mirror of
https://github.com/ZDoom/gzdoom.git
synced 2024-11-23 04:22:34 +00:00
334 lines
8.5 KiB
C++
334 lines
8.5 KiB
C++
// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
|
|
|
|
#include "Sap_Apu.h"
|
|
|
|
#include <string.h>
|
|
|
|
/* Copyright (C) 2006 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"
|
|
|
|
int const max_frequency = 12000; // pure waves above this frequency are silenced
|
|
|
|
static void gen_poly( blargg_ulong mask, int count, byte* out )
|
|
{
|
|
blargg_ulong n = 1;
|
|
do
|
|
{
|
|
int bits = 0;
|
|
int b = 0;
|
|
do
|
|
{
|
|
// implemented using "Galios configuration"
|
|
bits |= (n & 1) << b;
|
|
n = (n >> 1) ^ (mask & -(n & 1));
|
|
}
|
|
while ( b++ < 7 );
|
|
*out++ = bits;
|
|
}
|
|
while ( --count );
|
|
}
|
|
|
|
// poly5
|
|
int const poly5_len = (1 << 5) - 1;
|
|
blargg_ulong const poly5_mask = (1UL << poly5_len) - 1;
|
|
blargg_ulong const poly5 = 0x167C6EA1;
|
|
|
|
inline blargg_ulong run_poly5( blargg_ulong in, int shift )
|
|
{
|
|
return (in << shift & poly5_mask) | (in >> (poly5_len - shift));
|
|
}
|
|
|
|
#define POLY_MASK( width, tap1, tap2 ) \
|
|
((1UL << (width - 1 - tap1)) | (1UL << (width - 1 - tap2)))
|
|
|
|
Sap_Apu_Impl::Sap_Apu_Impl()
|
|
{
|
|
gen_poly( POLY_MASK( 4, 1, 0 ), sizeof poly4, poly4 );
|
|
gen_poly( POLY_MASK( 9, 5, 0 ), sizeof poly9, poly9 );
|
|
gen_poly( POLY_MASK( 17, 5, 0 ), sizeof poly17, poly17 );
|
|
|
|
if ( 0 ) // comment out to recauculate poly5 constant
|
|
{
|
|
byte poly5 [4];
|
|
gen_poly( POLY_MASK( 5, 2, 0 ), sizeof poly5, poly5 );
|
|
blargg_ulong n = poly5 [3] * 0x1000000L + poly5 [2] * 0x10000L +
|
|
poly5 [1] * 0x100L + poly5 [0];
|
|
blargg_ulong rev = n & 1;
|
|
for ( int i = 1; i < poly5_len; i++ )
|
|
rev |= (n >> i & 1) << (poly5_len - i);
|
|
debug_printf( "poly5: 0x%08lX\n", rev );
|
|
}
|
|
}
|
|
|
|
Sap_Apu::Sap_Apu()
|
|
{
|
|
impl = 0;
|
|
for ( int i = 0; i < osc_count; i++ )
|
|
osc_output( i, 0 );
|
|
}
|
|
|
|
void Sap_Apu::reset( Sap_Apu_Impl* new_impl )
|
|
{
|
|
impl = new_impl;
|
|
last_time = 0;
|
|
poly5_pos = 0;
|
|
poly4_pos = 0;
|
|
polym_pos = 0;
|
|
control = 0;
|
|
|
|
for ( int i = 0; i < osc_count; i++ )
|
|
memset( &oscs [i], 0, offsetof (osc_t,output) );
|
|
}
|
|
|
|
inline void Sap_Apu::calc_periods()
|
|
{
|
|
// 15/64 kHz clock
|
|
int divider = 28;
|
|
if ( this->control & 1 )
|
|
divider = 114;
|
|
|
|
for ( int i = 0; i < osc_count; i++ )
|
|
{
|
|
osc_t* const osc = &oscs [i];
|
|
|
|
int const osc_reload = osc->regs [0]; // cache
|
|
blargg_long period = (osc_reload + 1) * divider;
|
|
static byte const fast_bits [osc_count] = { 1 << 6, 1 << 4, 1 << 5, 1 << 3 };
|
|
if ( this->control & fast_bits [i] )
|
|
{
|
|
period = osc_reload + 4;
|
|
if ( i & 1 )
|
|
{
|
|
period = osc_reload * 0x100L + osc [-1].regs [0] + 7;
|
|
if ( !(this->control & fast_bits [i - 1]) )
|
|
period = (period - 6) * divider;
|
|
|
|
