Hi Oleksandr,
Oleksandr Tyshchenko <[email protected]> writes:
[...]
>> +static inline uint32_t vgic_get_reg_offset(uint32_t reg, uint32_t spi_base,
>> + uint32_t espi_base)
>> +{
>> + if ( reg < espi_base )
>> + return reg - spi_base;
>> + else
>> + return reg - espi_base;
>> +}
>
> I am wondering (I do not request a change) whether
> vgic_get_reg_offset() is really helpfull,
> e.g. is
> offset = vgic_get_reg_offset(reg, GICD_IPRIORITYR, GICD_IPRIORITYRnE);
> much better than:
> offset = reg < GICD_IPRIORITYRnE ? reg - GICD_IPRIORITYR : reg -
> GICD_IPRIORITYRnE;
>
IMO, it is easy to make a mistake, because you need to write register
name 3 times. Can cause errors during copy-pasting. But I saw clever
trick by Mykola Kvach, something like this:
#define vgic_get_reg_offset(addr, reg_name) ( addr < reg_name##nE ? \
addr - reg_name : addr - reg_name##nE )
And then you can just use this as
offset = vgic_get_reg_offset(reg, GICD_IPRIORITYR)
I don't know what maintainers think about this type of preprocessor
trickery, but in my opinion it is justified in this case, because it
leaves less room for a mistake.
--
WBR, Volodymyr
