Re: [Qemu-devel] [PATCH] SH7750/51: add register BCR3, NCR4, PCR, RTCOR, RTCNT, RTCSR, SDMR2, SDMR3 and fix BCR2 support

[Thiemo Seufer <ths@networkno.de>]

Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 00:36 Mon 15 Dec     , Shin-ichiro KAWASAKI wrote:
> > Jean-Christophe PLAGNIOL-VILLARD wrote:
> >>>>  -
> >>>> +static int inline is_sh7751r_cpu(SH7750State * s)
> >>>> +{
> >>>> +	return (s->cpu->id & (SH_CPU_SH7751R));
> >>>> +}
> >>>>  /**********************************************************************
> >>>>   I/O ports
> >>>>  **********************************************************************/
> >>>> @@ -212,8 +219,17 @@ static uint32_t sh7750_mem_readw(void *opaque, target_phys_addr_t addr)
> >>>>      switch (addr) {
> >>>>      case SH7750_BCR2_A7:
> >>>>  	return s->bcr2;
> >>>> +    case SH7750_BCR3_A7:
> >>>> +	if(is_sh7751r_cpu(s)) {
> >>>> +	    return s->bcr3;
> >>>> +	} else {
> >>>> +	    error_access("word read", addr);
> >>>> +	    assert(0);
> >>>> +	}
> >>> BCR3 exists not only for SH7751R, but also SH7750.
> >>> I think is_shh751r_cpu() check and error handling
> >>> should be removed to simplify the differcence.
> >> as write in the SH7751r datasheet
> >>
> >> Bus Control Register 3 (BCR3) (SH7751R Only)
> >> Bus Control Register 4 (BCR4) (SH7751R Only)
> >>
> >> That's why I've add the check
> >
> > I see.  Your code is right, but let me add one more comment.
> >
> > - SH7750 and SH7751 ... does not have BCR3 nor BCR4
> > - SH7750R and SH7751R ... have BCR3 and BCR4
> >
> > So, to make it better, how about renaming "is_h7751r_cpu()"
> > into "has_bcr3_and_bcr4()"?  It will be like this.
> >
> > static int inline has_bcr3_and_bcr4(SH7750State * s)
> > {
> >        return (s->cpu->id & (SH_CPU_SH7750R | SH_CPU_SH7751R));
> > }
> I've download the SH7750 & SH7751 datasheet and yes as it's only availlable on
> 'R' cpu revision
> 
> I'll update as it
> >
> >
> >>> Compared to 'if' statement, 'switch-case' might be more easy to
> >>> understand, like as follows.
> >>>   case SH7750_SDMR2 ... SH7750_SDMR2 + SDMR2_REGNB
> >> ok elvenif it's a gcc ony extension
> >
> > Ah, gccism policy seems not clear in QEMU project.
> > This extension is used in many hw/*.c, so I guessed it
> > as a QEMU's usual implementation style.
> > I hope comments on it from main developers.
> >
> Yes it will be nice

I believe "no new gcc-isms" would be a good policy.


Thiemo