0d2d3e38f7
The bitops.h functions that operate on a single bit in a bitfield are implemented by operating on the corresponding word location. In all cases the inner logic is valid if the mask being applied has more than one bit set, so this patch exposes those inner operations. Indeed, set_bits() was already available, but it duplicated code from set_bit() (rather than making the latter a wrapper) - it was also missing the PPC405_ERR77() workaround and the "volatile" address qualifier present in other APIs. This corrects that, and exposes the other multi-bit equivalents. One advantage of these multi-bit forms is that they allow word-sized variables to essentially be their own spinlocks, eg. very useful for state machines where an atomic "flags" variable can obviate the need for any additional locking. Signed-off-by: Geoff Thorpe <geoff@geoffthorpe.net> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
338 lines
9.8 KiB
C
338 lines
9.8 KiB
C
/*
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* PowerPC atomic bit operations.
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*
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* Merged version by David Gibson <david@gibson.dropbear.id.au>.
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* Based on ppc64 versions by: Dave Engebretsen, Todd Inglett, Don
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* Reed, Pat McCarthy, Peter Bergner, Anton Blanchard. They
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* originally took it from the ppc32 code.
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*
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* Within a word, bits are numbered LSB first. Lot's of places make
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* this assumption by directly testing bits with (val & (1<<nr)).
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* This can cause confusion for large (> 1 word) bitmaps on a
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* big-endian system because, unlike little endian, the number of each
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* bit depends on the word size.
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*
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* The bitop functions are defined to work on unsigned longs, so for a
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* ppc64 system the bits end up numbered:
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* |63..............0|127............64|191...........128|255...........196|
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* and on ppc32:
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* |31.....0|63....31|95....64|127...96|159..128|191..160|223..192|255..224|
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*
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* There are a few little-endian macros used mostly for filesystem
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* bitmaps, these work on similar bit arrays layouts, but
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* byte-oriented:
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* |7...0|15...8|23...16|31...24|39...32|47...40|55...48|63...56|
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*
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* The main difference is that bit 3-5 (64b) or 3-4 (32b) in the bit
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* number field needs to be reversed compared to the big-endian bit
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* fields. This can be achieved by XOR with 0x38 (64b) or 0x18 (32b).
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_POWERPC_BITOPS_H
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#define _ASM_POWERPC_BITOPS_H
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#ifdef __KERNEL__
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#ifndef _LINUX_BITOPS_H
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#error only <linux/bitops.h> can be included directly
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#endif
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#include <linux/compiler.h>
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#include <asm/asm-compat.h>
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#include <asm/synch.h>
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/*
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* clear_bit doesn't imply a memory barrier
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*/
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#define smp_mb__before_clear_bit() smp_mb()
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#define smp_mb__after_clear_bit() smp_mb()
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#define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
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#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
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#define BITOP_LE_SWIZZLE ((BITS_PER_LONG-1) & ~0x7)
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/* Macro for generating the ***_bits() functions */
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#define DEFINE_BITOP(fn, op, prefix, postfix) \
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static __inline__ void fn(unsigned long mask, \
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volatile unsigned long *_p) \
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{ \
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unsigned long old; \
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unsigned long *p = (unsigned long *)_p; \
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__asm__ __volatile__ ( \
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prefix \
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"1:" PPC_LLARX "%0,0,%3\n" \
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stringify_in_c(op) "%0,%0,%2\n" \
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PPC405_ERR77(0,%3) \
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PPC_STLCX "%0,0,%3\n" \
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"bne- 1b\n" \
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postfix \
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: "=&r" (old), "+m" (*p) \
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: "r" (mask), "r" (p) \
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: "cc", "memory"); \
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}
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DEFINE_BITOP(set_bits, or, "", "")
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DEFINE_BITOP(clear_bits, andc, "", "")
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DEFINE_BITOP(clear_bits_unlock, andc, LWSYNC_ON_SMP, "")
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DEFINE_BITOP(change_bits, xor, "", "")
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static __inline__ void set_bit(int nr, volatile unsigned long *addr)
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{
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set_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
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}
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static __inline__ void clear_bit(int nr, volatile unsigned long *addr)
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{
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clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
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}
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static __inline__ void clear_bit_unlock(int nr, volatile unsigned long *addr)
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{
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clear_bits_unlock(BITOP_MASK(nr), addr + BITOP_WORD(nr));
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}
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static __inline__ void change_bit(int nr, volatile unsigned long *addr)
