$:.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 'FileSystem'
#TRSDOS (and compatables, e.g. LDOS, NEWDOS)
#Reference - http://www.classic-computers.org.nz/system-80/software-manuals/manuals-NewDOS-80_v2.0_manual.pdf pages 99-101
#sectors 2-9 of the directory track (17) contain File Primary Directory Entries, which are 32 bytes made up of:
# byte $00: 
#     bit 7 : 0 = FPDE, 1 = FXDE
#     bit 6 : 1 means a SYSTEM file
#     bit 5 : undefined
#     bit 4 : 1 = in use, 0 = entry empty
#     bit 3 : 1 = file is hidden
#     bit 2 - 0 : access level code
# byte $01: 
#     bit 7 : 0 =  file may be allocated more space when necessary
#     bit 6 : 0 =  any excess space past the EOF may be deallocated
#     bit 5 : 1 = at least one sector of the file has been written to since this bit was last reset
#     bit 4 - 0 : undefined
# byte $02: undefined
# byte $03: low order byte of the file's EOF (position of the EOF within the EOF sector)
# byte $04: logical record length
# byte $05-$0C : file name (right padded with blanks)
# byte $0D-$0F: file extension (right padded with blanks)
# byte $10-$11 : encode of the upate password
# byte $12-$13 : encode of the access password
# byte $14 : middle order byte of the EOF
# byte $15 : high order byte of the EOF
# byte $16 - $1F : 5 pairs of extent elements, each pair made up of:
#     byte $00 : if $FF, then end of extent elements for this file. if $FE, then next byte contains the DEC for the first (or next) FXDE assigned to this file.
#                     any other value ($00-$FD) equals the number of the diskette's lump in which the area starts. 
#     byte $01  : bits 7-5 = number of granules (0-7) from the start of the lump to the start of the area
#                   : bits 4- 0 = number less one of contiguous granules assigned to this area.
#
# when a file has more than 4 space areas assigned, the additional extent elements are contained in FXDE's assigned to the file.
# the format of a FXDE is:
# byte $00: bits 7 and 4 are both 1 to indicate this entry is a FXDE, all other bits are 0
# bute $01: the DEC for the previous FPDE or FXDE of this file. This is a backward chain. the previous entry's byte $1E will be $FD, and it's byte $1F will contain the DEC of this FXDE
#
# the EOF value (bytes $03, $14, $15) is decoded as: 
#   if low order byte ($03) = 0, then EOF is in RBA format
#   if low order byte ($03) != 0, then EOF in the FPDE is equal to the RBA value plus 256 (the value in the high two bytes is incremented by 1)
#
# RBA = Relative Byte Address : a method of addressing where addressing starts at 0 rather than 1
#
# DEC = Directory Entry Code  - a one byte code used to specify a particular FDE. Format is rrrssss, where sssss+2 = the relative
# number within the directory of the sector containing the FDE, and rrr times $20 = the relative byte address within the sector
# of the FDE. 
class TrsDos<FileSystem

def self.host_system
  Trs80
end  
  
#standard TRSDOS has directory on track 17
def self.directory_track
  0x11
end

#for now, only SSSD images are supported
def self.sectors_per_granule(file_system_image)
  5
end

is_valid_file_system_if lambda {
  file_system_image.image_format.instance_of?(Trs80Jv1Dsk)
}

FDE_SIZE=0x20

def self.files(file_system_image)
  files=FileContainer.new
  granule_allocation_table=file_system_image.get_sector(directory_track,0)
  return files if granule_allocation_table.nil?
  file_system_image.volume_name=granule_allocation_table[0xd0,8].unpack("A*")
  (file_system_image.sectors_in_track(directory_track)-[0,1]).each do |sector_no|
    fde_sector=file_system_image.get_sector(directory_track,sector_no)
    (fde_sector.length/FDE_SIZE).times do |fde_number|
      fde=fde_sector[fde_number*FDE_SIZE,FDE_SIZE]
      attributes=fde[0x00]
      
      #for a valid FPDE, bit 7 is 0 and bite 4 is 1
      is_fpde  = ((attributes & 0b10010000)==(0b00010000))
      next if !is_fpde 
      eof_low=fde[0x03]
      filename_base=fde[0x05,8].unpack("A8")
      filename_extension=fde[0x0D,3].unpack("A8")
      filename="#{filename_base}/#{filename_extension}"
      contents=""
      eof_mid=fde[0x14]
      eof_high=fde[0x15]
      file_length=(eof_high<<16)+(eof_mid<<8)+eof_low
      if (eof_low>0) then
        file_length-=0x100
      end
# byte $16 - $1F : 5 pairs of extent elements, each pair made up of:
#     byte $00 : if $FF, then end of extent elements for this file. if $FE, then next byte contains the DEC for the first (or next) FXDE assigned to this file.
#                     any other value ($00-$FD) equals the number of the diskette's lump in which the area starts. 
#     byte $01  : bits 7-5 = number of granules (0-7) from the start of the lump to the start of the area
#                   : bits 4- 0 = number less one of contiguous granules assigned to this area.
      5.times do |extent_no|
        extent=fde[(extent_no*2)+0x16,2]
        break if extent[0]==0xFF
        raise "FXDE's not implemented yet" if extent[0]==0xFE
        track_no=extent[0]
        granule_offset=extent[1]>>5
        number_of_granules=1+(extent[1] & 0b00011111)
        start_sector=granule_offset*sectors_per_granule(file_system_image)
        number_of_sectors=number_of_granules*sectors_per_granule(file_system_image)
        number_of_sectors.times {|i| contents<<file_system_image.get_sector(track_no,start_sector+i)}        
      end
      contents=contents[0,file_length]
      files<<NativeFileType.best_fit(file_system_image,filename,contents,filename_extension)      
    end
  end
  files
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.