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/compiler.h>
   9 #include <asm/alternative.h>
  10
  11 /*
  12  * These have to be done with inline assembly: that way the bit-setting
  13  * is guaranteed to be atomic. All bit operations return 0 if the bit
  14  * was cleared before the operation and != 0 if it was not.
  15  *
  16  * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
  17  */
  18
  19 #define ADDR (*(volatile long *) addr)
  20
  21 /**
  22  * set_bit - Atomically set a bit in memory
  23  * @nr: the bit to set
  24  * @addr: the address to start counting from
  25  *
  26  * This function is atomic and may not be reordered.  See __set_bit()
  27  * if you do not require the atomic guarantees.
  28  *
  29  * Note: there are no guarantees that this function will not be reordered
  30  * on non x86 architectures, so if you are writing portable code,
  31  * make sure not to rely on its reordering guarantees.
  32  *
  33  * Note that @nr may be almost arbitrarily large; this function is not
  34  * restricted to acting on a single-word quantity.
  35  */
  36 static inline void set_bit(int nr, volatile unsigned long * addr)
  37 {
  38         __asm__ __volatile__( LOCK_PREFIX
  39                 "btsl %1,%0"
  40                 :"+m" (ADDR)
  41                 :"Ir" (nr));
  42 }
  43
  44 /**
  45  * __set_bit - Set a bit in memory
  46  * @nr: the bit to set
  47  * @addr: the address to start counting from
  48  *
  49  * Unlike set_bit(), this function is non-atomic and may be reordered.
  50  * If it's called on the same region of memory simultaneously, the effect
  51  * may be that only one operation succeeds.
  52  */
  53 static inline void __set_bit(int nr, volatile unsigned long * addr)
  54 {
  55         __asm__(
  56                 "btsl %1,%0"
  57                 :"+m" (ADDR)
  58                 :"Ir" (nr));
  59 }
  60
  61 /**
  62  * clear_bit - Clears a bit in memory
  63  * @nr: Bit to clear
  64  * @addr: Address to start counting from
  65  *
  66  * clear_bit() is atomic and may not be reordered.  However, it does
  67  * not contain a memory barrier, so if it is used for locking purposes,
  68  * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
  69  * in order to ensure changes are visible on other processors.
  70  */
  71 static inline void clear_bit(int nr, volatile unsigned long * addr)
  72 {
  73         __asm__ __volatile__( LOCK_PREFIX
  74                 "btrl %1,%0"
  75                 :"+m" (ADDR)
  76                 :"Ir" (nr));
  77 }
  78
  79 static inline void __clear_bit(int nr, volatile unsigned long * addr)
  80 {
  81         __asm__ __volatile__(
  82                 "btrl %1,%0"
  83                 :"+m" (ADDR)
  84                 :"Ir" (nr));
  85 }
  86 #define smp_mb__before_clear_bit()      barrier()
  87 #define smp_mb__after_clear_bit()       barrier()
  88
  89 /**
  90  * __change_bit - Toggle a bit in memory
  91  * @nr: the bit to change
  92  * @addr: the address to start counting from
  93  *
  94  * Unlike change_bit(), this function is non-atomic and may be reordered.
  95  * If it's called on the same region of memory simultaneously, the effect
  96  * may be that only one operation succeeds.
  97  */
  98 static inline void __change_bit(int nr, volatile unsigned long * addr)
  99 {
 100         __asm__ __volatile__(
 101                 "btcl %1,%0"
 102                 :"+m" (ADDR)
 103                 :"Ir" (nr));
 104 }
 105
 106 /**
 107  * change_bit - Toggle a bit in memory
 108  * @nr: Bit to change
 109  * @addr: Address to start counting from
 110  *
 111  * change_bit() is atomic and may not be reordered. It may be
 112  * reordered on other architectures than x86.
 113  * Note that @nr may be almost arbitrarily large; this function is not
 114  * restricted to acting on a single-word quantity.
 115  */
 116 static inline void change_bit(int nr, volatile unsigned long * addr)
 117 {
 118         __asm__ __volatile__( LOCK_PREFIX
 119                 "btcl %1,%0"
 120                 :"+m" (ADDR)
 121                 :"Ir" (nr));
 122 }
 123
 124 /**
 125  * test_and_set_bit - Set a bit and return its old value
 126  * @nr: Bit to set
 127  * @addr: Address to count from
 128  *
 129  * This operation is atomic and cannot be reordered.
 130  * It may be reordered on other architectures than x86.
 131  * It also implies a memory barrier.
 132  */
 133 static inline int test_and_set_bit(int nr, volatile unsigned long * addr)
 134 {
 135         int oldbit;
 136
 137         __asm__ __volatile__( LOCK_PREFIX
 138                 "btsl %2,%1\n\tsbbl %0,%0"
 139                 :"=r" (oldbit),"+m" (ADDR)
 140                 :"Ir" (nr) : "memory");
 141         return oldbit;
 142 }
 143
 144 /**
 145  * __test_and_set_bit - Set a bit and return its old value
 146  * @nr: Bit to set
 147  * @addr: Address to count from
 148  *
 149  * This operation is non-atomic and can be reordered.
