Float Format

wewa · Joined: 02 Jul 2008 Posts: 27

I've some problems with the float-format.

The standard IEEE float-format looks like this:

But the CCS Compiler changes sign and exponent. (The sign is on position 23 and the exponent goes from bit 24 to 31).
Why is that so or I am wrong?

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

I believe CCS still uses a format Microchip came up with before the IEEE came up with theirs. It is a choice between industry compatibility and backward compatibility.
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wewa · Joined: 02 Jul 2008 Posts: 27

Oh ok.

I had only some problems on communication with VB.

Ttelmah · Guest

It is also fractionally easier to write using the PIC instructions. You get about 5% faster performance using this layout, and a PIC, than with the IEEE layout and the PIC. This changes with the latest DSPICs, and CCS switches to using IEEE format on these. I wrote my own assembler PIC libraries for the earliest 16 chips, and it saved a noticeable amount of time to go with this layout.
Sending to VB shouldn't be a problem. There are PIC libraries for doing the conversion included with the compiler now, and in the past several people have also posted versions (I have posted VB versions several years ago).

Best Wishes