Hi Anton,
[...]
The only problem with this is that there is one piece of missing information, which is how do you get the value of the field that is masked as if it were a 4-bit or 3-bit number. That is, if I want the IPS_DIV value, I probably want:
(value & SCFR1_IPS_DIV_MASK) >> 20
Likewise, if I want to set the IPS divisor to 5 say, I would have to do:
(value & ~SCFR1_IPS_DIV_MASK) | (5 << 20)
In both cases the value 20 needs to come from somewhere. So you would probably end up having:
#define SCFR1_IPS_DIV_MASK 0x03800000 #define SCFR1_IPS_DIV_SHIFT 20
and
(value & SCFR1_IPS_DIV_MASK) >> SCFR1_IPS_DIV_SHIFT (value & ~SCFR1_IPS_DIV_MASK) | (5 << SCFR1_IPS_DIV_SHIFT)
And I think it would be great if these could turn into:
field_value = GET_FIELD(register_value, SCFR1_IPS_DIV) register_value = SET_FIELD(register_value, SCFR1_IPS_DIV, 5)
Let me take this opportunity to once more explain why I don't like this. As a big fan of functional programming, I personally have grown used to code as explicit as possible. So _all_ arguments to a function should be explicit in the call - reliance on state or such "hidden arguments" violate this principle strongly. I learnt that code following these principles written by other people is much easier for me to understand.
Cheers Detlev