mirror of
https://github.com/ZDoom/gzdoom.git
synced 2024-12-16 23:51:04 +00:00
395 lines
11 KiB
C++
395 lines
11 KiB
C++
// Game_Music_Emu 0.6.0. http://www.slack.net/~ant/
|
|
|
|
#include "Ay_Apu.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"
|
|
|
|
// Emulation inaccuracies:
|
|
// * Noise isn't run when not in use
|
|
// * Changes to envelope and noise periods are delayed until next reload
|
|
// * Super-sonic tone should attenuate output to about 60%, not 50%
|
|
|
|
// Tones above this frequency are treated as disabled tone at half volume.
|
|
// Power of two is more efficient (avoids division).
|
|
unsigned const inaudible_freq = 16384;
|
|
|
|
int const period_factor = 16;
|
|
|
|
static byte const amp_table [16] =
|
|
{
|
|
#define ENTRY( n ) byte (n * Ay_Apu::amp_range + 0.5)
|
|
// With channels tied together and 1K resistor to ground (as datasheet recommends),
|
|
// output nearly matches logarithmic curve as claimed. Approx. 1.5 dB per step.
|
|
ENTRY(0.000000),ENTRY(0.007813),ENTRY(0.011049),ENTRY(0.015625),
|
|
ENTRY(0.022097),ENTRY(0.031250),ENTRY(0.044194),ENTRY(0.062500),
|
|
ENTRY(0.088388),ENTRY(0.125000),ENTRY(0.176777),ENTRY(0.250000),
|
|
ENTRY(0.353553),ENTRY(0.500000),ENTRY(0.707107),ENTRY(1.000000),
|
|
|
|
/*
|
|
// Measured from an AY-3-8910A chip with date code 8611.
|
|
|
|
// Direct voltages without any load (very linear)
|
|
ENTRY(0.000000),ENTRY(0.046237),ENTRY(0.064516),ENTRY(0.089785),
|
|
ENTRY(0.124731),ENTRY(0.173118),ENTRY(0.225806),ENTRY(0.329032),
|
|
ENTRY(0.360215),ENTRY(0.494624),ENTRY(0.594624),ENTRY(0.672043),
|
|
ENTRY(0.766129),ENTRY(0.841935),ENTRY(0.926882),ENTRY(1.000000),
|
|
// With only some load
|
|
ENTRY(0.000000),ENTRY(0.011940),ENTRY(0.017413),ENTRY(0.024876),
|
|
ENTRY(0.036318),ENTRY(0.054229),ENTRY(0.072637),ENTRY(0.122388),
|
|
ENTRY(0.174129),ENTRY(0.239303),ENTRY(0.323881),ENTRY(0.410945),
|
|
ENTRY(0.527363),ENTRY(0.651741),ENTRY(0.832338),ENTRY(1.000000),
|
|
*/
|
|
#undef ENTRY
|
|
};
|
|
|
|
static byte const modes [8] =
|
|
{
|
|
#define MODE( a0,a1, b0,b1, c0,c1 ) \
|
|
(a0 | a1<<1 | b0<<2 | b1<<3 | c0<<4 | c1<<5)
|
|
MODE( 1,0, 1,0, 1,0 ),
|
|
MODE( 1,0, 0,0, 0,0 ),
|
|
MODE( 1,0, 0,1, 1,0 ),
|
|
MODE( 1,0, 1,1, 1,1 ),
|
|
MODE( 0,1, 0,1, 0,1 ),
|
|
MODE( 0,1, 1,1, 1,1 ),
|
|
MODE( 0,1, 1,0, 0,1 ),
|
|
MODE( 0,1, 0,0, 0,0 ),
|
|
};
|
|
|
|
Ay_Apu::Ay_Apu()
|
|
{
|
|
// build full table of the upper 8 envelope waveforms
|
|
for ( int m = 8; m--; )
|
|
{
|
|
byte* out = env.modes [m];
|
|
int flags = modes [m];
|
|
for ( int x = 3; --x >= 0; )
|
|
{
|
|
int amp = flags & 1;
|
|
int end = flags >> 1 & 1;
|
|
int step = end - amp;
|
|
amp *= 15;
|
|
for ( int y = 16; --y >= 0; )
|
|
{
|
|
*out++ = amp_table [amp];
|
|
amp += step;
|
|
}
|
|
flags >>= 2;
|
|
}
|
|
}
|
|
|
|
output( 0 );
|
|
volume( 1.0 );
