diff options
| author | Tim Peters <tim.peters@gmail.com> | 2001-04-08 23:39:38 (GMT) |
|---|---|---|
| committer | Tim Peters <tim.peters@gmail.com> | 2001-04-08 23:39:38 (GMT) |
| commit | f0e717bdb1729ba93f8f2524962ee95ab1d7d425 (patch) | |
| tree | d68c784ba9420c2d65df8680156838d2f66c6292 | |
| parent | 9cec8fba06e66e92769e56130d581ea569399563 (diff) | |
| download | cpython-f0e717bdb1729ba93f8f2524962ee95ab1d7d425.zip cpython-f0e717bdb1729ba93f8f2524962ee95ab1d7d425.tar.gz cpython-f0e717bdb1729ba93f8f2524962ee95ab1d7d425.tar.bz2 | |
Repair portability of sign extension when reading signed ints on boxes
where sizeof(long)==8. This *was* broken on boxes where signed right
shifts didn't sign-extend, but not elsewhere. Unfortunately, apart
from the Cray T3E I don't know of such a box, and Guido has so far
refused to buy me any Cray machines for home Python testing <wink>.
More immediately interesting would be if someone could please test
this on *any* sizeof(long)==8 box, to make sure I didn't break it.
| -rw-r--r-- | Modules/structmodule.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/Modules/structmodule.c b/Modules/structmodule.c index a28ca54..9d1c436 100644 --- a/Modules/structmodule.c +++ b/Modules/structmodule.c @@ -653,11 +653,9 @@ bu_int(const char *p, const formatdef *f) do { x = (x<<8) | (*p++ & 0xFF); } while (--i > 0); - i = 8*(sizeof(long) - f->size); - if (i) { - x <<= i; - x >>= i; - } + /* Extend the sign bit. */ + if (SIZEOF_LONG > f->size) + x |= -(x & (1L << (8*f->size - 1))); return PyInt_FromLong(x); } @@ -767,11 +765,9 @@ lu_int(const char *p, const formatdef *f) do { x = (x<<8) | (p[--i] & 0xFF); } while (i > 0); - i = 8*(sizeof(long) - f->size); - if (i) { - x <<= i; - x >>= i; - } + /* Extend the sign bit. */ + if (SIZEOF_LONG > f->size) + x |= -(x & (1L << (8*f->size - 1))); return PyInt_FromLong(x); } |