Intel® 64 and IA-32 Architectures Optimization Reference Manual

OPTIMIZING FOR SIMD INTEGER APPLICATIONSExample 5-26 shows how to clip signed words to an arbitrary range; the code forclipping unsigned bytes is similar.Example 5-26. Clipping to a Signed Range of Words [High, Low]; Input:; MM0 signed source operands; Output:; MM0 signed words clipped to the signed; range [high, low]pminsw mm0, packed_highpmaxswmm0, packed_lowExample 5-27. Clipping to an Arbitrary Signed Range [High, Low]; Input:; MM0 signed source operands; Output:; MM1 signed operands clipped to the unsigned; range [high, low]paddw mm0, packed_min ; add with no saturation; 0x8000 to convert to unsignedpadduswmm0, (packed_usmax - high_us); in effect this clips to highpsubuswmm0, (packed_usmax - high_us + low_us); in effect this clips to lowpaddw mm0, packed_low ; undo the previous two offsetsThe code above converts values to unsigned numbers first and then clips them to anunsigned range. The last instruction converts the data back to signed data and placesthe data within the signed range.Conversion to unsigned data is required for correct results when (High - Low) = 0X8000, simplify the algorithm as in Example 5-28.5-26