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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-17 02:20:36 +0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-17 02:20:36 +0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-arm/bitops.h
downloadlinux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * Copyright 1995, Russell King.
+ * Various bits and pieces copyrights include:
+ * Linus Torvalds (test_bit).
+ * Big endian support: Copyright 2001, Nicolas Pitre
+ * reworked by rmk.
+ *
+ * bit 0 is the LSB of an "unsigned long" quantity.
+ *
+ * Please note that the code in this file should never be included
+ * from user space. Many of these are not implemented in assembler
+ * since they would be too costly. Also, they require privileged
+ * instructions (which are not available from user mode) to ensure
+ * that they are atomic.
+ */
+
+#ifndef __ASM_ARM_BITOPS_H
+#define __ASM_ARM_BITOPS_H
+
+#ifdef __KERNEL__
+
+#include <asm/system.h>
+
+#define smp_mb__before_clear_bit() do { } while (0)
+#define smp_mb__after_clear_bit() do { } while (0)
+
+/*
+ * These functions are the basis of our bit ops.
+ *
+ * First, the atomic bitops. These use native endian.
+ */
+static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
+{
+ unsigned long flags;
+ unsigned long mask = 1UL << (bit & 31);
+
+ p += bit >> 5;
+
+ local_irq_save(flags);
+ *p |= mask;
+ local_irq_restore(flags);
+}
+
+static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
+{
+ unsigned long flags;
+ unsigned long mask = 1UL << (bit & 31);
+
+ p += bit >> 5;
+
+ local_irq_save(flags);
+ *p &= ~mask;
+ local_irq_restore(flags);
+}
+
+static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
+{
+ unsigned long flags;
+ unsigned long mask = 1UL << (bit & 31);
+
+ p += bit >> 5;
+
+ local_irq_save(flags);
+ *p ^= mask;
+ local_irq_restore(flags);
+}
+
+static inline int
+____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
+{
+ unsigned long flags;
+ unsigned int res;
+ unsigned long mask = 1UL << (bit & 31);
+
+ p += bit >> 5;
+
+ local_irq_save(flags);
+ res = *p;
+ *p = res | mask;
+ local_irq_restore(flags);
+
+ return res & mask;
+}
+
+static inline int
+____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
+{
+ unsigned long flags;
+ unsigned int res;
+ unsigned long mask = 1UL << (bit & 31);
+
+ p += bit >> 5;
+
+ local_irq_save(flags);
+ res = *p;
+ *p = res & ~mask;
+ local_irq_restore(flags);
+
+ return res & mask;
+}
+
+static inline int
+____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
+{
+ unsigned long flags;
+ unsigned int res;
+ unsigned long mask = 1UL << (bit & 31);
+
+ p += bit >> 5;
+
+ local_irq_save(flags);
+ res = *p;
+ *p = res ^ mask;
+ local_irq_restore(flags);
+
+ return res & mask;
+}
+
+/*
+ * Now the non-atomic variants. We let the compiler handle all
+ * optimisations for these. These are all _native_ endian.
+ */
+static inline void __set_bit(int nr, volatile unsigned long *p)
+{
+ p[nr >> 5] |= (1UL << (nr & 31));
+}
+
+static inline void __clear_bit(int nr, volatile unsigned long *p)
+{
+ p[nr >> 5] &= ~(1UL << (nr & 31));
+}
+
+static inline void __change_bit(int nr, volatile unsigned long *p)
+{
+ p[nr >> 5] ^= (1UL << (nr & 31));
+}
+
+static inline int __test_and_set_bit(int nr, volatile unsigned long *p)
+{
+ unsigned long oldval, mask = 1UL << (nr & 31);
+
+ p += nr >> 5;
+
+ oldval = *p;
+ *p = oldval | mask;
+ return oldval & mask;
+}
+
+static inline int __test_and_clear_bit(int nr, volatile unsigned long *p)
+{
+ unsigned long oldval, mask = 1UL << (nr & 31);
+
+ p += nr >> 5;
+
+ oldval = *p;
+ *p = oldval & ~mask;
+ return oldval & mask;
+}
+
+static inline int __test_and_change_bit(int nr, volatile unsigned long *p)
+{
+ unsigned long oldval, mask = 1UL << (nr & 31);
+
+ p += nr >> 5;
+
+ oldval = *p;
+ *p = oldval ^ mask;
+ return oldval & mask;
+}
+
+/*
+ * This routine doesn't need to be atomic.
+ */
+static inline int __test_bit(int nr, const volatile unsigned long * p)
+{
+ return (p[nr >> 5] >> (nr & 31)) & 1UL;
+}
+
+/*
+ * A note about Endian-ness.
