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Diffstat (limited to 'include/asm-i386/bitops.h')
| -rw-r--r-- | include/asm-i386/bitops.h | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/include/asm-i386/bitops.h b/include/asm-i386/bitops.h new file mode 100644 index 0000000..a3063ca --- /dev/null +++ b/include/asm-i386/bitops.h @@ -0,0 +1,384 @@ +#ifndef _I386_BITOPS_H +#define _I386_BITOPS_H + +/* + * Copyright 1992, Linus Torvalds. + */ + +#include <linux/config.h> + +/* + * These have to be done with inline assembly: that way the bit-setting + * is guaranteed to be atomic. All bit operations return 0 if the bit + * was cleared before the operation and != 0 if it was not. + * + * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1). + */ + +#ifdef CONFIG_SMP +#define LOCK_PREFIX "lock ; " +#else +#define LOCK_PREFIX "" +#endif + +#define ADDR (*(volatile long *) addr) + +/** + * set_bit - Atomically set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * This function is atomic and may not be reordered. See __set_bit() + * if you do not require the atomic guarantees. + * Note that @nr may be almost arbitrarily large; this function is not + * restricted to acting on a single-word quantity. + */ +static __inline__ void set_bit(int nr, volatile void * addr) +{ + __asm__ __volatile__( LOCK_PREFIX + "btsl %1,%0" + :"=m" (ADDR) + :"Ir" (nr)); +} + +/** + * __set_bit - Set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * Unlike set_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static __inline__ void __set_bit(int nr, volatile void * addr) +{ + __asm__( + "btsl %1,%0" + :"=m" (ADDR) + :"Ir" (nr)); +} + +/** + * clear_bit - Clears a bit in memory + * @nr: Bit to clear + * @addr: Address to start counting from + * + * clear_bit() is atomic and may not be reordered. However, it does + * not contain a memory barrier, so if it is used for locking purposes, + * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit() + * in order to ensure changes are visible on other processors. + */ +static __inline__ void clear_bit(int nr, volatile void * addr) +{ + __asm__ __volatile__( LOCK_PREFIX + "btrl %1,%0" + :"=m" (ADDR) + :"Ir" (nr)); +} +#define smp_mb__before_clear_bit() barrier() +#define smp_mb__after_clear_bit() barrier() + +/** + * __change_bit - Toggle a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * Unlike change_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static __inline__ void __change_bit(int nr, volatile void * addr) +{ + __asm__ __volatile__( + "btcl %1,%0" + :"=m" (ADDR) + :"Ir" (nr)); +} + +/** + * change_bit - Toggle a bit in memory + * @nr: Bit to clear + * @addr: Address to start counting from + * + * change_bit() is atomic and may not be reordered. + * Note that @nr may be almost arbitrarily large; this function is not + * restricted to acting on a single-word quantity. + */ +static __inline__ void change_bit(int nr, volatile void * addr) +{ + __asm__ __volatile__( LOCK_PREFIX + "btcl %1,%0" + :"=m" (ADDR) + :"Ir" (nr)); +} + +/** + * test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static __inline__ int test_and_set_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__ __volatile__( LOCK_PREFIX + "btsl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"Ir" (nr) : "memory"); + return oldbit; +} + +/** + * __test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static __inline__ int __test_and_set_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__( + "btsl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"Ir" (nr)); + return oldbit; +} + +/** + * test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static __inline__ int test_and_clear_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__ __volatile__( LOCK_PREFIX + "btrl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"Ir" (nr) : "memory"); + return oldbit; +} + +/** + * __test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static __inline__ int __test_and_clear_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__( + "btrl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"Ir" (nr)); + return oldbit; +} + +/* WARNING: non atomic and it can be reordered! */ +static __inline__ int __test_and_change_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__ __volatile__( + "btcl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"Ir" (nr) : "memory"); + return oldbit; +} + +/** + * test_and_change_bit - Change a bit and return its new value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static __inline__ int test_and_change_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__ __volatile__( LOCK_PREFIX + "btcl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"Ir" (nr) : "memory"); + return oldbit; +} + +#if 0 /* Fool kernel-doc since it doesn't do macros yet */ +/** + * test_bit - Determine whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + */ +static int test_bit(int nr, const volatile void * addr); +#endif + +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 variable_test_bit(int nr, volatile void * addr) +{ + int oldbit; + + __asm__ __volatile__( + "btl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit) + :"m" (ADDR),"Ir" (nr)); + return oldbit; +} + +#define test_bit(nr,addr) \ +(__builtin_constant_p(nr) ? \ + constant_test_bit((nr),(addr)) : \ + variable_test_bit((nr),(addr))) + +/** + * find_first_zero_bit - find the first zero bit in a memory region + * @addr: The address to start the search at + * @size: The maximum size to search + * + * Returns the bit-number of the first zero bit, not the number of the byte + * containing a bit. + */ +static __inline__ int find_first_zero_bit(void * addr, unsigned size) +{ + int d0, d1, d2; + int res; + + if (!size) + return 0; + /* This looks at memory. Mark it volatile to tell gcc not to move it around */ + __asm__ __volatile__( + "movl $-1,%%eax\n\t" + "xorl %%edx,%%edx\n\t" + "repe; scasl\n\t" + "je 1f\n\t" + "xorl -4(%%edi),%%eax\n\t" + "subl $4,%%edi\n\t" + "bsfl %%eax,%%edx\n" + "1:\tsubl %%ebx,%%edi\n\t" + "shll $3,%%edi\n\t" + "addl %%edi,%%edx" + :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2) + :"1" ((size + 31) >> 5), "2" (addr), "b" (addr)); + return res; +} + +/** + * find_next_zero_bit - find the first zero bit in a memory region + * @addr: The address to base the search on + * @offset: The bitnumber to start searching at + * @size: The maximum size to search + */ +static __inline__ int find_next_zero_bit (void * addr, int size, int offset) +{ + unsigned long * p = ((unsigned long *) addr) + (offset >> 5); + int set = 0, bit = offset & 31, res; + + if (bit) { + /* + * Look for zero in first byte + */ + __asm__("bsfl %1,%0\n\t" + "jne 1f\n\t" + "movl $32, %0\n" + "1:" + : "=r" (set) + : "r" (~(*p >> bit))); + if (set < (32 - bit)) + return set + offset; + set = 32 - bit; + p++; + } + /* + * No zero yet, search remaining full bytes for a zero + */ + res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr)); + return (offset + set + res); +} + +/** + * ffz - find first zero in word. + * @word: The word to search + * + * Undefined if no zero exists, so code should check against ~0UL first. + */ +static __inline__ unsigned long ffz(unsigned long word) +{ + __asm__("bsfl %1,%0" + :"=r" (word) + :"r" (~word)); + return word; +} + +#ifdef __KERNEL__ + +/** + * ffs - find first bit set + * @x: the word to search + * + * 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(int x) +{ + int r; + + __asm__("bsfl %1,%0\n\t" + "jnz 1f\n\t" + "movl $-1,%0\n" + "1:" : "=r" (r) : "g" (x)); + return r+1; +} + +/** + * hweightN - returns the hamming weight of a N-bit word + * @x: the word to weigh + * + * The Hamming Weight of a number is the total number of bits set in it. + */ + +#define hweight32(x) generic_hweight32(x) +#define hweight16(x) generic_hweight16(x) +#define hweight8(x) generic_hweight8(x) + +#endif /* __KERNEL__ */ + +#ifdef __KERNEL__ + +#define ext2_set_bit __test_and_set_bit +#define ext2_clear_bit __test_and_clear_bit +#define ext2_test_bit test_bit +#define ext2_find_first_zero_bit find_first_zero_bit +#define ext2_find_next_zero_bit find_next_zero_bit + +/* Bitmap functions for the minix filesystem. */ +#define minix_test_and_set_bit(nr,addr) __test_and_set_bit(nr,addr) +#define minix_set_bit(nr,addr) __set_bit(nr,addr) +#define minix_test_and_clear_bit(nr,addr) __test_and_clear_bit(nr,addr) +#define minix_test_bit(nr,addr) test_bit(nr,addr) +#define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size) + +#endif /* __KERNEL__ */ + +#endif /* _I386_BITOPS_H */ |