if ( (osc [-1].regs [1] & 0x1F) > 0x10 )
|
|
debug_printf( "Use of slave channel in 16-bit mode not supported\n" );
|
|
}
|
|
}
|
|
osc->period = period;
|
|
}
|
|
}
|
|
|
|
void Sap_Apu::run_until( blip_time_t end_time )
|
|
{
|
|
calc_periods();
|
|
Sap_Apu_Impl* const impl = this->impl; // cache
|
|
|
|
// 17/9-bit poly selection
|
|
byte const* polym = impl->poly17;
|
|
int polym_len = poly17_len;
|
|
if ( this->control & 0x80 )
|
|
{
|
|
polym_len = poly9_len;
|
|
polym = impl->poly9;
|
|
}
|
|
polym_pos %= polym_len;
|
|
|
|
for ( int i = 0; i < osc_count; i++ )
|
|
{
|
|
osc_t* const osc = &oscs [i];
|
|
blip_time_t time = last_time + osc->delay;
|
|
blip_time_t const period = osc->period;
|
|
|
|
// output
|
|
Blip_Buffer* output = osc->output;
|
|
if ( output )
|
|
{
|
|
output->set_modified();
|
|
|
|
int const osc_control = osc->regs [1]; // cache
|
|
int volume = (osc_control & 0x0F) * 2;
|
|
if ( !volume || osc_control & 0x10 || // silent, DAC mode, or inaudible frequency
|
|
((osc_control & 0xA0) == 0xA0 && period < 1789773 / 2 / max_frequency) )
|
|
{
|
|
if ( !(osc_control & 0x10) )
|
|
volume >>= 1; // inaudible frequency = half volume
|
|
|
|
int delta = volume - osc->last_amp;
|
|
if ( delta )
|
|
{
|
|
osc->last_amp = volume;
|
|
impl->synth.offset( last_time, delta, output );
|
|
}
|
|
|
|
// TODO: doesn't maintain high pass flip-flop (very minor issue)
|
|
}
|
|
else
|
|
{
|
|
// high pass
|
|
static byte const hipass_bits [osc_count] = { 1 << 2, 1 << 1, 0, 0 };
|
|
blip_time_t period2 = 0; // unused if no high pass
|
|
blip_time_t time2 = end_time;
|
|
if ( this->control & hipass_bits [i] )
|
|
{
|
|
period2 = osc [2].period;
|
|
time2 = last_time + osc [2].delay;
|
|
if ( osc->invert )
|
|
{
|
|
// trick inner wave loop into inverting output
|
|
osc->last_amp -= volume;
|
|
volume = -volume;
|
|
}
|
|
}
|
|
|
|
if ( time < end_time || time2 < end_time )
|
|
{
|
|
// poly source
|
|
static byte const poly1 [] = { 0x55, 0x55 }; // square wave
|
|
byte const* poly = poly1;
|
|
int poly_len = 8 * sizeof poly1; // can be just 2 bits, but this is faster
|
|
int poly_pos = osc->phase & 1;
|
|
int poly_inc = 1;
|
|
if ( !(osc_control & 0x20) )
|
|
{
|
|
poly = polym;
|
|
poly_len = polym_len;
|
|
poly_pos = polym_pos;
|
|
if ( osc_control & 0x40 )
|
|
{
|
|
poly = impl->poly4;
|
|
poly_len = poly4_len;
|
|
poly_pos = poly4_pos;
|
|
}
|
|
poly_inc = period % poly_len;
|
|
poly_pos = (poly_pos + osc->delay) % poly_len;
|
|
}
|
|
poly_inc -= poly_len; // allows more optimized inner loop below
|
|
|
|
// square/poly5 wave
|
|
blargg_ulong wave = poly5;
|
|
check( poly5 & 1 ); // low bit is set for pure wave
|
|
int poly5_inc = 0;
|
|
if ( !(osc_control & 0x80) )
|
|
{
|
|
wave = run_poly5( wave, (osc->delay + poly5_pos) % poly5_len );
|
|
poly5_inc = period % poly5_len;
|
|
}
|
|
|
|
// Run wave and high pass interleved with each catching up to the other.
