linux/include/asm-frv/bitops.h
David Howells f0d1b0b30d [PATCH] LOG2: Implement a general integer log2 facility in the kernel
This facility provides three entry points:

	ilog2()		Log base 2 of unsigned long
	ilog2_u32()	Log base 2 of u32
	ilog2_u64()	Log base 2 of u64

These facilities can either be used inside functions on dynamic data:

	int do_something(long q)
	{
		...;
		y = ilog2(x)
		...;
	}

Or can be used to statically initialise global variables with constant values:

	unsigned n = ilog2(27);

When performing static initialisation, the compiler will report "error:
initializer element is not constant" if asked to take a log of zero or of
something not reducible to a constant.  They treat negative numbers as
unsigned.

When not dealing with a constant, they fall back to using fls() which permits
them to use arch-specific log calculation instructions - such as BSR on
x86/x86_64 or SCAN on FRV - if available.

[akpm@osdl.org: MMC fix]
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Wojtek Kaniewski <wojtekka@toxygen.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 08:28:51 -08:00

315 lines
6.9 KiB
C

/* bitops.h: bit operations for the Fujitsu FR-V CPUs
*
* For an explanation of how atomic ops work in this arch, see:
* Documentation/fujitsu/frv/atomic-ops.txt
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_BITOPS_H
#define _ASM_BITOPS_H
#include <linux/compiler.h>
#include <asm/byteorder.h>
#include <asm/system.h>
#include <asm/atomic.h>
#ifdef __KERNEL__
#include <asm-generic/bitops/ffz.h>
/*
* clear_bit() doesn't provide any barrier for the compiler.
*/
#define smp_mb__before_clear_bit() barrier()
#define smp_mb__after_clear_bit() barrier()
static inline int test_and_clear_bit(int nr, volatile void *addr)
{
volatile unsigned long *ptr = addr;
unsigned long mask = 1UL << (nr & 31);
ptr += nr >> 5;
return (atomic_test_and_ANDNOT_mask(mask, ptr) & mask) != 0;
}
static inline int test_and_set_bit(int nr, volatile void *addr)
{
volatile unsigned long *ptr = addr;
unsigned long mask = 1UL << (nr & 31);
ptr += nr >> 5;
return (atomic_test_and_OR_mask(mask, ptr) & mask) != 0;
}
static inline int test_and_change_bit(int nr, volatile void *addr)
{
volatile unsigned long *ptr = addr;
unsigned long mask = 1UL << (nr & 31);
ptr += nr >> 5;
return (atomic_test_and_XOR_mask(mask, ptr) & mask) != 0;
}
static inline void clear_bit(int nr, volatile void *addr)
{
test_and_clear_bit(nr, addr);
}
static inline void set_bit(int nr, volatile void *addr)
{
test_and_set_bit(nr, addr);
}
static inline void change_bit(int nr, volatile void * addr)
{
test_and_change_bit(nr, addr);
}
static inline void __clear_bit(int nr, volatile void * addr)
{
volatile unsigned long *a = addr;
int mask;
a += nr >> 5;
mask = 1 << (nr & 31);
*a &= ~mask;
}
static inline void __set_bit(int nr, volatile void * addr)
{
volatile unsigned long *a = addr;
int mask;
a += nr >> 5;
mask = 1 << (nr & 31);
*a |= mask;
}
static inline void __change_bit(int nr, volatile void *addr)
{
volatile unsigned long *a = addr;
int mask;
a += nr >> 5;
mask = 1 << (nr & 31);
*a ^= mask;
}
static inline int __test_and_clear_bit(int nr, volatile void * addr)
{
volatile unsigned long *a = addr;
int mask, retval;
a += nr >> 5;
mask = 1 << (nr & 31);
retval = (mask & *a) != 0;
*a &= ~mask;
return retval;
}
static inline int __test_and_set_bit(int nr, volatile void * addr)
{
volatile unsigned long *a = addr;
int mask, retval;
a += nr >> 5;
mask = 1 << (nr & 31);
retval = (mask & *a) != 0;
*a |= mask;
return retval;
}
static inline int __test_and_change_bit(int nr, volatile void * addr)
{
volatile unsigned long *a = addr;
int mask, retval;
a += nr >> 5;
mask = 1 << (nr & 31);
retval = (mask & *a) != 0;
*a ^= mask;
return retval;
}
/*
* This routine doesn't need to be atomic.
*/
static inline int __constant_test_bit(int nr, const volatile void * addr)
{
return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0;
}
static inline int __test_bit(int nr, const volatile void * addr)
{
int * a = (int *) addr;
int mask;
a += nr >> 5;
mask = 1 << (nr & 0x1f);
return ((mask & *a) != 0);
}
#define test_bit(nr,addr) \
(__builtin_constant_p(nr) ? \
__constant_test_bit((nr),(addr)) : \
__test_bit((nr),(addr)))
#include <asm-generic/bitops/find.h>
/**
* fls - find last bit set
* @x: the word to search
*
* This is defined the same way as ffs:
* - return 32..1 to indicate bit 31..0 most significant bit set
* - return 0 to indicate no bits set
*/
#define fls(x) \
({ \
int bit; \
\
asm(" subcc %1,gr0,gr0,icc0 \n" \
" ckne icc0,cc4 \n" \
" cscan.p %1,gr0,%0 ,cc4,#1 \n" \
" csub %0,%0,%0 ,cc4,#0 \n" \
" csub %2,%0,%0 ,cc4,#1 \n" \
: "=&r"(bit) \
: "r"(x), "r"(32) \
: "icc0", "cc4" \
); \
\
bit; \
})
/**
* fls64 - find last bit set in a 64-bit value
* @n: the value to search
*
* This is defined the same way as ffs:
* - return 64..1 to indicate bit 63..0 most significant bit set
* - return 0 to indicate no bits set
*/
static inline __attribute__((const))
int fls64(u64 n)
{
union {
u64 ll;
struct { u32 h, l; };
} _;
int bit, x, y;
_.ll = n;
asm(" subcc.p %3,gr0,gr0,icc0 \n"
" subcc %4,gr0,gr0,icc1 \n"
" ckne icc0,cc4 \n"
" ckne icc1,cc5 \n"
" norcr cc4,cc5,cc6 \n"
" csub.p %0,%0,%0 ,cc6,1 \n"
" orcr cc5,cc4,cc4 \n"
" andcr cc4,cc5,cc4 \n"
" cscan.p %3,gr0,%0 ,cc4,0 \n"
" setlos #64,%1 \n"
" cscan.p %4,gr0,%0 ,cc4,1 \n"
" setlos #32,%2 \n"
" csub.p %1,%0,%0 ,cc4,0 \n"
" csub %2,%0,%0 ,cc4,1 \n"
: "=&r"(bit), "=r"(x), "=r"(y)
: "0r"(_.h), "r"(_.l)
: "icc0", "icc1", "cc4", "cc5", "cc6"
);
return bit;
}
/**
* ffs - find first bit set
* @x: the word to search
*
* - return 32..1 to indicate bit 31..0 most least significant bit set
* - return 0 to indicate no bits set
*/
static inline __attribute__((const))
int ffs(int x)
{
/* Note: (x & -x) gives us a mask that is the least significant
* (rightmost) 1-bit of the value in x.
*/
return fls(x & -x);
}
/**
* __ffs - find first bit set
* @x: the word to search
*
* - return 31..0 to indicate bit 31..0 most least significant bit set
* - if no bits are set in x, the result is undefined
*/
static inline __attribute__((const))
int __ffs(unsigned long x)
{
int bit;
asm("scan %1,gr0,%0" : "=r"(bit) : "r"(x & -x));
return 31 - bit;
}
/*
* special slimline version of fls() for calculating ilog2_u32()
* - note: no protection against n == 0
*/
#define ARCH_HAS_ILOG2_U32
static inline __attribute__((const))
int __ilog2_u32(u32 n)
{
int bit;
asm("scan %1,gr0,%0" : "=r"(bit) : "r"(n));
return 31 - bit;
}
/*
* special slimline version of fls64() for calculating ilog2_u64()
* - note: no protection against n == 0
*/
#define ARCH_HAS_ILOG2_U64
static inline __attribute__((const))
int __ilog2_u64(u64 n)
{
union {
u64 ll;
struct { u32 h, l; };
} _;
int bit, x, y;
_.ll = n;
asm(" subcc %3,gr0,gr0,icc0 \n"
" ckeq icc0,cc4 \n"
" cscan.p %3,gr0,%0 ,cc4,0 \n"
" setlos #63,%1 \n"
" cscan.p %4,gr0,%0 ,cc4,1 \n"
" setlos #31,%2 \n"
" csub.p %1,%0,%0 ,cc4,0 \n"
" csub %2,%0,%0 ,cc4,1 \n"
: "=&r"(bit), "=r"(x), "=r"(y)
: "0r"(_.h), "r"(_.l)
: "icc0", "cc4"
);
return bit;
}
#include <asm-generic/bitops/sched.h>
#include <asm-generic/bitops/hweight.h>
#include <asm-generic/bitops/ext2-non-atomic.h>
#define ext2_set_bit_atomic(lock,nr,addr) test_and_set_bit ((nr) ^ 0x18, (addr))
#define ext2_clear_bit_atomic(lock,nr,addr) test_and_clear_bit((nr) ^ 0x18, (addr))
#include <asm-generic/bitops/minix-le.h>
#endif /* __KERNEL__ */
#endif /* _ASM_BITOPS_H */