Double is the highest shared floating point number. But maybe if you implement soft float for 128-bit float, that can be used. (extended is not portable enough to really be a solution)
My previous point stands: nobody in their right mind gets involved with bit-twiddling floating points :-)
Well, we could definitely use such people, because for FPC we need software 128-bit FP support so that we can fully support cross compilation from platforms that don't support Extended (including x86_64-win64) to those that do. And while basic routines are already available functions like exp and ln as well as the trigonometry ones are missing...
"software 128-bit FP support" is a very generic term. Are the exact requirements noted down somewhere? Depending on these the task can vary from several man days to man years ...
* full implementation in FPC, or wrapper for an existing FP128 library?
* 32/64 bit and little-/big-endian architecture support?
* based on IEEE754?
* exposure of an internal, more efficient format too?
* designed to allow replacement of some kernel functions by asm routines?
* how much trade is allowed between exactness and speed?
* ...
Don't get me wrong - I'm not committing to anything here (yet)! I'm just a hobby programmer who's solely developing things for his own amusement. But I recently started explorations into FP128 based on IEEE754-2008 and this may coincide with my own ambitions.
Beside that, mmartin has recently announced an FP128 library, following the IEEE754 - however also his version is only covering basic functionality and does not include the desired elementary functions like ln, exp, etc.
Cheers,
MathMan