include/asm-generic/word-at-a-time.h

   1 #ifndef _ASM_WORD_AT_A_TIME_H
   2 #define _ASM_WORD_AT_A_TIME_H
   3
   4 /*
   5  * This says "generic", but it's actually big-endian only.
   6  * Little-endian can use more efficient versions of these
   7  * interfaces, see for example
   8  *       arch/x86/include/asm/word-at-a-time.h
   9  * for those.
  10  */
  11
  12 #include <linux/kernel.h>
  13
  14 struct word_at_a_time {
  15         const unsigned long high_bits, low_bits;
  16 };
  17
  18 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
  19
  20 /* Bit set in the bytes that have a zero */
  21 static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
  22 {
  23         unsigned long mask = (val & c->low_bits) + c->low_bits;
  24         return ~(mask | rhs);
  25 }
  26
  27 #define create_zero_mask(mask) (mask)
  28
  29 static inline long find_zero(unsigned long mask)
  30 {
  31         long byte = 0;
  32 #ifdef CONFIG_64BIT
  33         if (mask >> 32)
  34                 mask >>= 32;
  35         else
  36                 byte = 4;
  37 #endif
  38         if (mask >> 16)
  39                 mask >>= 16;
  40         else
  41                 byte += 2;
  42         return (mask >> 8) ? byte : byte + 1;
  43 }
  44
  45 static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
  46 {
  47         unsigned long rhs = val | c->low_bits;
  48         *data = rhs;
  49         return (val + c->high_bits) & ~rhs;
  50 }
  51
  52 #ifndef zero_bytemask
  53 #ifdef CONFIG_64BIT
  54 #define zero_bytemask(mask)     (~0ul << fls64(mask))
  55 #else
  56 #define zero_bytemask(mask)     (~0ul << fls(mask))
  57 #endif /* CONFIG_64BIT */
  58 #endif /* zero_bytemask */
  59
  60 #endif /* _ASM_WORD_AT_A_TIME_H */