redonkable/remarkable-linux
redonkable/remarkable-linux
1
0
Fork 0
Code Releases Activity

[XTENSA] fix bit operations in bitops.h

Browse source 
A macro used internally in the bitops.h file to identify the number of
leading zeros (__cntlz) was implemented incorrectly for Xtensa processors
that don't provide the 'nsa/nsau' instructions. As a result, the dependent
functions and macros (ffs, ffz, fls) were broken.

Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Chris Zankel 2007-05-31 17:41:14 -07:00
parent 3f0a6766e0
commit ef6051a90e
1 changed files with 26 additions and 34 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

60
include/asm-xtensa/bitops.h
View file

@ -7,7 +7,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2007 Tensilica Inc.
*/
#ifndef _XTENSA_BITOPS_H
@ -31,64 +31,44 @@
#if XCHAL_HAVE_NSA
static __inline__ int __cntlz (unsigned long x)
static inline unsigned long __cntlz (unsigned long x)
{
int lz;
asm ("nsau %0, %1" : "=r" (lz) : "r" (x));
return 31 - lz;
return lz;
}
#else
static __inline__ int __cntlz (unsigned long x)
{
unsigned long sum, x1, x2, x4, x8, x16;
x1 = x & 0xAAAAAAAA;
x2 = x & 0xCCCCCCCC;
x4 = x & 0xF0F0F0F0;
x8 = x & 0xFF00FF00;
x16 = x & 0xFFFF0000;
sum = x2 ? 2 : 0;
sum += (x16 != 0) * 16;
sum += (x8 != 0) * 8;
sum += (x4 != 0) * 4;
sum += (x1 != 0);
return sum;
}
#endif
/*
* ffz: Find first zero in word. Undefined if no zero exists.
* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
*/
static __inline__ int ffz(unsigned long x)
static inline int ffz(unsigned long x)
{
if ((x = ~x) == 0)
return 32;
return __cntlz(x & -x);
return 31 - __cntlz(~x & -~x);
}
/*
* __ffs: Find first bit set in word. Return 0 for bit 0
*/
static __inline__ int __ffs(unsigned long x)
static inline int __ffs(unsigned long x)
{
return __cntlz(x & -x);
return 31 - __cntlz(x & -x);
}
#ifdef __KERNEL__
/*
* ffs: Find first bit set in word. This is defined the same way as
* the libc and compiler builtin ffs routines, therefore
* differs in spirit from the above ffz (man ffs).
*/
static __inline__ int ffs(unsigned long x)
static inline int ffs(unsigned long x)
{
return __cntlz(x & -x) + 1;
return 32 - __cntlz(x & -x);
}
/*
@ -96,10 +76,22 @@ static __inline__ int ffs(unsigned long x)
* Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
*/
static __inline__ int fls (unsigned int x)
static inline int fls (unsigned int x)
{
return __cntlz(x);
return 32 - __cntlz(x);
}
#else
/* Use the generic implementation if we don't have the nsa/nsau instructions. */
# include <asm-generic/bitops/ffs.h>
# include <asm-generic/bitops/__ffs.h>
# include <asm-generic/bitops/ffz.h>
# include <asm-generic/bitops/fls.h>
#endif
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/ext2-non-atomic.h>