pragma Component_Alignment ( [Form =>] ALIGNMENT_CHOICE [, [Name =>] type_LOCAL_NAME]); ALIGNMENT_CHOICE ::= Component_Size | Component_Size_4 | Storage_Unit | Default
Specifies the alignment of components in array or record types.
The meaning of the
Form argument is as follows:
Aligns scalar components and subcomponents of the array or record type on boundaries appropriate to their inherent size (naturally aligned). For example, 1-byte components are aligned on byte boundaries, 2-byte integer components are aligned on 2-byte boundaries, 4-byte integer components are aligned on 4-byte boundaries and so on. These alignment rules correspond to the normal rules for C compilers on all machines except the VAX.
Naturally aligns components with a size of four or fewer bytes. Components that are larger than 4 bytes are placed on the next 4-byte boundary.
Specifies that array or record components are byte aligned, i.e.,
aligned on boundaries determined by the value of the constant
Specifies that array or record components are aligned on default
boundaries, appropriate to the underlying hardware or operating system or
Default choice is the same as
Name parameter is present,
refer to a local record or array type, and the specified alignment
choice applies to the specified type. The use of
Component_Alignment together with a pragma
Pack causes the
Component_Alignment pragma to be ignored. The use of
Component_Alignment together with a record representation clause
is only effective for fields not specified by the representation clause.
Name parameter is absent, the pragma can be used as either
a configuration pragma, in which case it applies to one or more units in
accordance with the normal rules for configuration pragmas, or it can be
used within a declarative part, in which case it applies to types that
are declared within this declarative part, or within any nested scope
within this declarative part. In either case it specifies the alignment
to be applied to any record or array type which has otherwise standard
If the alignment for a record or array type is not specified (using
Component_Alignment, or a record rep
clause), the GNAT uses the default alignment as described previously.