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

#include "Hes_Emu.h"

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

/* 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"

static int const timer_mask  = 0x04;
static int const vdp_mask    = 0x02;
static int const i_flag_mask = 0x04;
static int const unmapped    = 0xFF;

static long const period_60hz = 262 * 455L; // scanlines * clocks per scanline

using std::min;
using std::max;

Hes_Emu::Hes_Emu()
{
	timer.raw_load = 0;
	set_type( gme_hes_type );

	static const char* const names [Hes_Apu::osc_count] = {
		"Wave 1", "Wave 2", "Wave 3", "Wave 4", "Multi 1", "Multi 2"
	};
	set_voice_names( names );

	static int const types [Hes_Apu::osc_count] = {
		wave_type  | 0, wave_type  | 1, wave_type | 2, wave_type | 3,
		mixed_type | 0, mixed_type | 1
	};
	set_voice_types( types );
	set_silence_lookahead( 6 );
	set_gain( 1.11 );
}

Hes_Emu::~Hes_Emu() { }

void Hes_Emu::unload()
{
	rom.clear();
	Music_Emu::unload();
}

// Track info

static byte const* copy_field( byte const* in, char* out )
{
	if ( in )
	{
		int len = 0x20;
		if ( in [0x1F] && !in [0x2F] )
			len = 0x30; // fields are sometimes 16 bytes longer (ugh)

		// since text fields are where any data could be, detect non-text
		// and fields with data after zero byte terminator

		int i = 0;
		for ( i = 0; i < len && in [i]; i++ )
			if ( ((in [i] + 1) & 0xFF) < ' ' + 1 ) // also treat 0xFF as non-text
				return 0; // non-ASCII found

		for ( ; i < len; i++ )
			if ( in [i] )
				return 0; // data after terminator

		Gme_File::copy_field_( out, (char const*) in, len );
		in += len;
	}
	return in;
}

static void copy_hes_fields( byte const* in, track_info_t* out )
{
	if ( *in >= ' ' )
	{
		in = copy_field( in, out->game );
		in = copy_field( in, out->author );
		in = copy_field( in, out->copyright );
	}
}

blargg_err_t Hes_Emu::track_info_( track_info_t* out, int ) const
{
	copy_hes_fields( rom.begin() + 0x20, out );
	return 0;
}

static blargg_err_t check_hes_header( void const* header )
{
	if ( memcmp( header, "HESM", 4 ) )
		return gme_wrong_file_type;
	return 0;
}

struct Hes_File : Gme_Info_
{
	struct header_t {
		char header [Hes_Emu::header_size];
		char unused [0x20];
		byte fields [0x30 * 3];
	} h;

	Hes_File() { set_type( gme_hes_type ); }

	blargg_err_t load_( Data_Reader& in )
	{
		blaarg_static_assert( offsetof (header_t,fields) == Hes_Emu::header_size + 0x20, "HES header layout is incorrect!" );
		blargg_err_t err = in.read( &h, sizeof h );
		if ( err )
			return (err == in.eof_error ? gme_wrong_file_type : err);
		return check_hes_header( &h );
	}

	blargg_err_t track_info_( track_info_t* out, int ) const
	{
		copy_hes_fields( h.fields, out );
		return 0;
	}
};

static Music_Emu* new_hes_emu () { return BLARGG_NEW Hes_Emu ; }
static Music_Emu* new_hes_file() { return BLARGG_NEW Hes_File; }

static gme_type_t_ const gme_hes_type_ = { "PC Engine", 256, &new_hes_emu, &new_hes_file, "HES", 1 };
extern gme_type_t const gme_hes_type = &gme_hes_type_;


// Setup

blargg_err_t Hes_Emu::load_( Data_Reader& in )
{
	blaarg_static_assert( offsetof (header_t,unused [4]) == header_size, "HES header layout is incorrect!" );
	RETURN_ERR( rom.load( in, header_size, &header_, unmapped ) );

	RETURN_ERR( check_hes_header( header_.tag ) );

	if ( header_.vers != 0 )
		set_warning( "Unknown file version" );

	if ( memcmp( header_.data_tag, "DATA", 4 ) )
		set_warning( "Data header missing" );

	if ( memcmp( header_.unused, "\0\0\0\0", 4 ) )
		set_warning( "Unknown header data" );

	// File spec supports multiple blocks, but I haven't found any, and
	// many files have bad sizes in the only block, so it's simpler to
	// just try to load the damn data as best as possible.

