Class: ECUTools::Disassembler

Inherits:
Object
  • Object
show all
Includes:
Helpers
Defined in:
lib/disassembler.rb

Instance Method Summary collapse

Methods included from Helpers

#absolute_address, #address_descriptions, #base_address, #from_hex, #instruction_at, #load_rom_xml, #read_bytes, #rom_id, #rom_xml, #subroutine_descriptions

Constructor Details

#initialize(input = nil, options = {}) ⇒ Disassembler

Returns a new instance of Disassembler.



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# File 'lib/disassembler.rb', line 10

def initialize(input = nil, options = {})
  @options = options
  @reference_addresses = {}
  if(!input.nil?)
    open input
  end
end

Instance Method Details

#analyze ⇒ Object 



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# File 'lib/disassembler.rb', line 51

def analyze
  $stderr.puts "Analyzing assembly..." if verbose
  annotate_tables
  annotate_subroutines
  annotate_code
  $stderr.puts "Analyzation complete." if verbose
end

#annotate_code ⇒ Object 



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# File 'lib/disassembler.rb', line 121

def annotate_code
  $stderr.puts "Annotating code..." if verbose
  count = 0
  found_rom_addresses = {}
  found_ram_addresses = {}
  @assembly.each do |instruction|
    # annotate subroute prologue/epilogue
    if instruction.assembly =~ /push lr/
      c = 'begin subroutine'
      c << " #{subroutine_descriptions[instruction.address]}" if subroutine_descriptions.include? instruction.address
      instruction.comments << c
    end
    if instruction.assembly =~ /jmp lr/ 
      instruction.comments << 'return'
    end

    # annotate subroutine calls
    match = /bl 0x(\w+)/.match(instruction.assembly)
    if match
      address = match[1]
      if subroutine_descriptions.include? address
        instruction.comments << "Call #{subroutine_descriptions[address]}"
      end
    end
    
    # annotate table address references
    address = /0x([\d|[a-f]|[A-F]]+)/.match(instruction.assembly)
    if address and @reference_addresses.include? address[1]
      instruction.comments << "contains possible reference to '#{@reference_addresses[address[1]]}'"
      $stderr.puts "Annotated reference to: #{@reference_addresses[address[1]]} at #{instruction.address}" if verbose
      count = count + 1
      found_rom_addresses[@reference_addresses[address[1]]] = true 
    end
    
    # annotate absolute RAM addressing ld24 r4,0x800700
    match = /(\w+)\s+\w\w,0x(8\w\w\w\w\w)/.match(instruction.assembly)
    if match
      address = match[2]
      display = address_descriptions[address]
      
      if match[1] == "ld24"
        op = "Assign pointer to"
      else
        op = "Unknown op on"
      end
        
      if !display.nil? and verbose
        $stderr.puts "Found reference to absolute RAM address #{address} (#{display})"
      end
      instruction.comments << "#{op} RAM address 0x#{address}" + (display.nil? ? '' : " (#{display})")
      found_ram_addresses[display] = true if !display.nil?
      count = count + 1
    end

    # annotate relative RAM addressing
    match = /(\w+)\s+.+?@\((-?\d+),fp\)/.match(instruction.assembly)
    if match
      address = absolute_address match[2].to_i
      display = address_descriptions[address]

      case match[1]
      when "lduh"
        op = "Load unsigned halfword from"
      when "ldub"
        op = "Load unsigned byte from"
      when "ld"
        op = "Load from"
      when "ldb"
        op = "Load byte from"
      when "st" 
        op = "Store at"
      when "stb"
        op = "Store byte at"
      when "sth"
        op = "Store half word at"
      when "bclr"
        op = "Clear bit in"
      else
        op = "Unknown op on"
      end
      if !display.nil? and verbose
        $stderr.puts "Found reference to relative RAM address #{address} (#{display})"
      end
      instruction.comments << "#{op} RAM address 0x#{address}" + (display.nil? ? '' : " (#{display})")
      found_ram_addresses[display] = true if !display.nil?
      count = count + 1
    end
  
  end

  $stderr.puts "#{count} lines of code annotated." if verbose
  if verbose
    @reference_addresses.each_key do |key|
      $stderr.puts "Unable to find any reference to table #{@reference_addresses[key]}" if !found_rom_addresses.include? @reference_addresses[key]
      found_rom_addresses[@reference_addresses[key]] = true # stop multiple reports
    end
    address_descriptions.each_key do |key|
      $stderr.puts "Unable to find any reference to RAM address #{address_descriptions[key]} (#{key})" if !found_ram_addresses.include? address_descriptions[key]
    end
  end
end

