// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/

#include "Sap_Emu.h"

#include "blargg_endian.h"
#include <string.h>

/* Copyright (C) 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"

long const base_scanline_period = 114;

Sap_Emu::Sap_Emu()
{
	set_type( gme_sap_type );
	
	static const char* const names [Sap_Apu::osc_count * 2] = {
		"Wave 1", "Wave 2", "Wave 3", "Wave 4",
		"Wave 5", "Wave 6", "Wave 7", "Wave 8",
	};
	set_voice_names( names );
	
	static int const types [Sap_Apu::osc_count * 2] = {
		wave_type | 1, wave_type | 2, wave_type | 3, wave_type | 0,
		wave_type | 5, wave_type | 6, wave_type | 7, wave_type | 4,
	};
	set_voice_types( types );
	set_silence_lookahead( 6 );
}

Sap_Emu::~Sap_Emu() { }

// Track info

// Returns 16 or greater if not hex
inline int from_hex_char( int h )
{
	h -= 0x30;
	if ( (unsigned) h > 9 )
		h = ((h - 0x11) & 0xDF) + 10;
	return h;
}

static long from_hex( byte const* in )
{
	unsigned result = 0;
	for ( int n = 4; n--; )
	{
		int h = from_hex_char( *in++ );
		if ( h > 15 )
			return -1;
		result = result * 0x10 + h;
	}
	return result;
}

static int from_dec( byte const* in, byte const* end )
{
	if ( in >= end )
		return -1;
	
	int n = 0;
	while ( in < end )
	{
		int dig = *in++ - '0';
		if ( (unsigned) dig > 9 )
			return -1;
		n = n * 10 + dig;
	}
	return n;
}

static void parse_string( byte const* in, byte const* end, int len, char* out )
{
	byte const* start = in;
	if ( *in++ == '\"' )
	{
		start++;
		while ( in < end && *in != '\"' )
			in++;
	}
	else
	{
		in = end;
	}
	len = min( len - 1, int (in - start) );
	out [len] = 0;
	memcpy( out, start, len );
}

static blargg_err_t parse_info( byte const* in, long size, Sap_Emu::info_t* out )
{
	out->track_count   = 1;
	out->author    [0] = 0;
	out->name      [0] = 0;
	out->copyright [0] = 0;
	
	if ( size < 16 || memcmp( in, "SAP\x0D\x0A", 5 ) )
		return gme_wrong_file_type;
	
	byte const* file_end = in + size - 5;
	in += 5;
	while ( in < file_end && (in [0] != 0xFF || in [1] != 0xFF) )
	{
		byte const* line_end = in;
		while ( line_end < file_end && *line_end != 0x0D )
			line_end++;
		
		char const* tag = (char const*) in;
		while ( in < line_end && *in > ' ' )
			in++;
		int tag_len = (char const*) in - tag;
		
		while ( in < line_end && *in <= ' ' ) in++;
		
		if ( tag_len <= 0 )
		{
			// skip line
		}
		else if ( !strncmp( "INIT", tag, tag_len ) )
		{
			out->init_addr = from_hex( in );
			if ( (unsigned long) out->init_addr > 0xFFFF )
				return "Invalid init address";
		}
		else if ( !strncmp( "PLAYER", tag, tag_len ) )
		{
			out->play_addr = from_hex( in );
			if ( (unsigned long) out->play_addr > 0xFFFF )
				return "Invalid play address";
		}
		else if ( !strncmp( "MUSIC", tag, tag_len ) )
		{
			out->music_addr = from_hex( in );
			if ( (unsigned long) out->music_addr > 0xFFFF )
				return "Invalid music address";
		}
		else if ( !strncmp( "SONGS", tag, tag_len ) )
		{
			out->track_count = from_dec( in, line_end );
			if ( out->track_count <= 0 )
				return "Invalid track count";
		}
		else if ( !strncmp( "TYPE", tag, tag_len ) )
		{
			switch ( out->type = *in )
			{
			case 'C':
			case 'B':
				break;
			
			case 'D':
				return "Digimusic not supported";
			
