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Commit ef6051a9 authored by Chris Zankel's avatar Chris Zankel
Browse files

[XTENSA] fix bit operations in bitops.h 



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: default avatarChris Zankel <chris@zankel.net>
parent 3f0a6766

include/asm-xtensa/bitops.h

+26 −34
Original line number Diff line number Diff line
@@ -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>