Re: [Boost-users] crc.hpp and visual studio run time checking

Daryle Walker wrote:

On 12/16/05 2:03 PM, "Clarke, Trevor" wrote:

...

It's not a mask to stop data loss but to tell VS you want the data loss. I.E.

unsigned short a = 0x1234; return (a << 8) & 0xffff; [TRUNCATE past message context]

That mask retains 100% of the bits (if a "short" is 16 bits), so it effectively does nothing. That's a waste of cycles if the masking isn't optimized away. I don't get how this shuts up the RTC unless this construct was specifically created as a workaround.

There is no unsigned short arithmetic in C/C++; in a << 8 a is promoted to int or unsigned int first, then the result is implicitly converted to unsigned short by the return, and this causes high-order bits to be lost.