Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* asm/arch/bitops.h for Linux/CRISv10 */ |
| 2 | |
| 3 | #ifndef _CRIS_ARCH_BITOPS_H |
| 4 | #define _CRIS_ARCH_BITOPS_H |
| 5 | |
| 6 | /* |
| 7 | * Helper functions for the core of the ff[sz] functions, wrapping the |
| 8 | * syntactically awkward asms. The asms compute the number of leading |
| 9 | * zeroes of a bits-in-byte and byte-in-word and word-in-dword-swapped |
| 10 | * number. They differ in that the first function also inverts all bits |
| 11 | * in the input. |
| 12 | */ |
| 13 | extern inline unsigned long cris_swapnwbrlz(unsigned long w) |
| 14 | { |
| 15 | /* Let's just say we return the result in the same register as the |
| 16 | input. Saying we clobber the input but can return the result |
| 17 | in another register: |
| 18 | ! __asm__ ("swapnwbr %2\n\tlz %2,%0" |
| 19 | ! : "=r,r" (res), "=r,X" (dummy) : "1,0" (w)); |
| 20 | confuses gcc (sched.c, gcc from cris-dist-1.14). */ |
| 21 | |
| 22 | unsigned long res; |
| 23 | __asm__ ("swapnwbr %0 \n\t" |
| 24 | "lz %0,%0" |
| 25 | : "=r" (res) : "0" (w)); |
| 26 | return res; |
| 27 | } |
| 28 | |
| 29 | extern inline unsigned long cris_swapwbrlz(unsigned long w) |
| 30 | { |
| 31 | unsigned res; |
| 32 | __asm__ ("swapwbr %0 \n\t" |
| 33 | "lz %0,%0" |
| 34 | : "=r" (res) |
| 35 | : "0" (w)); |
| 36 | return res; |
| 37 | } |
| 38 | |
| 39 | /* |
| 40 | * ffz = Find First Zero in word. Undefined if no zero exists, |
| 41 | * so code should check against ~0UL first.. |
| 42 | */ |
| 43 | extern inline unsigned long ffz(unsigned long w) |
| 44 | { |
| 45 | return cris_swapnwbrlz(w); |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * __ffs - find first bit in word. |
| 50 | * @word: The word to search |
| 51 | * |
| 52 | * Undefined if no bit exists, so code should check against 0 first. |
| 53 | */ |
Mikael Starvik | 5d01e6c | 2005-07-27 11:44:43 -0700 | [diff] [blame] | 54 | extern inline unsigned long __ffs(unsigned long word) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 55 | { |
| 56 | return cris_swapnwbrlz(~word); |
| 57 | } |
| 58 | |
| 59 | /** |
| 60 | * ffs - find first bit set |
| 61 | * @x: the word to search |
| 62 | * |
| 63 | * 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 | extern inline unsigned long kernel_ffs(unsigned long w) |
| 69 | { |
| 70 | return w ? cris_swapwbrlz (w) + 1 : 0; |
| 71 | } |
| 72 | |
| 73 | #endif |