From acb0917556fc33681c1df5a530cf754193e67705 Mon Sep 17 00:00:00 2001
From: Andree Buschmann <AndreeBuschmann@t-online.de>
Date: Sun, 7 Aug 2011 20:01:04 +0000
Subject: Submit initial patch from FS#12176. Adds support for several new game
 music formats (AY, GBS, HES, KSS, SGC, VGM and VGZ) and replaces the current
 NSF and NSFE with a new implementation based on a port of the Game Music Emu
 library 'GME'. This first submit does not cover the full functionality
 provided by the author's original patch: Coleco-SGV is not supported, some
 GME-specific m3u-support has been removed and IRAM is not used yet. Further
 changes are very likely to follow this submit. Thanks to Mauricio Garrido.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30264 a1c6a512-1295-4272-9138-f99709370657
---
 apps/codecs/libgme/nes_vrc7_apu.c | 89 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 apps/codecs/libgme/nes_vrc7_apu.c

(limited to 'apps/codecs/libgme/nes_vrc7_apu.c')

diff --git a/apps/codecs/libgme/nes_vrc7_apu.c b/apps/codecs/libgme/nes_vrc7_apu.c
new file mode 100644
index 0000000000..d8768bfc7e
--- /dev/null
+++ b/apps/codecs/libgme/nes_vrc7_apu.c
@@ -0,0 +1,89 @@
+
+#include "nes_vrc7_apu.h"
+#include "blargg_source.h"
+
+int const period = 36; // NES CPU clocks per FM clock
+
+void Vrc7_init( struct Nes_Vrc7_Apu* this )
+{
+	Synth_init( &this->synth );
+	
+	OPLL_new ( &this->opll, 3579545, 3579545 / 72 );
+    OPLL_reset_patch( &this->opll, OPLL_VRC7_TONE );
+	
+	this->osc.output = 0;
+	this->osc.last_amp = 0;
+	this->mask = 0;
+
+	Vrc7_volume( this, 1.0 );
+	Vrc7_reset( this );
+}
+
+void Vrc7_reset( struct Nes_Vrc7_Apu* this )
+{
+	this->addr      = 0;
+	this->next_time = 0;
+	this->osc.last_amp = 0;
+
+	OPLL_reset (&this->opll);	
+	OPLL_setMask(&this->opll, this->mask);
+}
+
+void Vrc7_set_rate( struct Nes_Vrc7_Apu* this, double r )
+{
+	OPLL_set_quality( &this->opll, r < 44100 ? 0 : 1 );
+    OPLL_set_rate( &this->opll, (e_uint32)r );
+}
+
+void Vrc7_write_reg( struct Nes_Vrc7_Apu* this, int data )
+{
+	this->addr = data;
+}
+
+void Vrc7_run_until( struct Nes_Vrc7_Apu* this, blip_time_t end_time );
+void Vrc7_write_data( struct Nes_Vrc7_Apu* this, blip_time_t time, int data )
+{	
+	if ( time > this->next_time )
+		Vrc7_run_until( this, time );
+
+	OPLL_writeIO( &this->opll, 0, this->addr );
+	OPLL_writeIO( &this->opll, 1, data );
+}
+
+void Vrc7_end_frame( struct Nes_Vrc7_Apu* this, blip_time_t time )
+{
+	if ( time > this->next_time )
+		Vrc7_run_until( this, time );
+	
+	this->next_time -= time;
+	assert( this->next_time >= 0 );
+	
+	if ( this->osc.output )
+		Blip_set_modified( this->osc.output );
+}
+
+void Vrc7_run_until( struct Nes_Vrc7_Apu* this, blip_time_t end_time )
+{
+	require( end_time > this->next_time );
+
+	blip_time_t time = this->next_time;
+	OPLL* opll = &this->opll; // cache
+	struct Blip_Buffer* const output = this-> osc.output;
+	if ( output )
+	{
+		do
+		{
+			int amp = OPLL_calc( opll ) << 1;
+			int delta = amp - this->osc.last_amp;
+			if ( delta )
+			{
+				this->osc.last_amp = amp;
+				Synth_offset_inline( &this->synth, time, delta, output );
+			}
+			time += period;
+		}
+		while ( time < end_time );
+	}
+
+	this->next_time = time;
+}
-- 
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