|
|
reset();
|
|
}
|
|
|
|
void Ay_Apu::reset()
|
|
{
|
|
last_time = 0;
|
|
noise.delay = 0;
|
|
noise.lfsr = 1;
|
|
|
|
osc_t* osc = &oscs [osc_count];
|
|
do
|
|
{
|
|
osc--;
|
|
osc->period = period_factor;
|
|
osc->delay = 0;
|
|
osc->last_amp = 0;
|
|
osc->phase = 0;
|
|
}
|
|
while ( osc != oscs );
|
|
|
|
for ( int i = sizeof regs; --i >= 0; )
|
|
regs [i] = 0;
|
|
regs [7] = 0xFF;
|
|
write_data_( 13, 0 );
|
|
}
|
|
|
|
void Ay_Apu::write_data_( int addr, int data )
|
|
{
|
|
assert( (unsigned) addr < reg_count );
|
|
|
|
if ( (unsigned) addr >= 14 )
|
|
{
|
|
#ifdef debug_printf
|
|
debug_printf( "Wrote to I/O port %02X\n", (int) addr );
|
|
#endif
|
|
}
|
|
|
|
// envelope mode
|
|
if ( addr == 13 )
|
|
{
|
|
if ( !(data & 8) ) // convert modes 0-7 to proper equivalents
|
|
data = (data & 4) ? 15 : 9;
|
|
env.wave = env.modes [data - 7];
|
|
env.pos = -48;
|
|
env.delay = 0; // will get set to envelope period in run_until()
|
|
}
|
|
regs [addr] = data;
|
|
|
|
// handle period changes accurately
|
|
int i = addr >> 1;
|
|
if ( i < osc_count )
|
|
{
|
|
blip_time_t period = (regs [i * 2 + 1] & 0x0F) * (0x100L * period_factor) +
|
|
regs [i * 2] * period_factor;
|
|
if ( !period )
|
|
period = period_factor;
|
|
|
|
// adjust time of next timer expiration based on change in period
|
|
osc_t& osc = oscs [i];
|
|
if ( (osc.delay += period - osc.period) < 0 )
|
|
osc.delay = 0;
|
|
osc.period = period;
|
|
}
|
|
|
|
// TODO: same as above for envelope timer, and it also has a divide by two after it
|
|
}
|
|
|
|
int const noise_off = 0x08;
|
|
int const tone_off = 0x01;
|
|
|
|
void Ay_Apu::run_until( blip_time_t final_end_time )
|
|
{
|
|
require( final_end_time >= last_time );
|
|
|
|
// noise period and initial values
|
|
blip_time_t const noise_period_factor = period_factor * 2; // verified
|
|
blip_time_t noise_period = (regs [6] & 0x1F) * noise_period_factor;
|
|
if ( !noise_period )
|
|
noise_period = noise_period_factor;
|
|
blip_time_t const old_noise_delay = noise.delay;
|
|
blargg_ulong const old_noise_lfsr = noise.lfsr;
|
|
|
|
// envelope period
|
|
blip_time_t const env_period_factor = period_factor * 2; // verified
|
|
blip_time_t env_period = (regs [12] * 0x100L + regs [11]) * env_period_factor;
|
|
if ( !env_period )
|
|
env_period = env_period_factor; // same as period 1 on my AY chip
|
|
if ( !env.delay )
|
|
env.delay = env_period;
|
|
|
|
// run each osc separately
|
|
for ( int index = 0; index < osc_count; index++ )
|
|
{
|
|
osc_t* const osc = &oscs [index];
|
|
int osc_mode = regs [7] >> index;
|
|
|
|
// output
|
|
Blip_Buffer* const osc_output = osc->output;
|
|
if ( !osc_output )
|
|
continue;
|
|
osc_output->set_modified();
|
|
|
|
// period
|
|
int half_vol = 0;
|
|
blip_time_t inaudible_period = (blargg_ulong) (osc_output->clock_rate() +
