-
Notifications
You must be signed in to change notification settings - Fork 0
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Linus Torvalds
committed
Apr 6, 2012
1 parent
5086f66
commit 6333d6b
Showing
3 changed files
with
50 additions
and
33 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -1,2 +1,2 @@ | ||
--- | ||
refs/heads/master: 23f347ef63aa36b5a001b6791f657cd0e2a04de3 | ||
refs/heads/master: f68e556e23d1a4176b563bcb25d8baf2c5313f91 |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,46 @@ | ||
#ifndef _ASM_WORD_AT_A_TIME_H | ||
#define _ASM_WORD_AT_A_TIME_H | ||
|
||
/* | ||
* This is largely generic for little-endian machines, but the | ||
* optimal byte mask counting is probably going to be something | ||
* that is architecture-specific. If you have a reliably fast | ||
* bit count instruction, that might be better than the multiply | ||
* and shift, for example. | ||
*/ | ||
|
||
#ifdef CONFIG_64BIT | ||
|
||
/* | ||
* Jan Achrenius on G+: microoptimized version of | ||
* the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" | ||
* that works for the bytemasks without having to | ||
* mask them first. | ||
*/ | ||
static inline long count_masked_bytes(unsigned long mask) | ||
{ | ||
return mask*0x0001020304050608ul >> 56; | ||
} | ||
|
||
#else /* 32-bit case */ | ||
|
||
/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ | ||
static inline long count_masked_bytes(long mask) | ||
{ | ||
/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ | ||
long a = (0x0ff0001+mask) >> 23; | ||
/* Fix the 1 for 00 case */ | ||
return a & mask; | ||
} | ||
|
||
#endif | ||
|
||
#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) | ||
|
||
/* Return the high bit set in the first byte that is a zero */ | ||
static inline unsigned long has_zero(unsigned long a) | ||
{ | ||
return ((a - REPEAT_BYTE(0x01)) & ~a) & REPEAT_BYTE(0x80); | ||
} | ||
|
||
#endif /* _ASM_WORD_AT_A_TIME_H */ |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters