[fpc-devel] real, float, double specs

Martin Frb lazarus at mfriebe.de
Wed Feb 12 01:53:45 CET 2014

I am trying to figure out the internal representation of these. (So they 
can be converted, including conversion form sizes not present in fpc)

They are all floating point? Pascal has no fixed point? (nevertheless, 
rules for fixed point may also be of interest)

dwarf2 says it is specified in each platforms ABI, but I have not found 
that (not even found the ABI yet).
Only found: 

And http://www.freepascal.org/docs-html/ref/refsu6.html#x28-310003.1.2

> Type 	Range 	Significant digits 	Size
> ------------------------------------------------------------------------
> ------------------------------------------------------------------------
> ------------------------------------------------------------------------
> ------------------------------------------------------------------------
> Real 	platform dependant 	??? 	4 or 8
> Single 	1.5E-45 .. 3.4E38 	7-8 	4
> Double 	5.0E-324 .. 1.7E308 	15-16 	8
> Extended 	1.9E-4932 .. 1.1E4932 	19-20 	10
> Comp 	-2E64+1 .. 2E63-1 	19-20 	8
> Currency 	-922337203685477.5808 .. 922337203685477.5807 	19-20 	8
apparently there also is real46 (never heard of real16)

The size will actually be in the dwarf, so that I got.

But from that how do I know how many bits are in the exponent? (and how 
many in the number). Apparently it depends on the CPU? But where to get 
the info?
(later dwarf give bit sizes for the exponent.)

is missing images?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freepascal.org/pipermail/fpc-devel/attachments/20140212/98074a60/attachment.html>

More information about the fpc-devel mailing list