Re: IAR and AQ430 floating point library size

Paul,

That's exactly the problem. Since relative short distances are to be
calculated, i.e. delta values come close to 0.0001 (it's the way the
latitude and longitude are represented in a NMEA string), the error is such
that the result is always ZERO. Emulation with 64-point fp results in a
distance accuracy of <1 meter (which of course is already beyond the scope
of any regular GPS receiver). But for the sake of fp calculation this
illustrates the problem.

Thinking about this problem of integrating "double precision" into IAR
environment or any other 32 bits supported environment. Can the following
"mixing" solution be implemented:
(1) building a trig/math library based on 64-bit IEEE formatted routines
that accepts 32 bit floating point (or doubles as they are the same in IAR
enviroment) as input value. The result is returned as a float, but with
higher accuracy (as I assume). To save program space, a tailored library
(only containing the functions needed) could be build using a 64-bit
compiler.
(2) linking this lib with the project together with proper external function
prototype definitions
(3) calling the these routines from the program source code
Can in this way the 64-bit format issue be avoided in IAR, still gaining
from 64-bit based routines?

I'm wondering if Kris would be willing to share his "toy" with us
...... :-)

Thanks for your help. Nico

----- Original Message -----
From: "Paul Curtis" <plc@plc@...>
To: <msp430@msp4...>
Sent: Sunday, October 27, 2002 12:19 PM
Subject: RE: [msp430] IAR and AQ430 floating point library size

