# [PATCH] Use faster byte swapping when compiling with MSVC 7 messages from 2009-10-19 to 2009-10-20. Participants: Sebastian Schuberth, Junio C Hamano, Johannes Schindelin, Ludvig Strigeus, Erik Faye-Lund. Thread: https://gitlist.dev/t/21282 ## Sebastian Schuberth, 2009-10-19 16:37 Subject: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: URL: https://gitlist.dev/e/hbi4mt%24tjt%241%40ger.gmane.org ``` When compiling with MSVC on x86-compatible, use an intrinsic for byte swapping. In contrast to the GCC path, we do not prefer inline assembly here as it is not supported for the x64 platform. Signed-off-by: Sebastian Schuberth --- compat/bswap.h | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/compat/bswap.h b/compat/bswap.h index 5cc4acb..279e0b4 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -28,6 +28,16 @@ static inline uint32_t default_swab32(uint32_t val) } \ __res; }) +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) + +#include + +#define bswap32(x) _byteswap_ulong(x) + +#endif + +#ifdef bswap32 + #undef ntohl #undef htonl #define ntohl(x) bswap32(x) -- 1.6.5.rc2.13.g1be2 ``` ## Junio C Hamano, 2009-10-20 07:04 Subject: Re: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: <7vzl7mr1f5.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7vzl7mr1f5.fsf%40alter.siamese.dyndns.org In-Reply-To: ``` Sebastian Schuberth writes: > When compiling with MSVC on x86-compatible, use an intrinsic for byte swapping. > In contrast to the GCC path, we do not prefer inline assembly here as it is not > supported for the x64 platform. > > Signed-off-by: Sebastian Schuberth Unlike the other one this is not Acked by Marius, Dscho, or J6t; should I pick this up myself, or should I wait to be fed by one of msysgit people? > --- > compat/bswap.h | 10 ++++++++++ > 1 files changed, 10 insertions(+), 0 deletions(-) > > diff --git a/compat/bswap.h b/compat/bswap.h > index 5cc4acb..279e0b4 100644 > --- a/compat/bswap.h > +++ b/compat/bswap.h > @@ -28,6 +28,16 @@ static inline uint32_t default_swab32(uint32_t val) > } \ > __res; }) > > +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) > + > +#include > + > +#define bswap32(x) _byteswap_ulong(x) > + > +#endif > + > +#ifdef bswap32 > + > #undef ntohl > #undef htonl > #define ntohl(x) bswap32(x) > -- > 1.6.5.rc2.13.g1be2 ``` ## Sebastian Schuberth, 2009-10-20 08:56 Subject: Re: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: URL: https://gitlist.dev/e/bdca99240910200156x48511478w9eaa2239eb8342b4%40mail.gmail.com In-Reply-To: <7vzl7mr1f5.fsf@alter.siamese.dyndns.org> ``` On Tue, Oct 20, 2009 at 09:04, Junio C Hamano wrote: >> When compiling with MSVC on x86-compatible, use an intrinsic for byte swapping. >> In contrast to the GCC path, we do not prefer inline assembly here as it is not >> supported for the x64 platform. >> >> Signed-off-by: Sebastian Schuberth > > Unlike the other one this is not Acked by Marius, Dscho, or J6t; should I > pick this up myself, or should I wait to be fed by one of msysgit people? Well, in fact I am one of the msysgit poeple, although I mostly worked on the installer until now. In general, I like my patches to be reviewed, but this one is rather uncritical, I guess. So it's up to you, Junio, I'm perfectly OK with waiting for an ACK. -- Sebastian Schuberth ``` ## Johannes Schindelin, 2009-10-20 09:53 Subject: Re: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: URL: https://gitlist.dev/e/alpine.DEB.1.00.0910201149020.4985%40pacific.mpi-cbg.de In-Reply-To: ``` Hi, On Tue, 20 Oct 2009, Sebastian Schuberth wrote: > On Tue, Oct 20, 2009 at 09:04, Junio C Hamano wrote: > > >> When compiling with MSVC on x86-compatible, use an intrinsic for byte > >> swapping. In contrast to the GCC path, we do not prefer inline > >> assembly here as it is not supported for the x64 platform. > >> > >> Signed-off-by: Sebastian Schuberth > > > > Unlike the other one this is not Acked by Marius, Dscho, or J6t; > > should I pick this up myself, or should I wait to be fed by one of > > msysgit people? > > Well, in fact I am one of the msysgit poeple, although I mostly worked > on the installer until now. In general, I like my patches to be > reviewed, but this one is rather uncritical, I guess. So it's up to you, > Junio, I'm perfectly OK with waiting for an ACK. Apart from the fact that I do not have MSVC (and I don't want it, either), there is another strong reason why I think Sebastian does not need ACKs or SOBs on MSVC patches: he has plenty of experience as a maintainer of a rather big (commercial) software that has to compile on Windows, MacOSX and several Unix-type OSes (and it is known that Sebastian is a Windows guy). So I would trust Sebastian's patches (at least when it comes to MSVC) without even reviewing them. Ciao, Dscho ``` ## Ludvig Strigeus, 2009-10-20 12:20 Subject: Re: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: URL: https://gitlist.dev/e/loom.20091020T141138-782%40post.gmane.org In-Reply-To: ``` Sebastian Schuberth gmail.com> writes: > > When compiling with MSVC on x86-compatible, use an intrinsic for byte swapping. > In contrast to the GCC path, we do not prefer inline assembly here as it is not > supported for the x64 platform. > > > +#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) > + > +#include > + > +#define bswap32(x) _byteswap_ulong(x) > + > +#endif unsigned long (as used by _byteswap_ulong) is 64 bits on x64, right? Then it doesn't make sense to use _byteswap_ulong to swap 32-bit quantities (assuming that's what bswap32 does) would it? /Ludde ``` ## Erik Faye-Lund, 2009-10-20 12:44 Subject: Re: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: <40aa078e0910200544i3d8aadc1ud62cf62a6964dd5@mail.gmail.com> URL: https://gitlist.dev/e/40aa078e0910200544i3d8aadc1ud62cf62a6964dd5%40mail.gmail.com In-Reply-To: ``` On Tue, Oct 20, 2009 at 2:20 PM, Ludvig Strigeus wrote: > unsigned long (as used by _byteswap_ulong) is 64 bits on x64, right? Then it > doesn't make sense to use _byteswap_ulong to swap 32-bit quantities (assuming > that's what bswap32 does) would it? No, unsigned long is 32bit on x64 on Windows. --->8--- #include #include int main(int argc, char *argv[]) { printf("sizeof(void *) = %d\n", sizeof(void *)); printf("sizeof(unsigned long) = %d\n", sizeof(unsigned long)); return 0; } --->8--- sizeof(void *) = 8 sizeof(unsigned long) = 4 -- Erik "kusma" Faye-Lund ``` ## Junio C Hamano, 2009-10-20 16:55 Subject: Re: [PATCH] Use faster byte swapping when compiling with MSVC Message-ID: <7v4opuovhu.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7v4opuovhu.fsf%40alter.siamese.dyndns.org In-Reply-To: ``` Johannes Schindelin writes: >> Well, in fact I am one of the msysgit poeple, although I mostly worked >> on the installer until now. In general, I like my patches to be >> reviewed, but this one is rather uncritical, I guess. So it's up to you, >> Junio, I'm perfectly OK with waiting for an ACK. > > Apart from the fact that I do not have MSVC (and I don't want it, either), > there is another strong reason why I think Sebastian does not need ACKs or > SOBs on MSVC patches: he has plenty of experience as a maintainer of a > rather big (commercial) software that has to compile on Windows, MacOSX > and several Unix-type OSes (and it is known that Sebastian is a Windows > guy). > > So I would trust Sebastian's patches (at least when it comes to MSVC) > without even reviewing them. I very appreciate a strong Ack in a specific area like this. I do skim msysgit list from time to time, and in retrospect I realize I _could_ have recognized Sebastian's name but somehow it didn't click. I guess I should apply both patches to 'master', then. Thanks. ```