 150  * If two examples of this operation race, one can appear to succeed
 151  * but actually fail.  You must protect multiple accesses with a lock.
 152  */
 153 static inline int __test_and_set_bit(int nr, volatile unsigned long * addr)
 154 {
 155         int oldbit;
 156
 157         __asm__(
 158                 "btsl %2,%1\n\tsbbl %0,%0"
 159                 :"=r" (oldbit),"+m" (ADDR)
 160                 :"Ir" (nr));
 161         return oldbit;
 162 }
 163
 164 /**
 165  * test_and_clear_bit - Clear a bit and return its old value
 166  * @nr: Bit to clear
 167  * @addr: Address to count from
 168  *
 169  * This operation is atomic and cannot be reordered.
 170  * It can be reorderdered on other architectures other than x86.
 171  * It also implies a memory barrier.
 172  */
 173 static inline int test_and_clear_bit(int nr, volatile unsigned long * addr)
 174 {
 175         int oldbit;
 176
 177         __asm__ __volatile__( LOCK_PREFIX
 178                 "btrl %2,%1\n\tsbbl %0,%0"
 179                 :"=r" (oldbit),"+m" (ADDR)
 180                 :"Ir" (nr) : "memory");
 181         return oldbit;
 182 }
 183
 184 /**
 185  * __test_and_clear_bit - Clear a bit and return its old value
 186  * @nr: Bit to clear
 187  * @addr: Address to count from
 188  *
 189  * This operation is non-atomic and can be reordered.
 190  * If two examples of this operation race, one can appear to succeed
 191  * but actually fail.  You must protect multiple accesses with a lock.
 192  */
 193 static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
 194 {
 195         int oldbit;
 196
 197         __asm__(
 198                 "btrl %2,%1\n\tsbbl %0,%0"
 199                 :"=r" (oldbit),"+m" (ADDR)
 200                 :"Ir" (nr));
 201         return oldbit;
 202 }
 203
 204 /* WARNING: non atomic and it can be reordered! */
 205 static inline int __test_and_change_bit(int nr, volatile unsigned long *addr)
 206 {
 207         int oldbit;
 208
 209         __asm__ __volatile__(
 210                 "btcl %2,%1\n\tsbbl %0,%0"
 211                 :"=r" (oldbit),"+m" (ADDR)
 212                 :"Ir" (nr) : "memory");
 213         return oldbit;
 214 }
 215
 216 /**
 217  * test_and_change_bit - Change a bit and return its old value
 218  * @nr: Bit to change
 219  * @addr: Address to count from
 220  *
 221  * This operation is atomic and cannot be reordered.
 222  * It also implies a memory barrier.
 223  */
 224 static inline int test_and_change_bit(int nr, volatile unsigned long* addr)
 225 {
 226         int oldbit;
 227
 228         __asm__ __volatile__( LOCK_PREFIX
 229                 "btcl %2,%1\n\tsbbl %0,%0"
 230                 :"=r" (oldbit),"+m" (ADDR)
 231                 :"Ir" (nr) : "memory");
 232         return oldbit;
 233 }
 234
 235 #if 0 /* Fool kernel-doc since it doesn't do macros yet */
 236 /**
 237  * test_bit - Determine whether a bit is set
 238  * @nr: bit number to test
 239  * @addr: Address to start counting from
 240  */
 241 static int test_bit(int nr, const volatile void * addr);
 242 #endif
 243
 244 static __always_inline int constant_test_bit(int nr, const volatile unsigned long *addr)
 245 {
 246         return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
 247 }
 248
 249 static inline int variable_test_bit(int nr, const volatile unsigned long * addr)
 250 {
 251         int oldbit;
 252
 253         __asm__ __volatile__(
 254                 "btl %2,%1\n\tsbbl %0,%0"
 255                 :"=r" (oldbit)
 256                 :"m" (ADDR),"Ir" (nr));
 257         return oldbit;
 258 }
 259
 260 #define test_bit(nr,addr) \
 261 (__builtin_constant_p(nr) ? \
 262  constant_test_bit((nr),(addr)) : \
 263  variable_test_bit((nr),(addr)))
 264
 265 #undef ADDR
 266
 267 /**
 268  * find_first_zero_bit - find the first zero bit in a memory region
 269  * @addr: The address to start the search at
 270  * @size: The maximum size to search
 271  *
 272  * Returns the bit-number of the first zero bit, not the number of the byte
 273  * containing a bit.
