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Gbs_Emu.cpp
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Gbs_Emu.cpp
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// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
#include "Gbs_Emu.h"
#include "blargg_endian.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"
Gbs_Emu::equalizer_t const Gbs_Emu::handheld_eq = { -47.0, 2000 };
Gbs_Emu::equalizer_t const Gbs_Emu::headphones_eq = { 0.0, 300 };
Gbs_Emu::Gbs_Emu()
{
set_type( gme_gbs_type );
static const char* const names [Gb_Apu::osc_count] = {
"Square 1", "Square 2", "Wave", "Noise"
};
set_voice_names( names );
static int const types [Gb_Apu::osc_count] = {
wave_type | 1, wave_type | 2, wave_type | 0, mixed_type | 0
};
set_voice_types( types );
set_silence_lookahead( 6 );
set_max_initial_silence( 21 );
set_gain( 1.2 );
static equalizer_t const eq = { -1.0, 120 };
set_equalizer( eq );
}
Gbs_Emu::~Gbs_Emu() { }
void Gbs_Emu::unload()
{
rom.clear();
Music_Emu::unload();
}
// Track info
static void copy_gbs_fields( Gbs_Emu::header_t const& h, track_info_t* out )
{
GME_COPY_FIELD( h, out, game );
GME_COPY_FIELD( h, out, author );
GME_COPY_FIELD( h, out, copyright );
}
blargg_err_t Gbs_Emu::track_info_( track_info_t* out, int ) const
{
copy_gbs_fields( header_, out );
return 0;
}
static blargg_err_t check_gbs_header( void const* header )
{
if ( memcmp( header, "GBS", 3 ) )
return gme_wrong_file_type;
return 0;
}
struct Gbs_File : Gme_Info_
{
Gbs_Emu::header_t h;
Gbs_File() { set_type( gme_gbs_type ); }
blargg_err_t load_( Data_Reader& in )
{
blargg_err_t err = in.read( &h, Gbs_Emu::header_size );
if ( err )
return (err == in.eof_error ? gme_wrong_file_type : err);
set_track_count( h.track_count );
return check_gbs_header( &h );
}
blargg_err_t track_info_( track_info_t* out, int ) const
{
copy_gbs_fields( h, out );
return 0;
}
};
static Music_Emu* new_gbs_emu () { return BLARGG_NEW Gbs_Emu ; }
static Music_Emu* new_gbs_file() { return BLARGG_NEW Gbs_File; }
static gme_type_t_ const gme_gbs_type_ = { "Game Boy", 0, &new_gbs_emu, &new_gbs_file, "GBS", 1 };
gme_type_t const gme_gbs_type = &gme_gbs_type_;
// Setup
blargg_err_t Gbs_Emu::load_( Data_Reader& in )
{
assert( offsetof (header_t,copyright [32]) == header_size );
RETURN_ERR( rom.load( in, header_size, &header_, 0 ) );
set_track_count( header_.track_count );
RETURN_ERR( check_gbs_header( &header_ ) );
if ( header_.vers != 1 )
set_warning( "Unknown file version" );
if ( header_.timer_mode & 0x78 )
set_warning( "Invalid timer mode" );
unsigned load_addr = get_le16( header_.load_addr );
if ( (header_.load_addr [1] | header_.init_addr [1] | header_.play_addr [1]) > 0x7F ||
load_addr < 0x400 )
set_warning( "Invalid load/init/play address" );
set_voice_count( Gb_Apu::osc_count );
apu.volume( gain() );
return setup_buffer( 4194304 );
}
void Gbs_Emu::update_eq( blip_eq_t const& eq )
{
apu.treble_eq( eq );
}
void Gbs_Emu::set_voice( int i, Blip_Buffer* c, Blip_Buffer* l, Blip_Buffer* r )
{
apu.osc_output( i, c, l, r );
}
// Emulation
// see gb_cpu_io.h for read/write functions
void Gbs_Emu::set_bank( int n )
{
blargg_long addr = rom.mask_addr( n * (blargg_long) bank_size );
if ( addr == 0 && rom.size() > bank_size )
{
// TODO: what is the correct behavior? Current Game & Watch Gallery
// rip requires that this have no effect or set to bank 1.
