__uqasx intrinsic

This intrinsic inserts a UQASX instruction into the instruction stream generated by the compiler. It enables you to exchange the halfwords of the second operand and perform one unsigned 16-bit integer addition and one unsigned 16-bit subtraction, saturating the results to the 16-bit unsigned integer range 0 ≤ x ≤ 216 - 1.

unsigned int __uqasx(unsigned int val1, unsigned int val2)

Where:

val1

holds the first two halfword operands

val2

holds the second two halfword operands.

The __uqasx intrinsic returns:

The results are saturated to the 16-bit unsigned integer range 0 ≤ x ≤ 216 - 1.

Example:

unsigned int exchange_add_subtract(unsigned int val1, unsigned int val2)
{
  unsigned int res;

    res = __uqasx(val1,val2); /* res[15:0] = val1[15:0] - val2[31:16]
                                 res[31:16] = val1[31:16] + val2[15:0]
                               */
    return res;
}

Show/hideSee also

Copyright © 2010-2012 ARM. All rights reserved.ARM DUI 0491H
Non-ConfidentialID070912