Changeset: 7c7161485dfc for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=7c7161485dfc
Modified Files:
gdk/gdk_group.c
Branch: Jul2017
Log Message:
Minor tweaks.
diffs (74 lines):
diff --git a/gdk/gdk_group.c b/gdk/gdk_group.c
--- a/gdk/gdk_group.c
+++ b/gdk/gdk_group.c
@@ -336,38 +336,39 @@ static inline oid
rev(oid x)
{
#if SIZEOF_OID == 8
- x = (x & 0x5555555555555555) << 1 | (x & 0xAAAAAAAAAAAAAAAA) >> 1;
- x = (x & 0x3333333333333333) << 2 | (x & 0xCCCCCCCCCCCCCCCC) >> 2;
- x = (x & 0x0F0F0F0F0F0F0F0F) << 4 | (x & 0xF0F0F0F0F0F0F0F0) >> 4;
- x = (x & 0x00FF00FF00FF00FF) << 8 | (x & 0xFF00FF00FF00FF00) >> 8;
- x = (x & 0x0000FFFF0000FFFF) << 16 | (x & 0xFFFF0000FFFF0000) >> 16;
- x = (x & 0x00000000FFFFFFFF) << 32 | (x & 0xFFFFFFFF00000000) >> 32;
+ x = ((x & 0x5555555555555555) << 1) | ((x >> 1) & 0x5555555555555555);
+ x = ((x & 0x3333333333333333) << 2) | ((x >> 2) & 0x3333333333333333);
+ x = ((x & 0x0F0F0F0F0F0F0F0F) << 4) | ((x >> 4) & 0x0F0F0F0F0F0F0F0F);
+ x = ((x & 0x00FF00FF00FF00FF) << 8) | ((x >> 8) & 0x00FF00FF00FF00FF);
+ x = ((x & 0x0000FFFF0000FFFF) << 16) | ((x >> 16) & 0x0000FFFF0000FFFF);
+ x = ((x & 0x00000000FFFFFFFF) << 32) | ((x >> 32) & 0x00000000FFFFFFFF);
#else
- x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1;
- x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2;
- x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4;
- x = (x & 0x00FF00FF) << 8 | (x & 0xFF00FF00) >> 8;
- x = (x & 0x0000FFFF) << 16 | (x & 0xFFFF0000) >> 16;
+ x = ((x & 0x55555555) << 1) | ((x >> 1) & 0x55555555);
+ x = ((x & 0x33333333) << 2) | ((x >> 2) & 0x33333333);
+ x = ((x & 0x0F0F0F0F) << 4) | ((x >> 4) & 0x0F0F0F0F);
+ x = ((x & 0x00FF00FF) << 8) | ((x >> 8) & 0x00FF00FF);
+ x = ((x & 0x0000FFFF) << 16) | ((x >> 16) & 0x0000FFFF);
#endif
- return x >> 1; /* shift to be in OID range */
+ return x;
}
/* population count: count number of 1 bits in a value */
static inline int
pop(oid x)
{
+ /* divide and conquer implementation */
#if SIZEOF_OID == 8
- x = (x & 0x5555555555555555) + ((x >> 1) & 0x5555555555555555);
- x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333);
- x = (x & 0x0F0F0F0F0F0F0F0F) + ((x >> 4) & 0x0F0F0F0F0F0F0F0F);
- x = (x & 0x00FF00FF00FF00FF) + ((x >> 8) & 0x00FF00FF00FF00FF);
+ x = (x & 0x5555555555555555) + ((x >> 1) & 0x5555555555555555);
+ x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333);
+ x = (x & 0x0F0F0F0F0F0F0F0F) + ((x >> 4) & 0x0F0F0F0F0F0F0F0F);
+ x = (x & 0x00FF00FF00FF00FF) + ((x >> 8) & 0x00FF00FF00FF00FF);
x = (x & 0x0000FFFF0000FFFF) + ((x >> 16) & 0x0000FFFF0000FFFF);
x = (x & 0x00000000FFFFFFFF) + ((x >> 32) & 0x00000000FFFFFFFF);
#else
- x = (x & 0x55555555) + ((x >> 1) & 0x55555555);
- x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
- x = (x & 0x0F0F0F0F) + ((x >> 4) & 0x0F0F0F0F);
- x = (x & 0x00FF00FF) + ((x >> 8) & 0x00FF00FF);
+ x = (x & 0x55555555) + ((x >> 1) & 0x55555555);
+ x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
+ x = (x & 0x0F0F0F0F) + ((x >> 4) & 0x0F0F0F0F);
+ x = (x & 0x00FF00FF) + ((x >> 8) & 0x00FF00FF);
x = (x & 0x0000FFFF) + ((x >> 16) & 0x0000FFFF);
#endif
return (int) x;
@@ -1078,7 +1079,9 @@ BATgroup_internal(BAT **groups, BAT **ex
nme = BBP_physical(b->batCacheid);
nmelen = strlen(nme);
mask = MAX(HASHmask(cnt), 1 << 16);
- bits = 8 * SIZEOF_OID - pop(mask - 1) - 1;
+ /* mask is a power of two, so pop(mask - 1) tells us
+ * which power of two */
+ bits = 8 * SIZEOF_OID - pop(mask - 1);
if ((hp = GDKzalloc(sizeof(Heap))) == NULL ||
(hp->farmid = BBPselectfarm(TRANSIENT, b->ttype, hashheap))
< 0 ||
(hp->filename = GDKmalloc(nmelen + 30)) == NULL ||
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