$out  ||= $stdout
$dl_h = ARGV[0] || "dl.h"

# import DLSTACK_SIZE, DLSTACK_ARGS and so on
File.open($dl_h){|f|
  pre = ""
  f.each{|line|
    line.chop!
    if( line[-1] == ?\ )
      line.chop!
      line.concat(" ")
      pre += line
      next
    end
    if( pre.size > 0 )
      line = pre + line
      pre  = ""
    end
    case line
    when /#define\s+DLSTACK_SIZE\s+\(?(\d+)\)?/
      DLSTACK_SIZE = $1.to_i
    when /#define\s+DLSTACK_ARGS\s+(.+)/
      DLSTACK_ARGS = $1.to_i
    when /#define\s+DLTYPE_([A-Z_]+)\s+\(?(\d+)\)?/
      eval("#{$1} = #{$2}")
    when /#define\s+MAX_DLTYPE\s+\(?(\d+)\)?/
      MAX_DLTYPE  = $1.to_i
    when /#define\s+MAX_CALLBACK\s+\(?(\d+)\)?/
      MAX_CALLBACK = $1.to_i
    end
  }
}

CDECL = "cdecl"
STDCALL = "stdcall"

CALLTYPES = [CDECL, STDCALL]

DLTYPE = {
  VOID => {
    :name => 'void',
    :type => 'void',
    :conv => nil,
  },
  CHAR => {
    :name => 'char',
    :type => 'char',
    :conv => 'NUM2CHR(%s)'
  },
  SHORT => {
    :name => 'short',
    :type => 'short',
    :conv => 'NUM2INT(%s)',
  },
  INT => {
    :name => 'int',
    :type => 'int',
    :conv => 'NUM2INT(%s)',
  },
  LONG  => {
    :name => 'long',
    :type => 'long',
    :conv => 'NUM2LONG(%s)',
  },
  LONG_LONG => {
    :name => 'long_long',
    :type => 'LONG_LONG',
    :conv => 'NUM2LL(%s)',
  },
  FLOAT => {
    :name => 'float',
    :type => 'float',
    :conv => 'RFLOAT(%s)->value',
  },
  DOUBLE => {
    :name => 'double',
    :type => 'double',
    :conv => 'RFLOAT(%s)->value',
  },
  VOIDP => {
    :name => 'ptr',
    :type => 'void *',
    :conv => 'NUM2PTR(%s)',
  },
}


def func_name(ty, argc, n, calltype)
  "rb_dl_callback_#{DLTYPE[ty][:name]}_#{argc}_#{n}_#{calltype}"
end

$out << (<<EOS)
VALUE rb_DLCdeclCallbackAddrs, rb_DLCdeclCallbackProcs;
VALUE rb_DLStdcallCallbackAddrs, rb_DLStdcallCallbackProcs;
/*static void *cdecl_callbacks[MAX_DLTYPE][MAX_CALLBACK];*/
/*static void *stdcall_callbacks[MAX_DLTYPE][MAX_CALLBACK];*/
static ID   cb_call;
EOS

for calltype in CALLTYPES
  case calltype
  when CDECL
    proc_entry = "rb_DLCdeclCallbackProcs"
  when STDCALL
    proc_entry = "rb_DLStdcallCallbackProcs"
  else
    raise "unknown calltype: #{calltype}"
  end
  for ty in 0..(MAX_DLTYPE-1)
    for argc in 0..(DLSTACK_SIZE-1)
      for n in 0..(MAX_CALLBACK-1)
        $out << (<<-EOS)

FUNC_#{calltype.upcase}(static #{DLTYPE[ty][:type]}
#{func_name(ty,argc,n,calltype)}(#{(0...argc).collect{|i| "DLSTACK_TYPE stack" + i.to_s}.join(", ")}))
{
    VALUE ret, cb#{argc > 0 ? ", args[#{argc}]" : ""};
#{
      (0...argc).collect{|i|
	"    args[%d] = LONG2NUM(stack%d);" % [i,i]
      }.join("\n")
}
    cb = rb_ary_entry(rb_ary_entry(#{proc_entry}, #{ty}), #{(n * DLSTACK_SIZE) + argc});
    ret = rb_funcall2(cb, cb_call, #{argc}, #{argc > 0 ? 'args' : 'NULL'});
    return #{DLTYPE[ty][:conv] ? DLTYPE[ty][:conv] % "ret" : ""};
}

        EOS
      end
    end
  end
end

$out << (<<EOS)
static void
rb_dl_init_callbacks()
{
    cb_call = rb_intern("call");		       

    rb_DLCdeclCallbackProcs = rb_ary_new();
    rb_DLCdeclCallbackAddrs = rb_ary_new();
    rb_DLStdcallCallbackProcs = rb_ary_new();
    rb_DLStdcallCallbackAddrs = rb_ary_new();
    rb_define_const(rb_mDL, "CdeclCallbackProcs", rb_DLCdeclCallbackProcs);
    rb_define_const(rb_mDL, "CdeclCallbackAddrs", rb_DLCdeclCallbackAddrs);
    rb_define_const(rb_mDL, "StdcallCallbackProcs", rb_DLStdcallCallbackProcs);
    rb_define_const(rb_mDL, "StdcallCallbackAddrs", rb_DLStdcallCallbackAddrs);
#{
    (0...MAX_DLTYPE).collect{|ty|
      sprintf("    rb_ary_push(rb_DLCdeclCallbackProcs, rb_ary_new3(%d,%s));",
              MAX_CALLBACK * DLSTACK_SIZE,
              (0...MAX_CALLBACK).collect{
                (0...DLSTACK_SIZE).collect{ "Qnil" }.join(",")
              }.join(","))
    }.join("\n")
}
#{
    (0...MAX_DLTYPE).collect{|ty|
      sprintf("    rb_ary_push(rb_DLCdeclCallbackAddrs, rb_ary_new3(%d,%s));",
              MAX_CALLBACK * DLSTACK_SIZE,
              (0...MAX_CALLBACK).collect{|i|
                (0...DLSTACK_SIZE).collect{|argc|
                  "PTR2NUM(%s)" % func_name(ty,argc,i,CDECL)
                }.join(",")
              }.join(","))
    }.join("\n")
}
#{
    (0...MAX_DLTYPE).collect{|ty|
      sprintf("    rb_ary_push(rb_DLStdcallCallbackProcs, rb_ary_new3(%d,%s));",
              MAX_CALLBACK * DLSTACK_SIZE,
              (0...MAX_CALLBACK).collect{
                (0...DLSTACK_SIZE).collect{ "Qnil" }.join(",")
              }.join(","))
    }.join("\n")
}
#{
    (0...MAX_DLTYPE).collect{|ty|
      sprintf("    rb_ary_push(rb_DLStdcallCallbackAddrs, rb_ary_new3(%d,%s));",
              MAX_CALLBACK * DLSTACK_SIZE,
              (0...MAX_CALLBACK).collect{|i|
                (0...DLSTACK_SIZE).collect{|argc|
                  "PTR2NUM(%s)" % func_name(ty,argc,i,STDCALL)
                }.join(",")
              }.join(","))
    }.join("\n")
}
}
EOS