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#
# Copyright (C) 2008-2010 Wayne Meissner
#
# Version: EPL 1.0/GPL 2.0/LGPL 2.1
#
# The contents of this file are subject to the Common Public
# License Version 1.0 (the "License"); you may not use this file
# except in compliance with the License. You may obtain a copy of
# the License at http://www.eclipse.org/legal/cpl-v10.html
#
# Software distributed under the License is distributed on an "AS
# IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
# implied. See the License for the specific language governing
# rights and limitations under the License.
#
# Alternatively, the contents of this file may be used under the terms of
# either of the GNU General Public License Version 2 or later (the "GPL"),
# or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
# in which case the provisions of the GPL or the LGPL are applicable instead
# of those above. If you wish to allow use of your version of this file only
# under the terms of either the GPL or the LGPL, and not to allow others to
# use your version of this file under the terms of the EPL, indicate your
# decision by deleting the provisions above and replace them with the notice
# and other provisions required by the GPL or the LGPL. If you do not delete
# the provisions above, a recipient may use your version of this file under
# the terms of any one of the EPL, the GPL or the LGPL.
#
module FFI
class StructLayoutBuilder
attr_reader :size, :alignment
def initialize
@size = 0
@alignment = 1
@min_alignment = 1
@packed = false
@union = false
@fields = Array.new
end
def size=(size)
@size = size if size > @size
end
def alignment=(align)
@alignment = align if align > @alignment
@min_alignment = align
end
def union=(is_union)
@union = is_union
end
def union?
@union
end
def packed=(packed)
if packed.is_a?(Fixnum)
@alignment = packed
@packed = packed
else
@packed = packed ? 1 : 0
end
end
SCALAR_TYPES = [
Type::INT8,
Type::UINT8,
Type::INT16,
Type::UINT16,
Type::INT32,
Type::UINT32,
Type::LONG,
Type::ULONG,
Type::INT64,
Type::UINT64,
Type::FLOAT32,
Type::FLOAT64,
Type::BOOL,
]
def add(name, type, offset = nil)
if offset.nil? || offset == -1
offset = @union ? 0 : align(@size, @packed ? [ @packed, type.alignment ].min : [ @min_alignment, type.alignment ].max)
end
#
# If a FFI::Type type was passed in as the field arg, try and convert to a StructLayout::Field instance
#
field = type.is_a?(StructLayout::Field) ? type : field_for_type(name, offset, type)
@fields << field
@alignment = [ @alignment, field.alignment ].max unless @packed
@size = [ @size, field.size + (@union ? 0 : field.offset) ].max
return self
end
def add_field(name, type, offset = nil)
add(name, type, offset)
end
def add_struct(name, type, offset = nil)
add(name, Type::Struct.new(type), offset)
end
def add_array(name, type, count, offset = nil)
add(name, Type::Array.new(type, count), offset)
end
def build
# Add tail padding if the struct is not packed
size = @packed ? @size : align(@size, @alignment)
StructLayout.new(@fields, size, @alignment)
end
private
def align(offset, align)
align + ((offset - 1) & ~(align - 1));
end
def field_for_type(name, offset, type)
field_class = case
when type.is_a?(Type::Function)
StructLayout::Function
when type.is_a?(Type::Struct)
StructLayout::InnerStruct
when type.is_a?(Type::Array)
StructLayout::Array
when type.is_a?(FFI::Enum)
StructLayout::Enum
when SCALAR_TYPES.include?(type)
StructLayout::Number
when type == Type::POINTER
StructLayout::Pointer
when type == Type::STRING
StructLayout::String
when type.is_a?(Class) && type < StructLayout::Field
type
when type.is_a?(DataConverter)
return StructLayout::Mapped.new(name, offset, Type::Mapped.new(type), field_for_type(name, offset, type.native_type))
when type.is_a?(Type::Mapped)
return StructLayout::Mapped.new(name, offset, type, field_for_type(name, offset, type.native_type))
else
raise TypeError, "invalid struct field type #{type.inspect}"
end
field_class.new(name, offset, type)
end
end
end
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