diff options
Diffstat (limited to 'linux/src/include/asm-i386/bitops.h')
| -rw-r--r-- | linux/src/include/asm-i386/bitops.h | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/linux/src/include/asm-i386/bitops.h b/linux/src/include/asm-i386/bitops.h new file mode 100644 index 0000000..e2a4c14 --- /dev/null +++ b/linux/src/include/asm-i386/bitops.h @@ -0,0 +1,201 @@ +#ifndef _I386_BITOPS_H +#define _I386_BITOPS_H + +/* + * Copyright 1992, Linus Torvalds. + */ + +/* + * 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 __SMP__ +#define LOCK_PREFIX "lock ; " +#define SMPVOL volatile +#else +#define LOCK_PREFIX "" +#define SMPVOL +#endif + +/* + * Some hacks to defeat gcc over-optimizations.. + */ +struct __dummy { unsigned long a[100]; }; +#define ADDR (*(struct __dummy *) addr) +#define CONST_ADDR (*(const struct __dummy *) addr) + +static __inline__ int set_bit(int nr, SMPVOL void * addr) +{ + int oldbit; + + __asm__ __volatile__(LOCK_PREFIX + "btsl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"ir" (nr)); + return oldbit; +} + +static __inline__ int clear_bit(int nr, SMPVOL void * addr) +{ + int oldbit; + + __asm__ __volatile__(LOCK_PREFIX + "btrl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"ir" (nr)); + return oldbit; +} + +static __inline__ int change_bit(int nr, SMPVOL void * addr) +{ + int oldbit; + + __asm__ __volatile__(LOCK_PREFIX + "btcl %2,%1\n\tsbbl %0,%0" + :"=r" (oldbit),"=m" (ADDR) + :"ir" (nr)); + return oldbit; +} + +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)); + return oldbit; +} + +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)); + return oldbit; +} + +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)); + return oldbit; +} + + +/* + * This routine doesn't need to be atomic. + */ +static __inline__ int test_bit(int nr, const SMPVOL void * addr) +{ + return ((1UL << (nr & 31)) & (((const unsigned int *) addr)[nr >> 5])) != 0; +} + +/* + * Find-bit routines.. + */ +static __inline__ int find_first_zero_bit(void * addr, unsigned size) +{ + int d0, d1, d2; + int res; + + if (!size) + return 0; + __asm__("cld\n\t" + "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; +} + +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. 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. 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 (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) + +#endif /* __KERNEL__ */ + +#endif /* _I386_BITOPS_H */ |