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submodule
ffmpeg
Commits
c448a096
Commit
c448a096
authored
Jan 21, 2008
by
Michael Niedermayer
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Plain Diff
Faster ff_sqrt()
Originally committed as revision 11586 to
svn://svn.ffmpeg.org/ffmpeg/trunk
parent
b21cd0bc
Hide whitespace changes
Inline
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Showing
2 changed files
with
28 additions
and
20 deletions
+28
-20
internal.h
libavutil/internal.h
+19
-15
mathematics.c
libavutil/mathematics.c
+9
-5
No files found.
libavutil/internal.h
View file @
c448a096
...
...
@@ -178,24 +178,28 @@ extern const uint32_t ff_inverse[256];
# define FASTDIV(a,b) ((a)/(b))
#endif
extern
const
uint8_t
ff_sqrt_tab
[
128
];
extern
const
uint8_t
ff_sqrt_tab
[
256
];
static
inline
int
ff_sqrt
(
int
a
)
static
inline
int
av_log2_16bit
(
unsigned
int
v
);
static
inline
unsigned
int
ff_sqrt
(
unsigned
int
a
)
{
int
ret
=
0
;
int
s
,
b
;
if
(
a
<
128
)
return
ff_sqrt_tab
[
a
];
for
(
s
=
30
;
s
>=
0
;
s
-=
2
){
ret
+=
ret
;
b
=
(
1
+
2
*
ret
)
<<
s
;
if
(
b
<=
a
){
a
-=
b
;
ret
++
;
}
unsigned
int
b
;
if
(
a
<
255
)
return
(
ff_sqrt_tab
[
a
+
1
]
-
1
)
>>
4
;
else
if
(
a
<
(
1
<<
12
))
b
=
ff_sqrt_tab
[
a
>>
4
]
>>
2
;
#ifndef CONFIG_SMALL
else
if
(
a
<
(
1
<<
14
))
b
=
ff_sqrt_tab
[
a
>>
6
]
>>
1
;
else
if
(
a
<
(
1
<<
16
))
b
=
ff_sqrt_tab
[
a
>>
8
]
;
#endif
else
{
int
s
=
av_log2_16bit
(
a
>>
16
)
>>
1
;
unsigned
int
c
=
a
>>
(
s
+
2
);
b
=
ff_sqrt_tab
[
c
>>
(
s
+
8
)];
b
=
FASTDIV
(
c
,
b
)
+
(
b
<<
s
);
}
return
ret
;
return
b
-
(
a
<
b
*
b
);
}
#if defined(ARCH_X86)
...
...
libavutil/mathematics.c
View file @
c448a096
...
...
@@ -26,11 +26,15 @@
#include "common.h"
#include "mathematics.h"
const
uint8_t
ff_sqrt_tab
[
128
]
=
{
0
,
1
,
1
,
1
,
2
,
2
,
2
,
2
,
2
,
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,
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,
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,
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,
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,
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,
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,
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,
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,
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,
10
,
10
,
10
,
10
,
11
,
11
,
11
,
11
,
11
,
11
,
11
const
uint8_t
ff_sqrt_tab
[
256
]
=
{
0
,
16
,
23
,
28
,
32
,
36
,
40
,
43
,
46
,
48
,
51
,
54
,
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,
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,
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,
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,
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,
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,
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,
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,
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,
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,
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,
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,
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,
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,
255
,
255
,
255
};
const
uint8_t
ff_log2_tab
[
256
]
=
{
...
...
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