CodeWarrior for MCUのトピックRe: Weird results using floating point

Weird results using floating point

deneb — Thu, 18 Dec 2008 01:10:39 GMT

Dear All
I am trying to run a couple of floating point operations and simply cannot get it working. Here is the simplest code:

float temp;
temp = 23/3.5;

After this instruction, the value of temp is 18724.582131

I am using CW 5.0.14.8093 for an HCS12NE64 microcontroller. I am using ansilf.lib.

Would anyone help me?

Thanks
-Deneb

Re: Weird results using floating point

kef — Thu, 18 Dec 2008 17:26:52 GMT

Single precision float, of value 23/3.5 = ~6.5714285, read from memory as double, with any value of the second long word, is about 18724.5 .

I don't know what happens in your case, but it could be something like project settings (double and float sizes ) are incompatible with the libraries you are using.

Re: Weird results using floating point

deneb — Thu, 18 Dec 2008 17:38:51 GMT

Thanks kef. I figured it out by following the information in {CodeWarrior for HCS12 V4.7\lib\hc12c\readme.txt} file. It was some settings issue, as you mentioned, for the assembler. The following settings worked with ansil.lib file.

-D_HCS12 -Ml -W2 -Os -F2 -NoPath

However, I still cannot get ansilf.lib to work. I need it to use IEEE64 double values. Even when I put "-Cf", it gives the wrong results, which as I understand, is swapping the higher two bytes with the lower two bytes. Is it a bug?

Re: Weird results using floating point

CrasyCat — Thu, 18 Dec 2008 18:54:11 GMT

Hello

I did some tests with CodeWarrior for HC12 V4.7.

The code is returning the appropriate result.

I would suggest you to create a new project using the project wizard.

Specify from the beginning you want to use 64-bit for double encoding and large memory model and then plug your code in there.

This should be working.

CrasyCat

SOLVED: Weird results using floating point

deneb — Fri, 19 Dec 2008 20:59:37 GMT

Hello CrasyCat

Creating an empty project and setting appropriate options in the wizard dialogs did the trick.

Thanks to everybody