Re: [avr-gcc-list] Time-efficient read of high byte in two-byte variable

[Wallace White]

E. Weddington wrote:

> There's been a lot of discussion and it seems the most efficient way 
> is to use a union.
>
> #include <inttypes.h>
>
> typedef struct
> {
>         unsigned char lo;
>         unsigned char hi;
> } hilow_t;
>
> typedef union
> {
>         uint16_t word;
>         hilow_t byte;
> } mytype ;
>
> mytype encPosDetentsNow;
>
> ...
> {
>         ....
> 	encPosDetentsNow.word = 0xFFFF; 
> 	UDR = encPosDetentsNow.byte.hi;
>         ....
> }
>
> See what you get with this.

That indeed works well. Cool.

Let's see, my variable in question is a signed int... so I could change 
the typedef union

        typedef union
        {
                int16_t word;
                hilow_t byte;
        } mytype ;

and tack on .word to all my references to that variable... that should 
be fine, right?

Thanks,
Wallace