+ * -------------------------
+ *
+ * When the ARM is put into big endian mode via CR15, the processor
+ * merely swaps the order of bytes within words, thus:
+ *
+ * ------------ physical data bus bits -----------
+ * D31 ... D24 D23 ... D16 D15 ... D8 D7 ... D0
+ * little byte 3 byte 2 byte 1 byte 0
+ * big byte 0 byte 1 byte 2 byte 3
+ *
+ * This means that reading a 32-bit word at address 0 returns the same
+ * value irrespective of the endian mode bit.
+ *
+ * Peripheral devices should be connected with the data bus reversed in
+ * "Big Endian" mode. ARM Application Note 61 is applicable, and is
+ * available from http://www.arm.com/.
+ *
+ * The following assumes that the data bus connectivity for big endian
+ * mode has been followed.
+ *
+ * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
+ */
+
+/*
+ * Little endian assembly bitops. nr = 0 -> byte 0 bit 0.
+ */
+extern void _set_bit_le(int nr, volatile unsigned long * p);
+extern void _clear_bit_le(int nr, volatile unsigned long * p);
+extern void _change_bit_le(int nr, volatile unsigned long * p);
+extern int _test_and_set_bit_le(int nr, volatile unsigned long * p);
+extern int _test_and_clear_bit_le(int nr, volatile unsigned long * p);
+extern int _test_and_change_bit_le(int nr, volatile unsigned long * p);
+extern int _find_first_zero_bit_le(const void * p, unsigned size);
+extern int _find_next_zero_bit_le(const void * p, int size, int offset);
+extern int _find_first_bit_le(const unsigned long *p, unsigned size);
+extern int _find_next_bit_le(const unsigned long *p, int size, int offset);
+
+/*
+ * Big endian assembly bitops. nr = 0 -> byte 3 bit 0.
+ */
+extern void _set_bit_be(int nr, volatile unsigned long * p);
+extern void _clear_bit_be(int nr, volatile unsigned long * p);
+extern void _change_bit_be(int nr, volatile unsigned long * p);
+extern int _test_and_set_bit_be(int nr, volatile unsigned long * p);
+extern int _test_and_clear_bit_be(int nr, volatile unsigned long * p);
+extern int _test_and_change_bit_be(int nr, volatile unsigned long * p);
+extern int _find_first_zero_bit_be(const void * p, unsigned size);
+extern int _find_next_zero_bit_be(const void * p, int size, int offset);
+extern int _find_first_bit_be(const unsigned long *p, unsigned size);
+extern int _find_next_bit_be(const unsigned long *p, int size, int offset);
+
+/*
+ * The __* form of bitops are non-atomic and may be reordered.
+ */
+#define ATOMIC_BITOP_LE(name,nr,p) \
+ (__builtin_constant_p(nr) ? \
+ ____atomic_##name(nr, p) : \
+ _##name##_le(nr,p))
+
+#define ATOMIC_BITOP_BE(name,nr,p) \
+ (__builtin_constant_p(nr) ? \
+ ____atomic_##name(nr, p) : \
+ _##name##_be(nr,p))
+
+#define NONATOMIC_BITOP(name,nr,p) \
+ (____nonatomic_##name(nr, p))
+
+#ifndef __ARMEB__
+/*
+ * These are the little endian, atomic definitions.
+ */
+#define set_bit(nr,p) ATOMIC_BITOP_LE(set_bit,nr,p)
+#define clear_bit(nr,p) ATOMIC_BITOP_LE(clear_bit,nr,p)
+#define change_bit(nr,p) ATOMIC_BITOP_LE(change_bit,nr,p)
+#define test_and_set_bit(nr,p) ATOMIC_BITOP_LE(test_and_set_bit,nr,p)
+#define test_and_clear_bit(nr,p) ATOMIC_BITOP_LE(test_and_clear_bit,nr,p)
+#define test_and_change_bit(nr,p) ATOMIC_BITOP_LE(test_and_change_bit,nr,p)
+#define test_bit(nr,p) __test_bit(nr,p)
+#define find_first_zero_bit(p,sz) _find_first_zero_bit_le(p,sz)
+#define find_next_zero_bit(p,sz,off) _find_next_zero_bit_le(p,sz,off)
+#define find_first_bit(p,sz) _find_first_bit_le(p,sz)
+#define find_next_bit(p,sz,off) _find_next_bit_le(p,sz,off)
+
+#define WORD_BITOFF_TO_LE(x) ((x))
+
+#else
+
+/*
+ * These are the big endian, atomic definitions.
