1 /* $FreeBSD: src/sys/gnu/ext2fs/i386-bitops.h,v 1.5 1999/11/15 23:16:06 obrien Exp $ */
3 * this is mixture of i386/bitops.h and asm/string.h
4 * taken from the Linux source tree
6 * XXX replace with Mach routines or reprogram in C
8 #ifndef _SYS_GNU_EXT2FS_I386_BITOPS_H_
9 #define _SYS_GNU_EXT2FS_I386_BITOPS_H_
12 * Copyright 1992, Linus Torvalds.
16 * These have to be done with inline assembly: that way the bit-setting
17 * is guaranteed to be atomic. All bit operations return 0 if the bit
18 * was cleared before the operation and != 0 if it was not.
20 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
24 * Some hacks to defeat gcc over-optimizations..
26 struct __dummy { unsigned long a[100]; };
27 #define ADDR (*(struct __dummy *) addr)
29 static __inline__ int set_bit(int nr, void * addr)
33 __asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
34 :"=r" (oldbit),"=m" (ADDR)
39 static __inline__ int clear_bit(int nr, void * addr)
43 __asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
44 :"=r" (oldbit),"=m" (ADDR)
49 static __inline__ int change_bit(int nr, void * addr)
53 __asm__ __volatile__("btcl %2,%1\n\tsbbl %0,%0"
54 :"=r" (oldbit),"=m" (ADDR)
60 * This routine doesn't need to be atomic, but it's faster to code it
63 static __inline__ int test_bit(int nr, void * addr)
67 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
69 :"m" (ADDR),"ir" (nr));
76 static __inline__ int find_first_zero_bit(void * addr, unsigned size)
79 int _count = (size + 31) >> 5;
89 xorl -4(%%edi),%%eax \n\
92 1: subl %%ebx,%%edi \n\
95 : "=c" (_count), "=D" (addr), "=d" (res)
96 : "0" (_count), "1" (addr), "b" (addr)
101 static __inline__ int find_next_zero_bit (void * addr, int size, int offset)
103 unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
104 int set = 0, bit = offset & 31, res;
108 * Look for zero in first byte
116 : "r" (~(*p >> bit)));
117 if (set < (32 - bit))
123 * No zero yet, search remaining full bytes for a zero
125 res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
126 return (offset + set + res);
130 * ffz = Find First Zero in word. Undefined if no zero exists,
131 * so code should check against ~0UL first..
133 static __inline__ unsigned long ffz(unsigned long word)
142 * memscan() taken from linux asm/string.h
145 * find the first occurrence of byte 'c', or 1 past the area if none
147 static __inline__ char * memscan(void * addr, unsigned char c, int size)
157 : "=D" (addr), "=c" (size)
158 : "0" (addr), "1" (size), "a" (c));
162 #endif /* !_SYS_GNU_EXT2FS_I386_BITOPS_H_ */