examples/gzip.rb in bindata-0.9.0 vs examples/gzip.rb in bindata-0.9.1

@@ -8,73 +8,60 @@
 
   # Known compression methods
   DEFLATE = 8
 
   class Extra < BinData::MultiValue
-    uint16le :len,  :length => lambda { data.length }
-    string   :data, :read_length => :len
+    endian :little
+
+    uint16 :len,  :length => lambda { data.length }
+    string :data, :read_length => :len
   end
 
   class Header < BinData::MultiValue
-    uint16le :ident,      :value => 0x8b1f, :check_value => 0x8b1f
-    uint8    :compression_method, :initial_value => DEFLATE
-    uint8    :flags,      :value => :calculate_flags_val,
-                          # Upper 3 bits must be zero
-                          :check_value => lambda { (value & 0xe0) == 0 }
-    uint32le :mtime
-    uint8    :extra_flags
-    uint8    :os,         :initial_value => 255   # unknown OS
+    endian :little
 
-    # These fields are optional depending on the bits in flags
-    extra    :extra,      :readwrite => :extra?
-    stringz  :file_name,  :readwrite => :file_name?
-    stringz  :comment,    :readwrite => :comment?
-    uint16le :crc16,      :readwrite => :crc16?
+    uint16  :ident,      :value => 0x8b1f, :check_value => 0x8b1f
+    uint8   :compression_method, :initial_value => DEFLATE
 
+    bit3    :freserved,  :value => 0, :check_value => 0
+    bit1    :fcomment,   :value => lambda { comment.length > 0 ? 1 : 0 }
+    bit1    :ffile_name, :value => lambda { file_name.length > 0 ? 1 : 0 }
+    bit1    :fextra,     :value => lambda { extra.len > 0 ? 1 : 0 }
+    bit1    :fcrc16,     :value => 0  # see comment below
+    bit1    :ftext
 
-    ## Convenience methods for accessing and manipulating flags
+    # Never include header crc.  This is because the current versions of the
+    # command-line version of gzip (up through version 1.3.x) do not
+    # support header crc's, and will report that it is a "multi-part gzip
+    # file" and give up.
 
-    attr_writer :text
+    uint32  :mtime
+    uint8   :extra_flags
+    uint8   :os,         :initial_value => 255   # unknown OS
 
-    # Access bits of flags
-    def text?;      flag_val(0) end
-    def crc16?;     flag_val(1) end
-    def extra?;     flag_val(2) end
-    def file_name?; flag_val(3) end
-    def comment?;   flag_val(4) end
-
-    def flag_val(bit) (flags & (1 << bit)) != 0 end
-
-    # Calculate the value of flags based on current state.
-    def calculate_flags_val
-      ((@text               ? 1 : 0) << 0) |
-
-      # Never include header crc.  This is because the current versions of the
-      # command-line version of gzip (up through version 1.3.x) do not
-      # support header crc's, and will report that it is a "multi-part gzip
-      # file" and give up.
-      ((!clear?(:crc16)     ? 0 : 0) << 1) |
-
-      ((!clear?(:extra)     ? 1 : 0) << 2) |
-      ((!clear?(:file_name) ? 1 : 0) << 3) |
-      ((!clear?(:comment)   ? 1 : 0) << 4)
-    end
+    # These fields are optional depending on the bits in flags
+    extra   :extra,      :onlyif => lambda { fextra.nonzero? }
+    stringz :file_name,  :onlyif => lambda { ffile_name.nonzero? }
+    stringz :comment,    :onlyif => lambda { fcomment.nonzero? }
+    uint16  :crc16,      :onlyif => lambda { fcrc16.nonzero? }
   end
 
   class Footer < BinData::MultiValue
-    uint32le :crc32
-    uint32le :uncompressed_size
+    endian :little
+
+    uint32 :crc32
+    uint32 :uncompressed_size
   end
 
   def initialize
     @header = Header.new
     @footer = Footer.new
   end
 
   attr_accessor :compressed
-  def_delegators :@header, :file_name=, :file_name, :file_name?
-  def_delegators :@header, :comment=, :comment, :comment?
+  def_delegators :@header, :file_name=, :file_name
+  def_delegators :@header, :comment=, :comment
   def_delegators :@header, :compression_method
   def_delegators :@footer, :crc32, :uncompressed_size
 
   def mtime
     Time.at(@header.mtime)
@@ -164,10 +151,10 @@
                                                    g.mtime.strftime('%H:%M'),
                                                    g.total_size,
                                                    g.uncompressed_size,
                                                    ratio,
                                                    g.file_name]
-  puts "Comment: #{g.comment}" if g.comment?
+  puts "Comment: #{g.comment}" if g.comment != ""
   puts
 
   puts "Executing gzip -l -v"
   puts `gzip -l -v poetry.gz`
 end