1 files changed, 136 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libgme/nes_fme7_apu.c b/lib/rbcodec/codecs/libgme/nes_fme7_apu.c
new file mode 100644
index 0000000000..3e47e0b17c
--- /dev/null
+++ b/lib/rbcodec/codecs/libgme/nes_fme7_apu.c
@@ -0,0 +1,136 @@
+// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
+
+#include "nes_fme7_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"
+
+void Fme7_init( struct Nes_Fme7_Apu* this )
+{
+        Synth_init( &this->synth );
+        
+        Fme7_output( this, NULL );
+        Fme7_volume( this, (int)FP_ONE_VOLUME );
+        Fme7_reset( this );
+}
+
+void Fme7_reset( struct Nes_Fme7_Apu* this )
+{
+        this->last_time = 0;
+        
+        int i;
+        for ( i = 0; i < fme7_osc_count; i++ )
+                this->oscs [i].last_amp = 0;
+        
+        this->latch = 0;
+        memset( this->regs, 0, sizeof this->regs);
+        memset( this->phases, 0, sizeof this->phases );
+        memset( this->delays, 0, sizeof this->delays );
+}
+
+static unsigned char const amp_table [16] =
+{
+        #define ENTRY( n ) (unsigned char) (n * amp_range + 0.5)
+        ENTRY(0.0000), ENTRY(0.0078), ENTRY(0.0110), ENTRY(0.0156),
+        ENTRY(0.0221), ENTRY(0.0312), ENTRY(0.0441), ENTRY(0.0624),
+        ENTRY(0.0883), ENTRY(0.1249), ENTRY(0.1766), ENTRY(0.2498),
+        ENTRY(0.3534), ENTRY(0.4998), ENTRY(0.7070), ENTRY(1.0000)
+        #undef ENTRY
+};
+
+void Fme7_run_until( struct Nes_Fme7_Apu* this, blip_time_t end_time )
+{
+        require( end_time >= this->last_time );
+        
+        int index;
+        for ( index = 0; index < fme7_osc_count; index++ )
+        {
+                int mode = this->regs [7] >> index;
+                int vol_mode = this->regs [010 + index];
+                int volume = amp_table [vol_mode & 0x0F];
+                
+                struct Blip_Buffer* const osc_output = this->oscs [index].output;
+                if ( !osc_output )
+                        continue;
+                
+                // check for unsupported mode
+                #ifndef NDEBUG
+                        if ( (mode & 011) <= 001 && vol_mode & 0x1F )
+                                debug_printf( "FME7 used unimplemented sound mode: %02X, vol_mode: %02X\n",
+                                                mode, vol_mode & 0x1F );
+                #endif
+                
+                if ( (mode & 001) | (vol_mode & 0x10) )
+                        volume = 0; // noise and envelope aren't supported
+                
+                // period
+                int const period_factor = 16;
+                unsigned period = (this->regs [index * 2 + 1] & 0x0F) * 0x100 * period_factor +
+                                this->regs [index * 2] * period_factor;
+                if ( period < 50 ) // around 22 kHz
+                {
+                        volume = 0;
+                        if ( !period ) // on my AY-3-8910A, period doesn't have extra one added
+                                period = period_factor;
+                }
+                
+                // current amplitude
+                int amp = volume;
+                if ( !this->phases [index] )
+                        amp = 0;
+                
+                {
+                        int delta = amp - this->oscs [index].last_amp;
+                        if ( delta )
+                        {
+                                this->oscs [index].last_amp = amp;
+                                Blip_set_modified( osc_output );
+                                Synth_offset( &this->synth, this->last_time, delta, osc_output );
+                        }
+                }
+                
+                blip_time_t time = this->last_time + this->delays [index];
+                if ( time < end_time )
+                {
+                        int delta = amp * 2 - volume;
+                        Blip_set_modified( osc_output );
+                        if ( volume )
+                        {
+                                do
+                                {
+                                        delta = -delta;
+                                        Synth_offset_inline( &this->synth, time, delta, osc_output );
+                                        time += period;
+                                }
+                                while ( time < end_time );
+                                
+                                this->oscs [index].last_amp = (delta + volume) >> 1;
+                                this->phases [index] = (delta > 0);
+                        }
+                        else
+                        {
+                                // maintain phase when silent
+                                int count = (end_time - time + period - 1) / period;
+                                this->phases [index] ^= count & 1;
+                                time += count * period;
+                        }
+                }
+                
+                this->delays [index] = time - end_time;
+        }
+        
+        this->last_time = end_time;
+}
+