NaN Check

sei500510 · Joined: 19 Oct 2011 Posts: 2

hi,
how to check if float number is NAN?

IF (n != n)
...

don't work. Sad

Thanks

VC

Gabriel · Joined: 03 Aug 2009 Posts: 1067 Location: Panama

sei500510 · Joined: 19 Oct 2011 Posts: 2

Thanks Gabriel

if you look here:

http://en.wikipedia.org/wiki/NaN
you will find the example of code, but this trick don't work in CCS.
I want to read a floating number stored in eeprom. The first time, all the cells of eeprom contain 0xFF so the read_float_eeprom() return NAN

VC

Gabriel · Joined: 03 Aug 2009 Posts: 1067 Location: Panama

Then... you could define a range of "Valid" numbers, and if the number you read falls in this range its valid, else NAN.

Then again... 0xFF is a "valid" number (max 8 bit reading of ADC) so its still unclear what you are trying to do.

You want to know if the EEprom contains "real" data or if is still in its reset (0xff) state. Is this correct?

If so... unless 0xff is not a posible value in your stored data, then i do not see a way to determine this by just reading the value.

g.
_________________
CCS PCM 5.078 & CCS PCH 5.093

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

This thread has a discussion of methods to recognize if the eeprom data is
all equal to 0xFF:
http://www.ccsinfo.com/forum/viewtopic.php?t=40718