arch/arm/include/asm/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 privileged
  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 #ifndef _LINUX_BITOPS_H
  23 #error only <linux/bitops.h> can be included directly
  24 #endif
  25
  26 #include <linux/compiler.h>
  27 #include <linux/irqflags.h>
  28 #include <asm/barrier.h>
  29
  30 /*
  31  * These functions are the basis of our bit ops.
  32  *
  33  * First, the atomic bitops. These use native endian.
  34  */
  35 static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
  36 {
  37         unsigned long flags;
  38         unsigned long mask = BIT_MASK(bit);
  39
  40         p += BIT_WORD(bit);
  41
  42         raw_local_irq_save(flags);
  43         *p |= mask;
  44         raw_local_irq_restore(flags);
  45 }
  46
  47 static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
  48 {
  49         unsigned long flags;
  50         unsigned long mask = BIT_MASK(bit);
  51
  52         p += BIT_WORD(bit);
  53
  54         raw_local_irq_save(flags);
  55         *p &= ~mask;
  56         raw_local_irq_restore(flags);
  57 }
  58
  59 static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
  60 {
  61         unsigned long flags;
  62         unsigned long mask = BIT_MASK(bit);
  63
  64         p += BIT_WORD(bit);
  65
  66         raw_local_irq_save(flags);
  67         *p ^= mask;
  68         raw_local_irq_restore(flags);
  69 }
  70
  71 static inline int
  72 ____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
  73 {
  74         unsigned long flags;
  75         unsigned int res;
  76         unsigned long mask = BIT_MASK(bit);
  77
  78         p += BIT_WORD(bit);
  79
  80         raw_local_irq_save(flags);
  81         res = *p;
  82         *p = res | mask;
  83         raw_local_irq_restore(flags);
  84
  85         return (res & mask) != 0;
  86 }
  87
  88 static inline int
  89 ____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
  90 {
  91         unsigned long flags;
  92         unsigned int res;
  93         unsigned long mask = BIT_MASK(bit);
  94
  95         p += BIT_WORD(bit);
  96
  97         raw_local_irq_save(flags);
  98         res = *p;
  99         *p = res & ~mask;
 100         raw_local_irq_restore(flags);
 101
 102         return (res & mask) != 0;
 103 }
 104
 105 static inline int
 106 ____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
 107 {
 108         unsigned long flags;
 109         unsigned int res;
 110         unsigned long mask = BIT_MASK(bit);
 111
 112         p += BIT_WORD(bit);
 113
 114         raw_local_irq_save(flags);
 115         res = *p;
 116         *p = res ^ mask;
 117         raw_local_irq_restore(flags);
 118
 119         return (res & mask) != 0;
 120 }
 121
 122 #include <asm-generic/bitops/non-atomic.h>
 123
 124 /*
 125  *  A note about Endian-ness.
 126  *  -------------------------
 127  *
 128  * When the ARM is put into big endian mode via CR15, the processor
 129  * merely swaps the order of bytes within words, thus:
 130  *
 131  *          ------------ physical data bus bits -----------
 132  *          D31 ... D24  D23 ... D16  D15 ... D8  D7 ... D0
 133  * little     byte 3       byte 2       byte 1      byte 0
 134  * big        byte 0       byte 1       byte 2      byte 3
 135  *
 136  * This means that reading a 32-bit word at address 0 returns the same
 137  * value irrespective of the endian mode bit.
 138  *
 139  * Peripheral devices should be connected with the data bus reversed in
 140  * "Big Endian" mode.  ARM Application Note 61 is applicable, and is
 141  * available from http://www.arm.com/.
 142  *
 143  * The following assumes that the data bus connectivity for big endian
 144  * mode has been followed.
 145  *
 146  * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
 147  */
 148
 149 /*
 150  * Native endian assembly bitops.  nr = 0 -> word 0 bit 0.
 151  */
 152 extern void _set_bit(int nr, volatile unsigned long * p);
 153 extern void _clear_bit(int nr, volatile unsigned long * p);
 154 extern void _change_bit(int nr, volatile unsigned long * p);
 155 extern int _test_and_set_bit(int nr, volatile unsigned long * p);
 156 extern int _test_and_clear_bit(int nr, volatile unsigned long * p);
 157 extern int _test_and_change_bit(int nr, volatile unsigned long * p);
 158
 159 /*
 160  * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
 161  */
 162 extern int _find_first_zero_bit_le(const void * p, unsigned size);
 163 extern int _find_next_zero_bit_le(const void * p, int size, int offset);
 164 extern int _find_first_bit_le(const unsigned long *p, unsigned size);
 165 extern int _find_next_bit_le(const unsigned long *p, int size, int offset);
 166
 167 /*
 168  * Big endian assembly bitops.  nr = 0 -> byte 3 bit 0.
 169  */
 170 extern int _find_first_zero_bit_be(const void * p, unsigned size);
 171 extern int _find_next_zero_bit_be(const void * p, int size, int offset);
 172 extern int _find_first_bit_be(const unsigned long *p, unsigned size);
 173 extern int _find_next_bit_be(const unsigned long *p, int size, int offset);
 174
 175 #ifndef CONFIG_SMP
 176 /*
 177  * The __* form of bitops are non-atomic and may be reordered.
 178  */
 179 #define ATOMIC_BITOP(name,nr,p)                 \
 180         (__builtin_constant_p(nr) ? ____atomic_##name(nr, p) : _##name(nr,p))
 181 #else
 182 #define ATOMIC_BITOP(name,nr,p)         _##name(nr,p)
 183 #endif
 184
 185 /*
 186  * Native endian atomic definitions.
