Doing int1 Comparisions

Geps · Joined: 05 Jul 2010 Posts: 129

Hi,

Should I need to keep casting elements in an int1 array to int8?

This returns false when the data in the two elements is equal:

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

It also works if you put the array elements into temporary int1 variables
and compare the variables.

It just doesn't work if you compare the array elements directly.
I think it's a bug. You should report it.

I checked and in fact this bug has been around for a long time:
http://ccsinfo.com/forum/viewtopic.php?t=40661
It still fails in vs. 4.127. I doubt that it would be that hard for them to fix.

FvM · Joined: 27 Aug 2008 Posts: 2337 Location: Germany

It apparently had been fixed in V4.112 (my "stable" CCS C working version) but returned later.

Geps · Joined: 05 Jul 2010 Posts: 129

Thanks,

CCS have been informed.

asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

bilko · Joined: 17 Oct 2003 Posts: 24 Location: Dorset, UK

This is all getting a bit silly.

I am getting endless similar bugs with structures, unions etc.

I seem to spend more time checking the compiler output than writing code.

Time to give up and try another compiler maybe.

Bill

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

This may be a Chicken-&-Egg thing. I have used 1 structure and 2 unions in the last 15 years or so of programming with CCS. Maybe nobody uses them because they don't work well, or maybe CCS doesn't put the effort into making them work well because no one uses them.

All I can say is once I looked up in K&R how they should work, they worked fine for me.
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asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

i got burned in a similar way trying to manipulate int1 "arrays" too.

i managed to solve it this way:
in my instance, skipme is an unsigned int8 array of 12 bytes
set up to deal with 96 virtual int1 vars ,
but you can see how this concept can be expanded.

and of course , i is the array element number

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

For me the code listing above explains it all.
keep It Simple !!!

The PIC is very efficient in manipulating single bits inside a byte but once you try to manipulate individual bits combined with address arithmetic (pointers !) the number of required instructions explodes.

I do like the CCS compiler because of the great support in this forum, but I always keep in mind that it is a cheap compiler. Cheap comes at the price of reduced quality, I know and accept this. Keeping the code simple saves me a lot of time debugging compiler errors.

For me this is one of the reasons I minimize the use of int1 variables and use them only when I'm sure the compiler can replace it with a single bit manipulating instruction.