	long addr = get_le32( header_.addr );
	long size = get_le32( header_.size );
	long const rom_max = 0x100000;
	if ( addr & ~(rom_max - 1) )
	{
		set_warning( "Invalid address" );
		addr &= rom_max - 1;
	}
	if ( (unsigned long) (addr + size) > (unsigned long) rom_max )
		set_warning( "Invalid size" );

	if ( size != rom.file_size() )
	{
		if ( size <= rom.file_size() - 4 && !memcmp( rom.begin() + size, "DATA", 4 ) )
			set_warning( "Multiple DATA not supported" );
		else if ( size < rom.file_size() )
			set_warning( "Extra file data" );
		else
			set_warning( "Missing file data" );
	}

	rom.set_addr( addr );

	set_voice_count( apu.osc_count );

	apu.volume( gain() );

	return setup_buffer( 7159091 );
}

void Hes_Emu::update_eq( blip_eq_t const& eq )
{
	apu.treble_eq( eq );
}

void Hes_Emu::set_voice( int i, Blip_Buffer* center, Blip_Buffer* left, Blip_Buffer* right )
{
	apu.osc_output( i, center, left, right );
}

// Emulation

void Hes_Emu::recalc_timer_load()
{
	timer.load = timer.raw_load * timer_base + 1;
}

void Hes_Emu::set_tempo_( double t )
{
	play_period = hes_time_t (period_60hz / t);
	timer_base = int (1024 / t);
	recalc_timer_load();
}

blargg_err_t Hes_Emu::start_track_( int track )
{
	RETURN_ERR( Classic_Emu::start_track_( track ) );

	memset( ram, 0, sizeof ram ); // some HES music relies on zero fill
	memset( sgx, 0, sizeof sgx );

	apu.reset();
	cpu::reset();

	for ( unsigned i = 0; i < sizeof header_.banks; i++ )
		set_mmr( i, header_.banks [i] );
	set_mmr( page_count, 0xFF ); // unmapped beyond end of address space

	irq.disables  = timer_mask | vdp_mask;
	irq.timer     = future_hes_time;
	irq.vdp       = future_hes_time;

	timer.enabled = false;
	timer.raw_load= 0x80;
	timer.count   = timer.load;
	timer.fired   = false;
	timer.last_time = 0;

	vdp.latch     = 0;
	vdp.control   = 0;
	vdp.next_vbl  = 0;

	ram [0x1FF] = (idle_addr - 1) >> 8;
	ram [0x1FE] = (idle_addr - 1) & 0xFF;
	r.sp = 0xFD;
	r.pc = get_le16( header_.init_addr );
	r.a  = track;

	recalc_timer_load();
	last_frame_hook = 0;

	return 0;
}

// Hardware

void Hes_Emu::cpu_write_vdp( int addr, int data )
{
	switch ( addr )
	{
	case 0:
		vdp.latch = data & 0x1F;
		break;

	case 2:
		if ( vdp.latch == 5 )
		{
			if ( data & 0x04 )
				set_warning( "Scanline interrupt unsupported" );
			run_until( time() );
			vdp.control = data;
			irq_changed();
		}
		else
		{
			debug_printf( "VDP not supported: $%02X <- $%02X\n", vdp.latch, data );
		}
		break;

	case 3:
		debug_printf( "VDP MSB not supported: $%02X <- $%02X\n", vdp.latch, data );
		break;
	}
}

void Hes_Emu::cpu_write_( hes_addr_t addr, int data )
{
	if ( unsigned (addr - apu.start_addr) <= apu.end_addr - apu.start_addr )
	{
		GME_APU_HOOK( this, addr - apu.start_addr, data );
		// avoid going way past end when a long block xfer is writing to I/O space
		hes_time_t t = min( time(), end_time() + 8 );
		apu.write_data( t, addr, data );
		return;
	}

	hes_time_t time = this->time();
	switch ( addr )
	{
	case 0x0000:
	case 0x0002:
	case 0x0003:
		cpu_write_vdp( addr, data );
		return;

	case 0x0C00: {
		run_until( time );
		timer.raw_load = (data & 0x7F) + 1;
		recalc_timer_load();
		timer.count = timer.load;
		break;
	}

	case 0x0C01:
		data &= 1;
		if ( timer.enabled == data )
			return;
		run_until( time );
		timer.enabled = data;
		if ( data )
			timer.count = timer.load;
		break;

	case 0x1402:
		run_until( time );
		irq.disables = data;
		if ( (data & 0xF8) && (data & 0xF8) != 0xF8 ) // flag questionable values
			debug_printf( "Int mask: $%02X\n", data );
		break;

	case 0x1403:
		run_until( time );
		if ( timer.enabled )
			timer.count = timer.load;
		timer.fired = false;
		break;

