995,  9095,  9195,  9294,  9394,  9493,  9593,  9691,
    9790,  9889,  9987,  10085, 10182, 10280, 10377, 10474, 10570, 10666, 10762,
    10857, 10952, 11046, 11140, 11234, 11327, 11420, 11512, 11603, 11695, 11785,
    11875, 11965, 12054, 12142, 12230, 12317, 12404, 12489, 12575, 12659, 12743,
    12826, 12909, 12991, 13072, 13152, 13232, 13311, 13389, 13466, 13543, 13619,
    13693, 13767, 13841, 13913, 13985, 14055, 14125, 14194, 14262, 14329, 14395,
    14460, 14525, 14588, 14650, 14711, 14772, 14831, 14890, 14947, 15003, 15059,
    15113, 15166, 15219, 15270, 15320, 15369, 15417, 15464, 15509, 15554, 15597,
    15640, 15681, 15721, 15760, 15798, 15835, 15871, 15905, 15938, 15971, 16001,
    16031, 16060, 16087, 16113, 16138, 16162, 16185, 16206, 16227, 16246, 16263,
    16280, 16295, 16309, 16322, 16334, 16345, 16354, 16362, 16369, 16374, 16378,
    16382, 16383, 16384};

void WebRtcSpl_GetHanningWindow(int16_t* v, size_t size) {
  size_t jj;
  int16_t* vptr1;

  int32_t index;
  int32_t factor = ((int32_t)0x40000000);

  factor = WebRtcSpl_DivW32W16(factor, (int16_t)size);
  if (size < 513)
    index = (int32_t)-0x200000;
  else
    index = (int32_t)-0x100000;
  vptr1 = v;

  for (jj = 0; jj < size; jj++) {
    index += factor;
    (*vptr1++) = kHanningTable[index >> 22];
  }
}