include/qemu/bitops.h

   1 /*
   2  * Bitops Module
   3  *
   4  * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
   5  *
   6  * Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
   7  *
   8  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
   9  * See the COPYING.LIB file in the top-level directory.
  10  */
  11
  12 #ifndef BITOPS_H
  13 #define BITOPS_H
  14
  15 #include "qemu-common.h"
  16 #include "host-utils.h"
  17
  18 #define BITS_PER_BYTE           CHAR_BIT
  19 #define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)
  20
  21 #define BIT(nr)                 (1UL << (nr))
  22 #define BIT_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
  23 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
  24 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
  25
  26 /**
  27  * set_bit - Set a bit in memory
  28  * @nr: the bit to set
  29  * @addr: the address to start counting from
  30  */
  31 static inline void set_bit(int nr, unsigned long *addr)
  32 {
  33         unsigned long mask = BIT_MASK(nr);
  34         unsigned long *p = addr + BIT_WORD(nr);
  35
  36         *p  |= mask;
  37 }
  38
  39 /**
  40  * clear_bit - Clears a bit in memory
  41  * @nr: Bit to clear
  42  * @addr: Address to start counting from
  43  */
  44 static inline void clear_bit(int nr, unsigned long *addr)
  45 {
  46         unsigned long mask = BIT_MASK(nr);
  47         unsigned long *p = addr + BIT_WORD(nr);
  48
  49         *p &= ~mask;
  50 }
  51
  52 /**
  53  * change_bit - Toggle a bit in memory
  54  * @nr: Bit to change
  55  * @addr: Address to start counting from
  56  */
  57 static inline void change_bit(int nr, unsigned long *addr)
  58 {
  59         unsigned long mask = BIT_MASK(nr);
  60         unsigned long *p = addr + BIT_WORD(nr);
  61
  62         *p ^= mask;
  63 }
  64
  65 /**
  66  * test_and_set_bit - Set a bit and return its old value
  67  * @nr: Bit to set
  68  * @addr: Address to count from
  69  */
  70 static inline int test_and_set_bit(int nr, unsigned long *addr)
  71 {
  72         unsigned long mask = BIT_MASK(nr);
  73         unsigned long *p = addr + BIT_WORD(nr);
  74         unsigned long old = *p;
  75
  76         *p = old | mask;
  77         return (old & mask) != 0;
  78 }
  79
  80 /**
  81  * test_and_clear_bit - Clear a bit and return its old value
  82  * @nr: Bit to clear
  83  * @addr: Address to count from
  84  */
  85 static inline int test_and_clear_bit(int nr, unsigned long *addr)
  86 {
  87         unsigned long mask = BIT_MASK(nr);
  88         unsigned long *p = addr + BIT_WORD(nr);
  89         unsigned long old = *p;
  90
  91         *p = old & ~mask;
  92         return (old & mask) != 0;
  93 }
  94
  95 /**
  96  * test_and_change_bit - Change a bit and return its old value
  97  * @nr: Bit to change
  98  * @addr: Address to count from
  99  */
 100 static inline int test_and_change_bit(int nr, unsigned long *addr)
 101 {
 102         unsigned long mask = BIT_MASK(nr);
 103         unsigned long *p = addr + BIT_WORD(nr);
 104         unsigned long old = *p;
 105
 106         *p = old ^ mask;
 107         return (old & mask) != 0;
 108 }
 109
 110 /**
 111  * test_bit - Determine whether a bit is set
 112  * @nr: bit number to test
 113  * @addr: Address to start counting from
 114  */
 115 static inline int test_bit(int nr, const unsigned long *addr)
 116 {
 117         return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 118 }
 119
 120 /**
 121  * find_last_bit - find the last set bit in a memory region
 122  * @addr: The address to start the search at
 123  * @size: The maximum size to search
 124  *
 125  * Returns the bit number of the first set bit, or size.
 126  */
 127 unsigned long find_last_bit(const unsigned long *addr,
 128                             unsigned long size);
 129
 130 /**
 131  * find_next_bit - find the next set bit in a memory region
 132  * @addr: The address to base the search on
 133  * @offset: The bitnumber to start searching at
 134  * @size: The bitmap size in bits
 135  */
 136 unsigned long find_next_bit(const unsigned long *addr,
 137                                    unsigned long size, unsigned long offset);
 138
 139 /**
 140  * find_next_zero_bit - find the next cleared bit in a memory region
 141  * @addr: The address to base the search on
 142  * @offset: The bitnumber to start searching at
 143  * @size: The bitmap size in bits
 144  */
 145
 146 unsigned long find_next_zero_bit(const unsigned long *addr,
 147                                  unsigned long size,
 148                                  unsigned long offset);
 149
 150 /**
 151  * find_first_bit - find the first set bit in a memory region
 152  * @addr: The address to start the search at
 153  * @size: The maximum size to search
 154  *
 155  * Returns the bit number of the first set bit.