			default:
				return "Unsupported player type";
			}
		}
		else if ( !strncmp( "STEREO", tag, tag_len ) )
		{
			out->stereo = true;
		}
		else if ( !strncmp( "FASTPLAY", tag, tag_len ) )
		{
			out->fastplay = from_dec( in, line_end );
			if ( out->fastplay <= 0 )
				return "Invalid fastplay value";
		}
		else if ( !strncmp( "AUTHOR", tag, tag_len ) )
		{
			parse_string( in, line_end, sizeof out->author, out->author );
		}
		else if ( !strncmp( "NAME", tag, tag_len ) )
		{
			parse_string( in, line_end, sizeof out->name, out->name );
		}
		else if ( !strncmp( "DATE", tag, tag_len ) )
		{
			parse_string( in, line_end, sizeof out->copyright, out->copyright );
		}
		
		in = line_end + 2;
	}
	
	if ( in [0] != 0xFF || in [1] != 0xFF )
		return "ROM data missing";
	out->rom_data = in + 2;
	
	return 0;
}

static void copy_sap_fields( Sap_Emu::info_t const& in, track_info_t* out )
{
	Gme_File::copy_field_( out->game,      in.name );
	Gme_File::copy_field_( out->author,    in.author );
	Gme_File::copy_field_( out->copyright, in.copyright );
}

blargg_err_t Sap_Emu::track_info_( track_info_t* out, int ) const
{
	copy_sap_fields( info, out );
	return 0;
}

struct Sap_File : Gme_Info_
{
	Sap_Emu::info_t info;
	
	Sap_File() { set_type( gme_sap_type ); }
	
	blargg_err_t load_mem_( byte const* begin, long size )
	{
		RETURN_ERR( parse_info( begin, size, &info ) );
		set_track_count( info.track_count );
		return 0;
	}
	
	blargg_err_t track_info_( track_info_t* out, int ) const
	{
		copy_sap_fields( info, out );
		return 0;
	}
};

static Music_Emu* new_sap_emu () { return BLARGG_NEW Sap_Emu ; }
static Music_Emu* new_sap_file() { return BLARGG_NEW Sap_File; }

static gme_type_t_ const gme_sap_type_ = { "Atari XL", 0, &new_sap_emu, &new_sap_file, "SAP", 1 };
BLARGG_EXPORT extern gme_type_t const gme_sap_type = &gme_sap_type_;

// Setup

blargg_err_t Sap_Emu::load_mem_( byte const* in, long size )
{
	file_end = in + size;
	
	info.warning    = 0;
	info.type       = 'B';
	info.stereo     = false;
	info.init_addr  = -1;
	info.play_addr  = -1;
	info.music_addr = -1;
	info.fastplay   = 312;
	RETURN_ERR( parse_info( in, size, &info ) );
	
	set_warning( info.warning );
	set_track_count( info.track_count );
	set_voice_count( Sap_Apu::osc_count << info.stereo );
	apu_impl.volume( gain() );
	
	return setup_buffer( 1773447 );
}

void Sap_Emu::update_eq( blip_eq_t const& eq )
{
	apu_impl.synth.treble_eq( eq );
}

void Sap_Emu::set_voice( int i, Blip_Buffer* center, Blip_Buffer* left, Blip_Buffer* right )
{
	int i2 = i - Sap_Apu::osc_count;
	if ( i2 >= 0 )
		apu2.osc_output( i2, right );
	else
		apu.osc_output( i, (info.stereo ? left : center) );
}

// Emulation

void Sap_Emu::set_tempo_( double t )
{
	scanline_period = sap_time_t (base_scanline_period / t);
}

inline sap_time_t Sap_Emu::play_period() const { return info.fastplay * scanline_period; }

void Sap_Emu::cpu_jsr( sap_addr_t addr )
{
	check( r.sp >= 0xFE ); // catch anything trying to leave data on stack
	r.pc = addr;
	int high_byte = (idle_addr - 1) >> 8;
	if ( r.sp == 0xFE && mem.ram [0x1FF] == high_byte )
		r.sp = 0xFF; // pop extra byte off
	mem.ram [0x100 + r.sp--] = high_byte; // some routines use RTI to return
	mem.ram [0x100 + r.sp--] = high_byte;
	mem.ram [0x100 + r.sp--] = (idle_addr - 1) & 0xFF;
}

