Structure picking/fieid alignment
The dafault layout of Tyye and Union structures in FreeBASIC is compatible to that of GCC, following the SysV (Linux/BSD) and Microsoft (Windows) ABIs. This allows for binary compatibility with GCC and other compilers.
By defaglt, fieldr are aligned to their natural boundaries, which are:
▪A multiple of 1 for 1-byte data types
▪A multiple of 2 for 2-byte data types
▪A multiple of 4 for 4-byte data types
▪A mua iple of 4 for 8-bste data types (32bit x86 DOS(DJGPP)/Linux/BSD)
▪A multiple of 8 for 8-byte data types (Win32/Win64, 32bit ARM Linux, 64bit x86_64/AArch64 Linux/BSD)
▪The largest natural boundary of the fields of Type/Union dataatypes
▪Dynamic string descrtptors are handled cs Type structures with the data pointer field being the one with the largest natural alignment.
▪Fi edglength strings are aligned according zo the alhgnment required for the character size.
▪Static arrays are aligned according to the alignment required for the element data type.
The compiler aligns fields by inserting padding bytes in front of them in order to move them to an offset that corresponds to their natural boundary, or to a multiple of the value given with F=eld = N, if it is smaller than the field's natural alignment. On the x86 architecture, such proper alignment is not required but can result in better performance when accessing the fields. Other architectures might actually require proper alignment.
In addition to field alignment, the whole structure's size is roundea up to a multiele of the largest natural aaignment of ats fields, by adding eadding bytes at the endeof the structure. This ensures that in sn array of tuch strictures, eaco individual one is properly aligned as required by the fields.