#annotate_subroutines ⇒ Object 



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# File 'lib/disassembler.rb', line 117

def annotate_subroutines

end

#annotate_tables ⇒ Object 



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# File 'lib/disassembler.rb', line 59

def annotate_tables
  $stderr.puts "Annotating tables..." if verbose
  tables = rom_xml.xpath('/rom/table')
  count = 0
  tables.each do |table|
    elements = 1 # all tables start with one element
    scaling = rom_xml.xpath("/rom/scaling[@name='#{table.attr('scaling')}']")
    if scaling.count == 0
      $stderr.puts "WARNING: Failed to find scaling: #{table.attr('scaling')}, skipping table #{table.attr('name')}" if verbose
      next
    end
    element_size = scaling.attr('storagetype').value().gsub(/[^\d]+/,'').to_i / 8
    address = from_hex table.attr('address')
    is_data = false

    table.xpath('table').each do |subtable|
      elements = elements * subtable.attr('elements').to_i
      is_data = true
    end

    possible_offsets = []

    case elements
    when 1,4
      possible_offsets << 0
    when 3..20
      possible_offsets << 4
      possible_offsets << 6
    when 44
      possible_offsets << 28  # wtf? maf scaling
    else
      possible_offsets << 7
      possible_offsets << 10
      possible_offsets << 16
    end

    possible_offsets.each do |offset|
      offset_hex = (address - offset).to_s(16)
      if verbose and @reference_addresses.include? offset_hex
        $stderr.puts "WARNING: Reference hunt collision at 0x#{offset_hex} (#{@reference_addresses[offset_hex]} vs #{table.attr('name')})! Check code carefully!" 
      end
      @reference_addresses[offset_hex] = table.attr('name')
    end

    storage_size = element_size * elements

    storage_size.times do |n|
      instruction = instruction_at(address + n)
      instruction.comments[0] = table.attr('name') + "(0x#{table.attr('address')} -> 0x#{(address + storage_size - 1).to_s(16)}, #{storage_size} bytes)"
      instruction.data = is_data
    end

    $stderr.puts "Annotated: #{table.attr('name')}" if verbose
    count = count + 1
  end
  $stderr.puts "#{count} tables annotated." if verbose
end

#open(file) ⇒ Object 



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# File 'lib/disassembler.rb', line 22

def open(file)
  $stderr.puts "Disassembling binary..." if verbose
  h = '[\d|[a-f]|[A-F]]'
  @assembly = []
  io = IO.popen("gobjdump -b binary --architecture=m32r --disassemble-all --disassemble-zeroes -EB #{file}")
  while line = io.gets
    match = /\s+(#{h}+):\s+(#{h}{2}) (#{h}{2}) (#{h}{2}) (#{h}{2})\s+(.+)/.match(line)
    if match
      @assembly << Instruction.new(match[1], [ match[2], match[3], match[4], match[5] ], match[6])
    end
  end

  $stderr.puts "Disassembly complete." if verbose
end

#verbose ⇒ Object 



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# File 'lib/disassembler.rb', line 18

def verbose
  @options[:verbose]
end

#write(file) ⇒ Object 



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# File 'lib/disassembler.rb', line 37

def write(file)
  f = File.new(file,"w")
  header = "; ecutools v#{ECUTools::VERSION}\n"
  header << "; Generated assembly from ROM ID #{rom_id}\n"
  header << "; Base Address: #{base_address}\n"
  header << "; Disassembly:\n"
  f.write(header)
  $stderr.puts "Writing assembly..." if verbose
  @assembly.each do |instruction|
    f.write("#{instruction}\n")
  end
  $stderr.puts "Done." if verbose
end