include/asm-i386/bitops.h

   1 #ifndef _I386_BITOPS_H
   2 #define _I386_BITOPS_H
   3
   4 /*
   5  * Copyright 1992, Linus Torvalds.
   6  */
   7
   8 #include <linux/config.h>
   9 #include <linux/compiler.h>
  10 #include <asm/alternative.h>
  11
  12 /*
  13  * These have to be done with inline assembly: that way the bit-setting
  14  * is guaranteed to be atomic. All bit operations return 0 if the bit
  15  * was cleared before the operation and != 0 if it was not.
  16  *
  17  * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
  18  */
  19
  20 #define ADDR (*(volatile long *) addr)
  21
  22 /**
  23  * set_bit - Atomically set a bit in memory
  24  * @nr: the bit to set
  25  * @addr: the address to start counting from
  26  *
  27  * This function is atomic and may not be reordered.  See __set_bit()
  28  * if you do not require the atomic guarantees.
  29  *
  30  * Note: there are no guarantees that this function will not be reordered
  31  * on non x86 architectures, so if you are writting portable code,
  32  * make sure not to rely on its reordering guarantees.
  33  *
  34  * Note that @nr may be almost arbitrarily large; this function is not
  35  * restricted to acting on a single-word quantity.
  36  */
  37 static inline void set_bit(int nr, volatile unsigned long * addr)
  38 {
  39         __asm__ __volatile__( LOCK_PREFIX
  40                 "btsl %1,%0"
  41                 :"+m" (ADDR)
  42                 :"Ir" (nr));
  43 }
  44
  45 /**
  46  * __set_bit - Set a bit in memory
  47  * @nr: the bit to set
  48  * @addr: the address to start counting from
  49  *
  50  * Unlike set_bit(), this function is non-atomic and may be reordered.
  51  * If it's called on the same region of memory simultaneously, the effect
  52  * may be that only one operation succeeds.
  53  */
  54 static inline void __set_bit(int nr, volatile unsigned long * addr)
  55 {
  56         __asm__(
  57                 "btsl %1,%0"
  58                 :"+m" (ADDR)
  59                 :"Ir" (nr));
  60 }
  61
  62 /**
  63  * clear_bit - Clears a bit in memory
  64  * @nr: Bit to clear
  65  * @addr: Address to start counting from
  66  *
  67  * clear_bit() is atomic and may not be reordered.  However, it does
  68  * not contain a memory barrier, so if it is used for locking purposes,
  69  * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
  70  * in order to ensure changes are visible on other processors.
  71  */
  72 static inline void clear_bit(int nr, volatile unsigned long * addr)
  73 {
  74         __asm__ __volatile__( LOCK_PREFIX
  75                 "btrl %1,%0"
  76                 :"+m" (ADDR)
  77                 :"Ir" (nr));
  78 }
  79
  80 static inline void __clear_bit(int nr, volatile unsigned long * addr)
  81 {
  82         __asm__ __volatile__(
  83                 "btrl %1,%0"
  84                 :"+m" (ADDR)
  85                 :"Ir" (nr));
  86 }
  87 #define smp_mb__before_clear_bit()      barrier()
  88 #define smp_mb__after_clear_bit()       barrier()
  89
  90 /**
  91  * __change_bit - Toggle a bit in memory
  92  * @nr: the bit to change
  93  * @addr: the address to start counting from
  94  *
  95  * Unlike change_bit(), this function is non-atomic and may be reordered.
  96  * If it's called on the same region of memory simultaneously, the effect
  97  * may be that only one operation succeeds.
  98  */
  99 static inline void __change_bit(int nr, volatile unsigned long * addr)
 100 {
 101         __asm__ __volatile__(
 102                 "btcl %1,%0"
 103                 :"+m" (ADDR)
 104                 :"Ir" (nr));
 105 }
 106
 107 /**
 108  * change_bit - Toggle a bit in memory
 109  * @nr: Bit to change
 110  * @addr: Address to start counting from
 111  *
 112  * change_bit() is atomic and may not be reordered. It may be
 113  * reordered on other architectures than x86.
 114  * Note that @nr may be almost arbitrarily large; this function is not
 115  * restricted to acting on a single-word quantity.
