compiler/asm/machosymtab.rb

require 'asm/macho'
require 'asm/machosym'
require 'asm/symtab'

module Assembler
  
  class MachOSymtab < Symtab
    
    include MachO

    def const_offset
      return 0x2000
    end

    def bss_offset
      # TODO figure out how to calculate these, or how to let the linker do it!
      #      ... relocation tables perhaps?
      return 0x2800
    end

    def all_symbols
      symbols = []
      
      # Functions (section #1, __text)
      #
      # All labels are exported.  This should be changed and only functions exported!
      # TODO fixme ... 
      #
      # Note: Sorting a Ruby hash gives an alist, e.g. [[<key>, <value>], ...]
      #       We can use map on it as if it were a hash so it works nicely.
      #
      symbols +=
        @labels.sort { |a,b| a[1] <=> b[1] }.
                map do |name,addr|
                  MachOSym.new(name, N_SECT | N_EXT, 1, 0, addr)
                end
      
      # Constants (section #2, __const)
      symbols += @consts.sort { |a,b| a[1] <=> b[1] }.
                         map do |name, addr|
                           MachOSym.new(name, N_SECT, 2, 0, addr)
                         end
      
      # Variables (section #3, __bss)
      #
      # TODO FIXME the last var exported ends up after main somewhere... WTF?!
      symbols += @vars.sort { |a,b| a[1] <=> b[1] }.
                       map do |name, addr|
                         MachOSym.new(name, N_SECT, 3, 0, addr)
                       end
      
      return symbols
    end
    
    def nlist_ary
      symbols = {}
      strx = 1
      ary = []
      all_symbols.each do |sym|
        key = sym.name.to_sym
        unless symbols.has_key?(key)
          symbols[key] = strx
          strx += sym.name.length + 1 # +1 for the null byte
        end
        ary << sym.to_nlist(symbols[key])
      end
      return ary
    end
    
    def stab
      # The empty strings result in a string that begins and ends with
      ['', all_symbols, ''].flatten.map { |sym| sym.to_s }.join("\0")
    end

  end
  
end