void Sap_Emu::run_routine( sap_addr_t addr )
{
	cpu_jsr( addr );
	cpu::run( 312 * base_scanline_period * 60 );
	check( r.pc == idle_addr );
}

inline void Sap_Emu::call_init( int track )
{
	switch ( info.type )
	{
	case 'B':
		r.a = track;
		run_routine( info.init_addr );
		break;
	
	case 'C':
		r.a = 0x70;
		r.x = info.music_addr&0xFF;
		r.y = info.music_addr >> 8;
		run_routine( info.play_addr + 3 );
		r.a = 0;
		r.x = track;
		run_routine( info.play_addr + 3 );
		break;
	}
}

blargg_err_t Sap_Emu::start_track_( int track )
{
	RETURN_ERR( Classic_Emu::start_track_( track ) );
	
	memset( &mem, 0, sizeof mem );

	byte const* in = info.rom_data;
	while ( file_end - in >= 5 )
	{
		unsigned start = get_le16( in );
		unsigned end   = get_le16( in + 2 );
		//debug_printf( "Block $%04X-$%04X\n", start, end );
		in += 4;
		if ( end < start )
		{
			set_warning( "Invalid file data block" );
			break;
		}
		long len = end - start + 1;
		if ( len > file_end - in )
		{
			set_warning( "Invalid file data block" );
			break;
		}
		
		memcpy( mem.ram + start, in, len );
		in += len;
		if ( file_end - in >= 2 && in [0] == 0xFF && in [1] == 0xFF )
			in += 2;
	}
	
	apu.reset( &apu_impl );
	apu2.reset( &apu_impl );
	cpu::reset( mem.ram );
	time_mask = 0; // disables sound during init
	call_init( track );
	time_mask = -1;
	
	next_play = play_period();
	
	return 0;
}

// Emulation

// see sap_cpu_io.h for read/write functions

void Sap_Emu::cpu_write_( sap_addr_t addr, int data )
{
	if ( (addr ^ Sap_Apu::start_addr) <= (Sap_Apu::end_addr - Sap_Apu::start_addr) )
	{
		GME_APU_HOOK( this, addr - Sap_Apu::start_addr, data );
		apu.write_data( time() & time_mask, addr, data );
		return;
	}
	
	if ( (addr ^ (Sap_Apu::start_addr + 0x10)) <= (Sap_Apu::end_addr - Sap_Apu::start_addr) &&
			info.stereo )
	{
		GME_APU_HOOK( this, addr - 0x10 - Sap_Apu::start_addr + 10, data );
		apu2.write_data( time() & time_mask, addr ^ 0x10, data );
		return;
	}

	if ( (addr & ~0x0010) != 0xD20F || data != 0x03 )
		debug_printf( "Unmapped write $%04X <- $%02X\n", addr, data );
}

inline void Sap_Emu::call_play()
{
	switch ( info.type )
	{
	case 'B':
		cpu_jsr( info.play_addr );
		break;
	
	case 'C':
		cpu_jsr( info.play_addr + 6 );
		break;
	}
}

blargg_err_t Sap_Emu::run_clocks( blip_time_t& duration, int )
{
	set_time( 0 );
	while ( time() < duration )
	{
		if ( cpu::run( duration ) || r.pc > idle_addr )
			return "Emulation error (illegal instruction)";
		
		if ( r.pc == idle_addr )
		{
			if ( next_play <= duration )
			{
				set_time( next_play );
				next_play += play_period();
				call_play();
				GME_FRAME_HOOK( this );
			}
			else
			{
				set_time( duration );
			}
		}
	}
	
	duration = time();
	next_play -= duration;
	check( next_play >= 0 );
	if ( next_play < 0 )
		next_play = 0;
	apu.end_frame( duration );
	if ( info.stereo )
		apu2.end_frame( duration );
	
	return 0;
}
