RealView Compilation Tools - ARM Information Center

Compiler-specific Features
4.7.90 __uhsax intrinsic
This intrinsic inserts a UHSAX instruction into the instruction stream generated by the
compiler. It enables you to exchange the halfwords of the second operand, subtract the
high halfwords and add the low halfwords, halving the results.
unsigned int __uhsax(unsigned int val1, unsigned int val2)
Where:
val1
val2
holds the first operand for the addition in the low halfword, and the first
operand for the subtraction in the high halfword
holds the second operand for the addition in the high halfword, and the
second operand for the subtraction in the low halfword.
The __uhsax intrinsic returns:
• the halved addition of the high halfword in the second operand and the low
halfword in the first operand, in the low halfword of the return value
• the halved subtraction of the low halfword in the second operand from the high
halfword in the first operand, in the high halfword of the return value.
Example:
unsigned int exchange_subtract_add(unsigned int val1, unsigned int val2)
{
unsigned int res;
}
res = __uhsax(val1,val2); /* res[15:0] = (val1[15:0] + val2[31:16])