RealView Compilation Tools - ARM Information Center

Compiler-specific Features
4.7.64 __shsub16 intrinsic
This intrinsic inserts a SHSUB16 instruction into the instruction stream generated by the
compiler. It enables you to perform two signed 16-bit integer subtractions, halving the
results.
unsigned int __shsub16(unsigned int val1, unsigned int val2)
Where:
val1
val2
holds the first halfword operands
holds the second halfword operands.
The __shsub16 intrinsic returns:
• the halved subtraction of the low 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 high halfword in the second operand from the high
halfword in the first operand, in the high halfword of the return value.
Example:
unsigned int add_and_halve(unsigned int val1, unsigned int val2)
{
unsigned int res;
}
res = __shsub16(val1,val2); /* res[15:0] = (val1[15:0] - val2[15:0])