|
|
inaudible_freq) / (inaudible_freq * 2);
|
|
if ( osc->period <= inaudible_period && !(osc_mode & tone_off) )
|
|
{
|
|
half_vol = 1; // Actually around 60%, but 50% is close enough
|
|
osc_mode |= tone_off;
|
|
}
|
|
|
|
// envelope
|
|
blip_time_t start_time = last_time;
|
|
blip_time_t end_time = final_end_time;
|
|
int const vol_mode = regs [0x08 + index];
|
|
int volume = amp_table [vol_mode & 0x0F] >> half_vol;
|
|
int osc_env_pos = env.pos;
|
|
if ( vol_mode & 0x10 )
|
|
{
|
|
volume = env.wave [osc_env_pos] >> half_vol;
|
|
// use envelope only if it's a repeating wave or a ramp that hasn't finished
|
|
if ( !(regs [13] & 1) || osc_env_pos < -32 )
|
|
{
|
|
end_time = start_time + env.delay;
|
|
if ( end_time >= final_end_time )
|
|
end_time = final_end_time;
|
|
|
|
//if ( !(regs [12] | regs [11]) )
|
|
// debug_printf( "Used envelope period 0\n" );
|
|
}
|
|
else if ( !volume )
|
|
{
|
|
osc_mode = noise_off | tone_off;
|
|
}
|
|
}
|
|
else if ( !volume )
|
|
{
|
|
osc_mode = noise_off | tone_off;
|
|
}
|
|
|
|
// tone time
|
|
blip_time_t const period = osc->period;
|
|
blip_time_t time = start_time + osc->delay;
|
|
if ( osc_mode & tone_off ) // maintain tone's phase when off
|
|
{
|
|
blargg_long count = (final_end_time - time + period - 1) / period;
|
|
time += count * period;
|
|
osc->phase ^= count & 1;
|
|
}
|
|
|
|
// noise time
|
|
blip_time_t ntime = final_end_time;
|
|
blargg_ulong noise_lfsr = 1;
|
|
if ( !(osc_mode & noise_off) )
|
|
{
|
|
ntime = start_time + old_noise_delay;
|
|
noise_lfsr = old_noise_lfsr;
|
|
//if ( (regs [6] & 0x1F) == 0 )
|
|
// debug_printf( "Used noise period 0\n" );
|
|
}
|
|
|
|
// The following efficiently handles several cases (least demanding first):
|
|
// * Tone, noise, and envelope disabled, where channel acts as 4-bit DAC
|
|
// * Just tone or just noise, envelope disabled
|
|
// * Envelope controlling tone and/or noise
|
|
// * Tone and noise disabled, envelope enabled with high frequency
|
|
// * Tone and noise together
|
|
// * Tone and noise together with envelope
|
|
|
|
// This loop only runs one iteration if envelope is disabled. If envelope
|
|
// is being used as a waveform (tone and noise disabled), this loop will
|
|
// still be reasonably efficient since the bulk of it will be skipped.
|
|
while ( 1 )
|
|
{
|
|
// current amplitude
|
|
int amp = 0;
|
|
if ( (osc_mode | osc->phase) & 1 & (osc_mode >> 3 | noise_lfsr) )
|
|
amp = volume;
|
|
{
|
|
int delta = amp - osc->last_amp;
|
|
if ( delta )
|
|
{
|
|
osc->last_amp = amp;
|
|
synth_.offset( start_time, delta, osc_output );
|
|
}
|
|
}
|
|
|
|
// Run wave and noise interleved with each catching up to the other.
|
|
// If one or both are disabled, their "current time" will be past end time,
|
|
// so there will be no significant performance hit.
