21–23 of 23 posts
> We get lucky here because the flags field is at offset 202 How does one calculate this offset based on the fields in the struct?
Earlier quoted context omitted.
C structs are generally assumed to be laid out in the order defined with proper padding automatically inserted (as most platforms at best dislike unaligned accesses). Alignment information should only be necessary if you want to pack the structure or need to apply wider than standard alignment (e.g. need to align a 32 or 64b type to 128 bytes). The one possible issue is that reading padding is UB (i think). But here…
That's his point, you want to 1-align the struct to disable the padding to ensure the size of the structure is portable.
Earlier quoted context omitted.
C structs are generally assumed to be laid out in the order defined with proper padding automatically inserted (as most platforms at best dislike unaligned accesses). Alignment information should only be necessary if you want to pack the structure or need to apply wider than standard alignment (e.g. need to align a 32 or 64b type to 128 bytes). The one possible issue is that reading padding is UB (i think). But here…
Wider than standard alignment can be pretty important though. Especially for usage with SIMD instructions.