include/asm-arm/bitops.h

   1 /*
   2  * Copyright 1995, Russell King.
   3  * Various bits and pieces copyrights include:
   4  *  Linus Torvalds (test_bit).
   5  * Big endian support: Copyright 2001, Nicolas Pitre
   6  *  reworked by rmk.
   7  *
   8  * bit 0 is the LSB of an "unsigned long" quantity.
   9  *
  10  * Please note that the code in this file should never be included
  11  * from user space.  Many of these are not implemented in assembler
  12  * since they would be too costly.  Also, they require priviledged
  13  * instructions (which are not available from user mode) to ensure
  14  * that they are atomic.
  15  */
  16
  17 #ifndef __ASM_ARM_BITOPS_H
  18 #define __ASM_ARM_BITOPS_H
  19
  20 #ifdef __KERNEL__
  21
  22 #include <asm/system.h>
  23
  24 #define smp_mb__before_clear_bit()      do { } while (0)
  25 #define smp_mb__after_clear_bit()       do { } while (0)
  26
  27 /*
  28  * These functions are the basis of our bit ops.
  29  *
  30  * First, the atomic bitops. These use native endian.
  31  */
  32 static inline void ____atomic_set_bit(unsigned int bit, unsigned long *p)
  33 {
  34         unsigned long flags;
  35         unsigned long mask = 1UL << (bit & 31);
  36
  37         p += bit >> 5;
  38
  39         local_irq_save(flags);
  40         *p |= mask;
  41         local_irq_restore(flags);
  42 }
  43
  44 static inline void ____atomic_clear_bit(unsigned int bit, unsigned long *p)
  45 {
  46         unsigned long flags;
  47         unsigned long mask = 1UL << (bit & 31);
  48
  49         p += bit >> 5;
  50
  51         local_irq_save(flags);
  52         *p &= ~mask;
  53         local_irq_restore(flags);
  54 }
  55
  56 static inline void ____atomic_change_bit(unsigned int bit, unsigned long *p)
  57 {
  58         unsigned long flags;
  59         unsigned long mask = 1UL << (bit & 31);
  60
  61         p += bit >> 5;
  62
  63         local_irq_save(flags);
  64         *p ^= mask;
  65         local_irq_restore(flags);
  66 }
  67
  68 static inline int
  69 ____atomic_test_and_set_bit(unsigned int bit, unsigned long *p)
  70 {
  71         unsigned long flags;
  72         unsigned int res;
  73         unsigned long mask = 1UL << (bit & 31);
  74
  75         p += bit >> 5;
  76
  77         local_irq_save(flags);
  78         res = *p;
  79         *p = res | mask;
  80         local_irq_restore(flags);
  81
  82         return res & mask;
  83 }
  84
  85 static inline int
  86 ____atomic_test_and_clear_bit(unsigned int bit, unsigned long *p)
  87 {
  88         unsigned long flags;
  89         unsigned int res;
  90         unsigned long mask = 1UL << (bit & 31);
  91
  92         p += bit >> 5;
  93
  94         local_irq_save(flags);
  95         res = *p;
  96         *p = res & ~mask;
  97         local_irq_restore(flags);
  98
  99         return res & mask;
 100 }
 101
 102 static inline int
 103 ____atomic_test_and_change_bit(unsigned int bit, unsigned long *p)
 104 {
 105         unsigned long flags;
 106         unsigned int res;
 107         unsigned long mask = 1UL << (bit & 31);
 108
 109         p += bit >> 5;
 110
 111         local_irq_save(flags);
 112         res = *p;
 113         *p = res ^ mask;
 114         local_irq_restore(flags);
 115
 116         return res & mask;
 117 }
 118
 119 /*
 120  * Now the non-atomic variants.  We let the compiler handle all
 121  * optimisations for these.  These are all _native_ endian.
 122  */
 123 static inline void __set_bit(int nr, volatile unsigned long *p)
 124 {
 125         p[nr >> 5] |= (1UL << (nr & 31));
 126 }
 127
 128 static inline void __clear_bit(int nr, volatile unsigned long *p)
 129 {
 130         p[nr >> 5] &= ~(1UL << (nr & 31));
 131 }
 132
 133 static inline void __change_bit(int nr, volatile unsigned long *p)
 134 {
 135         p[nr >> 5] ^= (1UL << (nr & 31));
 136 }
 137
 138 static inline int __test_and_set_bit(int nr, volatile unsigned long *p)
 139 {
 140         unsigned long oldval, mask = 1UL << (nr & 31);
 141
 142         p += nr >> 5;
 143
 144         oldval = *p;
 145         *p = oldval | mask;
 146         return oldval & mask;
 147 }
 148
 149 static inline int __test_and_clear_bit(int nr, volatile unsigned long *p)
 150 {
 151         unsigned long oldval, mask = 1UL << (nr & 31);
 152
 153         p += nr >> 5;
 154
 155         oldval = *p;
 156         *p = oldval & ~mask;
 157         return oldval & mask;
 158 }
 159
 160 static inline int __test_and_change_bit(int nr, volatile unsigned long *p)
 161 {
 162         unsigned long oldval, mask = 1UL << (nr & 31);
 163
 164         p += nr >> 5;
 165
 166         oldval = *p;
 167         *p = oldval ^ mask;
 168         return oldval & mask;
 169 }
 170
 171 /*
 172  * This routine doesn't need to be atomic.
