Re: [Sdcc-user] Math Library

[Ryan B. <rya...@ya...>]

I've had difficulties with the floating point library
as well.

Besides its enormous size, I've noticed incorrect
results when tested
with random numbers (using a PC as reference).

I've cobbled together a limited (non-optimized)
floating point library
in assembly.  I tried to make it correct and
reasonably small.  It
takes less than 1K of code and works only on the mcs51
in small model.
It has a limited notion of infinity to avoid overflow
randomness.

It overrides the default __fsadd() __fssub() __fsmul()
and various
type conversion routines such as __uchar2fs().  It
does not have
__fsdiv() support.

The transcendental functions (sin cos sqrt etc) are
not implemented.
These functions do a lot of adding and multiplying
though, so using
this library may help a bit.  The overall size would
probably still be
large enough to exclude small model, in which case
this is of no help.
(Well maybe not -- I don't know about other models)

I may also be doing some non-standard stuff with
regards to rounding.
I round the LSB up if the next-lower bit is 1 (instead
of truncating).
This happens even when converting a float to a long,
so { long x =
__fstoslong (-2.5); } would set x to -3;

Ryan



		
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