91 lines
4.0 KiB
C#
91 lines
4.0 KiB
C#
/* Copyright (c) 2006-2011 Skype Limited. All Rights Reserved
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Ported to C# by Logan Stromberg
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Internet Society, IETF or IETF Trust, nor the
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names of specific contributors, may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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namespace Concentus.Silk
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{
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using Concentus.Common;
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using Concentus.Common.CPlusPlus;
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using Concentus.Silk.Enums;
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using Concentus.Silk.Structs;
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using System.Diagnostics;
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internal static class BWExpander
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{
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/// <summary>
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/// Chirp (bw expand) LP AR filter (Fixed point implementation)
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/// </summary>
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/// <param name="ar">I/O AR filter to be expanded (without leading 1)</param>
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/// <param name="d">I length of ar</param>
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/// <param name="chirp_Q16">I chirp factor (typically in range (0..1) )</param>
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internal static void silk_bwexpander_32(
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int[] ar, /* I/O AR filter to be expanded (without leading 1) */
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int d, /* I Length of ar */
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int chirp_Q16 /* I Chirp factor in Q16 */
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)
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{
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int i;
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int chirp_minus_one_Q16 = chirp_Q16 - 65536;
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for (i = 0; i < d - 1; i++)
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{
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ar[i] = Inlines.silk_SMULWW(chirp_Q16, ar[i]);
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chirp_Q16 += Inlines.silk_RSHIFT_ROUND(Inlines.silk_MUL(chirp_Q16, chirp_minus_one_Q16), 16);
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}
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ar[d - 1] = Inlines.silk_SMULWW(chirp_Q16, ar[d - 1]);
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}
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/// <summary>
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/// Chirp (bw expand) LP AR filter (Fixed point implementation)
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/// </summary>
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/// <param name="ar">I/O AR filter to be expanded (without leading 1)</param>
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/// <param name="d">I length of ar</param>
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/// <param name="chirp_Q16">I chirp factor (typically in range (0..1) )</param>
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internal static void silk_bwexpander(
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short[] ar,
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int d,
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int chirp_Q16)
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{
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int i;
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int chirp_minus_one_Q16 = chirp_Q16 - 65536;
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/* NB: Dont use silk_SMULWB, instead of silk_RSHIFT_ROUND( silk_MUL(), 16 ), below. */
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/* Bias in silk_SMULWB can lead to unstable filters */
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for (i = 0; i < d - 1; i++)
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{
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ar[i] = (short)Inlines.silk_RSHIFT_ROUND(Inlines.silk_MUL(chirp_Q16, ar[i]), 16);
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chirp_Q16 += Inlines.silk_RSHIFT_ROUND(Inlines.silk_MUL(chirp_Q16, chirp_minus_one_Q16), 16);
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}
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ar[d - 1] = (short)Inlines.silk_RSHIFT_ROUND(Inlines.silk_MUL(chirp_Q16, ar[d - 1]), 16);
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}
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}
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}
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