Corentin Chary | e0e53b2 | 2011-02-04 09:06:04 +0100 | [diff] [blame] | 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 | |
| 17 | #define BITS_PER_BYTE CHAR_BIT |
| 18 | #define BITS_PER_LONG (sizeof (unsigned long) * BITS_PER_BYTE) |
| 19 | |
| 20 | #define BIT(nr) (1UL << (nr)) |
| 21 | #define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG)) |
| 22 | #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) |
| 23 | #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) |
| 24 | |
| 25 | /** |
| 26 | * bitops_ffs - find first bit in word. |
| 27 | * @word: The word to search |
| 28 | * |
| 29 | * Undefined if no bit exists, so code should check against 0 first. |
| 30 | */ |
| 31 | static unsigned long bitops_ffsl(unsigned long word) |
| 32 | { |
| 33 | int num = 0; |
| 34 | |
| 35 | #if LONG_MAX > 0x7FFFFFFF |
| 36 | if ((word & 0xffffffff) == 0) { |
| 37 | num += 32; |
| 38 | word >>= 32; |
| 39 | } |
| 40 | #endif |
| 41 | if ((word & 0xffff) == 0) { |
| 42 | num += 16; |
| 43 | word >>= 16; |
| 44 | } |
| 45 | if ((word & 0xff) == 0) { |
| 46 | num += 8; |
| 47 | word >>= 8; |
| 48 | } |
| 49 | if ((word & 0xf) == 0) { |
| 50 | num += 4; |
| 51 | word >>= 4; |
| 52 | } |
| 53 | if ((word & 0x3) == 0) { |
| 54 | num += 2; |
| 55 | word >>= 2; |
| 56 | } |
| 57 | if ((word & 0x1) == 0) { |
| 58 | num += 1; |
| 59 | } |
| 60 | return num; |
| 61 | } |
| 62 | |
| 63 | /** |
| 64 | * bitops_fls - find last (most-significant) set bit in a long word |
| 65 | * @word: the word to search |
| 66 | * |
| 67 | * Undefined if no set bit exists, so code should check against 0 first. |
| 68 | */ |
Blue Swirl | 84803d7 | 2011-02-25 17:21:22 +0000 | [diff] [blame] | 69 | static inline unsigned long bitops_flsl(unsigned long word) |
Corentin Chary | e0e53b2 | 2011-02-04 09:06:04 +0100 | [diff] [blame] | 70 | { |
| 71 | int num = BITS_PER_LONG - 1; |
| 72 | |
| 73 | #if LONG_MAX > 0x7FFFFFFF |
| 74 | if (!(word & (~0ul << 32))) { |
| 75 | num -= 32; |
| 76 | word <<= 32; |
| 77 | } |
| 78 | #endif |
| 79 | if (!(word & (~0ul << (BITS_PER_LONG-16)))) { |
| 80 | num -= 16; |
| 81 | word <<= 16; |
| 82 | } |
| 83 | if (!(word & (~0ul << (BITS_PER_LONG-8)))) { |
| 84 | num -= 8; |
| 85 | word <<= 8; |
| 86 | } |
| 87 | if (!(word & (~0ul << (BITS_PER_LONG-4)))) { |
| 88 | num -= 4; |
| 89 | word <<= 4; |
| 90 | } |
| 91 | if (!(word & (~0ul << (BITS_PER_LONG-2)))) { |
| 92 | num -= 2; |
| 93 | |
| 94 | word <<= 2; |
| 95 | } |
| 96 | if (!(word & (~0ul << (BITS_PER_LONG-1)))) |
| 97 | num -= 1; |
| 98 | return num; |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * ffz - find first zero in word. |
| 103 | * @word: The word to search |
| 104 | * |
| 105 | * Undefined if no zero exists, so code should check against ~0UL first. |
| 106 | */ |
| 107 | static inline unsigned long ffz(unsigned long word) |
| 108 | { |
| 109 | return bitops_ffsl(~word); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * set_bit - Set a bit in memory |
| 114 | * @nr: the bit to set |
| 115 | * @addr: the address to start counting from |
| 116 | */ |
| 117 | static inline void set_bit(int nr, volatile unsigned long *addr) |
| 118 | { |
| 119 | unsigned long mask = BIT_MASK(nr); |
| 120 | unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
| 121 | |
| 122 | *p |= mask; |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * clear_bit - Clears a bit in memory |
| 127 | * @nr: Bit to clear |
| 128 | * @addr: Address to start counting from |
| 129 | */ |
| 130 | static inline void clear_bit(int nr, volatile unsigned long *addr) |
| 131 | { |
| 132 | unsigned long mask = BIT_MASK(nr); |
| 133 | unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
| 134 | |
| 135 | *p &= ~mask; |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * change_bit - Toggle a bit in memory |
| 140 | * @nr: Bit to change |
| 141 | * @addr: Address to start counting from |
| 142 | */ |
| 143 | static inline void change_bit(int nr, volatile unsigned long *addr) |
| 144 | { |
| 145 | unsigned long mask = BIT_MASK(nr); |
| 146 | unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
| 147 | |
| 148 | *p ^= mask; |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * test_and_set_bit - Set a bit and return its old value |
| 153 | * @nr: Bit to set |