//debug_printf( "Selected ROM bank 0\n" );
return;
//n = 1;
}
cpu::map_code( bank_size, bank_size, rom.at_addr( addr ) );
}
void Gbs_Emu::update_timer()
{
if ( header_.timer_mode & 0x04 )
{
static byte const rates [4] = { 10, 4, 6, 8 };
int shift = rates [ram [hi_page + 7] & 3] - (header_.timer_mode >> 7);
play_period = (256L - ram [hi_page + 6]) << shift;
}
else
{
play_period = 70224; // 59.73 Hz
}
if ( tempo() != 1.0 )
play_period = blip_time_t (play_period / tempo());
}
static BOOST::uint8_t const sound_data [Gb_Apu::register_count] = {
0x80, 0xBF, 0x00, 0x00, 0xBF, // square 1
0x00, 0x3F, 0x00, 0x00, 0xBF, // square 2
0x7F, 0xFF, 0x9F, 0x00, 0xBF, // wave
0x00, 0xFF, 0x00, 0x00, 0xBF, // noise
0x77, 0xF3, 0xF1, // vin/volume, status, power mode
0, 0, 0, 0, 0, 0, 0, 0, 0, // unused
0xAC, 0xDD, 0xDA, 0x48, 0x36, 0x02, 0xCF, 0x16, // waveform data
0x2C, 0x04, 0xE5, 0x2C, 0xAC, 0xDD, 0xDA, 0x48
};
void Gbs_Emu::cpu_jsr( gb_addr_t addr )
{
check( cpu::r.sp == get_le16( header_.stack_ptr ) );
cpu::r.pc = addr;
cpu_write( --cpu::r.sp, idle_addr >> 8 );
cpu_write( --cpu::r.sp, idle_addr&0xFF );
}
void Gbs_Emu::set_tempo_( double t )
{
apu.set_tempo( t );
update_timer();
}
blargg_err_t Gbs_Emu::start_track_( int track )
{
RETURN_ERR( Classic_Emu::start_track_( track ) );
memset( ram, 0, 0x4000 );
memset( ram + 0x4000, 0xFF, 0x1F80 );
memset( ram + 0x5F80, 0, sizeof ram - 0x5F80 );
ram [hi_page] = 0; // joypad reads back as 0
apu.reset();
for ( int i = 0; i < (int) sizeof sound_data; i++ )
apu.write_register( 0, i + apu.start_addr, sound_data [i] );
cpu::reset( rom.unmapped() );
unsigned load_addr = get_le16( header_.load_addr );
cpu::rst_base = load_addr;
rom.set_addr( load_addr );
cpu::map_code( ram_addr, 0x10000 - ram_addr, ram );
cpu::map_code( 0, bank_size, rom.at_addr( 0 ) );
set_bank( rom.size() > bank_size );
ram [hi_page + 6] = header_.timer_modulo;
ram [hi_page + 7] = header_.timer_mode;
update_timer();
next_play = play_period;
cpu::r.a = track;
cpu::r.pc = idle_addr;
cpu::r.sp = get_le16( header_.stack_ptr );
cpu_time = 0;
cpu_jsr( get_le16( header_.init_addr ) );
return 0;
}
blargg_err_t Gbs_Emu::run_clocks( blip_time_t& duration, int )
{
cpu_time = 0;
while ( cpu_time < duration )
{
long count = duration - cpu_time;
cpu_time = duration;
bool result = cpu::run( count );
cpu_time -= cpu::remain();
if ( result )
{
if ( cpu::r.pc == idle_addr )
{
if ( next_play > duration )
{
cpu_time = duration;
break;
}
if ( cpu_time < next_play )
cpu_time = next_play;
next_play += play_period;
cpu_jsr( get_le16( header_.play_addr ) );
GME_FRAME_HOOK( this );
// TODO: handle timer rates different than 60 Hz
}
else if ( cpu::r.pc > 0xFFFF )
{
debug_printf( "PC wrapped around\n" );
cpu::r.pc &= 0xFFFF;
}
else
{
set_warning( "Emulation error (illegal/unsupported instruction)" );
debug_printf( "Bad opcode $%.2x at $%.4x\n",
(int) *cpu::get_code( cpu::r.pc ), (int) cpu::r.pc );
cpu::r.pc = (cpu::r.pc + 1) & 0xFFFF;
cpu_time += 6;
}
}
}
duration = cpu_time;
next_play -= cpu_time;
if ( next_play < 0 ) // could go negative if routine is taking too long to return
next_play = 0;
apu.end_frame( cpu_time );
return 0;
}

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