Switching from CC5x to CCS C compiler

[anestho]

Hi,

I really like the feature rich CCS compiler, but I can't find a quick equivalent for the .low8, .high8 extensions. In CC5x, these allow you to read or write the MSB or LSB of a 16 bit word. It can be really useful to only affect the lower 8 bits or higher 8 bits. I know I can mask and use OR and AND to isolate the bits. There is also the MAKE8, MAKE16 commands.

Is there anything that will do:
int 8 A;
int16 B;

A = A + B.low8; //this is how I would do it in CC5x.
B.high8 ++; // add to MSB only

[Ken Johnson]

I thought I saw something like what you want, but can't find it in the help file. But, you can easily define a macro to do it, something like:

#define lobyte(x) (*((int8*) &x + 1)) // These may be backwards
#define hibyte(x) (*((int8*) &x + 0)) // I forget which "endian" ccs uses

int8 A;
int16 B;

A = A + lobyte(B);
hibyte(B)++;

This is off the top of my head, not tested, and likely has errors :(

But something like this

Ken

[ckielstra]

Another thread discussing this topic: http://www.ccsinfo.com/forum/viewtopic.php?t=20793

[libor]

You can use the #byte directive to map an alias variable name over an existing variable (or any direct address in RAM). Be sure to write no ; at the end of the #byte directive.