1 files changed, 336 insertions, 0 deletions
diff --git a/plugins/gme/Game_Music_Emu-0.5.2/gme/Gb_Oscs.cpp b/plugins/gme/Game_Music_Emu-0.5.2/gme/Gb_Oscs.cpp
new file mode 100644
index 00000000..735653fa
--- /dev/null
+++ b/plugins/gme/Game_Music_Emu-0.5.2/gme/Gb_Oscs.cpp
@@ -0,0 +1,336 @@
+// Gb_Snd_Emu 0.1.5. http://www.slack.net/~ant/
+
+#include "Gb_Apu.h"
+
+#include <string.h>
+
+/* Copyright (C) 2003-2006 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"
+
+// Gb_Osc
+
+void Gb_Osc::reset()
+{
+	delay = 0;
+	last_amp = 0;
+	length = 0;
+	output_select = 3;
+	output = outputs [output_select];
+}
+
+void Gb_Osc::clock_length()
+{
+	if ( (regs [4] & len_enabled_mask) && length )
+		length--;
+}
+
+// Gb_Env
+
+void Gb_Env::clock_envelope()
+{
+	if ( env_delay && !--env_delay )
+	{
+		env_delay = regs [2] & 7;
+		int v = volume - 1 + (regs [2] >> 2 & 2);
+		if ( (unsigned) v < 15 )
+			volume = v;
+	}
+}
+
+bool Gb_Env::write_register( int reg, int data )
+{
+	switch ( reg )
+	{
+	case 1:
+		length = 64 - (regs [1] & 0x3F);
+		break;
+	
+	case 2:
+		if ( !(data >> 4) )
+			enabled = false;
+		break;
+	
+	case 4:
+		if ( data & trigger )
+		{
+			env_delay = regs [2] & 7;
+			volume = regs [2] >> 4;
+			enabled = true;
+			if ( length == 0 )
+				length = 64;
+			return true;
+		}
+	}
+	return false;
+}
+
+// Gb_Square
+
+void Gb_Square::reset()
+{
+	phase = 0;
+	sweep_freq = 0;
+	sweep_delay = 0;
+	Gb_Env::reset();
+}
+
+void Gb_Square::clock_sweep()
+{
+	int sweep_period = (regs [0] & period_mask) >> 4;
+	if ( sweep_period && sweep_delay && !--sweep_delay )
+	{
+		sweep_delay = sweep_period;
+		regs [3] = sweep_freq & 0xFF;
+		regs [4] = (regs [4] & ~0x07) | (sweep_freq >> 8 & 0x07);
+		
+		int offset = sweep_freq >> (regs [0] & shift_mask);
+		if ( regs [0] & 0x08 )
+			offset = -offset;
+		sweep_freq += offset;
+		
+		if ( sweep_freq < 0 )
+		{
+			sweep_freq = 0;
+		}
+		else if ( sweep_freq >= 2048 )
+		{
+			sweep_delay = 0; // don't modify channel frequency any further
+			sweep_freq = 2048; // silence sound immediately
+		}
+	}
+}
+
+void Gb_Square::run( blip_time_t time, blip_time_t end_time, int playing )
+{
+	if ( sweep_freq == 2048 )
+		playing = false;
+	
+	static unsigned char const table [4] = { 1, 2, 4, 6 };
+	int const duty = table [regs [1] >> 6];
+	int amp = volume & playing;
+	if ( phase >= duty )
+		amp = -amp;
+	
+	int frequency = this->frequency();
+	if ( unsigned (frequency - 1) > 2040 ) // frequency < 1 || frequency > 2041
+	{
+		// really high frequency results in DC at half volume
+		amp = volume >> 1;
+		playing = false;
+	}
+	
+	{
+		int delta = amp - last_amp;
+		if ( delta )
+		{
+			last_amp = amp;
+			synth->offset( time, delta, output );
+		}
+	}
+	
+	time += delay;
+	if ( !playing )
+		time = end_time;
+	
+	if ( time < end_time )
+	{
+		int const period = (2048 - frequency) * 4;
+		Blip_Buffer* const output = this->output;
+		int phase = this->phase;
+		int delta = amp * 2;
+		do
+		{
+			phase = (phase + 1) & 7;
+			if ( phase == 0 || phase == duty )
+			{
+				delta = -delta;
+				synth->offset_inline( time, delta, output );
+			}
+			time += period;
+		}
+		while ( time < end_time );
+		
+		this->phase = phase;
+		last_amp = delta >> 1;
+	}
+	delay = time - end_time;
+}
+
+// Gb_Noise
+
+void Gb_Noise::run( blip_time_t time, blip_time_t end_time, int playing )
+{
+	int amp = volume & playing;
