Wolfgang Denk wd@denx.de writes:
Dear Måns Rullgård,
In message yw1x8uxc28y9.fsf@unicorn.mansr.com you wrote:
Something like this should be equivalent. That said, it looks suspiciously like it's meant to simply do a division and round up. If that is the case, +225 should be +249. It probably makes no difference for the values actually encountered.
Umm... this is the part which I do not understand.
The original code adds 90%; you add 90%, too. However, to round up, one usually adds only 50% ?
Adding 50% would round to nearest. For integer division to round up, you must add one less than the divisor.
Agreed. But do we want to round up? The original code used +90%, which is something else, too...
That rounds fractions >= 0.1 up while < 0.1 is rounded down. It's an unusual thing to do, which is why I suspect it's not quite correct in the first place.
Where are these 90% coming from? Are they in any way meaningful, or even critical?
My guess is that it was someone's approximation of 249 / 250. I don't know the hardware, so it's conceivable that it really should be this way, although it seems unlikely.
Are you able to test such a modificationon actual hardware?
No.