Reply to Witold,
Dnia 2009-06-23, wto o godzinie 16:01 +0000, BCS pisze:
I think you are in error here. IIRC IEEE-754 has some stuff about
"extended precision" values that work like the normal types but with
more bits. That is what 80 bit reals are. If you force rounding to
64-bits after each op, I think things will come out exactly the same
as for a 64-bit FPU.
this is exactly the same think which cpu already does when dealing
with doubles and floats. internal computations are performed in ext.
precision, and written somewhere, truncating to 64bits.
You misread me; if you need computation to exactly match 32 or 64bit math,
you will need to round after every single operation (+, -, *, /, etc.), what
most systems do is use full internal precision for intermediate value and
round only when the value is stored to a variable. If you don't need bit-for-bit
matches, then 80-bit matches IEEE-754 semantics just with more bits of precision.