| 154 | * @addr: Address to count from |
| 155 | */ |
| 156 | static inline int test_and_set_bit(int nr, volatile unsigned long *addr) |
| 157 | { |
| 158 | unsigned long mask = BIT_MASK(nr); |
| 159 | unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
| 160 | unsigned long old = *p; |
| 161 | |
| 162 | *p = old | mask; |
| 163 | return (old & mask) != 0; |
| 164 | } |
| 165 | |
| 166 | /** |
| 167 | * test_and_clear_bit - Clear a bit and return its old value |
| 168 | * @nr: Bit to clear |
| 169 | * @addr: Address to count from |
| 170 | */ |
| 171 | static inline int test_and_clear_bit(int nr, volatile unsigned long *addr) |
| 172 | { |
| 173 | unsigned long mask = BIT_MASK(nr); |
| 174 | unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
| 175 | unsigned long old = *p; |
| 176 | |
| 177 | *p = old & ~mask; |
| 178 | return (old & mask) != 0; |
| 179 | } |
| 180 | |
| 181 | /** |
| 182 | * test_and_change_bit - Change a bit and return its old value |
| 183 | * @nr: Bit to change |
| 184 | * @addr: Address to count from |
| 185 | */ |
| 186 | static inline int test_and_change_bit(int nr, volatile unsigned long *addr) |
| 187 | { |
| 188 | unsigned long mask = BIT_MASK(nr); |
| 189 | unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
Corentin Chary | 04483e1 | 2011-02-24 23:47:08 +0100 | [diff] [blame] | 190 | unsigned long old = *p; |
Corentin Chary | e0e53b2 | 2011-02-04 09:06:04 +0100 | [diff] [blame] | 191 | |
| 192 | *p = old ^ mask; |
| 193 | return (old & mask) != 0; |
| 194 | } |
| 195 | |
| 196 | /** |
| 197 | * test_bit - Determine whether a bit is set |
| 198 | * @nr: bit number to test |
| 199 | * @addr: Address to start counting from |
| 200 | */ |
| 201 | static inline int test_bit(int nr, const volatile unsigned long *addr) |
| 202 | { |
| 203 | return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); |
| 204 | } |
| 205 | |
| 206 | /** |
| 207 | * find_last_bit - find the last set bit in a memory region |
| 208 | * @addr: The address to start the search at |
| 209 | * @size: The maximum size to search |
| 210 | * |
| 211 | * Returns the bit number of the first set bit, or size. |
| 212 | */ |
| 213 | unsigned long find_last_bit(const unsigned long *addr, |
| 214 | unsigned long size); |
| 215 | |
| 216 | /** |
| 217 | * find_next_bit - find the next set bit in a memory region |
| 218 | * @addr: The address to base the search on |
| 219 | * @offset: The bitnumber to start searching at |
| 220 | * @size: The bitmap size in bits |
| 221 | */ |
| 222 | unsigned long find_next_bit(const unsigned long *addr, |
| 223 | unsigned long size, unsigned long offset); |
| 224 | |
| 225 | /** |
| 226 | * find_next_zero_bit - find the next cleared bit in a memory region |
| 227 | * @addr: The address to base the search on |
| 228 | * @offset: The bitnumber to start searching at |
| 229 | * @size: The bitmap size in bits |
| 230 | */ |
| 231 | |
| 232 | unsigned long find_next_zero_bit(const unsigned long *addr, |
| 233 | unsigned long size, |
| 234 | unsigned long offset); |
| 235 | |
| 236 | /** |
| 237 | * find_first_bit - find the first set bit in a memory region |
| 238 | * @addr: The address to start the search at |
| 239 | * @size: The maximum size to search |
| 240 | * |
| 241 | * Returns the bit number of the first set bit. |
| 242 | */ |
| 243 | static inline unsigned long find_first_bit(const unsigned long *addr, |
| 244 | unsigned long size) |
| 245 | { |
| 246 | return find_next_bit(addr, size, 0); |
| 247 | } |
| 248 | |
| 249 | /** |
| 250 | * find_first_zero_bit - find the first cleared bit in a memory region |
| 251 | * @addr: The address to start the search at |
| 252 | * @size: The maximum size to search |
| 253 | * |
| 254 | * Returns the bit number of the first cleared bit. |
| 255 | */ |
| 256 | static inline unsigned long find_first_zero_bit(const unsigned long *addr, |
| 257 | unsigned long size) |
| 258 | { |
| 259 | return find_next_zero_bit(addr, size, 0); |
| 260 | } |
| 261 | |
| 262 | static inline unsigned long hweight_long(unsigned long w) |
| 263 | { |
| 264 | unsigned long count; |
| 265 | |
| 266 | for (count = 0; w; w >>= 1) { |
| 267 | count += w & 1; |
| 268 | } |
| 269 | return count; |
| 270 | } |
| 271 | |
| 272 | #endif |