A pointer to a C structure
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 277
def CStructEntity.alignment(types)
max = 1
types.each do |type, count = 1|
if type.respond_to?(:entity_class)
n = type.alignment
else
n = ALIGN_MAP[type]
end
max = n if n > max
end
max
end
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 293
def CStructEntity.malloc(types, func = nil, size = size(types), &block)
if block_given?
super(size, func) do |struct|
struct.set_ctypes types
yield struct
end
else
struct = super(size, func)
struct.set_ctypes types
struct
end
end
Allocates a C struct with the types
provided.
See Fiddle::Pointer.malloc
for memory management issues.
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 340
def initialize(addr, types, func = nil)
if func && addr.is_a?(Pointer) && addr.free
raise ArgumentError, 'free function specified on both underlying struct Pointer and when creating a CStructEntity - who do you want to free this?'
end
set_ctypes(types)
super(addr, @size, func)
end
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
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 313
def CStructEntity.size(types)
offset = 0
max_align = types.map { |type, count = 1|
last_offset = offset
if type.respond_to?(:entity_class)
align = type.alignment
type_size = type.size
else
align = PackInfo::ALIGN_MAP[type]
type_size = PackInfo::SIZE_MAP[type]
end
offset = PackInfo.align(last_offset, align) +
(type_size * count)
align
}.max
PackInfo.align(offset, max_align)
end
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
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 413
def [](*args)
return super(*args) if args.size > 1
name = args[0]
idx = @members.index(name)
if( idx.nil? )
raise(ArgumentError, "no such member: #{name}")
end
ty = @ctypes[idx]
if( ty.is_a?(Array) )
if ty.first.respond_to?(:entity_class)
return @nested_structs[name]
else
r = super(@offset[idx], SIZE_MAP[ty[0]] * ty[1])
end
elsif ty.respond_to?(:entity_class)
return @nested_structs[name]
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 StructArray.new(self + @offset[idx], ty[0], val)
else
return val
end
end
Fetch struct member name
if only one argument is specified. If two arguments are specified, the first is an offset and the second is a length and this method returns the string of length
bytes beginning at offset
.
Examples:
my_struct = struct(['int id']).malloc my_struct.id = 1 my_struct['id'] # => 1 my_struct[0, 4] # => "\x01\x00\x00\x00".b
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 465
def []=(*args)
return super(*args) if args.size > 2
name, val = *args
name = name.to_s if name.is_a?(Symbol)
nested_struct = @nested_structs[name]
if nested_struct
if nested_struct.is_a?(StructArray)
if val.nil?
nested_struct.each do |s|
s.replace(nil)
end
else
val.each_with_index do |v, i|
nested_struct[i] = v
end
end
else
nested_struct.replace(val)
end
return val
end
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
Set
struct member name
, to value val
. If more arguments are specified, writes the string of bytes to the memory at the given offset
and length
.
Examples:
my_struct = struct(['int id']).malloc my_struct['id'] = 1 my_struct[0, 4] = "\x01\x00\x00\x00".b my_struct.id # => 1
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 349
def assign_names(members)
@members = []
@nested_structs = {}
members.each_with_index do |member, index|
if member.is_a?(Array) # nested struct
member_name = member[0]
struct_type, struct_count = @ctypes[index]
if struct_count.nil?
struct = struct_type.new(to_i + @offset[index])
else
structs = struct_count.times.map do |i|
struct_type.new(to_i + @offset[index] + i * struct_type.size)
end
struct = StructArray.new(to_i + @offset[index],
struct_type,
structs)
end
@nested_structs[member_name] = struct
else
member_name = member
end
@members << member_name
end
end
Set
the names of the members
in this C struct
# File tmp/rubies/ruby-3.3.0/ext/fiddle/lib/fiddle/struct.rb, line 375
def set_ctypes(types)
@ctypes = types
@offset = []
offset = 0
max_align = types.map { |type, count = 1|
orig_offset = offset
if type.respond_to?(:entity_class)
align = type.alignment
type_size = type.size
else
align = ALIGN_MAP[type]
type_size = SIZE_MAP[type]
end
offset = PackInfo.align(orig_offset, align)
@offset << offset
offset += (type_size * count)
align
}.max
@size = PackInfo.align(offset, max_align)
end
Calculates the offsets and sizes for the given types
in the struct.