[Python-checkins] cpython: The previous code is correct, but hard to verify: The libmpdec documentation

[stefan.krah]

http://hg.python.org/cpython/rev/7921a22b72f4
changeset:   76398:7921a22b72f4
user:        Stefan Krah <skrah at bytereef.org>
date:        Wed Apr 18 17:48:34 2012 +0200
summary:
  The previous code is correct, but hard to verify: The libmpdec documentation
rightfully states that an mpd_t with a coefficient flagged as MPD_CONST_DATA
must not be in the position of the result operand. In this particular case
several assumptions guarantee that a resize will never occur in all possible
code paths, which was the reason for using MPD_CONST_DATA and saving an
instruction by omitting the initialization of tmp.alloc.

For readability, tmp is now flagged as MPD_STATIC_DATA and tmp.alloc
is initialized.

files:
  Modules/_decimal/libmpdec/mpdecimal.c |  3 ++-
  1 files changed, 2 insertions(+), 1 deletions(-)


diff --git a/Modules/_decimal/libmpdec/mpdecimal.c b/Modules/_decimal/libmpdec/mpdecimal.c
--- a/Modules/_decimal/libmpdec/mpdecimal.c
+++ b/Modules/_decimal/libmpdec/mpdecimal.c
@@ -1280,7 +1280,8 @@
         /* At this point a->digits+a->exp <= MPD_RDIGITS+1,
          * so the shift fits. */
         tmp.data = tmp_data;
-        tmp.flags = MPD_STATIC|MPD_CONST_DATA;
+        tmp.flags = MPD_STATIC|MPD_STATIC_DATA;
+        tmp.alloc = 2;
         mpd_qsshiftr(&tmp, a, -a->exp);
         tmp.exp = 0;
         a = &tmp;

-- 
Repository URL: http://hg.python.org/cpython