[OpenBIOS] [PATCH] PowerPC: Fix milliseconds prom call

Laurent Vivier laurent at lvivier.info
Thu Jan 15 00:26:09 CET 2009

Le 14 janv. 09 à 15:46, Aurelien Jarno a écrit :

> The current implementation of the milliseconds prom call on PowerPC is
> totally buggy:
> - The timer frequency returned by get_timer_freq() does not correspond
>  to the timer which is read.
> - The dividend and the divisor of the division are swapped
> - If called very often, this function is not precise
> - Depending on the timer frequency and of the frequency of the calls,
>  the variable overflow after a few dozen of seconds.
> Please find in this patch a totally new implementation. This fixes the
> problem observed with the quik when a timeout is defined.
> The timer frequency is defined using #define, I wonder if there is a
> better place to put it.
> It reads both low and high part of the timer to make sure there is no
> overflow. It also removes the function that returns 0 on the first  
> call
> as this is not needed according to IEEE 1275-1994. Finally it computes
> the real value of the timer each time, instead of adding a small value
> to a variable at each function calls, in order to get a correct
> precision if this method is call very often.

Applied as r407, thanks.

-------------------- laurent at lvivier.info --------------------
"Tout ce qui est impossible reste à accomplir"    Jules Verne
"Things are only impossible until they're not" Jean-Luc Picard

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