78 lines
1.9 KiB
Ruby
78 lines
1.9 KiB
Ruby
# -*- coding: binary -*-
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require 'bit-struct/bit-struct'
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class BitStruct
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# Class for nesting a BitStruct as a field within another BitStruct.
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# Declared with BitStruct.nest.
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class NestedField < Field
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def initialize(*args)
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super
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end
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# Used in describe.
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def self.class_name
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@class_name ||= "nest"
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end
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def class_name
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@class_name ||= nested_class.name[/\w+$/]
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end
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def nested_class
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@nested_class ||= options[:nested_class] || options["nested_class"]
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end
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def describe opts
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if opts[:expand]
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opts = opts.dup
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opts[:byte_offset] = offset / 8
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opts[:omit_header] = opts[:omit_footer] = true
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nested_class.describe(nil, opts) {|desc| yield desc}
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else
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super
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end
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end
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def add_accessors_to(cl, attr = name) # :nodoc:
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unless offset % 8 == 0
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raise ArgumentError,
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"Bad offset, #{offset}, for nested field #{name}." +
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" Must be multiple of 8."
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end
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unless length % 8 == 0
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raise ArgumentError,
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"Bad length, #{length}, for nested field #{name}." +
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" Must be multiple of 8."
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end
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offset_byte = offset / 8
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length_byte = length / 8
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last_byte = offset_byte + length_byte - 1
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byte_range = offset_byte..last_byte
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nc = nested_class
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cl.class_eval do
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define_method attr do ||
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nc.new(self[byte_range])
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end
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define_method "#{attr}=" do |val|
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if val.length != length_byte
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raise ArgumentError, "Size mismatch in nested struct assignment " +
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"to #{attr} with value #{val.inspect}"
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end
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if val.class != nc
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warn "Type mismatch in nested struct assignment " +
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"to #{attr} with value #{val.inspect}"
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end
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self[byte_range] = val
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end
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end
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end
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end
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end
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