On 11/27/18 8:41 PM, David Gibson wrote:
On Wed, Nov 28, 2018 at 01:32:21PM +1100, Benjamin Herrenschmidt wrote:
On Wed, 2018-11-28 at 11:13 +1100, David Gibson wrote:
Don't you need a cast to avoid (nsr << 8) being a shift-wider-than-size?
Shouldn't be a problem as long as it fits in an int, no ?
I dunno, I can never remember the rules about when C extends and when
it doesn't. I'm not sure anybody does, which is kind of the point.
As soon as you perform arithmetic on a type narrower than int, it is
first promoted to at least int (possibly wider, depending on the type of
the other operand to the binary operator). And, since C guarantees that
int is larger than 8 bits, 'uint8_t << 8' and 'int8_t << 8' are both
well-defined, without needing a cast of nsr.
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