 274  */
 275 static inline int find_first_zero_bit(const unsigned long *addr, unsigned size)
 276 {
 277         int d0, d1, d2;
 278         int res;
 279
 280         if (!size)
 281                 return 0;
 282         /* This looks at memory. Mark it volatile to tell gcc not to move it around */
 283         __asm__ __volatile__(
 284                 "movl $-1,%%eax\n\t"
 285                 "xorl %%edx,%%edx\n\t"
 286                 "repe; scasl\n\t"
 287                 "je 1f\n\t"
 288                 "xorl -4(%%edi),%%eax\n\t"
 289                 "subl $4,%%edi\n\t"
 290                 "bsfl %%eax,%%edx\n"
 291                 "1:\tsubl %%ebx,%%edi\n\t"
 292                 "shll $3,%%edi\n\t"
 293                 "addl %%edi,%%edx"
 294                 :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
 295                 :"1" ((size + 31) >> 5), "2" (addr), "b" (addr) : "memory");
 296         return res;
 297 }
 298
 299 /**
 300  * find_next_zero_bit - find the first zero bit in a memory region
 301  * @addr: The address to base the search on
 302  * @offset: The bitnumber to start searching at
 303  * @size: The maximum size to search
 304  */
 305 int find_next_zero_bit(const unsigned long *addr, int size, int offset);
 306
 307 /**
 308  * __ffs - find first bit in word.
 309  * @word: The word to search
 310  *
 311  * Undefined if no bit exists, so code should check against 0 first.
 312  */
 313 static inline unsigned long __ffs(unsigned long word)
 314 {
 315         __asm__("bsfl %1,%0"
 316                 :"=r" (word)
 317                 :"rm" (word));
 318         return word;
 319 }
 320
 321 /**
 322  * find_first_bit - find the first set bit in a memory region
 323  * @addr: The address to start the search at
 324  * @size: The maximum size to search
 325  *
 326  * Returns the bit-number of the first set bit, not the number of the byte
 327  * containing a bit.
 328  */
 329 static inline unsigned find_first_bit(const unsigned long *addr, unsigned size)
 330 {
 331         unsigned x = 0;
 332
 333         while (x < size) {
 334                 unsigned long val = *addr++;
 335                 if (val)
 336                         return __ffs(val) + x;
 337                 x += (sizeof(*addr)<<3);
 338         }
 339         return x;
 340 }
 341
 342 /**
 343  * find_next_bit - find the first set bit in a memory region
 344  * @addr: The address to base the search on
 345  * @offset: The bitnumber to start searching at
 346  * @size: The maximum size to search
 347  */
 348 int find_next_bit(const unsigned long *addr, int size, int offset);
 349
 350 /**
 351  * ffz - find first zero in word.
 352  * @word: The word to search
 353  *
 354  * Undefined if no zero exists, so code should check against ~0UL first.
 355  */
 356 static inline unsigned long ffz(unsigned long word)
 357 {
 358         __asm__("bsfl %1,%0"
 359                 :"=r" (word)
 360                 :"r" (~word));
 361         return word;
 362 }
 363
 364 #ifdef __KERNEL__
 365
 366 #include <asm-generic/bitops/sched.h>
 367
 368 /**
 369  * ffs - find first bit set
 370  * @x: the word to search
 371  *
 372  * This is defined the same way as
 373  * the libc and compiler builtin ffs routines, therefore
 374  * differs in spirit from the above ffz() (man ffs).
 375  */
 376 static inline int ffs(int x)
 377 {
 378         int r;
 379
 380         __asm__("bsfl %1,%0\n\t"
 381                 "jnz 1f\n\t"
 382                 "movl $-1,%0\n"
 383                 "1:" : "=r" (r) : "rm" (x));
 384         return r+1;
 385 }
 386
 387 /**
 388  * fls - find last bit set
 389  * @x: the word to search
 390  *
 391  * This is defined the same way as ffs().
 392  */
 393 static inline int fls(int x)
 394 {
 395         int r;
 396
 397         __asm__("bsrl %1,%0\n\t"
 398                 "jnz 1f\n\t"
 399                 "movl $-1,%0\n"
 400                 "1:" : "=r" (r) : "rm" (x));
 401         return r+1;
 402 }
 403
 404 #include <asm-generic/bitops/hweight.h>
 405
 406 #endif /* __KERNEL__ */
 407
 408 #include <asm-generic/bitops/fls64.h>
 409
 410 #ifdef __KERNEL__
 411
 412 #include <asm-generic/bitops/ext2-non-atomic.h>
 413
 414 #define ext2_set_bit_atomic(lock,nr,addr) \
 415         test_and_set_bit((nr),(unsigned long*)addr)
 416 #define ext2_clear_bit_atomic(lock,nr, addr) \
 417                 test_and_clear_bit((nr),(unsigned long*)addr)
 418
 419 #include <asm-generic/bitops/minix.h>
 420
 421 #endif /* __KERNEL__ */
 422
 423 #endif /* _I386_BITOPS_H */