Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
bitops.h
Go to the documentation of this file.
1 #ifndef _ASM_CRIS_ARCH_BITOPS_H
2 #define _ASM_CRIS_ARCH_BITOPS_H
3 
4 /*
5  * Helper functions for the core of the ff[sz] functions. They compute the
6  * number of leading zeroes of a bits-in-byte, byte-in-word and
7  * word-in-dword-swapped number. They differ in that the first function also
8  * inverts all bits in the input.
9  */
10 
11 static inline unsigned long
12 cris_swapnwbrlz(unsigned long w)
13 {
14  unsigned long res;
15 
16  __asm__ __volatile__ ("swapnwbr %0\n\t"
17  "lz %0,%0"
18  : "=r" (res) : "0" (w));
19 
20  return res;
21 }
22 
23 static inline unsigned long
24 cris_swapwbrlz(unsigned long w)
25 {
26  unsigned long res;
27 
28  __asm__ __volatile__ ("swapwbr %0\n\t"
29  "lz %0,%0"
30  : "=r" (res) : "0" (w));
31 
32  return res;
33 }
34 
35 /*
36  * Find First Zero in word. Undefined if no zero exist, so the caller should
37  * check against ~0 first.
38  */
39 static inline unsigned long
40 ffz(unsigned long w)
41 {
42  return cris_swapnwbrlz(w);
43 }
44 
45 /*
46  * Find First Set bit in word. Undefined if no 1 exist, so the caller
47  * should check against 0 first.
48  */
49 static inline unsigned long
50 __ffs(unsigned long w)
51 {
52  return cris_swapnwbrlz(~w);
53 }
54 
55 /*
56  * Find First Bit that is set.
57  */
58 static inline unsigned long
59 kernel_ffs(unsigned long w)
60 {
61  return w ? cris_swapwbrlz (w) + 1 : 0;
62 }
63 
64 #endif /* _ASM_CRIS_ARCH_BITOPS_H */