|
|
if ( ntime < end_time || time < end_time )
|
|
{
|
|
// Since amplitude was updated above, delta will always be +/- volume,
|
|
// so we can avoid using last_amp every time to calculate the delta.
|
|
int delta = amp * 2 - volume;
|
|
int delta_non_zero = delta != 0;
|
|
int phase = osc->phase | (osc_mode & tone_off); assert( tone_off == 0x01 );
|
|
do
|
|
{
|
|
// run noise
|
|
blip_time_t end = end_time;
|
|
if ( end_time > time ) end = time;
|
|
if ( phase & delta_non_zero )
|
|
{
|
|
while ( ntime <= end ) // must advance *past* time to avoid hang
|
|
{
|
|
int changed = noise_lfsr + 1;
|
|
noise_lfsr = ((blargg_ulong)-(blargg_long)(noise_lfsr & 1) & 0x12000) ^ (noise_lfsr >> 1);
|
|
if ( changed & 2 )
|
|
{
|
|
delta = -delta;
|
|
synth_.offset( ntime, delta, osc_output );
|
|
}
|
|
ntime += noise_period;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// 20 or more noise periods on average for some music
|
|
blargg_long remain = end - ntime;
|
|
blargg_long count = remain / noise_period;
|
|
if ( remain >= 0 )
|
|
ntime += noise_period + count * noise_period;
|
|
}
|
|
|
|
// run tone
|
|
end = end_time;
|
|
if ( end_time > ntime ) end = ntime;
|
|
if ( noise_lfsr & delta_non_zero )
|
|
{
|
|
while ( time < end )
|
|
{
|
|
delta = -delta;
|
|
synth_.offset( time, delta, osc_output );
|
|
time += period;
|
|
//phase ^= 1;
|
|
}
|
|
//assert( phase == (delta > 0) );
|
|
phase = unsigned (-delta) >> (CHAR_BIT * sizeof (unsigned) - 1);
|
|
// (delta > 0)
|
|
}
|
|
else
|
|
{
|
|
// loop usually runs less than once
|
|
//SUB_CASE_COUNTER( (time < end) * (end - time + period - 1) / period );
|
|
|
|
while ( time < end )
|
|
{
|
|
time += period;
|
|
phase ^= 1;
|
|
}
|
|
}
|
|
}
|
|
while ( time < end_time || ntime < end_time );
|
|
|
|
osc->last_amp = (delta + volume) >> 1;
|
|
if ( !(osc_mode & tone_off) )
|
|
osc->phase = phase;
|
|
}
|
|
|
|
if ( end_time >= final_end_time )
|
|
break; // breaks first time when envelope is disabled
|
|
|
|
// next envelope step
|
|
if ( ++osc_env_pos >= 0 )
|
|
osc_env_pos -= 32;
|
|
volume = env.wave [osc_env_pos] >> half_vol;
|
|
|
|
start_time = end_time;
|
|
end_time += env_period;
|
|
if ( end_time > final_end_time )
|
|
end_time = final_end_time;
|
|
}
|
|
osc->delay = time - final_end_time;
|
|
|
|
if ( !(osc_mode & noise_off) )
|
|
{
|
|
noise.delay = ntime - final_end_time;
|
|
noise.lfsr = noise_lfsr;
|
|
}
|
|
}
|
|
|
|
// TODO: optimized saw wave envelope?
|
|
|
|
// maintain envelope phase
|
|
blip_time_t remain = final_end_time - last_time - env.delay;
|
|
if ( remain >= 0 )
|
|
{
|
|
blargg_long count = (remain + env_period) / env_period;
|
|
env.pos += count;
|
|
if ( env.pos >= 0 )
|
|
env.pos = (env.pos & 31) - 32;
|
|
remain -= count * env_period;
|
|
assert( -remain <= env_period );
|
|
}
|
|
env.delay = -remain;
|
|
assert( env.delay > 0 );
|
|
assert( env.pos < 0 );
|
|
|
|
last_time = final_end_time;
|
|
}
|