 173  */
 174 static inline int __test_bit(int nr, const unsigned long * p)
 175 {
 176         return p[nr >> 5] & (1UL << (nr & 31));
 177 }
 178
 179 /*
 180  *  A note about Endian-ness.
 181  *  -------------------------
 182  *
 183  * When the ARM is put into big endian mode via CR15, the processor
 184  * merely swaps the order of bytes within words, thus:
 185  *
 186  *          ------------ physical data bus bits -----------
 187  *          D31 ... D24  D23 ... D16  D15 ... D8  D7 ... D0
 188  * little     byte 3       byte 2       byte 1      byte 0
 189  * big        byte 0       byte 1       byte 2      byte 3
 190  *
 191  * This means that reading a 32-bit word at address 0 returns the same
 192  * value irrespective of the endian mode bit.
 193  *
 194  * Peripheral devices should be connected with the data bus reversed in
 195  * "Big Endian" mode.  ARM Application Note 61 is applicable, and is
 196  * available from http://www.arm.com/.
 197  *
 198  * The following assumes that the data bus connectivity for big endian
 199  * mode has been followed.
 200  *
 201  * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
 202  */
 203
 204 /*
 205  * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
 206  */
 207 extern void _set_bit_le(int nr, unsigned long * p);
 208 extern void _clear_bit_le(int nr, unsigned long * p);
 209 extern void _change_bit_le(int nr, unsigned long * p);
 210 extern int _test_and_set_bit_le(int nr, unsigned long * p);
 211 extern int _test_and_clear_bit_le(int nr, unsigned long * p);
 212 extern int _test_and_change_bit_le(int nr, unsigned long * p);
 213 extern int _find_first_zero_bit_le(void * p, unsigned size);
 214 extern int _find_next_zero_bit_le(void * p, int size, int offset);
 215
 216 /*
 217  * Big endian assembly bitops.  nr = 0 -> byte 3 bit 0.
 218  */
 219 extern void _set_bit_be(int nr, unsigned long * p);
 220 extern void _clear_bit_be(int nr, unsigned long * p);
 221 extern void _change_bit_be(int nr, unsigned long * p);
 222 extern int _test_and_set_bit_be(int nr, unsigned long * p);
 223 extern int _test_and_clear_bit_be(int nr, unsigned long * p);
 224 extern int _test_and_change_bit_be(int nr, unsigned long * p);
 225 extern int _find_first_zero_bit_be(void * p, unsigned size);
 226 extern int _find_next_zero_bit_be(void * p, int size, int offset);
 227
 228
 229 /*
 230  * The __* form of bitops are non-atomic and may be reordered.
 231  */
 232 #define ATOMIC_BITOP_LE(name,nr,p)              \
 233         (__builtin_constant_p(nr) ?             \
 234          ____atomic_##name(nr, p) :             \
 235          _##name##_le(nr,p))
 236
 237 #define ATOMIC_BITOP_BE(name,nr,p)              \
 238         (__builtin_constant_p(nr) ?             \
 239          ____atomic_##name(nr, p) :             \
 240          _##name##_be(nr,p))
 241
 242 #define NONATOMIC_BITOP(name,nr,p)              \
 243         (____nonatomic_##name(nr, p))
 244
 245 #ifndef __ARMEB__
 246 /*
 247  * These are the little endian, atomic definitions.
 248  */
 249 #define set_bit(nr,p)                   ATOMIC_BITOP_LE(set_bit,nr,p)
 250 #define clear_bit(nr,p)                 ATOMIC_BITOP_LE(clear_bit,nr,p)
 251 #define change_bit(nr,p)                ATOMIC_BITOP_LE(change_bit,nr,p)
 252 #define test_and_set_bit(nr,p)          ATOMIC_BITOP_LE(test_and_set_bit,nr,p)
 253 #define test_and_clear_bit(nr,p)        ATOMIC_BITOP_LE(test_and_clear_bit,nr,p)
 254 #define test_and_change_bit(nr,p)       ATOMIC_BITOP_LE(test_and_change_bit,nr,p)
 255 #define test_bit(nr,p)                  __test_bit(nr,p)
 256 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_le(p,sz)
 257 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_le(p,sz,off)
 258
 259 #define WORD_BITOFF_TO_LE(x)            ((x))
 260
 261 #else
 262
 263 /*
 264  * These are the big endian, atomic definitions.
