topic Re: Initializing variables of type long long in CodeWarrior for MCU

Initializing variables of type long long

lowpy — Sun, 15 May 2011 01:30:42 GMT

I have a problem initializing variables of type long long.

Normally this should work:

long long x = 0x428A2F98D728AE22LL;

but when I compile I get the following error: C2704: Illegal number

Is this not supported by CW compiler or am I doing something wrong ?

Thanks in advance!

Re: Initializing variables of type long long

BlackNight — Sun, 15 May 2011 03:14:23 GMT

Hello,

yes, 64bit integers are not supported. long long is supported with 32bit max.

Anyway, doing 64bit math with a HCS08 or HCS12 will be rather a performance bottleneck.

So if you are using a 8 or 16bit processor for 64bit math, you might use the wrong cpu for it.

Re: Initializing variables of type long long

kef — Sun, 15 May 2011 15:34:27 GMT

What if lossless 64bit computation is required one or few times per second? Even 4-bits MCU can do it.

Re: Initializing variables of type long long

lowpy — Sun, 15 May 2011 17:15:59 GMT

Let me just see it I got this right.

Even if I manage to initialize the variable in another way, operations on that variable will only affect the lower 32 bits ?

Re: Initializing variables of type long long

BlackNight — Sun, 15 May 2011 17:22:06 GMT

sizeof(long long) will return 4, means it occupies 4 bytes (32bit) in memory. You will only have 32bit available.

An alternative would be to use/implement a software library, with something like

int64_t Add64(int64_t, int64_t);

I did not check, but maybe things like that is already awailable as open source.

Re: Initializing variables of type long long

bigmac — Mon, 16 May 2011 10:05:48 GMT

Hello,

Your variable could be treated as an array of two double words, four words, or eight bytes, or maybe a union of all three to provide greater flexibility. Arithmetic operations would then need to be performed on the individual array elements.

Regards,

Mac

Re: Initializing variables of type long long

Lundin — Mon, 16 May 2011 17:56:00 GMT

I believe neither the HCS08 nor the HCS12 Codewarrior supports C99. If you need to use C99 features, the first thing you should do is to get a C99 compiler.