+ */
+#define set_bit(nr,p) ATOMIC_BITOP_BE(set_bit,nr,p)
+#define clear_bit(nr,p) ATOMIC_BITOP_BE(clear_bit,nr,p)
+#define change_bit(nr,p) ATOMIC_BITOP_BE(change_bit,nr,p)
+#define test_and_set_bit(nr,p) ATOMIC_BITOP_BE(test_and_set_bit,nr,p)
+#define test_and_clear_bit(nr,p) ATOMIC_BITOP_BE(test_and_clear_bit,nr,p)
+#define test_and_change_bit(nr,p) ATOMIC_BITOP_BE(test_and_change_bit,nr,p)
+#define test_bit(nr,p) __test_bit(nr,p)
+#define find_first_zero_bit(p,sz) _find_first_zero_bit_be(p,sz)
+#define find_next_zero_bit(p,sz,off) _find_next_zero_bit_be(p,sz,off)
+#define find_first_bit(p,sz) _find_first_bit_be(p,sz)
+#define find_next_bit(p,sz,off) _find_next_bit_be(p,sz,off)
+
+#define WORD_BITOFF_TO_LE(x) ((x) ^ 0x18)
+
+#endif
+
+#if __LINUX_ARM_ARCH__ < 5
+
+/*
+ * ffz = Find First Zero in word. Undefined if no zero exists,
+ * so code should check against ~0UL first..
+ */
+static inline unsigned long ffz(unsigned long word)
+{
+ int k;
+
+ word = ~word;
+ k = 31;
+ if (word & 0x0000ffff) { k -= 16; word <<= 16; }
+ if (word & 0x00ff0000) { k -= 8; word <<= 8; }
+ if (word & 0x0f000000) { k -= 4; word <<= 4; }
+ if (word & 0x30000000) { k -= 2; word <<= 2; }
+ if (word & 0x40000000) { k -= 1; }
+ return k;
+}
+
+/*
+ * ffz = Find First Zero in word. Undefined if no zero exists,
+ * so code should check against ~0UL first..
+ */
+static inline unsigned long __ffs(unsigned long word)
+{
+ int k;
+
+ k = 31;
+ if (word & 0x0000ffff) { k -= 16; word <<= 16; }
+ if (word & 0x00ff0000) { k -= 8; word <<= 8; }
+ if (word & 0x0f000000) { k -= 4; word <<= 4; }
+ if (word & 0x30000000) { k -= 2; word <<= 2; }
+ if (word & 0x40000000) { k -= 1; }
+ return k;
+}
+
+/*
+ * fls: find last bit set.
+ */
+
+#define fls(x) generic_fls(x)
+
+/*
+ * ffs: find first bit set. This is defined the same way as
+ * the libc and compiler builtin ffs routines, therefore
+ * differs in spirit from the above ffz (man ffs).
+ */
+
+#define ffs(x) generic_ffs(x)
+
+#else
+
+/*
+ * On ARMv5 and above those functions can be implemented around
+ * the clz instruction for much better code efficiency.
+ */
+
+static __inline__ int generic_fls(int x);
+#define fls(x) \
+ ( __builtin_constant_p(x) ? generic_fls(x) : \
+ ({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) )
+#define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); })
+#define __ffs(x) (ffs(x) - 1)
+#define ffz(x) __ffs( ~(x) )
+
+#endif
+
+/*
+ * Find first bit set in a 168-bit bitmap, where the first
+ * 128 bits are unlikely to be set.
+ */
+static inline int sched_find_first_bit(const unsigned long *b)
+{
+ unsigned long v;
+ unsigned int off;
+
+ for (off = 0; v = b[off], off < 4; off++) {
+ if (unlikely(v))
+ break;
+ }
+ return __ffs(v) + off * 32;
+}
+
+/*
+ * hweightN: returns the hamming weight (i.e. the number
+ * of bits set) of a N-bit word
+ */
+
+#define hweight32(x) generic_hweight32(x)
+#define hweight16(x) generic_hweight16(x)
+#define hweight8(x) generic_hweight8(x)
+
+/*
+ * Ext2 is defined to use little-endian byte ordering.
+ * These do not need to be atomic.
+ */
+#define ext2_set_bit(nr,p) \
+ __test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define ext2_set_bit_atomic(lock,nr,p) \
+ test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define ext2_clear_bit(nr,p) \
+ __test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define ext2_clear_bit_atomic(lock,nr,p) \
+ test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define ext2_test_bit(nr,p) \
+ __test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define ext2_find_first_zero_bit(p,sz) \
+ _find_first_zero_bit_le(p,sz)
+#define ext2_find_next_zero_bit(p,sz,off) \
+ _find_next_zero_bit_le(p,sz,off)
+
+/*
+ * Minix is defined to use little-endian byte ordering.
+ * These do not need to be atomic.
+ */
+#define minix_set_bit(nr,p) \
+ __set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define minix_test_bit(nr,p) \
+ __test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define minix_test_and_set_bit(nr,p) \
+ __test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define minix_test_and_clear_bit(nr,p) \
+ __test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
+#define minix_find_first_zero_bit(p,sz) \
+ _find_first_zero_bit_le(p,sz)
+
+#endif /* __KERNEL__ */
+
+#endif /* _ARM_BITOPS_H */