Class: Fiddle::CStructEntity

Inherits:
Pointer
  • Object
show all
Includes:
PackInfo, ValueUtil
Defined in:
lib/fiddle/struct.rb

Overview

A C struct wrapper

Direct Known Subclasses

CUnionEntity

Constant Summary

Constants included from PackInfo

PackInfo::ALIGN_MAP, PackInfo::PACK_MAP, PackInfo::SIZE_MAP

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ValueUtil

#signed_value, #unsigned_value, #wrap_arg, #wrap_args

Methods included from PackInfo

align

Methods inherited from Pointer

#+, #+@, #-, #-@, #<=>, #==, [], #eql?, #free, #free=, #inspect, #null?, #ptr, #ref, #size, #size=, #to_i, #to_int, to_ptr, #to_str, #to_value

Constructor Details

#initialize(addr, types, func = nil) ⇒ CStructEntity

Wraps the C pointer addr as a C struct with the given types.

When the instance is garbage collected, the C function func is called.

See also Fiddle::Pointer.new



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# File 'lib/fiddle/struct.rb', line 119

def initialize(addr, types, func = nil)
  set_ctypes(types)
  super(addr, @size, func)
end

Class Method Details

.malloc(types, func = nil) ⇒ Object

Allocates a C struct with the types provided.

When the instance is garbage collected, the C function func is called.



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# File 'lib/fiddle/struct.rb', line 86

def CStructEntity.malloc(types, func = nil)
  addr = Fiddle.malloc(CStructEntity.size(types))
  CStructEntity.new(addr, types, func)
end

.size(types) ⇒ Object

Returns the offset for the packed sizes for the given types.

Fiddle::CStructEntity.size(
  [ Fiddle::TYPE_DOUBLE,
    Fiddle::TYPE_INT,
    Fiddle::TYPE_CHAR,
    Fiddle::TYPE_VOIDP ]) #=> 24



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# File 'lib/fiddle/struct.rb', line 98

def CStructEntity.size(types)
  offset = 0

  max_align = types.map { |type, count = 1|
    last_offset = offset

    align = PackInfo::ALIGN_MAP[type]
    offset = PackInfo.align(last_offset, align) +
             (PackInfo::SIZE_MAP[type] * count)

    align
  }.max

  PackInfo.align(offset, max_align)
end

Instance Method Details

#[](name) ⇒ Object

Fetch struct member name



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# File 'lib/fiddle/struct.rb', line 151

def [](name)
  idx = @members.index(name)
  if( idx.nil? )
    raise(ArgumentError, "no such member: #{name}")
  end
  ty = @ctypes[idx]
  if( ty.is_a?(Array) )
    r = super(@offset[idx], SIZE_MAP[ty[0]] * ty[1])
  else
    r = super(@offset[idx], SIZE_MAP[ty.abs])
  end
  packer = Packer.new([ty])
  val = packer.unpack([r])
  case ty
  when Array
    case ty[0]
    when TYPE_VOIDP
      val = val.collect{|v| Pointer.new(v)}
    end
  when TYPE_VOIDP
    val = Pointer.new(val[0])
  else
    val = val[0]
  end
  if( ty.is_a?(Integer) && (ty < 0) )
    return unsigned_value(val, ty)
  elsif( ty.is_a?(Array) && (ty[0] < 0) )
    return val.collect{|v| unsigned_value(v,ty[0])}
  else
    return val
  end
end

#[]=(name, val) ⇒ Object

Set struct member name, to value val



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# File 'lib/fiddle/struct.rb', line 185

def []=(name, val)
  idx = @members.index(name)
  if( idx.nil? )
    raise(ArgumentError, "no such member: #{name}")
  end
  ty  = @ctypes[idx]
  packer = Packer.new([ty])
  val = wrap_arg(val, ty, [])
  buff = packer.pack([val].flatten())
  super(@offset[idx], buff.size, buff)
  if( ty.is_a?(Integer) && (ty < 0) )
    return unsigned_value(val, ty)
  elsif( ty.is_a?(Array) && (ty[0] < 0) )
    return val.collect{|v| unsigned_value(v,ty[0])}
  else
    return val
  end
end

#assign_names(members) ⇒ Object

Set the names of the members in this C struct



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# File 'lib/fiddle/struct.rb', line 125

def assign_names(members)
  @members = members
end

#set_ctypes(types) ⇒ Object

Calculates the offsets and sizes for the given types in the struct.



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# File 'lib/fiddle/struct.rb', line 130

def set_ctypes(types)
  @ctypes = types
  @offset = []
  offset = 0

  max_align = types.map { |type, count = 1|
    orig_offset = offset
    align = ALIGN_MAP[type]
    offset = PackInfo.align(orig_offset, align)

    @offset << offset

    offset += (SIZE_MAP[type] * count)

    align
  }.max

  @size = PackInfo.align(offset, max_align)
end

#to_s ⇒ Object

:nodoc:



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# File 'lib/fiddle/struct.rb', line 204

def to_s() # :nodoc:
  super(@size)
end