bitops.h 4.0 KB

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  1. /*
  2. * Copyright (c) 2011 The Chromium OS Authors.
  3. *
  4. * Modified from Linux arch/arm/include/asm/bitops.h
  5. *
  6. * Copyright 1995, Russell King.
  7. * Various bits and pieces copyrights include:
  8. * Linus Torvalds (test_bit).
  9. *
  10. * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
  11. *
  12. * Please note that the code in this file should never be included
  13. * from user space. Many of these are not implemented in assembler
  14. * since they would be too costly. Also, they require priviledged
  15. * instructions (which are not available from user mode) to ensure
  16. * that they are atomic.
  17. */
  18. #ifndef __ASM_SANDBOX_BITOPS_H
  19. #define __ASM_SANDBOX_BITOPS_H
  20. #include <linux/compiler.h>
  21. #include <asm/system.h>
  22. #include <asm-generic/bitops/fls.h>
  23. #include <asm-generic/bitops/__fls.h>
  24. #include <asm-generic/bitops/fls64.h>
  25. #include <asm-generic/bitops/__ffs.h>
  26. #ifdef __KERNEL__
  27. #define smp_mb__before_clear_bit() do { } while (0)
  28. #define smp_mb__after_clear_bit() do { } while (0)
  29. /*
  30. * Function prototypes to keep gcc -Wall happy.
  31. */
  32. extern void set_bit(int nr, void *addr);
  33. extern void clear_bit(int nr, void *addr);
  34. extern void change_bit(int nr, void *addr);
  35. static inline void __change_bit(int nr, void *addr)
  36. {
  37. unsigned long mask = BIT_MASK(nr);
  38. unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  39. *p ^= mask;
  40. }
  41. static inline int __test_and_set_bit(int nr, void *addr)
  42. {
  43. unsigned long mask = BIT_MASK(nr);
  44. unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  45. unsigned long old = *p;
  46. *p = old | mask;
  47. return (old & mask) != 0;
  48. }
  49. static inline int test_and_set_bit(int nr, void *addr)
  50. {
  51. unsigned long __always_unused flags;
  52. int out;
  53. local_irq_save(flags);
  54. out = __test_and_set_bit(nr, addr);
  55. local_irq_restore(flags);
  56. return out;
  57. }
  58. static inline int __test_and_clear_bit(int nr, void *addr)
  59. {
  60. unsigned long mask = BIT_MASK(nr);
  61. unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  62. unsigned long old = *p;
  63. *p = old & ~mask;
  64. return (old & mask) != 0;
  65. }
  66. static inline int test_and_clear_bit(int nr, void *addr)
  67. {
  68. unsigned long __always_unused flags;
  69. int out;
  70. local_irq_save(flags);
  71. out = __test_and_clear_bit(nr, addr);
  72. local_irq_restore(flags);
  73. return out;
  74. }
  75. extern int test_and_change_bit(int nr, void *addr);
  76. static inline int __test_and_change_bit(int nr, void *addr)
  77. {
  78. unsigned long mask = BIT_MASK(nr);
  79. unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  80. unsigned long old = *p;
  81. *p = old ^ mask;
  82. return (old & mask) != 0;
  83. }
  84. extern int find_first_zero_bit(void *addr, unsigned size);
  85. extern int find_next_zero_bit(void *addr, int size, int offset);
  86. /*
  87. * This routine doesn't need to be atomic.
  88. */
  89. static inline int test_bit(int nr, const void *addr)
  90. {
  91. return ((unsigned char *) addr)[nr >> 3] & (1U << (nr & 7));
  92. }
  93. /*
  94. * ffz = Find First Zero in word. Undefined if no zero exists,
  95. * so code should check against ~0UL first..
  96. */
  97. static inline unsigned long ffz(unsigned long word)
  98. {
  99. int k;
  100. word = ~word;
  101. k = 31;
  102. if (word & 0x0000ffff) {
  103. k -= 16; word <<= 16;
  104. }
  105. if (word & 0x00ff0000) {
  106. k -= 8; word <<= 8;
  107. }
  108. if (word & 0x0f000000) {
  109. k -= 4; word <<= 4;
  110. }
  111. if (word & 0x30000000) {
  112. k -= 2; word <<= 2;
  113. }
  114. if (word & 0x40000000)
  115. k -= 1;
  116. return k;
  117. }
  118. /*
  119. * hweightN: returns the hamming weight (i.e. the number
  120. * of bits set) of a N-bit word
  121. */
  122. #define hweight32(x) generic_hweight32(x)
  123. #define hweight16(x) generic_hweight16(x)
  124. #define hweight8(x) generic_hweight8(x)
  125. #define ext2_set_bit test_and_set_bit
  126. #define ext2_clear_bit test_and_clear_bit
  127. #define ext2_test_bit test_bit
  128. #define ext2_find_first_zero_bit find_first_zero_bit
  129. #define ext2_find_next_zero_bit find_next_zero_bit
  130. /* Bitmap functions for the minix filesystem. */
  131. #define minix_test_and_set_bit(nr, addr) test_and_set_bit(nr, addr)
  132. #define minix_set_bit(nr, addr) set_bit(nr, addr)
  133. #define minix_test_and_clear_bit(nr, addr) test_and_clear_bit(nr, addr)
  134. #define minix_test_bit(nr, addr) test_bit(nr, addr)
  135. #define minix_find_first_zero_bit(addr, size) find_first_zero_bit(addr, size)
  136. #endif /* __KERNEL__ */
  137. #endif /* _ARM_BITOPS_H */