Changeset: 50b7b59af500 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=50b7b59af500
Modified Files:
gdk/gdk_select.c
Branch: Oct2014
Log Message:
Avoid loop, use a single expression to set bits in bit mask.
diffs (25 lines):
diff --git a/gdk/gdk_select.c b/gdk/gdk_select.c
--- a/gdk/gdk_select.c
+++ b/gdk/gdk_select.c
@@ -251,13 +251,18 @@ do {
\
do { \
uint##B##_t *im = (uint##B##_t *) imprints->imps; \
uint##B##_t mask = 0, innermask; \
- int j, lbin, hbin; \
+ int lbin, hbin; \
lbin = IMPSgetbin(ATOMstorage(b->ttype), imprints->bits, \
imprints->bins, tl); \
hbin = IMPSgetbin(ATOMstorage(b->ttype), imprints->bits, \
imprints->bins, th); \
- for (j = lbin; j <= hbin; j++) \
- mask = IMPSsetBit(B, mask, j); \
+ /* note: (1<<n)-1 gives a sequence o n one bits */ \
+ /* to set bits hbin..lbin inclusive, we would do: */ \
+ /* mask = ((1 << (hbin + 1)) - 1) - ((1 << lbin) - 1); */ \
+ /* except ((1 << (hbin + 1)) - 1) is not defined if */ \
+ /* hbin == sizeof(uint##B##_t)*8 - 1 */ \
+ /* the following does work, however */ \
+ mask = (((((uint##B##_t) 1 << hbin) - 1) << 1) | 1) - (((uint##B##_t) 1
<< lbin) - 1); \
innermask = mask; \
if (!b->T->nonil || vl != minval) \
innermask = IMPSunsetBit(B, innermask, lbin); \
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