> Nico,
>
> > The calculation that requires "double precision" is given by
> > the formula:
> >    Result = A * acos[sin(x1)*sin(x2)+cos(x1)*cos(x2)*cos(y2-y1)]
> > It calculates a distance based on latitude (rad) and
> > longitude (rad) values. A 32-bit fp gives to much deviation
> > from the "real" value, compared to a off-chip emulated
> > 64-bits fp. So, for best accuracy 64-bits fp should be used.
> > That's why.
>
> Hmm.  Ok.  I'll go away and play.
>
> > Are you refering to the v4.01 fpp of TI?
>
> Nope.
>
> > Can you give more info on that compiler that supports
> > 64-bit doubles and competent trig lib for the MSP430?
>
> It's Kris' latest toy, the "beta" compiler and IDE. 
However, 64-bit is
> expensive both in speed and accuracy, but a hardware multiplier helps.
> As I wrote the 32-bit and 64-bit IEEE routines and the 8, 16, 32, and
> 64-bit integer routines for the MSP430 compiler, plus the full C99 trig
> library, I have some experience with this stuff.
>
> > Can such lib be integrated somehow in the IAR environment?
>
> Not really.  AFAIK, the IAR compiler treats float and double as one and
> the same, and so there is no way for a user to provide 64-bit floating
> point.  However, it is possible to compute such things using fixed
> point, so perhaps you can do that if you wish to stick with IAR?  Ahh.
> I see IAR doesn't support 64-bit ints and unsigneds.  How quaint.
> It's even harder if you don't have *any* 64-bit type.
>
> -- Paul.
>
> > ----- Original Message -----
> > From: "Paul Curtis" <plc@plc@...>
> > To: <msp430@msp4...>
> > Sent: Sunday, October 27, 2002 8:36 AM
> > Subject: RE: [msp430] IAR and AQ430 floating point library size
> >
> >
> > > Why do you need 64-bit floating-point?  Given that IAR support
only
> > > 32-bit fp with a 24-bit mantissa, your only hope is a compiler
with
> > > 64-bit doubles and a 53-bit mantissa.  I do know of one for
> > the MSP430
> > > with 64-bit doubles and a competent trig library, but I
> > still wonder
> > > why such precision is required.  Can you elucidate?
> > >
> > > -- Paul.
> > >
> > > > -----Original Message-----
> > > > From: Nico_Resiproc [mailto:N.Arends@N.Ar...]
> > > > Sent: 27 October 2002 03:25
> > > > To: msp430@msp4...
> > > > Subject: Re: [msp430] IAR and AQ430 floating point library
size
> > > >
> > > >
> > > > Hi there,
> > > >
> > > > Just picking up the discussion about FPP.
> > > > I'm working with the full licienced version of IAR WB,
> > already two
> > > > years now. Upgrading my "old" 1.24 version to the
1.26
> > version will
> > > > be charged by IAR with G400.00 GBP
> > > > (!!!!!!!!!) while having already spent so much money on the
IAR
> > > > package. What is their policy towards programmers like us?
> > > >
> > > > Anyhow, I need a double precision Floating Point
> > (multiply cos and
> > > > acos
> > > > calculations) on a MSP430F149 device.
> > > > The IAR math lib really has a poor performance (lots of
rounding
> > > > errors and only 7 digits resolution). Can anybody tell me
whether
> > > > the TI FPP v4.01 has a better performance, and how to
integrate
> > > > these routines in my C program. Can it be done with the
> > 1.24 version
> > > > of IAR, as I understood that TI FP formats are not
> > supported by IAR
> > > > (float and double are treated the same way).
> > > >
> > > > I really hope this discussion proceeds, since floating
> > point is an
> > > > important issue after all.
> > > >
> > > > Nico
> > > >
> > > > ----- Original Message -----
> > > > From: "To chi kin" <to_chi_kin@to_c...>
> > > > To: <msp430@msp4...>
> > > > Sent: Wednesday, October 23, 2002 6:30 AM
> > > > Subject: Re: [msp430] IAR and AQ430 floating point library
size
> > > >
> > > >
> > > > > Dear Kris,
> > > > >
> > > > > Thanks for you advice!
> > > > >
> > > > > So, I also heard T.I. has a Floating Point Package,
> > > > > FPP, v4.01 for T.I. Assembler and IAR. How do I update
> > > > > it to IAR and does it help the floating point
functionality of
> > > > > IAR? (I am currently using v1.26A evaluation version.)
> > > > >
> > > > > By the way, where to get T.I. assembler and simulator?
> > > > >
> > > > > have a good day
> > > > > Ken
> > > > >
> > > > >
> > > > >  --- Kris De Vos <microbit@micr...>
ao?lDo?oRe!G> Hi
> > > > > Ken,
> > > > > >
> > > > > > As you indicate concern for floating point, I
should
> > point out a
> > > > > > few floating point issues on EW430 :
> > > > > >
> > > > > > 1.    Don't expect too good precision of IAR
floats
> > > > > > for MSP430 . It's full of rounding errors
that I
> > > > > > don't get with other
> > > > > >        tools.
> > > > > >        Furthermore, be VERY careful when you store
> > results with
> > > > > > functions like sscanf(). It STILL happily writes
> > > > > >        floats in odd-alignment at certain
exceptions.........
> > > > > >        (The best way is to check alignment
yourself
> > > > > > at runtime, and adjust it in your own S/W ,
because
> > > > > > it
> > > > > >        indeed is not always possible for the
> > > > > > compiler nor linek to know about runtime, and
> > > > > > actually is impossible.
> > > > > >        (At least the "new tool" I'm
testing prompts
> > > > > > an "odd alignment" possibility, nowhere
to be seen
> > > > > > with EW430 after
> > > > > >        18 months of promises)
> > > > > > 2.    Be careful when it is possible to come
across
> > > > > > NaNs (Not a Number), or + and - infinities.
> > > > > >       Try giving +/- INF to IAR's
printf()
> > > > > > .................. It never returns.
> > > > > >       I've queried this with IAR about 1 year
ago,
> > > > > > and I was told not to feed NANs to printf() ......
> > > > > >       "Not Good Enough"...
> > > > > >
> > > > > > If you are specifically after floating point
> > > > > > operation, you *might* not have your needs
fulfilled
> > > > > > on EW430....
> > > > > > Each case is different, but my specific code
> > > > > > couldn't afford to (and shouldn't have
to !) check
> > > > > > for NaNs etc. at runtime
> > > > > > before I call printf().
> > > > > >
> > > > > > Printf() should handle that itself.........
> > > > > >
> > > > > > Kris
> > > > > >
> > > > > >   ----- Original Message -----
> > > > > >   From: To chi kin
> > > > > >   To: msp430@msp4...
> > > > > >   Sent: Monday, October 21, 2002 7:20 PM
> > > > > >   Subject: [msp430] IAR and AQ430 floating point
library size
> > > > > >
> > > > > >
> > > > > >   Dear all,
> > > > > >
> > > > > >   Once again, I am a newbee for MSP430. I am still
> > > > > >   searching for a right C toolchain for my 1st
> > > > > > MSP430
> > > > > >   project.
> > > > > >
> > > > > >   And floating point support is one of my major
> > > > > > concern,
> > > > > >   so I modify the MSP430F413 FET C example a bit
to
> > > > > > try
> > > > > >   it out. I just want to test a floating +, - , *,
/
> > > > > >   library size. And I wondering the result. And
> > > > > > except
> > > > > >   the C source code, I change nothing regarding
the
> > > > > >   complier or linker setting?
> > > > > >
> > > > > >   Generated code size:
> > > > > >   IAR: 808 byte
> > > > > >   AQ430: 3002 byte
> > > > > >
> > > > > >   Is that the truth? Ok, if that's the truth!
I also
> > > > > >   feel more confortable when I pay so much $$$ for
> > > > > > it.
> > > > > >
> > > > > >   Thanks in advance!
> > > > > >
> > > > > >   have a good day
> > > > > >   Ken
> > > > > >
> > > > > >   test code:
> > > > > >   #include  <msp430x41x.h>
> > > > > >
> > > > > >   float a, b, c;
> > > > > >
> > > > > >   void main(void)
> > > > > >   {
> > > > > >
> > > > > >     WDTCTL = WDTPW + WDTHOLD;
> > > > > >     P5DIR |= 0x02;
> > > > > >
> > > > > >         a = 100.0;
> > > > > >         b = 2.5;
> > > > > >         c = a + b;
> > > > > >         c = a * b;
> > > > > >         c = a / b;
> > > > > >         c = a - b;
> > > > > >
> > > > > >     for (;;)
> > > > > >     {
> > > > > >       unsigned int i;
> > > > > >
> > > > > >       P5OUT ^= 0x02;
> > > > > >       i = 50000;
> > > > > >       do (i--);
> > > > > >       while (i != 0);
> > > > > >     }
> > > > > >   }
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
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Re: IAR and AQ430 floating point library size

Beginning Microcontrollers with the MSP430

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