Re: [PATCH 2/4] target/m68k: increase size of m68k CPU features from uint32_t to uint64_t

[Philippe Mathieu-Daudé]

On 17/9/22 14:09, BALATON Zoltan wrote:
> On Sat, 17 Sep 2022, Mark Cave-Ayland wrote:
> > There are already 32 feature bits in use, so change the size of the m68k
> > CPU features to uint64_t (allong with the associated m68k_feature()
> > functions) to allow up to 64 feature bits to be used.
> >
> > Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> > ---
> > target/m68k/cpu.c | 4 ++--
> > target/m68k/cpu.h | 6 +++---
> > 2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
> > index f681be3a2a..7b4797e2f1 100644
> > --- a/target/m68k/cpu.c
> > +++ b/target/m68k/cpu.c
> > @@ -38,12 +38,12 @@ static bool m68k_cpu_has_work(CPUState *cs)
> >
> > static void m68k_set_feature(CPUM68KState *env, int feature)
> > {
> > -    env->features |= (1u << feature);
> > +    env->features |= (1ul << feature);

        env->features = deposit64(env->features, feature, 1, 1);

> > }
> >
> > static void m68k_unset_feature(CPUM68KState *env, int feature)
> > {
> > -    env->features &= (-1u - (1u << feature));
> > +    env->features &= (-1ul - (1ul << feature));

        env->features = deposit64(env->features, feature, 1, 0);

> Should these be ull instead of ul?

Yes. Not needed if using the <qemu/bitops.h> extract/deposit API.

> > }
> >
> > static void m68k_cpu_reset(DeviceState *dev)
> > diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
> > index 67b6c12c28..d3384e5d98 100644
> > --- a/target/m68k/cpu.h
> > +++ b/target/m68k/cpu.h
> > @@ -154,7 +154,7 @@ typedef struct CPUArchState {
> >     struct {} end_reset_fields;
> >
> >     /* Fields from here on are preserved across CPU reset. */
> > -    uint32_t features;
> > +    uint64_t features;
> > } CPUM68KState;
> >
> > /*
> > @@ -539,9 +539,9 @@ enum m68k_features {
> >     M68K_FEATURE_TRAPCC,
> > };
> >
> > -static inline int m68k_feature(CPUM68KState *env, int feature)
> > +static inline uint64_t m68k_feature(CPUM68KState *env, int feature)

Why uint64_t? Can we simplify using a boolean?

> > {
> > -    return (env->features & (1u << feature)) != 0;
> > +    return (env->features & (1ul << feature)) != 0;

        return extract64(env->features, feature, 1) == 1;

> > }
> >
> > void m68k_cpu_list(void);