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Compiler-specific Features
4.7.95 __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 ≤ 2 16 - 1.
unsigned int __uqasx(unsigned int val1, unsigned int val2)
Where:
val1
val2
holds the first two halfword operands
holds the second two halfword operands.
The __uqasx intrinsic returns:
• the 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 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.
The results are saturated to the 16-bit unsigned integer range 0 ≤ x ≤ 2 16 - 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[15:0]
res[31:16] = val1[31:16] + val2[31:16]
*/
return res;
See also
• ARMv6 SIMD intrinsics on page 4-109
• Instruction summary on page 4-2 in the Assembler Guide
• Parallel add and subtract on page 4-99 in the Assembler Guide.
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