LXR uboot/include/linux/bitops.h

   1#ifndef _LINUX_BITOPS_H
   2#define _LINUX_BITOPS_H
   3
   4#include <asm/types.h>
   5
   6/*
   7 * ffs: find first bit set. This is defined the same way as
   8 * the libc and compiler builtin ffs routines, therefore
   9 * differs in spirit from the above ffz (man ffs).
  10 */
  11
  12static inline int generic_ffs(int x)
  13{
  14        int r = 1;
  15
  16        if (!x)
  17                return 0;
  18        if (!(x & 0xffff)) {
  19                x >>= 16;
  20                r += 16;
  21        }
  22        if (!(x & 0xff)) {
  23                x >>= 8;
  24                r += 8;
  25        }
  26        if (!(x & 0xf)) {
  27                x >>= 4;
  28                r += 4;
  29        }
  30        if (!(x & 3)) {
  31                x >>= 2;
  32                r += 2;
  33        }
  34        if (!(x & 1)) {
  35                x >>= 1;
  36                r += 1;
  37        }
  38        return r;
  39}
  40
  41/**
  42 * fls - find last (most-significant) bit set
  43 * @x: the word to search
  44 *
  45 * This is defined the same way as ffs.
  46 * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  47 */
  48static inline int generic_fls(int x)
  49{
  50        int r = 32;
  51
  52        if (!x)
  53                return 0;
  54        if (!(x & 0xffff0000u)) {
  55                x <<= 16;
  56                r -= 16;
  57        }
  58        if (!(x & 0xff000000u)) {
  59                x <<= 8;
  60                r -= 8;
  61        }
  62        if (!(x & 0xf0000000u)) {
  63                x <<= 4;
  64                r -= 4;
  65        }
  66        if (!(x & 0xc0000000u)) {
  67                x <<= 2;
  68                r -= 2;
  69        }
  70        if (!(x & 0x80000000u)) {
  71                x <<= 1;
  72                r -= 1;
  73        }
  74        return r;
  75}
  76
  77
  78/*
  79 * hweightN: returns the hamming weight (i.e. the number
  80 * of bits set) of a N-bit word
  81 */
  82
  83static inline unsigned int generic_hweight32(unsigned int w)
  84{
  85        unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
  86        res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
  87        res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
  88        res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
  89        return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
  90}
  91
  92static inline unsigned int generic_hweight16(unsigned int w)
  93{
  94        unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
  95        res = (res & 0x3333) + ((res >> 2) & 0x3333);
  96        res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
  97        return (res & 0x00FF) + ((res >> 8) & 0x00FF);
  98}
  99
 100static inline unsigned int generic_hweight8(unsigned int w)
 101{
 102        unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
 103        res = (res & 0x33) + ((res >> 2) & 0x33);
 104        return (res & 0x0F) + ((res >> 4) & 0x0F);
 105}
 106
 107#define BIT_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
 108#define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
 109
 110#include <asm/bitops.h>
 111
 112/* linux/include/asm-generic/bitops/non-atomic.h */
 113
 114#ifndef PLATFORM__SET_BIT
 115# define __set_bit generic_set_bit
 116#endif
 117
 118#ifndef PLATFORM__CLEAR_BIT
 119# define __clear_bit generic_clear_bit
 120#endif
 121
 122#ifndef PLATFORM_FFS
 123# define ffs generic_ffs
 124#endif
 125
 126#ifndef PLATFORM_FLS
 127# define fls generic_fls
 128#endif
 129
 130/**
 131 * __set_bit - Set a bit in memory
 132 * @nr: the bit to set
 133 * @addr: the address to start counting from
 134 *
 135 * Unlike set_bit(), this function is non-atomic and may be reordered.
 136 * If it's called on the same region of memory simultaneously, the effect
 137 * may be that only one operation succeeds.
 138 */
 139static inline void generic_set_bit(int nr, volatile unsigned long *addr)
 140{
 141        unsigned long mask = BIT_MASK(nr);
 142        unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
 143
 144        *p  |= mask;
 145}
 146
 147static inline void generic_clear_bit(int nr, volatile unsigned long *addr)
 148{
 149        unsigned long mask = BIT_MASK(nr);
 150        unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
 151
 152        *p &= ~mask;
 153}
 154
 155#endif
 156