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{
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change_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr));
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}
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/* Like DEFINE_BITOP(), with changes to the arguments to 'op' and the output
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* operands. */
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#define DEFINE_TESTOP(fn, op, prefix, postfix) \
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static __inline__ unsigned long fn( \
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unsigned long mask, \
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volatile unsigned long *_p) \
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{ \
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unsigned long old, t; \
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unsigned long *p = (unsigned long *)_p; \
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__asm__ __volatile__ ( \
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prefix \
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"1:" PPC_LLARX "%0,0,%3\n" \
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stringify_in_c(op) "%1,%0,%2\n" \
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PPC405_ERR77(0,%3) \
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PPC_STLCX "%1,0,%3\n" \
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"bne- 1b\n" \
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postfix \
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: "=&r" (old), "=&r" (t) \
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: "r" (mask), "r" (p) \
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: "cc", "memory"); \
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return (old & mask); \
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}
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DEFINE_TESTOP(test_and_set_bits, or, LWSYNC_ON_SMP, ISYNC_ON_SMP)
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DEFINE_TESTOP(test_and_set_bits_lock, or, "", ISYNC_ON_SMP)
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DEFINE_TESTOP(test_and_clear_bits, andc, LWSYNC_ON_SMP, ISYNC_ON_SMP)
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DEFINE_TESTOP(test_and_change_bits, xor, LWSYNC_ON_SMP, ISYNC_ON_SMP)
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static __inline__ int test_and_set_bit(unsigned long nr,
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volatile unsigned long *addr)
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{
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return test_and_set_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
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}
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static __inline__ int test_and_set_bit_lock(unsigned long nr,
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volatile unsigned long *addr)
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{
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return test_and_set_bits_lock(BITOP_MASK(nr),
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addr + BITOP_WORD(nr)) != 0;
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}
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static __inline__ int test_and_clear_bit(unsigned long nr,
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volatile unsigned long *addr)
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{
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return test_and_clear_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
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}
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static __inline__ int test_and_change_bit(unsigned long nr,
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volatile unsigned long *addr)
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{
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return test_and_change_bits(BITOP_MASK(nr), addr + BITOP_WORD(nr)) != 0;
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}
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#include <asm-generic/bitops/non-atomic.h>
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static __inline__ void __clear_bit_unlock(int nr, volatile unsigned long *addr)
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{
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__asm__ __volatile__(LWSYNC_ON_SMP "" ::: "memory");
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__clear_bit(nr, addr);
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}
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/*
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* Return the zero-based bit position (LE, not IBM bit numbering) of
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* the most significant 1-bit in a double word.
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*/
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static __inline__ __attribute__((const))
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int __ilog2(unsigned long x)
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{
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int lz;
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asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x));
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return BITS_PER_LONG - 1 - lz;
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}
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static inline __attribute__((const))
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int __ilog2_u32(u32 n)
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{
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int bit;
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asm ("cntlzw %0,%1" : "=r" (bit) : "r" (n));
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return 31 - bit;
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}
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#ifdef __powerpc64__
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static inline __attribute__((const))
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int __ilog2_u64(u64 n)
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{
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int bit;
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asm ("cntlzd %0,%1" : "=r" (bit) : "r" (n));
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return 63 - bit;
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}
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#endif
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/*
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* Determines the bit position of the least significant 0 bit in the
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* specified double word. The returned bit position will be
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* zero-based, starting from the right side (63/31 - 0).
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*/
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static __inline__ unsigned long ffz(unsigned long x)
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{
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/* no zero exists anywhere in the 8 byte area. */
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if ((x = ~x) == 0)
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return BITS_PER_LONG;
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/*
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* Calculate the bit position of the least signficant '1' bit in x
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* (since x has been changed this will actually be the least signficant
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* '0' bit in * the original x). Note: (x & -x) gives us a mask that
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* is the least significant * (RIGHT-most) 1-bit of the value in x.