 116  */
 117 static inline void change_bit(int nr, volatile unsigned long * addr)
 118 {
 119         __asm__ __volatile__( LOCK_PREFIX
 120                 "btcl %1,%0"
 121                 :"+m" (ADDR)
 122                 :"Ir" (nr));
 123 }
 124
 125 /**
 126  * test_and_set_bit - Set a bit and return its old value
 127  * @nr: Bit to set
 128  * @addr: Address to count from
 129  *
 130  * This operation is atomic and cannot be reordered.
 131  * It may be reordered on other architectures than x86.
 132  * It also implies a memory barrier.
 133  */
 134 static inline int test_and_set_bit(int nr, volatile unsigned long * addr)
 135 {
 136         int oldbit;
 137
 138         __asm__ __volatile__( LOCK_PREFIX
 139                 "btsl %2,%1\n\tsbbl %0,%0"
 140                 :"=r" (oldbit),"+m" (ADDR)
 141                 :"Ir" (nr) : "memory");
 142         return oldbit;
 143 }
 144
 145 /**
 146  * __test_and_set_bit - Set a bit and return its old value
 147  * @nr: Bit to set
 148  * @addr: Address to count from
 149  *
 150  * This operation is non-atomic and can be reordered.
 151  * If two examples of this operation race, one can appear to succeed
 152  * but actually fail.  You must protect multiple accesses with a lock.
 153  */
 154 static inline int __test_and_set_bit(int nr, volatile unsigned long * addr)
 155 {
 156         int oldbit;
 157
 158         __asm__(
 159                 "btsl %2,%1\n\tsbbl %0,%0"
 160                 :"=r" (oldbit),"+m" (ADDR)
 161                 :"Ir" (nr));
 162         return oldbit;
 163 }
 164
 165 /**
 166  * test_and_clear_bit - Clear a bit and return its old value
 167  * @nr: Bit to clear
 168  * @addr: Address to count from
 169  *
 170  * This operation is atomic and cannot be reordered.
 171  * It can be reorderdered on other architectures other than x86.
 172  * It also implies a memory barrier.
 173  */
 174 static inline int test_and_clear_bit(int nr, volatile unsigned long * addr)
 175 {
 176         int oldbit;
 177
 178         __asm__ __volatile__( LOCK_PREFIX
 179                 "btrl %2,%1\n\tsbbl %0,%0"
 180                 :"=r" (oldbit),"+m" (ADDR)
 181                 :"Ir" (nr) : "memory");
 182         return oldbit;
 183 }
 184
 185 /**
 186  * __test_and_clear_bit - Clear a bit and return its old value
 187  * @nr: Bit to clear
 188  * @addr: Address to count from
 189  *
 190  * This operation is non-atomic and can be reordered.
 191  * If two examples of this operation race, one can appear to succeed
 192  * but actually fail.  You must protect multiple accesses with a lock.
 193  */
 194 static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
 195 {
 196         int oldbit;
 197
 198         __asm__(
 199                 "btrl %2,%1\n\tsbbl %0,%0"
 200                 :"=r" (oldbit),"+m" (ADDR)
 201                 :"Ir" (nr));
 202         return oldbit;
 203 }
 204
 205 /* WARNING: non atomic and it can be reordered! */
 206 static inline int __test_and_change_bit(int nr, volatile unsigned long *addr)
 207 {
 208         int oldbit;
 209
 210         __asm__ __volatile__(
 211                 "btcl %2,%1\n\tsbbl %0,%0"
 212                 :"=r" (oldbit),"+m" (ADDR)
 213                 :"Ir" (nr) : "memory");
 214         return oldbit;
 215 }
 216
 217 /**
 218  * test_and_change_bit - Change a bit and return its old value
 219  * @nr: Bit to change
 220  * @addr: Address to count from
 221  *
 222  * This operation is atomic and cannot be reordered.
 223  * It also implies a memory barrier.
