From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44276) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dcExV-0005zk-2S for qemu-devel@nongnu.org; Mon, 31 Jul 2017 13:58:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dcExS-0004lT-1w for qemu-devel@nongnu.org; Mon, 31 Jul 2017 13:58:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47806) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dcExR-0004kq-Rj for qemu-devel@nongnu.org; Mon, 31 Jul 2017 13:58:21 -0400 Date: Mon, 31 Jul 2017 18:58:16 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170731175815.GF2122@work-vm> References: <1501229198-30588-1-git-send-email-peterx@redhat.com> <1501229198-30588-6-git-send-email-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1501229198-30588-6-git-send-email-peterx@redhat.com> Subject: Re: [Qemu-devel] [RFC 05/29] bitmap: introduce bitmap_count_one() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: qemu-devel@nongnu.org, Laurent Vivier , Alexey Perevalov , Juan Quintela , Andrea Arcangeli * Peter Xu (peterx@redhat.com) wrote: > Count how many bits set in the bitmap. > > Signed-off-by: Peter Xu > --- > include/qemu/bitmap.h | 10 ++++++++++ > util/bitmap.c | 15 +++++++++++++++ > 2 files changed, 25 insertions(+) > > diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h > index 460d899..9c18da0 100644 > --- a/include/qemu/bitmap.h > +++ b/include/qemu/bitmap.h > @@ -83,6 +83,7 @@ int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, > int slow_bitmap_intersects(const unsigned long *bitmap1, > const unsigned long *bitmap2, long bits); > void slow_bitmap_invert(unsigned long *bitmap, long nbits); > +long slow_bitmap_count_one(const unsigned long *bitmap, long nbits); > > static inline unsigned long *bitmap_try_new(long nbits) > { > @@ -226,6 +227,15 @@ static inline void bitmap_invert(unsigned long *bitmap, long nbits) > } > } > > +static inline long bitmap_count_one(const unsigned long *bitmap, long nbits) > +{ > + if (small_nbits(nbits)) { > + return (ctpopl(*bitmap & BITMAP_LAST_WORD_MASK(nbits))); > + } else { > + return slow_bitmap_count_one(bitmap, nbits); > + } > +} > + > void bitmap_set(unsigned long *map, long i, long len); > void bitmap_set_atomic(unsigned long *map, long i, long len); > void bitmap_clear(unsigned long *map, long start, long nr); > diff --git a/util/bitmap.c b/util/bitmap.c > index 9b7408c..73a1063 100644 > --- a/util/bitmap.c > +++ b/util/bitmap.c > @@ -368,3 +368,18 @@ void slow_bitmap_invert(unsigned long *bitmap, long nbits) > bitmap[k] ^= BITMAP_LAST_WORD_MASK(nbits); > } > } > + > +long slow_bitmap_count_one(const unsigned long *bitmap, long nbits) > +{ > + long k, lim = nbits/BITS_PER_LONG, result = 0; > + > + for (k = 0; k < lim; k++) { > + result += ctpopl(bitmap[k]); > + } > + > + if (nbits % BITS_PER_LONG) { > + result += ctpopl(bitmap[k] & BITMAP_LAST_WORD_MASK(nbits)); > + } > + > + return result; > +} Reviewed-by: Dr. David Alan Gilbert (I checked what happens with BITMAP_LAST_WORD_MASK(0) interestingly it's all 1 - so you do need that if) > -- > 2.7.4 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK