/*
  * Header file for hardcoded DSD tables
  * based on BSD licensed dsd2pcm by Sebastian Gesemann
  * Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved.
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVCODEC_DSD_TABLEGEN_H
 #define AVCODEC_DSD_TABLEGEN_H
 
 #include <stdint.h>
 #include "libavutil/attributes.h"
 
 #define HTAPS   48                /** number of FIR constants */
 #define CTABLES ((HTAPS + 7) / 8) /** number of "8 MACs" lookup tables */
 
 #if CONFIG_HARDCODED_TABLES
 #define dsd_ctables_tableinit()
 #include "libavcodec/dsd_tables.h"
 #else
 #include "libavutil/common.h"
 
 /*
  * Properties of this 96-tap lowpass filter when applied on a signal
  * with sampling rate of 44100*64 Hz:
  *
  * () has a delay of 17 microseconds.
  *
  * () flat response up to 48 kHz
  *
  * () if you downsample afterwards by a factor of 8, the
  *    spectrum below 70 kHz is practically alias-free.
  *
  * () stopband rejection is about 160 dB
  *
  * The coefficient tables ("ctables") take only 6 Kibi Bytes and
  * should fit into a modern processor's fast cache.
  */
 
 /**
  * The 2nd half (48 coeffs) of a 96-tap symmetric lowpass filter
  */
 static const double htaps[HTAPS] = {
      0.09950731974056658,    0.09562845727714668,    0.08819647126516944,
      0.07782552527068175,    0.06534876523171299,    0.05172629311427257,
      0.0379429484910187,     0.02490921351762261,    0.0133774746265897,
      0.003883043418804416,  -0.003284703416210726,  -0.008080250212687497,
     -0.01067241812471033,   -0.01139427235000863,   -0.0106813877974587,
     -0.009007905078766049,  -0.006828859761015335,  -0.004535184322001496,
     -0.002425035959059578,  -0.0006922187080790708,  0.0005700762133516592,
      0.001353838005269448,   0.001713709169690937,   0.001742046839472948,
      0.001545601648013235,   0.001226696225277855,   0.0008704322683580222,
      0.0005381636200535649,  0.000266446345425276,   7.002968738383528e-05,
     -5.279407053811266e-05, -0.0001140625650874684, -0.0001304796361231895,
     -0.0001189970287491285, -9.396247155265073e-05, -6.577634378272832e-05,
     -4.07492895872535e-05,  -2.17407957554587e-05,  -9.163058931391722e-06,
     -2.017460145032201e-06,  1.249721855219005e-06,  2.166655190537392e-06,
      1.930520892991082e-06,  1.319400334374195e-06,  7.410039764949091e-07,
      3.423230509967409e-07,  1.244182214744588e-07,  3.130441005359396e-08
 };
 
 static float ctables[CTABLES][256];
 
 static av_cold void dsd_ctables_tableinit(void)
 {
     int t, e, m, k;
     double acc;
     for (t = 0; t < CTABLES; ++t) {
         k = FFMIN(HTAPS - t * 8, 8);
         for (e = 0; e < 256; ++e) {
             acc = 0.0;
             for (m = 0; m < k; ++m)
                 acc += (((e >> (7 - m)) & 1) * 2 - 1) * htaps[t * 8 + m];
             ctables[CTABLES - 1 - t][e] = (float)acc;
         }
     }
 }
 #endif /* CONFIG_HARDCODED_TABLES */
 
 #endif /* AVCODEC_DSD_TABLEGEN_H */