#ifndef NDEBUG
	case 0x1000: // I/O port
	case 0x0402: // palette
	case 0x0403:
	case 0x0404:
	case 0x0405:
		return;

	default:
		debug_printf( "unmapped write $%04X <- $%02X\n", addr, data );
		return;
#endif
	}

	irq_changed();
}

int Hes_Emu::cpu_read_( hes_addr_t addr )
{
	hes_time_t time = this->time();
	addr &= page_size - 1;
	switch ( addr )
	{
	case 0x0000:
		if ( irq.vdp > time )
			return 0;
		irq.vdp = future_hes_time;
		run_until( time );
		irq_changed();
		return 0x20;

	case 0x0002:
	case 0x0003:
		debug_printf( "VDP read not supported: %d\n", addr );
		return 0;

	case 0x0C01:
		//return timer.enabled; // TODO: remove?
	case 0x0C00:
		run_until( time );
		debug_printf( "Timer count read\n" );
		return (unsigned) (timer.count - 1) / timer_base;

	case 0x1402:
		return irq.disables;

	case 0x1403:
		{
			int status = 0;
			if ( irq.timer <= time ) status |= timer_mask;
			if ( irq.vdp   <= time ) status |= vdp_mask;
			return status;
		}

	#ifndef NDEBUG
		case 0x1000: // I/O port
		case 0x180C: // CD-ROM
		case 0x180D:
			break;

		default:
			debug_printf( "unmapped read  $%04X\n", addr );
	#endif
	}

	return unmapped;
}

// see hes_cpu_io.h for core read/write functions

// Emulation

void Hes_Emu::run_until( hes_time_t present )
{
	while ( vdp.next_vbl < present )
		vdp.next_vbl += play_period;

	hes_time_t elapsed = present - timer.last_time;
	if ( elapsed > 0 )
	{
		if ( timer.enabled )
		{
			timer.count -= elapsed;
			if ( timer.count <= 0 )
				timer.count += timer.load;
		}
		timer.last_time = present;
	}
}

void Hes_Emu::irq_changed()
{
	hes_time_t present = time();

	if ( irq.timer > present )
	{
		irq.timer = future_hes_time;
		if ( timer.enabled && !timer.fired )
			irq.timer = present + timer.count;
	}

	if ( irq.vdp > present )
	{
		irq.vdp = future_hes_time;
		if ( vdp.control & 0x08 )
			irq.vdp = vdp.next_vbl;
	}

	hes_time_t time = future_hes_time;
	if ( !(irq.disables & timer_mask) ) time = irq.timer;
	if ( !(irq.disables &   vdp_mask) ) time = min( time, irq.vdp );

	set_irq_time( time );
}

int Hes_Emu::cpu_done()
{
	check( time() >= end_time() ||
			(!(r.status & i_flag_mask) && time() >= irq_time()) );

	if ( !(r.status & i_flag_mask) )
	{
		hes_time_t present = time();

		if ( irq.timer <= present && !(irq.disables & timer_mask) )
		{
			timer.fired = true;
			irq.timer = future_hes_time;
			irq_changed(); // overkill, but not worth writing custom code
			#if GME_FRAME_HOOK_DEFINED
			{
				unsigned const threshold = period_60hz / 30;
				unsigned long elapsed = present - last_frame_hook;
				if ( elapsed - period_60hz + threshold / 2 < threshold )
				{
					last_frame_hook = present;
					GME_FRAME_HOOK( this );
				}
			}
			#endif
			return 0x0A;
		}

		if ( irq.vdp <= present && !(irq.disables & vdp_mask) )
		{
			// work around for bugs with music not acknowledging VDP
			//run_until( present );
			//irq.vdp = future_hes_time;
			//irq_changed();
			#if GME_FRAME_HOOK_DEFINED
				last_frame_hook = present;
				GME_FRAME_HOOK( this );
			#endif
			return 0x08;
		}
	}
	return 0;
}

static void adjust_time( blargg_long& time, hes_time_t delta )
{
	if ( time < future_hes_time )
	{
		time -= delta;
		if ( time < 0 )
			time = 0;
	}
}

blargg_err_t Hes_Emu::run_clocks( blip_time_t& duration_, int )
{
	blip_time_t const duration = duration_; // cache

	if ( cpu::run( duration ) )
		set_warning( "Emulation error (illegal instruction)" );

	check( time() >= duration );
	//check( time() - duration < 20 ); // Txx instruction could cause going way over

	run_until( duration );

	// end time frame
	timer.last_time -= duration;
	vdp.next_vbl    -= duration;
	#if GME_FRAME_HOOK_DEFINED
		last_frame_hook -= duration;
	#endif
	cpu::end_frame( duration );
	::adjust_time( irq.timer, duration );
	::adjust_time( irq.vdp,   duration );
	apu.end_frame( duration );

	return 0;
}
