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kernel/linux-imx6_3.14.28/include/asm-generic/word-at-a-time.h 1.24 KB
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  #ifndef _ASM_WORD_AT_A_TIME_H
  #define _ASM_WORD_AT_A_TIME_H
  
  /*
   * This says "generic", but it's actually big-endian only.
   * Little-endian can use more efficient versions of these
   * interfaces, see for example
   *	 arch/x86/include/asm/word-at-a-time.h
   * for those.
   */
  
  #include <linux/kernel.h>
  
  struct word_at_a_time {
  	const unsigned long high_bits, low_bits;
  };
  
  #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
  
  /* Bit set in the bytes that have a zero */
  static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
  {
  	unsigned long mask = (val & c->low_bits) + c->low_bits;
  	return ~(mask | rhs);
  }
  
  #define create_zero_mask(mask) (mask)
  
  static inline long find_zero(unsigned long mask)
  {
  	long byte = 0;
  #ifdef CONFIG_64BIT
  	if (mask >> 32)
  		mask >>= 32;
  	else
  		byte = 4;
  #endif
  	if (mask >> 16)
  		mask >>= 16;
  	else
  		byte += 2;
  	return (mask >> 8) ? byte : byte + 1;
  }
  
  static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
  {
  	unsigned long rhs = val | c->low_bits;
  	*data = rhs;
  	return (val + c->high_bits) & ~rhs;
  }
  
  #ifndef zero_bytemask
  #define zero_bytemask(mask) (~0ul << __fls(mask) << 1)
  #endif
  
  #endif /* _ASM_WORD_AT_A_TIME_H */