RealView Compilation Tools - ARM Information Center

Compiler-specific Features
4.7.62 __shasx intrinsic
This intrinsic inserts a SHASX instruction into the instruction stream generated by the
compiler. It enables you to exchange the two halfwords of one operand, perform one
signed 16-bit integer addition and one signed 16-bit subtraction, and halve the results.
unsigned int __shasx(unsigned int val1, unsigned int val2)
Where:
val1
val2
holds the first halfword operands
holds the second halfword operands.
The __shasx intrinsic returns:
• the halved subtraction of the high halfword in the second operand from 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_add_subract_halve(unsigned int val1, unsigned int val2)
{
unsigned int res;
}
res = __shasx(val1,val2); /* res[15:0] = (val1[15:0] - val2[31:16])