Class: BitStruct::UnsignedField
- Defined in:
- lib/bit-struct/unsigned-field.rb
Overview
Class for unsigned integers in network order, 1-16 bits, or 8n bits. Declared with BitStruct.unsigned.
Instance Attribute Summary
Attributes inherited from Field
#default, #display_name, #format, #length, #name, #offset, #options
Class Method Summary collapse
-
.class_name ⇒ Object
Used in describe.
Instance Method Summary collapse
Methods inherited from Field
#class_name, default, #describe, #initialize, #inspect_in_object, #inspectable?
Constructor Details
This class inherits a constructor from BitStruct::Field
Class Method Details
.class_name ⇒ Object
Used in describe.
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# File 'lib/bit-struct/unsigned-field.rb', line 6 def self.class_name @class_name ||= "unsigned" end |
Instance Method Details
#add_accessors_to(cl, attr = name) ⇒ Object
:nodoc:
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# File 'lib/bit-struct/unsigned-field.rb', line 10 def add_accessors_to(cl, attr = name) # :nodoc: offset_byte = offset / 8 offset_bit = offset % 8 length_bit = offset_bit + length length_byte = (length_bit/8.0).ceil last_byte = offset_byte + length_byte - 1 divisor = [:fixed] || ["fixed"] divisor_f = divisor && divisor.to_f endian = ([:endian] || ["endian"]).to_s case endian when "native" ctl = length_byte <= 2 ? "S" : "L" when "little" ctl = length_byte <= 2 ? "v" : "V" when "network", "big", "" ctl = length_byte <= 2 ? "n" : "N" else raise ArgumentError, "Unrecognized endian option: #{endian.inspect}" end data_is_big_endian = ([1234].pack(ctl) == [1234].pack(length_byte <= 2 ? "n" : "N")) if length_byte == 1 rest = 8 - length_bit mask = ["0"*offset_bit + "1"*length + "0"*rest].pack("B8")[0].ord mask2 = ["1"*offset_bit + "0"*length + "1"*rest].pack("B8")[0].ord cl.class_eval do if divisor define_method attr do || ((self[offset_byte] & mask) >> rest) / divisor_f end define_method "#{attr}=" do |val| val = (val * divisor).round self[offset_byte] = (self[offset_byte] & mask2) | ((val<<rest) & mask) end else define_method attr do || (self[offset_byte] & mask) >> rest end define_method "#{attr}=" do |val| self[offset_byte] = (self[offset_byte] & mask2) | ((val<<rest) & mask) end end end elsif offset_bit == 0 and length % 8 == 0 field_length = length byte_range = offset_byte..last_byte cl.class_eval do case field_length when 8 if divisor define_method attr do || self[offset_byte] / divisor_f end define_method "#{attr}=" do |val| val = (val * divisor).round self[offset_byte] = val end else define_method attr do || self[offset_byte] end define_method "#{attr}=" do |val| self[offset_byte] = val end end when 16, 32 if divisor define_method attr do || self[byte_range].unpack(ctl).first / divisor_f end define_method "#{attr}=" do |val| val = (val * divisor).round self[byte_range] = [val].pack(ctl) end else define_method attr do || self[byte_range].unpack(ctl).first end define_method "#{attr}=" do |val| self[byte_range] = [val].pack(ctl) end end else reader_helper = proc do |substr| bytes = substr.unpack("C*") bytes.reverse! unless data_is_big_endian bytes.inject do |sum, byte| (sum << 8) + byte end end writer_helper = proc do |val| bytes = [] while val > 0 bytes.push val % 256 val = val >> 8 end if bytes.length < length_byte bytes.concat [0] * (length_byte - bytes.length) end bytes.reverse! if data_is_big_endian bytes.pack("C*") end if divisor define_method attr do || reader_helper[self[byte_range]] / divisor_f end define_method "#{attr}=" do |val| self[byte_range] = writer_helper[(val * divisor).round] end else define_method attr do || reader_helper[self[byte_range]] end define_method "#{attr}=" do |val| self[byte_range] = writer_helper[val] end end end end elsif length_byte == 2 # unaligned field that fits within two whole bytes byte_range = offset_byte..last_byte rest = 16 - length_bit mask = ["0"*offset_bit + "1"*length + "0"*rest] mask = mask.pack("B16").unpack(ctl).first mask2 = ["1"*offset_bit + "0"*length + "1"*rest] mask2 = mask2.pack("B16").unpack(ctl).first cl.class_eval do if divisor define_method attr do || ((self[byte_range].unpack(ctl).first & mask) >> rest) / divisor_f end define_method "#{attr}=" do |val| val = (val * divisor).round x = (self[byte_range].unpack(ctl).first & mask2) | ((val<<rest) & mask) self[byte_range] = [x].pack(ctl) end else define_method attr do || (self[byte_range].unpack(ctl).first & mask) >> rest end define_method "#{attr}=" do |val| x = (self[byte_range].unpack(ctl).first & mask2) | ((val<<rest) & mask) self[byte_range] = [x].pack(ctl) end end end elsif length_byte == 3 # unaligned field that fits within 3 whole bytes byte_range = offset_byte..last_byte rest = 32 - length_bit mask = ["0"*offset_bit + "1"*length + "0"*rest] mask = mask.pack("B32").unpack(ctl).first mask2 = ["1"*offset_bit + "0"*length + "1"*rest] mask2 = mask2.pack("B32").unpack(ctl).first cl.class_eval do if divisor define_method attr do || bytes = self[byte_range] bytes << 0 ((bytes.unpack(ctl).first & mask) >> rest) / divisor_f end define_method "#{attr}=" do |val| val = (val * divisor).round bytes = self[byte_range] bytes << 0 x = (bytes.unpack(ctl).first & mask2) | ((val<<rest) & mask) self[byte_range] = [x].pack(ctl)[0..2] end else define_method attr do || bytes = self[byte_range] bytes << 0 (bytes.unpack(ctl).first & mask) >> rest end define_method "#{attr}=" do |val| bytes = self[byte_range] bytes << 0 x = (bytes.unpack(ctl).first & mask2) | ((val<<rest) & mask) self[byte_range] = [x].pack(ctl)[0..2] end end end else raise "unsupported: #{inspect}" end end |