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*/
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return __ilog2(x & -x);
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}
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static __inline__ int __ffs(unsigned long x)
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{
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return __ilog2(x & -x);
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}
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/*
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* ffs: find first bit set. This is defined the same way as
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* the libc and compiler builtin ffs routines, therefore
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* differs in spirit from the above ffz (man ffs).
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*/
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static __inline__ int ffs(int x)
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{
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unsigned long i = (unsigned long)x;
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return __ilog2(i & -i) + 1;
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}
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/*
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* fls: find last (most-significant) bit set.
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* Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
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*/
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static __inline__ int fls(unsigned int x)
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{
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int lz;
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asm ("cntlzw %0,%1" : "=r" (lz) : "r" (x));
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return 32 - lz;
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}
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static __inline__ unsigned long __fls(unsigned long x)
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{
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return __ilog2(x);
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}
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/*
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* 64-bit can do this using one cntlzd (count leading zeroes doubleword)
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* instruction; for 32-bit we use the generic version, which does two
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* 32-bit fls calls.
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*/
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#ifdef __powerpc64__
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static __inline__ int fls64(__u64 x)
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{
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int lz;
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asm ("cntlzd %0,%1" : "=r" (lz) : "r" (x));
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return 64 - lz;
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}
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#else
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#include <asm-generic/bitops/fls64.h>
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#endif /* __powerpc64__ */
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#include <asm-generic/bitops/hweight.h>
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#include <asm-generic/bitops/find.h>
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/* Little-endian versions */
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static __inline__ int test_le_bit(unsigned long nr,
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__const__ unsigned long *addr)
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{
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__const__ unsigned char *tmp = (__const__ unsigned char *) addr;
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return (tmp[nr >> 3] >> (nr & 7)) & 1;
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}
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#define __set_le_bit(nr, addr) \
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__set_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
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#define __clear_le_bit(nr, addr) \
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__clear_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
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#define test_and_set_le_bit(nr, addr) \
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test_and_set_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
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#define test_and_clear_le_bit(nr, addr) \
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test_and_clear_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
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#define __test_and_set_le_bit(nr, addr) \
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__test_and_set_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
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#define __test_and_clear_le_bit(nr, addr) \
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__test_and_clear_bit((nr) ^ BITOP_LE_SWIZZLE, (addr))
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#define find_first_zero_le_bit(addr, size) generic_find_next_zero_le_bit((addr), (size), 0)
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unsigned long generic_find_next_zero_le_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset);
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unsigned long generic_find_next_le_bit(const unsigned long *addr,
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unsigned long size, unsigned long offset);
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/* Bitmap functions for the ext2 filesystem */
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#define ext2_set_bit(nr,addr) \
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__test_and_set_le_bit((nr), (unsigned long*)addr)
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#define ext2_clear_bit(nr, addr) \
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__test_and_clear_le_bit((nr), (unsigned long*)addr)
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#define ext2_set_bit_atomic(lock, nr, addr) \
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test_and_set_le_bit((nr), (unsigned long*)addr)
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#define ext2_clear_bit_atomic(lock, nr, addr) \
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test_and_clear_le_bit((nr), (unsigned long*)addr)
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#define ext2_test_bit(nr, addr) test_le_bit((nr),(unsigned long*)addr)
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#define ext2_find_first_zero_bit(addr, size) \
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find_first_zero_le_bit((unsigned long*)addr, size)
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#define ext2_find_next_zero_bit(addr, size, off) \
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generic_find_next_zero_le_bit((unsigned long*)addr, size, off)
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#define ext2_find_next_bit(addr, size, off) \
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generic_find_next_le_bit((unsigned long *)addr, size, off)
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/* Bitmap functions for the minix filesystem. */
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#define minix_test_and_set_bit(nr,addr) \
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__test_and_set_le_bit(nr, (unsigned long *)addr)
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#define minix_set_bit(nr,addr) \
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__set_le_bit(nr, (unsigned long *)addr)
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#define minix_test_and_clear_bit(nr,addr) \
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__test_and_clear_le_bit(nr, (unsigned long *)addr)
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#define minix_test_bit(nr,addr) \
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test_le_bit(nr, (unsigned long *)addr)
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#define minix_find_first_zero_bit(addr,size) \
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find_first_zero_le_bit((unsigned long *)addr, size)
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#include <asm-generic/bitops/sched.h>
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_BITOPS_H */
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