// Game_Music_Emu 0.5.2. 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 Nes_Fme7_Apu::reset() { last_time = 0; for ( int i = 0; i < osc_count; i++ ) oscs [i].last_amp = 0; fme7_apu_state_t* state = this; memset( state, 0, sizeof *state ); } unsigned char const Nes_Fme7_Apu::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 Nes_Fme7_Apu::run_until( blip_time_t end_time ) { require( end_time >= last_time ); for ( int index = 0; index < osc_count; index++ ) { int mode = regs [7] >> index; int vol_mode = regs [010 + index]; int volume = amp_table [vol_mode & 0x0F]; Blip_Buffer* const osc_output = oscs [index].output; if ( !osc_output ) continue; osc_output->set_modified(); // check for unsupported mode #ifndef NDEBUG if ( (mode & 011) <= 001 && vol_mode & 0x1F ) dprintf( "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 = (regs [index * 2 + 1] & 0x0F) * 0x100 * period_factor + 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 ( !phases [index] ) amp = 0; { int delta = amp - oscs [index].last_amp; if ( delta ) { oscs [index].last_amp = amp; synth.offset( last_time, delta, osc_output ); } } blip_time_t time = last_time + delays [index]; if ( time < end_time ) { int delta = amp * 2 - volume; if ( volume ) { do { delta = -delta; synth.offset_inline( time, delta, osc_output ); time += period; } while ( time < end_time ); oscs [index].last_amp = (delta + volume) >> 1; phases [index] = (delta > 0); } else { // maintain phase when silent int count = (end_time - time + period - 1) / period; phases [index] ^= count & 1; time += (blargg_long) count * period; } } delays [index] = time - end_time; } last_time = end_time; }