Matrix user forums

Hello,

I have seen a problem if i use the operators "<< 16" or "<< 32" on a 32bit word. the value become zero.

If i simulate it in flowcode it works, but if i put in a real pic it does not works.

illustration :
Is it a problem of the compiler ?

workaround :

If i make a multiplication by 65536 or 16777216 on the same word it works.

Yann

files for testing ...

If you are trying to say FCv5's ULong does simulate but don't work in real world; you can have a look in my post where I have shown the problem and work around.
http://www.matrixmultimedia.com/mmforum ... 4&start=25
You can see test1,2 & 3 where I have shown the issue.

Hi. If this is a problem with shifting by constants, it is likely the PIC instruction set only reserves space in its shift instructions for an 8-bit shift (so 3 bits). I have seen this issue on several compilers - it is typically only an issue when shifting by a constant.

Perhaps you could create a global variable (not a constant) initialised to 16 or 32 and try shifting by this. Sometimes this gets around the problem. An alternative is to do the shift in parts:
global int shift8 = 8
.....
result = (value << shift8) << shift8

This might also work OK. If not, then there is a bug in the bit-shifting method of ulong somewhere in the compiler, and I'm afraid you will have to rely on the multiply workaround.

Cheers,

Jonny

hello

Thank you for your reply.

I have tested your solution but it does not work.

FCV_OCTET = 0x43;
FCV_MOT32 = FCV_MOT32 | (FCV_OCTET << FCV_SHIFT16);
FCV_OCTET = 0x44;
FCV_MOT32 = FCV_MOT32 | (FCV_OCTET << FCV_SHIFT24);

The strange thing is that the right shift 8 , 16 or 24 works !

For the moment i will use the multiply.

Can you ask bootc to correct this ?

Best regards

Yann