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Re: 1100 Multiply and Divide Fractional Instructions

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On 2/23/26 15:27, R Daneel Olivaw wrote:
> Stephen Boyd wrote:
>> On 2/23/26 12:22, R Daneel Olivaw wrote:
>>>
>>> Look at the code FTN generates when converting REAL to INTEGER (or 
>>> vice versa), it makes use of something along those lines.  You can 
>>> then check the equivalent for Double Precision.
>>> I had to do this for a piece of MASM coding around 41 years ago so my 
>>> memory of the exact code generated is more than sketchy.
>>
>> Ah! I can kind of see where that would be useful in that situation. 
>> Not being a mathematician I would have to do some serious thinking to 
>> completely wrap my head around it.
>>
>> Whenever I have to convert between floating point and integer or vice 
>> versa I usually end up doing a bunch of floating point arithmetic to 
>> make it happen. I can see where being able to use integer instructions 
>> would be a lot faster.
>>
>> Thanks
>>
> 
> Well I cheated back then - "FTN has to do it and whatever it does will 
> be bombproof, so @FTN,L (on a tiny subroutine) is the way to go".
> My comment in the MASM routine became legendary, "I don't know why this 
> works but it does so leave it alone".

I found another use for MF. Converting Fieldata to binary. Like the 
Fortran code mentioned above I don't really know why this works but I 
tried it and it does.

Convert the 6 fieldata numerals in A0 to binary in A1.

         AND     A0,(0171717171717).   STRIP OFF 'ZONE' BITS
         AND     A1,(-0,0,-0,0,-0,0).  EXTRACT ALTERNATE DIGITS
         MF      A2,(54*/29).
         AN      A1,A2.                3 PAIRS OF DIGITS CONVERTED
         AND     A1,(0,-0,0).
         MF      A2,((1*/12-100)*/23).
         AN      A1,A2.                RIGHT 4 DIGITS NOW DONE
         AND     A1,(-0,0,0).
         MF      A2,((1*/24-10000)*/11).
         AN      A1,A2.                DONE. RESULT IN A1, ORIGINAL IN A0.

I found this at http://fourmilab.org/documents/univac/cute-tricks.html

Steve B

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1100 Multiply and Divide Fractional Instructions Stephen Boyd <sboydlns@gmail.com> - 2026-02-23 11:59 -0500
  Re: 1100 Multiply and Divide Fractional Instructions R Daneel Olivaw <Danni@hyperspace.vogon.gov.invalid> - 2026-02-23 18:22 +0100
    Re: 1100 Multiply and Divide Fractional Instructions Stephen Boyd <sboydlns@gmail.com> - 2026-02-23 14:27 -0500
      Re: 1100 Multiply and Divide Fractional Instructions R Daneel Olivaw <Danni@hyperspace.vogon.gov.invalid> - 2026-02-23 21:27 +0100
        Re: 1100 Multiply and Divide Fractional Instructions Stephen Boyd <sboydlns@gmail.com> - 2026-02-24 10:32 -0500
        Re: 1100 Multiply and Divide Fractional Instructions Stephen Boyd <sboydlns@gmail.com> - 2026-03-09 14:30 -0400
          Re: 1100 Multiply and Divide Fractional Instructions R Daneel Olivaw <Danni@hyperspace.vogon.gov.invalid> - 2026-03-09 19:47 +0100
            Re: 1100 Multiply and Divide Fractional Instructions Stephen Boyd <sboydlns@gmail.com> - 2026-03-10 10:29 -0400
              Re: 1100 Multiply and Divide Fractional Instructions R Daneel Olivaw <Danni@hyperspace.vogon.gov.invalid> - 2026-03-10 22:00 +0100
                Re: 1100 Multiply and Divide Fractional Instructions Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-03-11 14:37 -0700
                Re: 1100 Multiply and Divide Fractional Instructions R Daneel Olivaw <Danni@hyperspace.vogon.gov.invalid> - 2026-03-12 09:53 +0100
                Re: 1100 Multiply and Divide Fractional Instructions Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-03-12 07:31 -0700
                Re: 1100 Multiply and Divide Fractional Instructions R Daneel Olivaw <Danni@hyperspace.vogon.gov.invalid> - 2026-03-12 15:50 +0100
                Re: 1100 Multiply and Divide Fractional Instructions Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-03-12 12:03 -0700
      Re: 1100 Multiply and Divide Fractional Instructions Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-02-23 12:54 -0800
        Re: 1100 Multiply and Divide Fractional Instructions Stephen Boyd <sboydlns@gmail.com> - 2026-02-24 10:33 -0500

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