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// Game_Music_Emu 0.6-pre. http://www.slack.net/~ant/
#include "Sap_Core.h"
/* Copyright (C) 2006-2008 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"
int const idle_addr = 0xD2D2;
Sap_Core::Sap_Core()
{
set_tempo( 1 );
}
void Sap_Core::push( int b )
{
mem.ram [0x100 + cpu.r.sp--] = (byte) b;
}
void Sap_Core::jsr_then_stop( addr_t addr )
{
cpu.r.pc = addr;
// Some rips pop three bytes off stack before RTS.
push( (idle_addr - 1) >> 8 );
push( idle_addr - 1 );
// 3 bytes so that RTI or RTS will jump to idle_addr.
// RTI will use the first two bytes as the address, 0xD2D2.
// RTS will use the last two bytes, 0xD2D1, which it internally increments.
push( (idle_addr - 1) >> 8 );
push( (idle_addr - 1) >> 8 );
push( idle_addr - 1 );
}
// Runs routine and allows it up to one second to return
void Sap_Core::run_routine( addr_t addr )
{
jsr_then_stop( addr );
run_cpu( lines_per_frame * base_scanline_period * 60 );
check( cpu.r.pc == idle_addr );
check( cpu.r.sp >= 0xFF - 6 );
}
inline void Sap_Core::call_init( int track )
{
cpu.r.a = track;
switch ( info.type )
{
case 'B':
run_routine( info.init_addr );
break;
case 'C':
cpu.r.a = 0x70;
cpu.r.x = info.music_addr&0xFF;
cpu.r.y = info.music_addr >> 8;
run_routine( info.play_addr + 3 );
cpu.r.a = 0;
cpu.r.x = track;
run_routine( info.play_addr + 3 );
break;
case 'D':
check( info.fastplay == lines_per_frame );
jsr_then_stop( info.init_addr );
break;
}
}
void Sap_Core::setup_ram()
{
memset( &mem, 0, sizeof mem );
ram() [idle_addr] = cpu.halt_opcode;
addr_t const irq_addr = idle_addr - 1;
ram() [irq_addr] = cpu.halt_opcode;
ram() [0xFFFE] = (byte) irq_addr;
ram() [0xFFFF] = irq_addr >> 8;
}
blargg_err_t Sap_Core::start_track( int track, info_t const& new_info )
{
info = new_info;
check( ram() [idle_addr] == cpu.halt_opcode );
apu_ .reset( &apu_impl_ );
apu2_.reset( &apu_impl_ );
cpu.reset( ram() );
frame_start = 0;
next_play = play_period() * 4;
saved_state.pc = idle_addr;
time_mask = 0; // disables sound during init
call_init( track );
time_mask = ~0;
return blargg_ok;
}
blargg_err_t Sap_Core::run_until( time_t end )
{
while ( cpu.time() < end )
{
time_t next = min( next_play, end );
if ( (run_cpu( next ) && cpu.r.pc != idle_addr) || cpu.error_count() )
// TODO: better error
return BLARGG_ERR( BLARGG_ERR_GENERIC, "Emulation error (illegal instruction)" );
if ( cpu.r.pc == idle_addr )
{
if ( saved_state.pc == idle_addr )
{
// no code to run until next play call
cpu.set_time( next );
}
else
{
// play had interrupted non-returning init, so restore registers
// init routine was running
check( cpu.r.sp == saved_state.sp - 3 );
cpu.r = saved_state;
saved_state.pc = idle_addr;
}
}
if ( cpu.time() >= next_play )
{
next_play += play_period();
if ( cpu.r.pc == idle_addr || info.type == 'D' )
{
// Save state if init routine is still running
if ( cpu.r.pc != idle_addr )
{
check( info.type == 'D' );
check( saved_state.pc == idle_addr );
saved_state = cpu.r;
}
addr_t addr = info.play_addr;
if ( info.type == 'C' )
addr += 6;
jsr_then_stop( addr );
}
else
{
dprintf( "init/play hadn't returned before next play call\n" );
}
}
}
return blargg_ok;
}
blargg_err_t Sap_Core::end_frame( time_t end )
{
RETURN_ERR( run_until( end ) );
cpu.adjust_time( -end );
time_t frame_time = lines_per_frame * scanline_period;
while ( frame_start < end )
frame_start += frame_time;
frame_start -= end + frame_time;
if ( (next_play -= end) < 0 )
{
next_play = 0;
check( false );
}
apu_.end_frame( end );
if ( info.stereo )
apu2_.end_frame( end );
return blargg_ok;
}
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