 224  */
 225 static inline int test_and_change_bit(int nr, volatile unsigned long* addr)
 226 {
 227         int oldbit;
 228
 229         __asm__ __volatile__( LOCK_PREFIX
 230                 "btcl %2,%1\n\tsbbl %0,%0"
 231                 :"=r" (oldbit),"+m" (ADDR)
 232                 :"Ir" (nr) : "memory");
 233         return oldbit;
 234 }
 235
 236 #if 0 /* Fool kernel-doc since it doesn't do macros yet */
 237 /**
 238  * test_bit - Determine whether a bit is set
 239  * @nr: bit number to test
 240  * @addr: Address to start counting from
 241  */
 242 static int test_bit(int nr, const volatile void * addr);
 243 #endif
 244
 245 static __always_inline int constant_test_bit(int nr, const volatile unsigned long *addr)
 246 {
 247         return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
 248 }
 249
 250 static inline int variable_test_bit(int nr, const volatile unsigned long * addr)
 251 {
 252         int oldbit;
 253
 254         __asm__ __volatile__(
 255                 "btl %2,%1\n\tsbbl %0,%0"
 256                 :"=r" (oldbit)
 257                 :"m" (ADDR),"Ir" (nr));
 258         return oldbit;
 259 }
 260
 261 #define test_bit(nr,addr) \
 262 (__builtin_constant_p(nr) ? \
 263  constant_test_bit((nr),(addr)) : \
 264  variable_test_bit((nr),(addr)))
 265
 266 #undef ADDR
 267
 268 /**
 269  * find_first_zero_bit - find the first zero bit in a memory region
 270  * @addr: The address to start the search at
 271  * @size: The maximum size to search
 272  *
 273  * Returns the bit-number of the first zero bit, not the number of the byte
 274  * containing a bit.
 275  */
 276 static inline int find_first_zero_bit(const unsigned long *addr, unsigned size)
 277 {
 278         int d0, d1, d2;
 279         int res;
 280
 281         if (!size)
 282                 return 0;
 283         /* This looks at memory. Mark it volatile to tell gcc not to move it around */
 284         __asm__ __volatile__(
 285                 "movl $-1,%%eax\n\t"
 286                 "xorl %%edx,%%edx\n\t"
 287                 "repe; scasl\n\t"
 288                 "je 1f\n\t"
 289                 "xorl -4(%%edi),%%eax\n\t"
 290                 "subl $4,%%edi\n\t"
 291                 "bsfl %%eax,%%edx\n"
 292                 "1:\tsubl %%ebx,%%edi\n\t"
 293                 "shll $3,%%edi\n\t"
 294                 "addl %%edi,%%edx"
 295                 :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
 296                 :"1" ((size + 31) >> 5), "2" (addr), "b" (addr) : "memory");
 297         return res;
 298 }
 299
 300 /**
 301  * find_next_zero_bit - find the first zero bit in a memory region
 302  * @addr: The address to base the search on
 303  * @offset: The bitnumber to start searching at
 304  * @size: The maximum size to search
 305  */
 306 int find_next_zero_bit(const unsigned long *addr, int size, int offset);
 307
 308 /**
 309  * __ffs - find first bit in word.
 310  * @word: The word to search
 311  *
 312  * Undefined if no bit exists, so code should check against 0 first.
 313  */
 314 static inline unsigned long __ffs(unsigned long word)
 315 {
 316         __asm__("bsfl %1,%0"
 317                 :"=r" (word)
 318                 :"rm" (word));
 319         return word;
 320 }
 321
 322 /**
 323  * find_first_bit - find the first set bit in a memory region
 324  * @addr: The address to start the search at
 325  * @size: The maximum size to search
 326  *
 327  * Returns the bit-number of the first set bit, not the number of the byte
 328  * containing a bit.
 329  */
 330 static inline unsigned find_first_bit(const unsigned long *addr, unsigned size)
 331 {
 332         unsigned x = 0;
 333
 334         while (x < size) {
 335                 unsigned long val = *addr++;
 336                 if (val)
 337                         return __ffs(val) + x;
 338                 x += (sizeof(*addr)<<3);
 339         }
 340         return x;
 341 }
 342
 343 /**
 344  * find_next_bit - find the first set bit in a memory region
 345  * @addr: The address to base the search on
 346  * @offset: The bitnumber to start searching at
 347  * @size: The maximum size to search
 348  */
 349 int find_next_bit(const unsigned long *addr, int size, int offset);
 350
 351 /**
 352  * ffz - find first zero in word.
 353  * @word: The word to search
 354  *
 355  * Undefined if no zero exists, so code should check against ~0UL first.
