Mercurial > cpython-lru_cache-weakref
diff Modules/structmodule.c @ 17343:de9858530a55 legacy-trunk
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.
| author | Tim Peters <tim.peters@gmail.com> |
|---|---|
| date | Sun, 08 Apr 2001 23:39:38 +0000 |
| parents | 25ddd3dc7a7a |
| children | 104223b3226a 8e187740aa96 |
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--- a/Modules/structmodule.c Sun Apr 08 15:05:16 2001 +0000 +++ b/Modules/structmodule.c Sun Apr 08 23:39:38 2001 +0000 @@ -653,11 +653,9 @@ 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 @@ 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); }