1 #ifndef _ASM_GENERIC_BITOPS_H_ 2 #define _ASM_GENERIC_BITOPS_H_ 3 4 /* 5 * For the benefit of those who are trying to port Linux to another 6 * architecture, here are some C-language equivalents. You should 7 * recode these in the native assembly language, if at all possible. 8 * To guarantee atomicity, these routines call cli() and sti() to 9 * disable interrupts while they operate. (You have to provide inline 10 * routines to cli() and sti().) 11 * 12 * Also note, these routines assume that you have 32 bit longs. 13 * You will have to change this if you are trying to port Linux to the 14 * Alpha architecture or to a Cray. :-) 15 * 16 * C language equivalents written by Theodore Ts'o, 9/26/92 17 */ 18 19 extern __inline__ int set_bit(int nr,long * addr) 20 { 21 int mask, retval; 22 23 addr += nr >> 5; 24 mask = 1 << (nr & 0x1f); 25 cli(); 26 retval = (mask & *addr) != 0; 27 *addr |= mask; 28 sti(); 29 return retval; 30 } 31 32 extern __inline__ int clear_bit(int nr, long * addr) 33 { 34 int mask, retval; 35 36 addr += nr >> 5; 37 mask = 1 << (nr & 0x1f); 38 cli(); 39 retval = (mask & *addr) != 0; 40 *addr &= ~mask; 41 sti(); 42 return retval; 43 } 44 45 extern __inline__ int test_bit(int nr, const unsigned long * addr) 46 { 47 int mask; 48 49 addr += nr >> 5; 50 mask = 1 << (nr & 0x1f); 51 return ((mask & *addr) != 0); 52 } 53 54 /* 55 * fls: find last bit set. 56 */ 57 58 #define fls(x) generic_fls(x) 59 60 #ifdef __KERNEL__ 61 62 /* 63 * ffs: find first bit set. This is defined the same way as 64 * the libc and compiler builtin ffs routines, therefore 65 * differs in spirit from the above ffz (man ffs). 66 */ 67 68 #define ffs(x) generic_ffs(x) 69 70 /* 71 * hweightN: returns the hamming weight (i.e. the number 72 * of bits set) of a N-bit word 73 */ 74 75 #define hweight32(x) generic_hweight32(x) 76 #define hweight16(x) generic_hweight16(x) 77 #define hweight8(x) generic_hweight8(x) 78 79 #endif /* __KERNEL__ */ 80 81 #endif /* _ASM_GENERIC_BITOPS_H */ 82