3 ms·

So, if I have an array of extint(3), does it pack them nicely into 10-per-32-bit-word? Or 21-per-64-bit-word? Will a struct with six extint(5) fields fit into 4

• tom_mellior 6y ago
  http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2472.pdf http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2472.pdf does not mention structs at all, which is disappointing. I quoted this language below: "_ExtInt types are bit-aligned to the next greatest power-of-2 up to 64 bits: the bit alignment A is min(64, next power-of-2(>=N)). The size of these types is the smallest multiple of the alignment greater than or equal to N. Formally, let M be the smallest integer such that A * M >= N. The size of these types for the purposes of layout and sizeof is the number of bits aligned to this calculated alignment, A * M. This permits the use of these types in allocated arrays using the common sizeof(Array)/sizeof(ElementType) pattern." But to be honest I don't understand what it's trying to say. If bit width N = 3, the next power of 2 is 4, so would that mean that "bit alignment(?)" A = 4? Then M = 1 is the smallest integer such that A * M >= 3. Then the size of the type would be 4 bits? That wouldn't fly with sizeof.