I cannot discern the meaning of the statement from the standard saying
that if a bit-field is larger than int or unsigned int, no integral
promotions apply to it. It's in 4.5 par. 3.

Assuming a machine with a size of general-purpose register equal 32
bits (where a byte takes up 8 bits) and a C++ implementation where an
int is 32 bits and a long is 64 bits. And the following snippet of
code:

struct ExternalInterface {
  long field1:36, field2:28;
};

int main() {
  ExternalInterface  myinstance = { 0x100000001L, 0x12,};
  if(myinstance.field1 < 0x100000002L) { //do something }
}

Does the standard prohibit the implementation from promoting field1's
value into two general purpose registers? And imposes a with it using
masks or shift operations? What else could that phraze mean?

Either alternative is implementation specific, so I don't understand
why the phraze "If the bit-field is larger yet, no integral promotions
apply to it".

Thanks for any clarification.

Kiril

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{Dear moderators, please disregard the prev. posting of mine under the
same name}

I cannot discern the meaning of the statement from the standard saying
that if a bit-field is larger than int or unsigned int, no integral
promotions apply to it. It's in 4.5 par. 3.

Assuming a machine with a size of general-purpose register equal 32
bits (where a byte takes up 8 bits) and a C++ implementation where an
int is 32 bits and a long is 64 bits. And the following snippet of
code:

struct ExternalInterface {
  long field1:36, field2:28;
};

int main() {
  ExternalInterface  myinstance = { 0x100000001L, 0x12,};
  if(myinstance.field1 < 0x100000002L) { //do something }
}

Does the standard prohibit the implementation from promoting field1's
value into two general purpose registers? And imposes a burden of
using shift operations to work with the field's value? What else could
that phraze mean?

Either alternative is implementation specific, so I don't understand
why the phraze "If the bit-field is larger yet, no integral promotions
apply to it" made it to the standard.

Thanks for any clarification.

Kiril

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.research.att.com/~austern/csc/faq.html                ]