 265  */
 266 #define set_bit(nr,p)                   ATOMIC_BITOP_BE(set_bit,nr,p)
 267 #define clear_bit(nr,p)                 ATOMIC_BITOP_BE(clear_bit,nr,p)
 268 #define change_bit(nr,p)                ATOMIC_BITOP_BE(change_bit,nr,p)
 269 #define test_and_set_bit(nr,p)          ATOMIC_BITOP_BE(test_and_set_bit,nr,p)
 270 #define test_and_clear_bit(nr,p)        ATOMIC_BITOP_BE(test_and_clear_bit,nr,p)
 271 #define test_and_change_bit(nr,p)       ATOMIC_BITOP_BE(test_and_change_bit,nr,p)
 272 #define test_bit(nr,p)                  __test_bit(nr,p)
 273 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_be(p,sz)
 274 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_be(p,sz,off)
 275
 276 #define WORD_BITOFF_TO_LE(x)            ((x) ^ 0x18)
 277
 278 #endif
 279
 280 /*
 281  * ffz = Find First Zero in word. Undefined if no zero exists,
 282  * so code should check against ~0UL first..
 283  */
 284 static inline unsigned long ffz(unsigned long word)
 285 {
 286         int k;
 287
 288         word = ~word;
 289         k = 31;
 290         if (word & 0x0000ffff) { k -= 16; word <<= 16; }
 291         if (word & 0x00ff0000) { k -= 8;  word <<= 8;  }
 292         if (word & 0x0f000000) { k -= 4;  word <<= 4;  }
 293         if (word & 0x30000000) { k -= 2;  word <<= 2;  }
 294         if (word & 0x40000000) { k -= 1; }
 295         return k;
 296 }
 297
 298 /*
 299  * ffz = Find First Zero in word. Undefined if no zero exists,
 300  * so code should check against ~0UL first..
 301  */
 302 static inline unsigned long __ffs(unsigned long word)
 303 {
 304         int k;
 305
 306         k = 31;
 307         if (word & 0x0000ffff) { k -= 16; word <<= 16; }
 308         if (word & 0x00ff0000) { k -= 8;  word <<= 8;  }
 309         if (word & 0x0f000000) { k -= 4;  word <<= 4;  }
 310         if (word & 0x30000000) { k -= 2;  word <<= 2;  }
 311         if (word & 0x40000000) { k -= 1; }
 312         return k;
 313 }
 314
 315 /*
 316  * fls: find last bit set.
 317  */
 318
 319 #define fls(x) generic_fls(x)
 320
 321 /*
 322  * ffs: find first bit set. This is defined the same way as
 323  * the libc and compiler builtin ffs routines, therefore
 324  * differs in spirit from the above ffz (man ffs).
 325  */
 326
 327 #define ffs(x) generic_ffs(x)
 328
 329 /*
 330  * Find first bit set in a 168-bit bitmap, where the first
 331  * 128 bits are unlikely to be set.
 332  */
 333 static inline int sched_find_first_bit(unsigned long *b)
 334 {
 335         unsigned long v;
 336         unsigned int off;
 337
 338         for (off = 0; v = b[off], off < 4; off++) {
 339                 if (unlikely(v))
 340                         break;
 341         }
 342         return __ffs(v) + off * 32;
 343 }
 344
 345 /*
 346  * hweightN: returns the hamming weight (i.e. the number
 347  * of bits set) of a N-bit word
 348  */
 349
 350 #define hweight32(x) generic_hweight32(x)
 351 #define hweight16(x) generic_hweight16(x)
 352 #define hweight8(x) generic_hweight8(x)
 353
 354 /*
 355  * Ext2 is defined to use little-endian byte ordering.
 356  * These do not need to be atomic.
 357  */
 358 #define ext2_set_bit(nr,p)                      \
 359                 __test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 360 #define ext2_clear_bit(nr,p)                    \
 361                 __test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 362 #define ext2_test_bit(nr,p)                     \
 363                 __test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 364 #define ext2_find_first_zero_bit(p,sz)          \
 365                 _find_first_zero_bit_le(p,sz)
 366 #define ext2_find_next_zero_bit(p,sz,off)       \
 367                 _find_next_zero_bit_le(p,sz,off)
 368
 369 /*
 370  * Minix is defined to use little-endian byte ordering.
 371  * These do not need to be atomic.
 372  */
 373 #define minix_set_bit(nr,p)                     \
 374                 __set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 375 #define minix_test_bit(nr,p)                    \
 376                 __test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 377 #define minix_test_and_set_bit(nr,p)            \
 378                 __test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 379 #define minix_test_and_clear_bit(nr,p)          \
 380                 __test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
 381 #define minix_find_first_zero_bit(p,sz)         \
 382                 _find_first_zero_bit_le(p,sz)
 383
 384 #endif /* __KERNEL__ */
 385
 386 #endif /* _ARM_BITOPS_H */