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ruanhaishen
redis
Commits
5fc55a1a
Commit
5fc55a1a
authored
Dec 02, 2014
by
Sun He
Committed by
antirez
Dec 09, 2014
Browse files
bitops.c/redisPopcount: little optimization in loop
parent
5ab2c311
Changes
1
Hide whitespace changes
Inline
Side-by-side
src/bitops.c
View file @
5fc55a1a
...
...
@@ -70,16 +70,19 @@ size_t redisPopcount(void *s, long count) {
count
--
;
}
/* Count bits
16
bytes at a time */
/* Count bits
28
bytes at a time */
p4
=
(
uint32_t
*
)
p
;
while
(
count
>=
16
)
{
uint32_t
aux1
,
aux2
,
aux3
,
aux4
;
while
(
count
>=
28
)
{
uint32_t
aux1
,
aux2
,
aux3
,
aux4
,
aux5
,
aux6
,
aux7
;
aux1
=
*
p4
++
;
aux2
=
*
p4
++
;
aux3
=
*
p4
++
;
aux4
=
*
p4
++
;
count
-=
16
;
aux5
=
*
p4
++
;
aux6
=
*
p4
++
;
aux7
=
*
p4
++
;
count
-=
28
;
aux1
=
aux1
-
((
aux1
>>
1
)
&
0x55555555
);
aux1
=
(
aux1
&
0x33333333
)
+
((
aux1
>>
2
)
&
0x33333333
);
...
...
@@ -89,10 +92,19 @@ size_t redisPopcount(void *s, long count) {
aux3
=
(
aux3
&
0x33333333
)
+
((
aux3
>>
2
)
&
0x33333333
);
aux4
=
aux4
-
((
aux4
>>
1
)
&
0x55555555
);
aux4
=
(
aux4
&
0x33333333
)
+
((
aux4
>>
2
)
&
0x33333333
);
bits
+=
((((
aux1
+
(
aux1
>>
4
))
&
0x0F0F0F0F
)
*
0x01010101
)
>>
24
)
+
((((
aux2
+
(
aux2
>>
4
))
&
0x0F0F0F0F
)
*
0x01010101
)
>>
24
)
+
((((
aux3
+
(
aux3
>>
4
))
&
0x0F0F0F0F
)
*
0x01010101
)
>>
24
)
+
((((
aux4
+
(
aux4
>>
4
))
&
0x0F0F0F0F
)
*
0x01010101
)
>>
24
);
aux5
=
aux5
-
((
aux5
>>
1
)
&
0x55555555
);
aux5
=
(
aux5
&
0x33333333
)
+
((
aux5
>>
2
)
&
0x33333333
);
aux6
=
aux6
-
((
aux6
>>
1
)
&
0x55555555
);
aux6
=
(
aux6
&
0x33333333
)
+
((
aux6
>>
2
)
&
0x33333333
);
aux7
=
aux7
-
((
aux7
>>
1
)
&
0x55555555
);
aux7
=
(
aux7
&
0x33333333
)
+
((
aux7
>>
2
)
&
0x33333333
);
bits
+=
((((
aux1
+
(
aux1
>>
4
))
&
0x0F0F0F0F
)
+
((
aux2
+
(
aux2
>>
4
))
&
0x0F0F0F0F
)
+
((
aux3
+
(
aux3
>>
4
))
&
0x0F0F0F0F
)
+
((
aux4
+
(
aux4
>>
4
))
&
0x0F0F0F0F
)
+
((
aux5
+
(
aux5
>>
4
))
&
0x0F0F0F0F
)
+
((
aux6
+
(
aux6
>>
4
))
&
0x0F0F0F0F
)
+
((
aux7
+
(
aux7
>>
4
))
&
0x0F0F0F0F
))
*
0x01010101
)
>>
24
;
}
/* Count the remaining bytes. */
p
=
(
unsigned
char
*
)
p4
;
...
...
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