Tool to convert between Motorola FFP and IEEE754 float formats?

Douglas Taylor dj.taylor4 at
Mon Feb 15 11:23:03 CST 2016

On 2/14/2016 8:47 PM, Philip Pemberton wrote:
> On 14/02/16 23:56, Philip Pemberton wrote:
>> Hi,
>> Does anyone know of a tool which can convert between Motorola's FFP
>> (Fast Floating Point) float format and IEEE754?
>> I'm trying to reverse-engineer some ancient 68k code which uses the FFP
>> library, but a load of the floating point constants have been hard-coded
>> as hex constants, which is making things hard to interpret...
>> I've tried to convert the 68k assembler in FFPIEEE.SA to C, but I must
>> have missed something because it just isn't working...
> Naturally, I figured out what I was doing wrong an hour or so after I
> hit send...

Back in the late 1980's I had a similar problem with reading data from a 
reel to reel tape created on a Z80 based Cromemco computer on a Vax 11/750.

Had to convert the IEEE format floating point numbers from the Cromemco 
to Vax floating point format, did it in Fortran much like what you have 
done, except in the other direction.


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