|
|
// Disabled high pass has no performance effect since inner wave loop
|
|
// makes no compromise for high pass, and only runs once in that case.
|
|
int osc_last_amp = osc->last_amp;
|
|
do
|
|
{
|
|
// run high pass
|
|
if ( time2 < time )
|
|
{
|
|
int delta = -osc_last_amp;
|
|
if ( volume < 0 )
|
|
delta += volume;
|
|
if ( delta )
|
|
{
|
|
osc_last_amp += delta - volume;
|
|
volume = -volume;
|
|
impl->synth.offset( time2, delta, output );
|
|
}
|
|
}
|
|
while ( time2 <= time ) // must advance *past* time to avoid hang
|
|
time2 += period2;
|
|
|
|
// run wave
|
|
blip_time_t end = end_time;
|
|
if ( end > time2 )
|
|
end = time2;
|
|
while ( time < end )
|
|
{
|
|
if ( wave & 1 )
|
|
{
|
|
int amp = volume & -(poly [poly_pos >> 3] >> (poly_pos & 7) & 1);
|
|
if ( (poly_pos += poly_inc) < 0 )
|
|
poly_pos += poly_len;
|
|
int delta = amp - osc_last_amp;
|
|
if ( delta )
|
|
{
|
|
osc_last_amp = amp;
|
|
impl->synth.offset( time, delta, output );
|
|
}
|
|
}
|
|
wave = run_poly5( wave, poly5_inc );
|
|
time += period;
|
|
}
|
|
}
|
|
while ( time < end_time || time2 < end_time );
|
|
|
|
osc->phase = poly_pos;
|
|
osc->last_amp = osc_last_amp;
|
|
}
|
|
|
|
osc->invert = 0;
|
|
if ( volume < 0 )
|
|
{
|
|
// undo inversion trickery
|
|
osc->last_amp -= volume;
|
|
osc->invert = 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
// maintain divider
|
|
blip_time_t remain = end_time - time;
|
|
if ( remain > 0 )
|
|
{
|
|
blargg_long count = (remain + period - 1) / period;
|
|
osc->phase ^= count;
|
|
time += count * period;
|
|
}
|
|
osc->delay = time - end_time;
|
|
}
|
|
|
|
// advance polies
|
|
blip_time_t duration = end_time - last_time;
|
|
last_time = end_time;
|
|
poly4_pos = (poly4_pos + duration) % poly4_len;
|
|
poly5_pos = (poly5_pos + duration) % poly5_len;
|
|
polym_pos += duration; // will get %'d on next call
|
|
}
|
|
|
|
void Sap_Apu::write_data( blip_time_t time, unsigned addr, int data )
|
|
{
|
|
run_until( time );
|
|
int i = (addr ^ 0xD200) >> 1;
|
|
if ( i < osc_count )
|
|
{
|
|
oscs [i].regs [addr & 1] = data;
|
|
}
|
|
else if ( addr == 0xD208 )
|
|
{
|
|
control = data;
|
|
}
|
|
else if ( addr == 0xD209 )
|
|
{
|
|
oscs [0].delay = 0;
|
|
oscs [1].delay = 0;
|
|
oscs [2].delay = 0;
|
|
oscs [3].delay = 0;
|
|
}
|
|
/*
|
|
// TODO: are polynomials reset in this case?
|
|
else if ( addr == 0xD20F )
|
|
{
|
|
if ( (data & 3) == 0 )
|
|
polym_pos = 0;
|
|
}
|
|
*/
|
|
}
|
|
|
|
void Sap_Apu::end_frame( blip_time_t end_time )
|
|
{
|
|
if ( end_time > last_time )
|
|
run_until( end_time );
|
|
|
|
last_time -= end_time;
|
|
}
|