[C28x] Intrinsics - difference between __byte and __mov_byte

Lori Heustess said:

First question:

• The prototype for __byte in the compiler guide says: int &__byte(int *array, unsigned int byte_index);
• The '&' seems to be a typo.  Is that correct?

It's not a typo, the __byte intrinsic returns a C++-style reference, even in C mode.

Lori Heustess said:

I've been trying to work out the difference between __byte and __mov_byte

__byte can be used on the left-hand side to set values.  This is the reason it needs to return a reference.

#include <stdio.h>

int array[3] = { 0xaaaa, 0xbbbb, 0xcccc };

void main()
{
    int i;

    __byte(array, 0) = 0;

    for (i=0;i<3;i++)
        printf("%x\n", array[i]);

    for (i=0;i<6;i++)
        printf("%x\n", __mov_byte(array, i));
}

__mov_byte is much older, and was implemented before the compiler could support an intrinsic that returns a reference.  To maintain backward compatibility, __mov_byte was left as-is, and a new intrinsic (__byte) was added which returns the reference.  You are right, there's nothing you can do with __mov_byte that you can't do with __byte.