include/asm-arm/bitops.h

   1 /*
   2  * Copyright 1995, Russell King.
   3  * Various bits and pieces copyrights include:
   4  *  Linus Torvalds (test_bit).
   5  *
   6  * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
   7  *
   8  * Please note that the code in this file should never be included
   9  * from user space.  Many of these are not implemented in assembler
  10  * since they would be too costly.  Also, they require priviledged
  11  * instructions (which are not available from user mode) to ensure
  12  * that they are atomic.
  13  */
  14
  15 #ifndef __ASM_ARM_BITOPS_H
  16 #define __ASM_ARM_BITOPS_H
  17
  18 #ifdef __KERNEL__
  19
  20 /*
  21  * Function prototypes to keep gcc -Wall happy.
  22  */
  23 extern void set_bit(int nr, volatile void * addr);
  24 extern void clear_bit(int nr, volatile void * addr);
  25 extern void change_bit(int nr, volatile void * addr);
  26
  27 extern int test_and_set_bit(int nr, volatile void * addr);
  28 extern int test_and_clear_bit(int nr, volatile void * addr);
  29 extern int test_and_change_bit(int nr, volatile void * addr);
  30 extern int find_first_zero_bit(void * addr, unsigned size);
  31 extern int find_next_zero_bit(void * addr, int size, int offset);
  32
  33 /*
  34  * This routine doesn't need to be atomic.
  35  */
  36 extern __inline__ int test_bit(int nr, const void * addr)
  37 {
  38     return ((unsigned char *) addr)[nr >> 3] & (1U << (nr & 7));
  39 }
  40
  41 /*
  42  * ffz = Find First Zero in word. Undefined if no zero exists,
  43  * so code should check against ~0UL first..
  44  */
  45 extern __inline__ unsigned long ffz(unsigned long word)
  46 {
  47         int k;
  48
  49         word = ~word;
  50         k = 31;
  51         if (word & 0x0000ffff) { k -= 16; word <<= 16; }
  52         if (word & 0x00ff0000) { k -= 8;  word <<= 8;  }
  53         if (word & 0x0f000000) { k -= 4;  word <<= 4;  }
  54         if (word & 0x30000000) { k -= 2;  word <<= 2;  }
  55         if (word & 0x40000000) { k -= 1; }
  56         return k;
  57 }
  58
  59 /*
  60  * ffs: find first bit set. This is defined the same way as
  61  * the libc and compiler builtin ffs routines, therefore
  62  * differs in spirit from the above ffz (man ffs).
  63  */
  64
  65 #define ffs(x) generic_ffs(x)
  66
  67 /*
  68  * hweightN: returns the hamming weight (i.e. the number
  69  * of bits set) of a N-bit word
  70  */
  71
  72 #define hweight32(x) generic_hweight32(x)
  73 #define hweight16(x) generic_hweight16(x)
  74 #define hweight8(x) generic_hweight8(x)
  75
  76 #define ext2_set_bit                    test_and_set_bit
  77 #define ext2_clear_bit                  test_and_clear_bit
  78 #define ext2_test_bit                   test_bit
  79 #define ext2_find_first_zero_bit        find_first_zero_bit
  80 #define ext2_find_next_zero_bit         find_next_zero_bit
  81
  82 /* Bitmap functions for the minix filesystem. */
  83 #define minix_test_and_set_bit(nr,addr) test_and_set_bit(nr,addr)
  84 #define minix_set_bit(nr,addr)          set_bit(nr,addr)
  85 #define minix_test_and_clear_bit(nr,addr)       test_and_clear_bit(nr,addr)
  86 #define minix_test_bit(nr,addr)         test_bit(nr,addr)
  87 #define minix_find_first_zero_bit(addr,size)    find_first_zero_bit(addr,size)
  88
  89 #endif /* __KERNEL__ */
  90
  91 #endif /* _ARM_BITOPS_H */