mirror of
https://github.com/SourMesen/Mesen-S.git
synced 2024-06-23 06:41:55 -04:00
70 lines
1.7 KiB
C++
70 lines
1.7 KiB
C++
#include "stdafx.h"
|
|
// snes_spc 0.9.0. http://www.slack.net/~ant/
|
|
|
|
#include "SPC_Filter.h"
|
|
|
|
#include <string.h>
|
|
|
|
/* Copyright (C) 2007 Shay Green. This module 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. This
|
|
module 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 this module; if not, write to the Free Software Foundation,
|
|
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
|
|
|
|
#include "blargg_source.h"
|
|
|
|
void SPC_Filter::clear() { memset( ch, 0, sizeof ch ); }
|
|
|
|
SPC_Filter::SPC_Filter()
|
|
{
|
|
gain = gain_unit;
|
|
bass = bass_norm;
|
|
clear();
|
|
}
|
|
|
|
void SPC_Filter::run( short* io, int count )
|
|
{
|
|
require( (count & 1) == 0 ); // must be even
|
|
|
|
int const gain = this->gain;
|
|
int const bass = this->bass;
|
|
chan_t* c = &ch [2];
|
|
do
|
|
{
|
|
// cache in registers
|
|
int sum = (--c)->sum;
|
|
int pp1 = c->pp1;
|
|
int p1 = c->p1;
|
|
|
|
for ( int i = 0; i < count; i += 2 )
|
|
{
|
|
// Low-pass filter (two point FIR with coeffs 0.25, 0.75)
|
|
int f = io [i] + p1;
|
|
p1 = io [i] * 3;
|
|
|
|
// High-pass filter ("leaky integrator")
|
|
int delta = f - pp1;
|
|
pp1 = f;
|
|
int s = sum >> (gain_bits + 2);
|
|
sum += (delta * gain) - (sum >> bass);
|
|
|
|
// Clamp to 16 bits
|
|
if ( (short) s != s )
|
|
s = (s >> 31) ^ 0x7FFF;
|
|
|
|
io [i] = (short) s;
|
|
}
|
|
|
|
c->p1 = p1;
|
|
c->pp1 = pp1;
|
|
c->sum = sum;
|
|
++io;
|
|
}
|
|
while ( c != ch );
|
|
}
|