On Sat, Jun 19, 2010 at 02:12:21AM +0100, Mark Brown wrote:
On Sat, Jun 19, 2010 at 08:24:36AM +1000, Stuart Longland wrote:
- /* Page 1 */
- if (page == 1) {
if (reg <= 4)return 1;I can't help but think that this'd be more legible with switch () statements (GCC has an extension for ranges in switch statements which you could use).
I gave this some further thought... I'm not certain that a switch statement is going to be much clearer. There are two ways I can tackle this.
One is to go on a page-by-page basis, which is how I do it using the if statements. Here; I define my ranges so that I start from the very end... anything beyond page 70 is invalid ... voila, I eliminate those early on. A number of pages have a similar register pattern, and so I make use of nested if statements to explain this. The if block for pages following always use the block before to define the upper, non-inclusive bound.
The register tests start from register 0. I could perhaps reverse the outer ifs to start at page 0 and work forwards too... but I instead work backwards from page 70.
I exit the function as early as possible to skip unneeded checks, as soon as I know a range is valid or not, I return 1 or 0. Perhaps the 1 or 0 could be made clearer (a couple of #defines maybe?) but to me, it looks fairly clear.
I could use switch statements to replace some or all of the if statements. There'd be a small benefit I suppose in making the outer if statements a switch, but little anywhere else from what I can see.
The other way is that I ignore pages completely; and use the AIC3204_PGREG macro to define ranges of absolute register addresses. This may have a small benefit in speed since these are compiled in... as opposed to runtime masking/shifting, but I don't see that being much clearer either. I'd still come to a case statement, then return.
This is a function largely intended for debugging, in fact, I'm thinking I should probably wrap it in #ifdef CONFIG_DEBUG_FS, since the function isn't called unless debugfs is enabled. So I'm not certain that performance is worth chasing here given the intended purpose -- it's not something that's called all the time, nor something that will be used in a production environment.
That's my thoughts on the issue, perhaps naïve, but I'm not sure there's any real gain in refactoring this.