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(nasm.info)Section B.4.239

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B.4.239. `PMULHRWA': Multiply Packed 16-bit Integers With Rounding, and Store High Word
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     PMULHRWA mm1,mm2/m64          ; 0F 0F /r B7     [PENT,3DNOW]

   `PMULHRWA' takes two packed 16-bit integer inputs, multiplies the
values in the inputs, rounds on bit 16 of each result, then stores bits
16- 31 of each result to the corresponding position of the destination
register.

   The operation of this instruction is:

        dst[0-15]  := (src1[0-15] *src2[0-15]  + 0x00008000)[16-31];
        dst[16-31] := (src1[16-31]*src2[16-31] + 0x00008000)[16-31];
        dst[32-47] := (src1[32-47]*src2[32-47] + 0x00008000)[16-31];
        dst[48-63] := (src1[48-63]*src2[48-63] + 0x00008000)[16-31].

   See also `PMULHRWC' (*Note Section B.4.238::) for a Cyrix version of
this instruction.