arch/powerpc/lib/bitops.c

   1 #include <linux/types.h>
   2 #include <linux/module.h>
   3 #include <asm/byteorder.h>
   4 #include <asm/bitops.h>
   5
   6 /**
   7  * find_next_bit - find the next set bit in a memory region
   8  * @addr: The address to base the search on
   9  * @offset: The bitnumber to start searching at
  10  * @size: The maximum size to search
  11  */
  12 unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
  13                             unsigned long offset)
  14 {
  15         const unsigned long *p = addr + BITOP_WORD(offset);
  16         unsigned long result = offset & ~(BITS_PER_LONG-1);
  17         unsigned long tmp;
  18
  19         if (offset >= size)
  20                 return size;
  21         size -= result;
  22         offset %= BITS_PER_LONG;
  23         if (offset) {
  24                 tmp = *(p++);
  25                 tmp &= (~0UL << offset);
  26                 if (size < BITS_PER_LONG)
  27                         goto found_first;
  28                 if (tmp)
  29                         goto found_middle;
  30                 size -= BITS_PER_LONG;
  31                 result += BITS_PER_LONG;
  32         }
  33         while (size & ~(BITS_PER_LONG-1)) {
  34                 if ((tmp = *(p++)))
  35                         goto found_middle;
  36                 result += BITS_PER_LONG;
  37                 size -= BITS_PER_LONG;
  38         }
  39         if (!size)
  40                 return result;
  41         tmp = *p;
  42
  43 found_first:
  44         tmp &= (~0UL >> (BITS_PER_LONG - size));
  45         if (tmp == 0UL)         /* Are any bits set? */
  46                 return result + size;   /* Nope. */
  47 found_middle:
  48         return result + __ffs(tmp);
  49 }
  50 EXPORT_SYMBOL(find_next_bit);
  51
  52 /*
  53  * This implementation of find_{first,next}_zero_bit was stolen from
  54  * Linus' asm-alpha/bitops.h.
  55  */
  56 unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
  57                                  unsigned long offset)
  58 {
  59         const unsigned long *p = addr + BITOP_WORD(offset);
  60         unsigned long result = offset & ~(BITS_PER_LONG-1);
  61         unsigned long tmp;
  62
  63         if (offset >= size)
  64                 return size;
  65         size -= result;
  66         offset %= BITS_PER_LONG;
  67         if (offset) {
  68                 tmp = *(p++);
  69                 tmp |= ~0UL >> (BITS_PER_LONG - offset);
  70                 if (size < BITS_PER_LONG)
  71                         goto found_first;
  72                 if (~tmp)
  73                         goto found_middle;
  74                 size -= BITS_PER_LONG;
  75                 result += BITS_PER_LONG;
  76         }
  77         while (size & ~(BITS_PER_LONG-1)) {
  78                 if (~(tmp = *(p++)))
  79                         goto found_middle;
  80                 result += BITS_PER_LONG;
  81                 size -= BITS_PER_LONG;
  82         }
  83         if (!size)
  84                 return result;
  85         tmp = *p;
  86
  87 found_first:
  88         tmp |= ~0UL << size;
  89         if (tmp == ~0UL)        /* Are any bits zero? */
  90                 return result + size;   /* Nope. */
  91 found_middle:
  92         return result + ffz(tmp);
  93 }
  94 EXPORT_SYMBOL(find_next_zero_bit);
  95
  96 static inline unsigned int ext2_ilog2(unsigned int x)
  97 {
  98         int lz;
  99
 100         asm("cntlzw %0,%1": "=r"(lz):"r"(x));
 101         return 31 - lz;
 102 }
 103
 104 static inline unsigned int ext2_ffz(unsigned int x)
 105 {
 106         u32 rc;
 107         if ((x = ~x) == 0)
 108                 return 32;
 109         rc = ext2_ilog2(x & -x);
 110         return rc;
 111 }
 112
 113 unsigned long find_next_zero_le_bit(const unsigned long *addr,
 114                                     unsigned long size, unsigned long offset)
 115 {
 116         const unsigned int *p = ((const unsigned int *)addr) + (offset >> 5);
 117         unsigned int result = offset & ~31;
 118         unsigned int tmp;
 119
 120         if (offset >= size)
 121                 return size;
 122         size -= result;
 123         offset &= 31;
 124         if (offset) {
 125                 tmp = cpu_to_le32p(p++);
 126                 tmp |= ~0U >> (32 - offset);    /* bug or feature ? */
 127                 if (size < 32)
 128                         goto found_first;
 129                 if (tmp != ~0)
 130                         goto found_middle;
 131                 size -= 32;
 132                 result += 32;
 133         }
 134         while (size >= 32) {
 135                 if ((tmp = cpu_to_le32p(p++)) != ~0)
 136                         goto found_middle;
 137                 result += 32;
 138                 size -= 32;
 139         }
 140         if (!size)
 141                 return result;
 142         tmp = cpu_to_le32p(p);
 143 found_first:
 144         tmp |= ~0 << size;
 145         if (tmp == ~0)          /* Are any bits zero? */
 146                 return result + size;   /* Nope. */
 147 found_middle:
 148         return result + ext2_ffz(tmp);
 149 }
 150 EXPORT_SYMBOL(find_next_zero_le_bit);