This intrinsic inserts instructions equivalent to the saturating add of an integer with itself into the instruction stream generated by the compiler. It enables you to obtain the saturating double of an integer from within your C or C++ code.
int __qdbl(int val)
Where:
valis the data value to be doubled.
The __qdbl intrinsic returns the saturating add of val with itself, or equivalently, __qadd(val, , val).