Lets restate the hole thing, considering unit ncon.pas and pexpr.pas
units in FPC 2.6.4
compiler.
1° It is not possible, without using some ad hoc adjustements, to have
always an EXACT CURRENCY stored in a DOUBLE or EXTENDED because Double or
Extended being expressed as Sign*2^exp*Base2(n).
Lets restate the hole thing, considering unit ncon.pas and pexpr.pas units
in FPC 2.6.4
compiler.
1° It is not possible, without using some ad hoc adjustements, to have
always an EXACT CURRENCY stored in a DOUBLE or EXTENDED because Double or
Extended being expressed as Sign*2^exp*Base2(n).
You have troubled me seriously, so I have dug in the compiler source.
:-)
It appears that when parsing the source, Currency constants are cast
to type BestReal (EXTENDED on I386) before being converted to the 8
byte currency written to the PPU or EXE or whatever is done.
it was my
Did you check that infamous coprocessor Pentium FDIV bug?
http://en.wikipedia.org/wiki/Pentium_FDIV_bug#Affected_models
The even give values to test:
The correct value is
4195835/3145727 = 1.333820449136241002
However, the value returned by the flawed Pentium is incorrect at or
Did you check that infamous coprocessor Pentium FDIV bug?
http://en.wikipedia.org/wiki/Pentium_FDIV_bug#Affected_models
The even give values to test:
The correct value is
4195835/3145727 = 1.333820449136241002
However, the value returned by the flawed Pentium is incorrect at or
Bruno Krayenbuhl wrote / napísal(a):
I have absolutely no idea of how the compiler does translate Currency
constant to code, sorry.
May be it uses the FPU when translating from String representation to
assembler value, but I have absolutely no idea where that would be
done in the
Bruno Krayenbuhl wrote / napísal(a):
2 - Difference between 2.6.4 on Win98 and WinXP.
I suspect that these 2 are on different computers and thus do not
have exactly the same floating point unit.
Yes Win 98 is on PC with Intel Pentium 4 CPU and Win XP on PC with Intel
Core 2 Duo CPU
But
My point N°2 regarding potential FPU difference was only concerning instruction
line
e:=c;
=
I have absolutely no idea of how the compiler does translate Currency constant
to code, sorry.
May be it uses the FPU when translating from String representation to assembler