+	int tap = 13 - (regs [3] & 8);
+	if ( bits >> tap & 2 )
+		amp = -amp;
+	
+	{
+		int delta = amp - last_amp;
+		if ( delta )
+		{
+			last_amp = amp;
+			synth->offset( time, delta, output );
+		}
+	}
+	
+	time += delay;
+	if ( !playing )
+		time = end_time;
+	
+	if ( time < end_time )
+	{
+		static unsigned char const table [8] = { 8, 16, 32, 48, 64, 80, 96, 112 };
+		int period = table [regs [3] & 7] << (regs [3] >> 4);
+		
+		// keep parallel resampled time to eliminate time conversion in the loop
+		Blip_Buffer* const output = this->output;
+		const blip_resampled_time_t resampled_period =
+				output->resampled_duration( period );
+		blip_resampled_time_t resampled_time = output->resampled_time( time );
+		unsigned bits = this->bits;
+		int delta = amp * 2;
+		
+		do
+		{
+			unsigned changed = (bits >> tap) + 1;
+			time += period;
+			bits <<= 1;
+			if ( changed & 2 )
+			{
+				delta = -delta;
+				bits |= 1;
+				synth->offset_resampled( resampled_time, delta, output );
+			}
+			resampled_time += resampled_period;
+		}
+		while ( time < end_time );
+		
+		this->bits = bits;
+		last_amp = delta >> 1;
+	}
+	delay = time - end_time;
+}
+
+// Gb_Wave
+
+inline void Gb_Wave::write_register( int reg, int data )
+{
+	switch ( reg )
+	{
+	case 0:
+		if ( !(data & 0x80) )
+			enabled = false;
+		break;
+	
+	case 1:
+		length = 256 - regs [1];
+		break;
+	
+	case 2:
+		volume = data >> 5 & 3;
+		break;
+	
+	case 4:
+		if ( data & trigger & regs [0] )
+		{
+			wave_pos = 0;
+			enabled = true;
+			if ( length == 0 )
+				length = 256;
+		}
+	}
+}
+
+void Gb_Wave::run( blip_time_t time, blip_time_t end_time, int playing )
+{
+	int volume_shift = (volume - 1) & 7; // volume = 0 causes shift = 7
+	int frequency;
+	{
+		int amp = (wave [wave_pos] >> volume_shift & playing) * 2;
+		
+		frequency = this->frequency();
+		if ( unsigned (frequency - 1) > 2044 ) // frequency < 1 || frequency > 2045
+		{
+			amp = 30 >> volume_shift & playing;
+			playing = false;
+		}
+		
+		int delta = amp - last_amp;
+		if ( delta )
+		{
+			last_amp = amp;
+			synth->offset( time, delta, output );
+		}
+	}
+	
+	time += delay;
+	if ( !playing )
+		time = end_time;
+	
+	if ( time < end_time )
+	{
+		Blip_Buffer* const output = this->output;
+		int const period = (2048 - frequency) * 2;
+	 	int wave_pos = (this->wave_pos + 1) & (wave_size - 1);
+	 	
+		do
+		{
+			int amp = (wave [wave_pos] >> volume_shift) * 2;
+			wave_pos = (wave_pos + 1) & (wave_size - 1);
+			int delta = amp - last_amp;
+			if ( delta )
+			{
+				last_amp = amp;
+				synth->offset_inline( time, delta, output );
+			}
+			time += period;
+		}
+		while ( time < end_time );
+		
+		this->wave_pos = (wave_pos - 1) & (wave_size - 1);
+	}
+	delay = time - end_time;
+}
+
+// Gb_Apu::write_osc
+
+void Gb_Apu::write_osc( int index, int reg, int data )
+{
+	reg -= index * 5;
+	Gb_Square* sq = &square2;
+	switch ( index )
+	{
+	case 0:
+		sq = &square1;
+	case 1:
+		if ( sq->write_register( reg, data ) && index == 0 )
+		{
+			square1.sweep_freq = square1.frequency();
+			if ( (regs [0] & sq->period_mask) && (regs [0] & sq->shift_mask) )
+			{
+				square1.sweep_delay = 1; // cause sweep to recalculate now
+				square1.clock_sweep();
+			}
+		}
+		break;
+	
+	case 2:
+		wave.write_register( reg, data );
+		break;
+	
+	case 3:
+		if ( noise.write_register( reg, data ) )
+			noise.bits = 0x7FFF;
+	}
+}