xdiff: resolve signed unsigned comparison warning
Since the value won't be changed inside the code (because context lines
feature was removed by D2705), let's just remove the variable and inline
the 0 value.
The code might be potentially further simplified. But I'd like to make sure
correctness is easily verifiable in this patch.
Differential Revision: https://phab.mercurial-scm.org/D2766
xdiff: use int64 for hash table size
Follow-up of the previous "long" -> "int64" change. Now xdiff only uses int
for return values and small integers (ex. booleans, shifting score, bits in
hash table size, etc) so it should be able to handle large input.
Differential Revision: https://phab.mercurial-scm.org/D2765
xdiff: remove unused xpp and xecfg parameters
They are unused. Thus removed.
Differential Revision: https://phab.mercurial-scm.org/D2764
xdiff: remove unused flags parameter
After D2683, the flags parameter in some functions is no longer needed.
Thus removed.
Differential Revision: https://phab.mercurial-scm.org/D2763
xdiff: replace {unsigned ,}long with {u,}int64_t
MSVC treats "long" as 4-byte. That could cause overflows since the xdiff
code uses "long" in places where "size_t" or "ssize_t" should be used.
Let's use explicit 8 byte integers to avoid
FWIW git avoids that overflow by limiting diff size to 1GB [1]. After
examining the code, I think the remaining risk (the use of "int") is low
since "int" is only used for return values and hash table size. Although a
wrong hash table size would not affect the correctness of the code, but that
could make the code extremely slow. The next patch will change hash table
size to 8-byte integer so the 1GB limit is unlikely needed.
This patch was done by using `sed`.
[1]: https://github.com/git/git/commit/
dcd1742e56ebb944c4ff62346da4548e1e3be67
Differential Revision: https://phab.mercurial-scm.org/D2762
xdiff: add comments for fields in xdfile_t
This makes the related code easier to understand.
Differential Revision: https://phab.mercurial-scm.org/D2685