$:.unshift(File.dirname(__FILE__)) unless
	$:.include?(File.dirname(__FILE__)) || $:.include?(File.expand_path(File.dirname(__FILE__)))

$:.unshift(File.dirname(__FILE__+"\\..")) unless
	$:.include?(File.dirname(__FILE__+"\\..")) || $:.include?(File.expand_path(File.dirname(__FILE__+"\\..")))

require 'ImageFormat'

class G64 < D64
	
#
# raw GCR binary representation of a 1541 diskette
#
# References: 
#     http://www.unusedino.de/ec64/technical/formats/g64.html
#     http://www.baltissen.org/newhtm/1541c.htm
#     http://www.scribd.com/doc/40438/The-Commodore-1541-Disk-Drive-Users-Guide
#

CBM_GCR_CODES={
	"01010"=>0x00,
	"01011"=>0x01,
	"10010"=>0x02,
	"10011"=>0x03,
	"01110"=>0x04,
	"01111"=>0x05,
	"10110"=>0x06,
	"10111"=>0x07,
	"01001"=>0x08,
	"11001"=>0x09,
	"11010"=>0x0A,
	"11011"=>0x0B,
	"01101"=>0x0C,
	"11101"=>0x0D,
	"11110"=>0x0E,
	"10101"=>0x0F
}

#G64 format starts with a signature 
is_valid_image_if lambda {
  file_system_image.file_bytes[0,8]=="GCR-1541"
}


def initialize(file_bytes)
  @file_bytes=file_bytes
  @tracks={}
  @end_track=0
  signature,version,raw_track_count,track_length=file_bytes.unpack("A8ccv")
  
  0.upto(raw_track_count-1) do |raw_track_no|
	cbm_track_no=(raw_track_no+2.0)/2
	track_offset=file_bytes[0x0c+4*raw_track_no,4].unpack("V")[0]
	if track_offset>0 then
		@end_track=cbm_track_no
	end
end

end
def self.possible_extensions
    ['.g64']
end  

def track_count
  @end_track
end

def end_track
  @end_track
end

def get_sector(track_no,sector_no)
#puts "TR #{track_no} : #{sector_no}"
parse_raw_track((track_no-1)*2) if @tracks[track_no].nil?
@tracks[track_no][sector_no]
  
end

private 

def parse_raw_track(raw_track_no)
  
#  cbm_track_no=(raw_track_no+2.0)/2
  track_offset=file_bytes[0x0c+4*raw_track_no,4].unpack("V")[0]
  if track_offset>0 then
    track_length=file_bytes[track_offset,2].unpack("v")[0]
    track_bytes=file_bytes[track_offset+2,track_length]
#      puts "RAW #{raw_track_no} CBM #{cbm_track_no} OFFSET #{track_offset} #{track_bytes.length}"      
    s=""
    track_bytes.each_byte do |byte|
      s+="%08b" % byte
    end

    raw_blocks=s.split(/1{10,200}/)
    decoded_blocks=[]	
    
    raw_blocks.each do |raw_block|
      this_byte=0
      high_nibble=true
      decoded_block_bytes=""
      0.upto([(raw_block.length/5-1),518].min) do |i|
        gcr_bits=raw_block[i*5,5]
        this_nibble=CBM_GCR_CODES[gcr_bits]
        if this_nibble.nil? then
  #				puts "invalid GCR bits #{gcr_bits} in #{raw_block} offset #{i*5}" 
        else
          if (high_nibble) then
            this_byte=this_nibble*0x10
            high_nibble=false
          else
            this_byte+=this_nibble
            high_nibble=true
            decoded_block_bytes<<this_byte			
          end
        end

      end
      decoded_blocks<<decoded_block_bytes
  #puts ">>>>"
  #puts raw_block
  #puts "ID BYTE %02X %02X " % [decoded_block_bytes[0],decoded_block_bytes.length]
  #decoded_block_bytes.each {|x| print "%02x " % x}
  #puts "<<<<"
  #puts
    end	
    0.upto(decoded_blocks.length-2) do |i|
      if (decoded_blocks[i][0]==0x08) && (decoded_blocks[i+1][0]==0x07) then
        header_block=decoded_blocks[i]
        data_block=decoded_blocks[i+1]			
        sector_no=header_block[2]
        track_no=header_block[3]
        format_id=header_block[4]+header_block[5]
        @tracks[track_no]={} if @tracks[track_no].nil?
#          puts "TRACK %02X SECTOR %02X ID #{format_id} LENGTH %02x" % [track_no,sector_no,data_block.length]
          sector_data=data_block[1,data_block.length-1]
        @tracks[track_no][sector_no]=sector_data
        #puts hex_dump(data_block[1,256])
      end		
    end
  end    
end

end
# == Author
# Jonno Downes (jonno@jamtronix.com)
#
# == Copyright
# Copyright (c) 2008 Jonno Downes (jonno@jamtronix.com)
#
#Permission is hereby granted, free of charge, to any person obtaining
#a copy of this software and associated documentation files (the
#"Software"), to deal in the Software without restriction, including
#without limitation the rights to use, copy, modify, merge, publish,
#distribute, sublicense, and/or sell copies of the Software, and to
#permit persons to whom the Software is furnished to do so, subject to
#the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.