#!/usr/bin/env python
import os.path
import gzip
import spidev
import time
import RPi.GPIO as GPIO

commandPosition = 0
commandOffset = 0
pcmPosition = 0
pcmOffset = 0

spi = spidev.SpiDev()
GPIO.setmode(GPIO.BCM)
spi.open(0,0)
spi.max_speed_hz=125000000
SN_RDY = 17;
GPIO.setup( SN_RDY, GPIO.IN )
state = 0xCF
YM_CS = ( 1 << 0 )
YM_IC = ( 1 << 1 )
YM_RD = ( 1 << 2 )
YM_WR = ( 1 << 3 )
YM_A0 = ( 1 << 4 )
YM_A1 = ( 1 << 5 )
SN_CS = ( 1 << 6 )
SN_WE = ( 1 << 7 )

def get_uncompressed_size( file ):
	fileobj = open( file, 'r' )
	fileobj.seek( -8, 2 )
	crc32 = gzip.read32( fileobj )
	isize = gzip.read32( fileobj )  # may exceed 2GB
	fileobj.close()
	return isize

def pushOut( var, data ):
	spi.xfer2( [ var, data ] )
	#spi.xfer2( [ 0x55, 0xAA ] )
	#spi.xfer2( [ 0xAA, 0x55 ] )
	
def writeSN76489( data ):
	pushOut((( state & ~( SN_CS )) & ~( SN_WE )), data )
	#time.sleep( 0.00000007 )
	#channel = GPIO.wait_for_edge( SN_RDY, GPIO.RISING, timeout = 1 )
	pushOut( state, data )

def writeYM2612( port, addr, data ):
	newState = state;
	if port == 0:
		newState = ((newState & ~( YM_CS )) & ~( YM_A0 )) & ~( YM_A1 )
	else:
		newState = ((newState & ~( YM_CS )) & ~( YM_A0 )) | ( YM_A1 )
	newState &= ~( YM_WR )
	pushOut( newState, addr )
	#time.sleep( 0.00000001 )
	newState |= YM_WR
	pushOut( newState, addr )
	#time.sleep( 0.00000001 )
	newState = ( newState | YM_A0 )
	pushOut( newState, data )
	#time.sleep( 0.00000001 )
	newState &= ~( YM_WR )
	pushOut( newState, data )
	#time.sleep( 0.00000001 )
	newState = newState | YM_WR
	pushOut( newState, data )
	#time.sleep( 0.00000001 )
	pushOut( state, data )
	
def main():
	vgmSize = get_uncompressed_size( 'Sonic the Hedgehog - Staff Roll.vgz' )
	print "VGM Size:", vgmSize
	vgmFile = gzip.open( 'Sonic the Hedgehog - Staff Roll.vgz' )	
	vgmBuf = bytearray( vgmSize )
	vgmBuf = vgmFile.read()
	print "Ident:", "".join( n for n in vgmBuf[ 0 : 4 ] )
	eofOffset = 0
	for i in range( 0, 4 ):
		eofOffset += ord( vgmBuf[ i + 4 ]) << ( 8 * i )
	print "EOF Offset:", eofOffset
	print "Version:", "".join( format( ord( n ), 'x' ) for n in reversed( vgmBuf[ 8 : 12 ]))
	snClock = 0
	for i in range( 0, 4 ):
		snClock += ord(vgmBuf[ i + 12 ]) << ( 8 * i )
	print "SN76489 Clock:", snClock
	
	loopOffset = 0
	for i in range( 0, 4 ):
		loopOffset += ord(vgmBuf[ i + 0x1c ]) << ( 8 * i )
	print "Loop Offset:", loopOffset
	
	loopNumber = 0
	for i in range( 0, 4 ):
		loopNumber += ord(vgmBuf[ i + 0x20 ]) << ( 8 * i )
	print "Loop Number:", loopNumber
	
	snClock = 0
	for i in range( 0, 4 ):
		snClock += ord(vgmBuf[ i + 12 ]) << ( 8 * i )
	print "SN76489 Clock:", snClock
	
	vgmDataOffset = 0
	for i in range( 0, 4 ):
		vgmDataOffset += ord( vgmBuf[ i + 0x34 ]) << ( 8 * i )
	if vgmDataOffset == 0 or vgmDataOffset == 0x0C:
		vgmDataOffset = 0x40;
	print "VGM Data Offset:", hex( vgmDataOffset )
	
	commandPosition = vgmDataOffset
	pause = 0
	data = ord( vgmBuf[ commandPosition ] )
	commandPosition += 1
	done = 0
	while ( done != 1 ) or ( loopNumber > 0 ):
		#print hex( data ) 
		if data == 0x4f: 
			writeSN76489( ord( vgmBuf[ commandPosition ] ) )
			commandPosition += 1
			
		elif data == 0x50:
			writeSN76489( ord( vgmBuf[ commandPosition ] ) )
			commandPosition += 1
			
		elif data == 0x52:
			addr = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			data = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			writeYM2612( 0, addr, data );
			
		elif data == 0x53:
			addr = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			data = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			writeYM2612( 1, addr, data );
			
		elif data == 0x61:
			pause = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			pause += ord( vgmBuf[ commandPosition ] ) << 8
			commandPosition += 1
			time.sleep( pause * 0.000022675737 )
			
		elif data == 0x62:
			pause = 735;
			time.sleep( pause * 0.000022675737 )
			
		elif data == 0x63:
			pause = 882;
			time.sleep( pause * 0.000022675737 )
			
		elif data == 0x66:
		  if loopOffset > 0:
			  commandPointer = loopOffset + vgmDataOffset
			  loopOffset = 0
		  done = 1;
		  return 0
		  
		elif data == 0x67:
			temp = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			dataBlockType = ord( vgmBuf[ commandPosition ] )
			commandPosition += 1
			if dataBlockType < 0x40 :
				size = 0
				for i in range( 0, 4 ):
					size += ord( vgmBuf[ commandPosition ] ) << ( 8 * i )
					commandPosition += 1
				print size
				pcmOffset = commandPosition;
				commandPosition += size
			else:
				print "wrong pcm type", dataBlockType
				done = 1; 
				
		elif ( data >> 4 ) == 0x07:
			time.sleep(( data & 0x0F ) * 0.000022675737 )
			addr = 0x2A
			
		elif ( data >> 4 ) == 0x08:
			pause = data & 0x0F
			addr = 0x2A
			data = ord( vgmBuf[ pcmPosition ] )
			pcmPosition += 1
			writeYM2612( 0, addr, data )
			time.sleep( pause * 0.000022675737 )
			
		elif data == 0xE0:
			s = 0
			for i in range( 0, 4 ):
				s += ord( vgmBuf[ commandPosition ] ) << ( 8 * i )
				commandPosition += 1
			pcmPosition = s + pcmOffset;
			
		else:
		  print "unknown command", data
		
		if ( loopOffset == 0 ) and ( loopNumber > 0 ):
			loopNumber -= 1
			
		data = ord( vgmBuf[ commandPosition ] )
		commandPosition += 1
	
	return 0

if __name__ == '__main__':
	main()