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