 356  */
 357 static inline unsigned long ffz(unsigned long word)
 358 {
 359         __asm__("bsfl %1,%0"
 360                 :"=r" (word)
 361                 :"r" (~word));
 362         return word;
 363 }
 364
 365 #define fls64(x)   generic_fls64(x)
 366
 367 #ifdef __KERNEL__
 368
 369 /*
 370  * Every architecture must define this function. It's the fastest
 371  * way of searching a 140-bit bitmap where the first 100 bits are
 372  * unlikely to be set. It's guaranteed that at least one of the 140
 373  * bits is cleared.
 374  */
 375 static inline int sched_find_first_bit(const unsigned long *b)
 376 {
 377         if (unlikely(b[0]))
 378                 return __ffs(b[0]);
 379         if (unlikely(b[1]))
 380                 return __ffs(b[1]) + 32;
 381         if (unlikely(b[2]))
 382                 return __ffs(b[2]) + 64;
 383         if (b[3])
 384                 return __ffs(b[3]) + 96;
 385         return __ffs(b[4]) + 128;
 386 }
 387
 388 /**
 389  * ffs - find first bit set
 390  * @x: the word to search
 391  *
 392  * This is defined the same way as
 393  * the libc and compiler builtin ffs routines, therefore
 394  * differs in spirit from the above ffz (man ffs).
 395  */
 396 static inline int ffs(int x)
 397 {
 398         int r;
 399
 400         __asm__("bsfl %1,%0\n\t"
 401                 "jnz 1f\n\t"
 402                 "movl $-1,%0\n"
 403                 "1:" : "=r" (r) : "rm" (x));
 404         return r+1;
 405 }
 406
 407 /**
 408  * fls - find last bit set
 409  * @x: the word to search
 410  *
 411  * This is defined the same way as ffs.
 412  */
 413 static inline int fls(int x)
 414 {
 415         int r;
 416
 417         __asm__("bsrl %1,%0\n\t"
 418                 "jnz 1f\n\t"
 419                 "movl $-1,%0\n"
 420                 "1:" : "=r" (r) : "rm" (x));
 421         return r+1;
 422 }
 423
 424 /**
 425  * hweightN - returns the hamming weight of a N-bit word
 426  * @x: the word to weigh
 427  *
 428  * The Hamming Weight of a number is the total number of bits set in it.
 429  */
 430
 431 #define hweight32(x) generic_hweight32(x)
 432 #define hweight16(x) generic_hweight16(x)
 433 #define hweight8(x) generic_hweight8(x)
 434
 435 #endif /* __KERNEL__ */
 436
 437 #ifdef __KERNEL__
 438
 439 #define ext2_set_bit(nr,addr) \
 440         __test_and_set_bit((nr),(unsigned long*)addr)
 441 #define ext2_set_bit_atomic(lock,nr,addr) \
 442         test_and_set_bit((nr),(unsigned long*)addr)
 443 #define ext2_clear_bit(nr, addr) \
 444         __test_and_clear_bit((nr),(unsigned long*)addr)
 445 #define ext2_clear_bit_atomic(lock,nr, addr) \
 446                 test_and_clear_bit((nr),(unsigned long*)addr)
 447 #define ext2_test_bit(nr, addr)      test_bit((nr),(unsigned long*)addr)
 448 #define ext2_find_first_zero_bit(addr, size) \
 449         find_first_zero_bit((unsigned long*)addr, size)
 450 #define ext2_find_next_zero_bit(addr, size, off) \
 451         find_next_zero_bit((unsigned long*)addr, size, off)
 452
 453 /* Bitmap functions for the minix filesystem.  */
 454 #define minix_test_and_set_bit(nr,addr) __test_and_set_bit(nr,(void*)addr)
 455 #define minix_set_bit(nr,addr) __set_bit(nr,(void*)addr)
 456 #define minix_test_and_clear_bit(nr,addr) __test_and_clear_bit(nr,(void*)addr)
 457 #define minix_test_bit(nr,addr) test_bit(nr,(void*)addr)
 458 #define minix_find_first_zero_bit(addr,size) \
 459         find_first_zero_bit((void*)addr,size)
 460
 461 #endif /* __KERNEL__ */
 462
 463 #endif /* _I386_BITOPS_H */