[Python-checkins] r77491 - python/trunk/Python/dtoa.c
mark.dickinson
python-checkins at python.org
Thu Jan 14 14:14:49 CET 2010
Author: mark.dickinson
Date: Thu Jan 14 14:14:49 2010
New Revision: 77491
Log:
Issue 7632: fix a dtoa.c bug (bug 6) causing incorrect rounding. Tests to follow.
Modified:
python/trunk/Python/dtoa.c
Modified: python/trunk/Python/dtoa.c
==============================================================================
--- python/trunk/Python/dtoa.c (original)
+++ python/trunk/Python/dtoa.c Thu Jan 14 14:14:49 2010
@@ -1204,7 +1204,7 @@
bigcomp(U *rv, const char *s0, BCinfo *bc)
{
Bigint *b, *d;
- int b2, bbits, d2, dd, i, nd, nd0, p2, p5;
+ int b2, bbits, d2, dd, i, nd, nd0, odd, p2, p5;
dd = 0; /* silence compiler warning about possibly unused variable */
nd = bc->nd;
@@ -1237,6 +1237,9 @@
b = lshift(b, ++i);
if (b == NULL)
return -1;
+ /* record whether the lsb of rv/2^(bc->scale) is odd: in the exact halfway
+ case, this is used for round to even. */
+ odd = b->x[0] & 2;
b->x[0] |= 1;
p2 -= p5 + i;
@@ -1291,7 +1294,7 @@
dd = -1;
goto ret;
}
-
+
/* Compare b/d with s0 */
for(i = 0; i < nd0; i++) {
b = multadd(b, 10, 0);
@@ -1329,14 +1332,8 @@
ret:
Bfree(b);
Bfree(d);
- if (dd > 0)
+ if (dd > 0 || (dd == 0 && odd))
dval(rv) += sulp(rv, bc);
- else if (dd == 0) {
- /* Exact half-way case: apply round-even rule. */
- if (word1(rv) & 1)
- dval(rv) += sulp(rv, bc);
- }
-
return 0;
}
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