| Message ID | 1343127865-16608-37-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 07/24/2012 05:04 AM, Paolo Bonzini wrote: > We can provide fast versions based on the other functions defined > by host-utils.h. Some care is required on glibc, which provides > ffsl already. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > host-utils.h | 45 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > +#ifdef __GLIBC__ > +#define ffsl qemu_ffsl > +#endif > +static inline int ffsl(long val) ffsl() makes sense in comparison to the standardized ffs() (why POSIX doesn't specify one is beyond me). > + > +static inline int flsl(long val) But what good is flsl (I'm assuming you mean find-last-set, or the most-significant set bit), especially since there is no standardized fls() and no fls() in host-utils.h?
Il 27/07/2012 18:05, Eric Blake ha scritto: >> > +static inline int flsl(long val) > But what good is flsl (I'm assuming you mean find-last-set, or the > most-significant set bit), especially since there is no standardized > fls() and no fls() in host-utils.h? No idea why I thought that fls existed. Paolo
diff --git a/host-utils.h b/host-utils.h index 821db93..4250eb0 100644 --- a/host-utils.h +++ b/host-utils.h @@ -24,6 +24,7 @@ */ #include "compiler.h" /* QEMU_GNUC_PREREQ */ +#include <string.h> /* ffsl */ #if defined(__x86_64__) #define __HAVE_FAST_MULU64__ @@ -234,3 +235,47 @@ static inline int ctpop64(uint64_t val) return val; #endif } + +/* glibc does not provide an inline version of ffsl, so always define + * ours. + */ +#ifdef __GLIBC__ +#define ffsl qemu_ffsl +#endif +static inline int ffsl(long val) +{ + if (!val) { + return 0; + } + +#if QEMU_GNUC_PREREQ(3, 4) + return __builtin_ctzl(val) + 1; +#else + if (sizeof(long) == 4) { + return ctz32(val) + 1; + } else if (sizeof(long) == 8) { + return ctz64(val) + 1; + } else { + abort(); + } +#endif +} + +static inline int flsl(long val) +{ + if (!val) { + return 0; + } + +#if QEMU_GNUC_PREREQ(3, 4) + return __builtin_clzl(val) + 1; +#else + if (sizeof(long) == 4) { + return clz32(val) + 1; + } else if (sizeof(long) == 8) { + return clz64(val) + 1; + } else { + abort(); + } +#endif +}
We can provide fast versions based on the other functions defined by host-utils.h. Some care is required on glibc, which provides ffsl already. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- host-utils.h | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+)