Re: [Qemu-devel] [PATCH v3 4/9] mips: remove muldiv64()

[Leon Alrae]

On 27/08/15 20:33, Laurent Vivier wrote:
> Originally, timers were ticks based, and it made sense to
> add ticks to current time to know when to trigger an alarm.
> 
> But since commit:
> 
> 7447545 change all other clock references to use nanosecond resolution 
> accessors
> 
> All timers use nanoseconds and we need to convert ticks to nanoseconds, by
> doing something like:
> 
>     y = muldiv64(x, get_ticks_per_sec(), TIMER_FREQ)
> 
> where x is the number of device ticks and y the number of system ticks.
> 
> y is used as nanoseconds in timer functions,
> it works because 1 tick is 1 nanosecond.
> (get_ticks_per_sec() is 10^9)
> 
> But as MIPS timer frequency is 100 MHz, we can also do:
> 
>     y = x * 10; /* 100 MHz period is 10 ns */
> 
> Signed-off-by: Laurent Vivier <address@hidden>
> ---
>  hw/mips/cputimer.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)

Reviewed-by: Leon Alrae <address@hidden>