1 files changed, 208 insertions, 0 deletions
diff --git a/plugins/gme/game-music-emu-0.6pre/gme/Gbs_Core.cpp b/plugins/gme/game-music-emu-0.6pre/gme/Gbs_Core.cpp
new file mode 100644
index 00000000..1c366d2a
--- /dev/null
+++ b/plugins/gme/game-music-emu-0.6pre/gme/Gbs_Core.cpp
@@ -0,0 +1,208 @@
+// Game_Music_Emu 0.6-pre. http://www.slack.net/~ant/
+
+#include "Gbs_Core.h"
+
+#include "blargg_endian.h"
+
+/* Copyright (C) 2003-2009 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 tempo_unit = 16;
+int const idle_addr = 0xF00D;
+int const bank_size = 0x4000;
+
+Gbs_Core::Gbs_Core() : rom( bank_size )
+{
+	tempo = tempo_unit;
+	assert( offsetof (header_t,copyright [32]) == header_t::size );
+}
+
+Gbs_Core::~Gbs_Core() { }
+
+void Gbs_Core::unload()
+{
+	header_.timer_mode = 0; // set_tempo() reads this
+	rom.clear();
+	Gme_Loader::unload();
+}
+
+bool Gbs_Core::header_t::valid_tag() const
+{
+	return 0 == memcmp( tag, "GBS", 3 );
+}
+
+blargg_err_t Gbs_Core::load_( Data_Reader& in )
+{
+	RETURN_ERR( rom.load( in, header_.size, &header_, 0 ) );
+	
+	if ( !header_.valid_tag() )
+		return blargg_err_file_type;
+	
+	if ( header_.vers != 1 )
+		set_warning( "Unknown file version" );
+	
+	if ( header_.timer_mode & 0x78 )
+		set_warning( "Invalid timer mode" );
+	
+	addr_t 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" );
+	
+	cpu.rst_base = load_addr;
+	rom.set_addr( load_addr );
+	
+	return blargg_ok;
+}
+
+void Gbs_Core::set_bank( int n )
+{
+	addr_t addr = rom.mask_addr( n * bank_size );
+	if ( addr == 0 && rom.size() > bank_size )
+		addr = bank_size; // MBC1&2 behavior, bank 0 acts like bank 1
+	cpu.map_code( bank_size, bank_size, rom.at_addr( addr ) );
+}
+
+void Gbs_Core::update_timer()
+{
+	play_period_ = 70224 / tempo_unit; // 59.73 Hz
+	
+	if ( header_.timer_mode & 0x04 ) 
+	{
+		// Using custom rate
+		static byte const rates [4] = { 6, 0, 2, 4 };
+		// TODO: emulate double speed CPU mode rather than halving timer rate
+		int double_speed = header_.timer_mode >> 7;
+		int shift = rates [ram [hi_page + 7] & 3] - double_speed;
+		play_period_ = (256 - ram [hi_page + 6]) << shift;
+	}
+	
+	play_period_ *= tempo;
+}
+
+void Gbs_Core::set_tempo( double t )
+{
+	tempo = (int) (tempo_unit / t + 0.5);
+	apu_.set_tempo( t );
+	update_timer();
+}
+
+// Jumps to routine, given pointer to address in file header. Pushes idle_addr
+// as return address, NOT old PC.
+void Gbs_Core::jsr_then_stop( byte const addr [] )
+{
+	check( cpu.r.sp == get_le16( header_.stack_ptr ) );
+	cpu.r.pc = get_le16( addr );
+	write_mem( --cpu.r.sp, idle_addr >> 8 );
+	write_mem( --cpu.r.sp, idle_addr      );
+}
+
+blargg_err_t Gbs_Core::start_track( int track, Gb_Apu::mode_t mode )
+{
+	// Reset APU to state expected by most rips
+	static byte const sound_data [] = {
+		0x80, 0xBF, 0x00, 0x00, 0xB8, // square 1 DAC disabled
+		0x00, 0x3F, 0x00, 0x00, 0xB8, // square 2 DAC disabled
+		0x7F, 0xFF, 0x9F, 0x00, 0xB8, // wave     DAC disabled
+		0x00, 0xFF, 0x00, 0x00, 0xB8, // noise    DAC disabled
+		0x77, 0xFF, 0x80, // max volume, all chans in center, power on
+	};
+	apu_.reset( mode );
+	apu_.write_register( 0, 0xFF26, 0x80 ); // power on
+	for ( int i = 0; i < (int) sizeof sound_data; i++ )
+		apu_.write_register( 0, i + apu_.io_addr, sound_data [i] );
+	apu_.end_frame( 1 ); // necessary to get click out of the way
+	
+	// Init memory and I/O registers
+	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
+	ram [idle_addr - ram_addr] = 0xED; // illegal instruction
+	ram [hi_page + 6] = header_.timer_modulo;
+	ram [hi_page + 7] = header_.timer_mode;
+	
+	// Map memory
+	cpu.reset( rom.unmapped() );
+	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 );
+	
+	// CPU registers, timing
+	update_timer();
+	next_play = play_period_;
+	cpu.r.fa = track;
+	cpu.r.sp = get_le16( header_.stack_ptr );
+	jsr_then_stop( header_.init_addr );
+	
+	return blargg_ok;
+}
+
+blargg_err_t Gbs_Core::run_until( int end )
+{
+	end_time = end;
+	cpu.set_time( cpu.time() - end );
+	while ( true )
+	{
+		run_cpu();
+		if ( cpu.time() >= 0 )
+			break;
+		
+		if ( cpu.r.pc == idle_addr )
+		{
+			if ( next_play > end_time )
+			{
+				cpu.set_time( 0 );
+				break;
+			}
+			
+			if ( cpu.time() < next_play - end_time )
+				cpu.set_time( next_play - end_time );
+			next_play += play_period_;
+			jsr_then_stop( header_.play_addr );
+		}
+		else if ( cpu.r.pc > 0xFFFF )
+		{
+			dprintf( "PC wrapped around\n" );
+			cpu.r.pc &= 0xFFFF;
+		}
+		else
+		{
+			set_warning( "Emulation error (illegal/unsupported instruction)" );
+			dprintf( "Bad opcode $%02X at $%04X\n",
+					(int) *cpu.get_code( cpu.r.pc ), (int) cpu.r.pc );
+			cpu.r.pc = (cpu.r.pc + 1) & 0xFFFF;
+			cpu.set_time( cpu.time() + 6 );
+		}
+	}
+	
+	return blargg_ok;
+}
+
+blargg_err_t Gbs_Core::end_frame( int end )
+{
+	RETURN_ERR( run_until( end ) );
+	
+	next_play -= end;
+	if ( next_play < 0 ) // happens when play routine takes too long
+	{
+		#if !GBS_IGNORE_STARVED_PLAY
+			check( false );
+		#endif
+		next_play = 0;
+	}
+	
+	apu_.end_frame( end );
+	
+	return blargg_ok;
+}