 156  */
 157 static inline unsigned long find_first_bit(const unsigned long *addr,
 158                                            unsigned long size)
 159 {
 160     return find_next_bit(addr, size, 0);
 161 }
 162
 163 /**
 164  * find_first_zero_bit - find the first cleared bit in a memory region
 165  * @addr: The address to start the search at
 166  * @size: The maximum size to search
 167  *
 168  * Returns the bit number of the first cleared bit.
 169  */
 170 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
 171                                                 unsigned long size)
 172 {
 173     return find_next_zero_bit(addr, size, 0);
 174 }
 175
 176 static inline unsigned long hweight_long(unsigned long w)
 177 {
 178     unsigned long count;
 179
 180     for (count = 0; w; w >>= 1) {
 181         count += w & 1;
 182     }
 183     return count;
 184 }
 185
 186 /**
 187  * extract32:
 188  * @value: the value to extract the bit field from
 189  * @start: the lowest bit in the bit field (numbered from 0)
 190  * @length: the length of the bit field
 191  *
 192  * Extract from the 32 bit input @value the bit field specified by the
 193  * @start and @length parameters, and return it. The bit field must
 194  * lie entirely within the 32 bit word. It is valid to request that
 195  * all 32 bits are returned (ie @length 32 and @start 0).
 196  *
 197  * Returns: the value of the bit field extracted from the input value.
 198  */
 199 static inline uint32_t extract32(uint32_t value, int start, int length)
 200 {
 201     assert(start >= 0 && length > 0 && length <= 32 - start);
 202     return (value >> start) & (~0U >> (32 - length));
 203 }
 204
 205 /**
 206  * extract64:
 207  * @value: the value to extract the bit field from
 208  * @start: the lowest bit in the bit field (numbered from 0)
 209  * @length: the length of the bit field
 210  *
 211  * Extract from the 64 bit input @value the bit field specified by the
 212  * @start and @length parameters, and return it. The bit field must
 213  * lie entirely within the 64 bit word. It is valid to request that
 214  * all 64 bits are returned (ie @length 64 and @start 0).
 215  *
 216  * Returns: the value of the bit field extracted from the input value.
 217  */
 218 static inline uint64_t extract64(uint64_t value, int start, int length)
 219 {
 220     assert(start >= 0 && length > 0 && length <= 64 - start);
 221     return (value >> start) & (~0ULL >> (64 - length));
 222 }
 223
 224 /**
 225  * deposit32:
 226  * @value: initial value to insert bit field into
 227  * @start: the lowest bit in the bit field (numbered from 0)
 228  * @length: the length of the bit field
 229  * @fieldval: the value to insert into the bit field
 230  *
 231  * Deposit @fieldval into the 32 bit @value at the bit field specified
 232  * by the @start and @length parameters, and return the modified
 233  * @value. Bits of @value outside the bit field are not modified.
 234  * Bits of @fieldval above the least significant @length bits are
 235  * ignored. The bit field must lie entirely within the 32 bit word.
 236  * It is valid to request that all 32 bits are modified (ie @length
 237  * 32 and @start 0).
 238  *
 239  * Returns: the modified @value.
 240  */
 241 static inline uint32_t deposit32(uint32_t value, int start, int length,
 242                                  uint32_t fieldval)
 243 {
 244     uint32_t mask;
 245     assert(start >= 0 && length > 0 && length <= 32 - start);
 246     mask = (~0U >> (32 - length)) << start;
 247     return (value & ~mask) | ((fieldval << start) & mask);
 248 }
 249
 250 /**
 251  * deposit64:
 252  * @value: initial value to insert bit field into
 253  * @start: the lowest bit in the bit field (numbered from 0)
 254  * @length: the length of the bit field
 255  * @fieldval: the value to insert into the bit field
 256  *
 257  * Deposit @fieldval into the 64 bit @value at the bit field specified
 258  * by the @start and @length parameters, and return the modified
 259  * @value. Bits of @value outside the bit field are not modified.
 260  * Bits of @fieldval above the least significant @length bits are
 261  * ignored. The bit field must lie entirely within the 64 bit word.
 262  * It is valid to request that all 64 bits are modified (ie @length
 263  * 64 and @start 0).
 264  *
 265  * Returns: the modified @value.
 266  */
 267 static inline uint64_t deposit64(uint64_t value, int start, int length,
 268                                  uint64_t fieldval)
 269 {
 270     uint64_t mask;
 271     assert(start >= 0 && length > 0 && length <= 64 - start);
 272     mask = (~0ULL >> (64 - length)) << start;
 273     return (value & ~mask) | ((fieldval << start) & mask);
 274 }
 275
 276 #endif