193 lines
4.6 KiB
C++
193 lines
4.6 KiB
C++
// Game_Music_Emu $vers. http://www.slack.net/~ant/
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#include "Sap_Core.h"
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/* Copyright (C) 2006-2008 Shay Green. This module is free software; you
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can redistribute it and/or modify it under the terms of the GNU Lesser
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General Public License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version. This
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module is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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details. You should have received a copy of the GNU Lesser General Public
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License along with this module; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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#include "blargg_source.h"
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int const idle_addr = 0xD2D2;
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Sap_Core::Sap_Core()
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{
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set_tempo( 1 );
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}
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void Sap_Core::push( int b )
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{
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mem.ram [0x100 + cpu.r.sp--] = (byte) b;
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}
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void Sap_Core::jsr_then_stop( addr_t addr )
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{
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cpu.r.pc = addr;
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// Some rips pop three bytes off stack before RTS.
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push( (idle_addr - 1) >> 8 );
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push( idle_addr - 1 );
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// 3 bytes so that RTI or RTS will jump to idle_addr.
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// RTI will use the first two bytes as the address, 0xD2D2.
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// RTS will use the last two bytes, 0xD2D1, which it internally increments.
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push( (idle_addr - 1) >> 8 );
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push( (idle_addr - 1) >> 8 );
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push( idle_addr - 1 );
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}
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// Runs routine and allows it up to one second to return
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void Sap_Core::run_routine( addr_t addr )
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{
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jsr_then_stop( addr );
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run_cpu( lines_per_frame * base_scanline_period * 60 );
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check( cpu.r.pc == idle_addr );
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check( cpu.r.sp >= 0xFF - 6 );
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}
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inline void Sap_Core::call_init( int track )
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{
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cpu.r.a = track;
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switch ( info.type )
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{
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case 'B':
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run_routine( info.init_addr );
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break;
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case 'C':
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cpu.r.a = 0x70;
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cpu.r.x = info.music_addr&0xFF;
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cpu.r.y = info.music_addr >> 8;
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run_routine( info.play_addr + 3 );
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cpu.r.a = 0;
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cpu.r.x = track;
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run_routine( info.play_addr + 3 );
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break;
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case 'D':
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check( info.fastplay == lines_per_frame );
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jsr_then_stop( info.init_addr );
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break;
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}
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}
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void Sap_Core::setup_ram()
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{
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memset( &mem, 0, sizeof mem );
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ram() [idle_addr] = cpu.halt_opcode;
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addr_t const irq_addr = idle_addr - 1;
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ram() [irq_addr] = cpu.halt_opcode;
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ram() [0xFFFE] = (byte) irq_addr;
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ram() [0xFFFF] = irq_addr >> 8;
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}
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blargg_err_t Sap_Core::start_track( int track, info_t const& new_info )
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{
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info = new_info;
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check( ram() [idle_addr] == cpu.halt_opcode );
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apu_ .reset( &apu_impl_ );
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apu2_.reset( &apu_impl_ );
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cpu.reset( ram() );
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frame_start = 0;
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next_play = play_period() * 4;
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saved_state.pc = idle_addr;
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time_mask = 0; // disables sound during init
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call_init( track );
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time_mask = ~0;
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return blargg_ok;
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}
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blargg_err_t Sap_Core::run_until( time_t end )
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{
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while ( cpu.time() < end )
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{
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time_t next = min( next_play, end );
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if ( (run_cpu( next ) && cpu.r.pc != idle_addr) || cpu.error_count() )
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// TODO: better error
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return BLARGG_ERR( BLARGG_ERR_GENERIC, "Emulation error (illegal instruction)" );
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if ( cpu.r.pc == idle_addr )
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{
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if ( saved_state.pc == idle_addr )
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{
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// no code to run until next play call
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cpu.set_time( next );
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}
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else
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{
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// play had interrupted non-returning init, so restore registers
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// init routine was running
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check( cpu.r.sp == saved_state.sp - 3 );
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cpu.r = saved_state;
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saved_state.pc = idle_addr;
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}
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}
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if ( cpu.time() >= next_play )
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{
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next_play += play_period();
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if ( cpu.r.pc == idle_addr || info.type == 'D' )
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{
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// Save state if init routine is still running
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if ( cpu.r.pc != idle_addr )
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{
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check( info.type == 'D' );
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check( saved_state.pc == idle_addr );
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saved_state = cpu.r;
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}
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addr_t addr = info.play_addr;
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if ( info.type == 'C' )
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addr += 6;
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jsr_then_stop( addr );
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}
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else
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{
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dprintf( "init/play hadn't returned before next play call\n" );
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}
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}
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}
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return blargg_ok;
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}
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blargg_err_t Sap_Core::end_frame( time_t end )
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{
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RETURN_ERR( run_until( end ) );
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cpu.adjust_time( -end );
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time_t frame_time = lines_per_frame * scanline_period;
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while ( frame_start < end )
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frame_start += frame_time;
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frame_start -= end + frame_time;
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if ( (next_play -= end) < 0 )
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{
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next_play = 0;
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check( false );
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}
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apu_.end_frame( end );
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if ( info.stereo )
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apu2_.end_frame( end );
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return blargg_ok;
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}
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