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Compiler-specific Features
4.7.54 __qsub16 intrinsic
This intrinsic inserts a QSUB16 instruction into the instruction stream generated by the
compiler. It enables you to perform two 16-bit integer subtractions, saturating the
results to the 16-bit signed integer range -2 15 ≤ x ≤ 2 15 - 1.
unsigned int __qsub16(unsigned int val1, unsigned int val2)
Where:
val1
val2
holds the first halfword operands
holds the second halfword operands.
The __qsub16 intrinsic returns:
• the saturated subtraction of the low halfword in the second operand from the low
halfword in the first operand, in the low halfword of the returned result
• the saturated subtraction of the high halfword in the second operand from the high
halfword in the first operand, in the high halfword of the returned result.
The returned results are saturated to the 16-bit signed integer range -2 15 ≤ x ≤ 2 15 - 1.
Example:
unsigned int subtract_halfwords(unsigned int val1, unsigned int val2)
{
unsigned int res;
}
res = __qsub16(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
• Saturating instructions on page 4-93 in the Assembler Guide
• Parallel add and subtract on page 4-99 in the Assembler Guide.
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