From f0e717bdb1729ba93f8f2524962ee95ab1d7d425 Mon Sep 17 00:00:00 2001 From: Tim Peters Date: Sun, 8 Apr 2001 23:39:38 +0000 Subject: 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 . 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. --- Modules/structmodule.c | 16 ++++++---------- 1 file 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); } -- cgit v0.12