Re: 64bit/64bit fixed point division?

But there is no need to use FIST/FILD.
You can also write/read an extended precision
floating point (10 bytes) in memory with a value,
and use fld tword [edx] where edx is the address.
(for Turbo Assembler it's fld [tbyte edx]),
and vice versa with fst.
Only then you must also write/read the exponent,
which will be a little slower.

"Phil Carmody" <thefatphil_demunged@xxxxxxxxxxx> wrote in message
news:87lkpdfouz.fsf@xxxxxxxxxxxxxxxxxxxxxxx
"Maarten Kronenburg" <spamtrap@xxxxxxxxxx> writes:
Phil,
The mantissa for extended precision 80-bit floating point
is the full 64-bit, only bit number 63 is always 1.
The sign bit is bit number 79, see for example
http://babbage.cs.qc.edu/courses/cs341/IEEE-754references.html
and the book The Intel Microprocessors by Barry Brey.
So you can put a 64-bit integer into an extended precision
80-bit floating point without loss of precision.

I know. The FPU's fine, it's the interface from FP to integer
that's the problem. You can't (just) use a FISTP though.
(Unless you know that the answer is unique modulo 2^64.)

Phil
--
"Home taping is killing big business profits. We left this side blank
so you can help." -- Dead Kennedys, written upon the B-side of tapes of
/In God We Trust, Inc./.


.

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