Re: [linuxsh-dev] Dreamcast RTC

[Philipp R. <pr...@pa...>]

On Wed, Dec 06, 2000 at 07:36:39PM -0600, M. R. Brown wrote:
> On Thu, 7 Dec 2000, Rene Malmgren wrote:
> > These funktions can be switched in att compile time or dynamicly at runtime.
> > Then we simply write an rtc_gen.c and a rtc_dc.c, or perhaps even an
> > rtc_sh3_gen.c, rtc_sh4_gen.c and an rtc_sh4_dc.c. Then we make all the other
> > functions that use ther RTC access it through these two funktions. The
> > get_timer_freq for instance. No modification has to be made to the generic
> > code at all. You just simply chose the type of timer you want. We should
> > consider doing the same thing to the timers aswell.

> Rene, what you just described is *exactly* what Phillip is planning to do.
> He's moving generic SH4 RTC code into rtc.c so the generic SH4 target (and
> any other machine that uses the SH4's builtin RTC) can use it.  Then he's
> adding get_timer_frequency, get_rtc_time, and set_rtc_time to the machine

that's the main difference between Rene's proposal and mine:  I think using
gettimeofday for the timer calibration is too expensive - it adds 1.5 seconds
to our average boot time.  since many systems can use the 1/128 s - 1/64 s
code or can determine their clocks statically (eg get it from firmware).

It's a tradeoff.  4 bytes of bloat versus 1.5 wasted seconds. (the actual code
can be allocated in initmem).

Actually, if we start counting bytes, we might want to split up machvecs into
initmem and permanent parts - but I'm not sure it's worth the obfuscation.


	Philipp