 187  */
 188 #define set_bit(nr,p)                   ATOMIC_BITOP(set_bit,nr,p)
 189 #define clear_bit(nr,p)                 ATOMIC_BITOP(clear_bit,nr,p)
 190 #define change_bit(nr,p)                ATOMIC_BITOP(change_bit,nr,p)
 191 #define test_and_set_bit(nr,p)          ATOMIC_BITOP(test_and_set_bit,nr,p)
 192 #define test_and_clear_bit(nr,p)        ATOMIC_BITOP(test_and_clear_bit,nr,p)
 193 #define test_and_change_bit(nr,p)       ATOMIC_BITOP(test_and_change_bit,nr,p)
 194
 195 #ifndef __ARMEB__
 196 /*
 197  * These are the little endian, atomic definitions.
 198  */
 199 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_le(p,sz)
 200 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_le(p,sz,off)
 201 #define find_first_bit(p,sz)            _find_first_bit_le(p,sz)
 202 #define find_next_bit(p,sz,off)         _find_next_bit_le(p,sz,off)
 203
 204 #else
 205 /*
 206  * These are the big endian, atomic definitions.
 207  */
 208 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_be(p,sz)
 209 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_be(p,sz,off)
 210 #define find_first_bit(p,sz)            _find_first_bit_be(p,sz)
 211 #define find_next_bit(p,sz,off)         _find_next_bit_be(p,sz,off)
 212
 213 #endif
 214
 215 #if __LINUX_ARM_ARCH__ < 5
 216
 217 #include <asm-generic/bitops/ffz.h>
 218 #include <asm-generic/bitops/__fls.h>
 219 #include <asm-generic/bitops/__ffs.h>
 220 #include <asm-generic/bitops/fls.h>
 221 #include <asm-generic/bitops/ffs.h>
 222
 223 #else
 224
 225 static inline int constant_fls(int x)
 226 {
 227         int r = 32;
 228
 229         if (!x)
 230                 return 0;
 231         if (!(x & 0xffff0000u)) {
 232                 x <<= 16;
 233                 r -= 16;
 234         }
 235         if (!(x & 0xff000000u)) {
 236                 x <<= 8;
 237                 r -= 8;
 238         }
 239         if (!(x & 0xf0000000u)) {
 240                 x <<= 4;
 241                 r -= 4;
 242         }
 243         if (!(x & 0xc0000000u)) {
 244                 x <<= 2;
 245                 r -= 2;
 246         }
 247         if (!(x & 0x80000000u)) {
 248                 x <<= 1;
 249                 r -= 1;
 250         }
 251         return r;
 252 }
 253
 254 /*
 255  * On ARMv5 and above those functions can be implemented around the
 256  * clz instruction for much better code efficiency.  __clz returns
 257  * the number of leading zeros, zero input will return 32, and
 258  * 0x80000000 will return 0.
 259  */
 260 static inline unsigned int __clz(unsigned int x)
 261 {
 262         unsigned int ret;
 263
 264         asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
 265
 266         return ret;
 267 }
 268
 269 /*
 270  * fls() returns zero if the input is zero, otherwise returns the bit
 271  * position of the last set bit, where the LSB is 1 and MSB is 32.
 272  */
 273 static inline int fls(int x)
 274 {
 275         if (__builtin_constant_p(x))
 276                return constant_fls(x);
 277
 278         return 32 - __clz(x);
 279 }
 280
 281 /*
 282  * __fls() returns the bit position of the last bit set, where the
 283  * LSB is 0 and MSB is 31.  Zero input is undefined.
 284  */
 285 static inline unsigned long __fls(unsigned long x)
 286 {
 287         return fls(x) - 1;
 288 }
 289
 290 /*
 291  * ffs() returns zero if the input was zero, otherwise returns the bit
 292  * position of the first set bit, where the LSB is 1 and MSB is 32.
 293  */
 294 static inline int ffs(int x)
 295 {
 296         return fls(x & -x);
 297 }
 298
 299 /*
 300  * __ffs() returns the bit position of the first bit set, where the
 301  * LSB is 0 and MSB is 31.  Zero input is undefined.
 302  */
 303 static inline unsigned long __ffs(unsigned long x)
 304 {
 305         return ffs(x) - 1;
 306 }
 307
 308 #define ffz(x) __ffs( ~(x) )
 309
 310 #endif
 311
 312 #include <asm-generic/bitops/fls64.h>
 313
 314 #include <asm-generic/bitops/sched.h>
 315 #include <asm-generic/bitops/hweight.h>
 316 #include <asm-generic/bitops/lock.h>
 317
 318 #ifdef __ARMEB__
 319
 320 static inline int find_first_zero_bit_le(const void *p, unsigned size)
 321 {
 322         return _find_first_zero_bit_le(p, size);
 323 }
 324 #define find_first_zero_bit_le find_first_zero_bit_le
 325
 326 static inline int find_next_zero_bit_le(const void *p, int size, int offset)
 327 {
 328         return _find_next_zero_bit_le(p, size, offset);
 329 }
 330 #define find_next_zero_bit_le find_next_zero_bit_le
 331
 332 static inline int find_next_bit_le(const void *p, int size, int offset)
 333 {
 334         return _find_next_bit_le(p, size, offset);
 335 }
 336 #define find_next_bit_le find_next_bit_le
 337
 338 #endif
 339
 340 #include <asm-generic/bitops/le.h>
 341
 342 /*
 343  * Ext2 is defined to use little-endian byte ordering.
 344  */
 345 #include <asm-generic/bitops/ext2-atomic-setbit.h>
 346
 347 #endif /* __KERNEL__ */
 348
 349 #endif /* _ARM_BITOPS_H */