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5c0d8c6369
* Add "offsetof" to Struct classes
I need to get the offset of a member inside a struct without allocating
the struct. This patch adds an "offsetof" class method to structs that
are generated.
The usage is like this:
```ruby
MyStruct = struct [
"int64_t i",
"char c",
]
MyStruct.offsetof("i") # => 0
MyStruct.offsetof("c") # => 8
```
* Update test/fiddle/test_c_struct_builder.rb
Co-authored-by: Sutou Kouhei <kou@cozmixng.org>
https://github.com/ruby/fiddle/commit/4e3b60c5b6
Co-authored-by: Sutou Kouhei <kou@cozmixng.org>
36 lines
1.3 KiB
Ruby
36 lines
1.3 KiB
Ruby
# frozen_string_literal: true
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begin
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require_relative 'helper'
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require 'fiddle/struct'
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require 'fiddle/cparser'
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rescue LoadError
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end
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module Fiddle
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class TestCStructBuilder < TestCase
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include Fiddle::CParser
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def test_offsetof
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types, members = parse_struct_signature(['int64_t i','char c'])
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my_struct = Fiddle::CStructBuilder.create(Fiddle::CStruct, types, members)
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assert_equal 0, my_struct.offsetof("i")
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assert_equal Fiddle::SIZEOF_INT64_T, my_struct.offsetof("c")
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end
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def test_offset_with_gap
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types, members = parse_struct_signature(['void *p', 'char c', 'long x'])
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my_struct = Fiddle::CStructBuilder.create(Fiddle::CStruct, types, members)
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assert_equal PackInfo.align(0, ALIGN_VOIDP), my_struct.offsetof("p")
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assert_equal PackInfo.align(SIZEOF_VOIDP, ALIGN_CHAR), my_struct.offsetof("c")
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assert_equal SIZEOF_VOIDP + PackInfo.align(SIZEOF_CHAR, ALIGN_LONG), my_struct.offsetof("x")
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end
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def test_union_offsetof
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types, members = parse_struct_signature(['int64_t i','char c'])
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my_struct = Fiddle::CStructBuilder.create(Fiddle::CUnion, types, members)
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assert_equal 0, my_struct.offsetof("i")
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assert_equal 0, my_struct.offsetof("c")
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end
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end
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end if defined?(Fiddle)
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