Hi, On Wed, 9 May 2007, Petr Baudis wrote: > On Wed, May 09, 2007 at 02:19:03PM CEST, Johannes Schindelin wrote: > > diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt > > index 2d58bb0..55934db 100644 > > --- a/Documentation/user-manual.txt > > +++ b/Documentation/user-manual.txt > > @@ -3197,7 +3197,15 @@ basically _the_ header file which is included by _all_ of Git's C sources. > > If you grasp the ideas in that initial commit (it is really small and you > > can get into it really fast, and it will help you recognize things in the > > much larger code base we have now), you should go on skimming `cache.h`, > > -`object.h` and `commit.h`. > > +`object.h` and `commit.h` in the current version. > > + > > +In the early days, Git (in the tradition of UNIX) was a bunch of programs > > +which were extremely simple, and which you used in scripts, piping the > > +output of one into another. This turned out to be good for initial > > +development, since it was easier to test new things. However, recently > > +many of these parts have become builtins, and some of the core has been > > +"libified", i.e. put into libgit.a for performance, portability reasons, > > +and to avoid code duplication. > > > > By now, you know what the index is (and find the corresponding data > > structures in `cache.h`), and that there are just a couple of object types > > I disagree, especially with the past tense of the first half of the > paragraph. Git is _still_ a bunch of programs you use in scripts, piping > the output of one into another. Another point is that > implementation-wise many of the code is currently shared in an internal > library, etc. No. Many parts are _not_ simple programs piped into each other. git-log, git-show, git-mv come to mind. That is why I wrote "many" and not "all". > I'd be a bit careful to talk about libgit.a so leisurely since it might > give the reader an impression that there really _is_ "the git library", > with API and everything, that they can use externally. Of course you > need to mention libgit.a, but I'd also mention that it is so far meant > only for internal git's use and has no solidified API. Frankly, this is just a birdview thing. If you want to go and make a hacker's manual, go ahead! > > @@ -3300,8 +3321,10 @@ Two things are interesting here: > > > > - the variable `sha1` in the function signature of `get_sha1()` is `unsigned > > char *`, but is actually expected to be a pointer to `unsigned > > - char[20]`. This variable will contain the big endian version of the > > - 40-character hex string representation of the SHA-1. > > + char[20]`. This variable will contain the 160-bit SHA-1 of the given > > + commit. Note that whenever a SHA-1 is passed as "unsigned char *", it > > + is the binary representation (big-endian), as opposed to the ASCII > > + representation in hex characters, which is passed as "char *". > > > > You will see both of these things throughout the code. > > To be honest, I wouldn't even be *thinking* about the endianity of SHA-1 > octet representation (you don't usually really deal with the hash as > with a number, so expecting to have it in native endianity is not very > natural; you just deal with it as with a data blob) and the > "(big-endian)" would only confuse me and get me thinking about "huh, do > they swap the bytes, or wait, they don't, ...?!". > > But that's maybe just me. But then, maybe it is just me? I got it completely wrong the first time, fully expecting the calculations to be carried out in host endianness for performance reasons. Ciao, Dscho - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
