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Diffstat (limited to 'plugins/gme/game-music-emu-0.6.0/gme/Ay_Apu.cpp')
-rw-r--r--plugins/gme/game-music-emu-0.6.0/gme/Ay_Apu.cpp395
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diff --git a/plugins/gme/game-music-emu-0.6.0/gme/Ay_Apu.cpp b/plugins/gme/game-music-emu-0.6.0/gme/Ay_Apu.cpp
deleted file mode 100644
index 8204abf2..00000000
--- a/plugins/gme/game-music-emu-0.6.0/gme/Ay_Apu.cpp
+++ /dev/null
@@ -1,395 +0,0 @@
-// Game_Music_Emu 0.5.5. 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 = (-(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;
-}
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