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Rev | Author | Line No. | Line |
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3391 | Serge | 1 | /* |
2 | * lib/bitmap.c |
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3 | * Helper functions for bitmap.h. |
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4 | * |
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5056 | serge | 5 | * This source code is licensed under the GNU General Public License, |
3391 | Serge | 6 | * Version 2. See the file COPYING for more details. |
7 | */ |
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8 | #include |
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9 | #include |
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10 | //#include |
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11 | #include |
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12 | #include |
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13 | #include |
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14 | #include |
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15 | #include |
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16 | //#include |
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17 | |||
18 | /* |
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19 | * bitmaps provide an array of bits, implemented using an an |
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20 | * array of unsigned longs. The number of valid bits in a |
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21 | * given bitmap does _not_ need to be an exact multiple of |
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22 | * BITS_PER_LONG. |
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23 | * |
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24 | * The possible unused bits in the last, partially used word |
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25 | * of a bitmap are 'don't care'. The implementation makes |
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26 | * no particular effort to keep them zero. It ensures that |
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27 | * their value will not affect the results of any operation. |
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28 | * The bitmap operations that return Boolean (bitmap_empty, |
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29 | * for example) or scalar (bitmap_weight, for example) results |
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30 | * carefully filter out these unused bits from impacting their |
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31 | * results. |
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32 | * |
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33 | * These operations actually hold to a slightly stronger rule: |
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34 | * if you don't input any bitmaps to these ops that have some |
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35 | * unused bits set, then they won't output any set unused bits |
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36 | * in output bitmaps. |
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37 | * |
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38 | * The byte ordering of bitmaps is more natural on little |
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39 | * endian architectures. See the big-endian headers |
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40 | * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h |
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41 | * for the best explanations of this ordering. |
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42 | */ |
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43 | |||
44 | int __bitmap_equal(const unsigned long *bitmap1, |
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5056 | serge | 45 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 46 | { |
5056 | serge | 47 | unsigned int k, lim = bits/BITS_PER_LONG; |
3391 | Serge | 48 | for (k = 0; k < lim; ++k) |
49 | if (bitmap1[k] != bitmap2[k]) |
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50 | return 0; |
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51 | |||
52 | if (bits % BITS_PER_LONG) |
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53 | if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) |
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54 | return 0; |
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55 | |||
56 | return 1; |
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57 | } |
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58 | EXPORT_SYMBOL(__bitmap_equal); |
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59 | |||
5056 | serge | 60 | void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits) |
3391 | Serge | 61 | { |
5056 | serge | 62 | unsigned int k, lim = bits/BITS_PER_LONG; |
3391 | Serge | 63 | for (k = 0; k < lim; ++k) |
64 | dst[k] = ~src[k]; |
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65 | |||
66 | if (bits % BITS_PER_LONG) |
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5056 | serge | 67 | dst[k] = ~src[k]; |
3391 | Serge | 68 | } |
69 | EXPORT_SYMBOL(__bitmap_complement); |
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70 | |||
71 | /** |
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72 | * __bitmap_shift_right - logical right shift of the bits in a bitmap |
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73 | * @dst : destination bitmap |
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74 | * @src : source bitmap |
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75 | * @shift : shift by this many bits |
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6082 | serge | 76 | * @nbits : bitmap size, in bits |
3391 | Serge | 77 | * |
78 | * Shifting right (dividing) means moving bits in the MS -> LS bit |
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79 | * direction. Zeros are fed into the vacated MS positions and the |
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80 | * LS bits shifted off the bottom are lost. |
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81 | */ |
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6082 | serge | 82 | void __bitmap_shift_right(unsigned long *dst, const unsigned long *src, |
83 | unsigned shift, unsigned nbits) |
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3391 | Serge | 84 | { |
6082 | serge | 85 | unsigned k, lim = BITS_TO_LONGS(nbits); |
86 | unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; |
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87 | unsigned long mask = BITMAP_LAST_WORD_MASK(nbits); |
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3391 | Serge | 88 | for (k = 0; off + k < lim; ++k) { |
89 | unsigned long upper, lower; |
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90 | |||
91 | /* |
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92 | * If shift is not word aligned, take lower rem bits of |
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93 | * word above and make them the top rem bits of result. |
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94 | */ |
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95 | if (!rem || off + k + 1 >= lim) |
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96 | upper = 0; |
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97 | else { |
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98 | upper = src[off + k + 1]; |
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6082 | serge | 99 | if (off + k + 1 == lim - 1) |
3391 | Serge | 100 | upper &= mask; |
6082 | serge | 101 | upper <<= (BITS_PER_LONG - rem); |
3391 | Serge | 102 | } |
103 | lower = src[off + k]; |
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6082 | serge | 104 | if (off + k == lim - 1) |
3391 | Serge | 105 | lower &= mask; |
6082 | serge | 106 | lower >>= rem; |
107 | dst[k] = lower | upper; |
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3391 | Serge | 108 | } |
109 | if (off) |
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110 | memset(&dst[lim - off], 0, off*sizeof(unsigned long)); |
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111 | } |
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112 | EXPORT_SYMBOL(__bitmap_shift_right); |
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113 | |||
114 | |||
115 | /** |
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116 | * __bitmap_shift_left - logical left shift of the bits in a bitmap |
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117 | * @dst : destination bitmap |
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118 | * @src : source bitmap |
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119 | * @shift : shift by this many bits |
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6082 | serge | 120 | * @nbits : bitmap size, in bits |
3391 | Serge | 121 | * |
122 | * Shifting left (multiplying) means moving bits in the LS -> MS |
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123 | * direction. Zeros are fed into the vacated LS bit positions |
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124 | * and those MS bits shifted off the top are lost. |
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125 | */ |
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126 | |||
6082 | serge | 127 | void __bitmap_shift_left(unsigned long *dst, const unsigned long *src, |
128 | unsigned int shift, unsigned int nbits) |
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3391 | Serge | 129 | { |
6082 | serge | 130 | int k; |
131 | unsigned int lim = BITS_TO_LONGS(nbits); |
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132 | unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; |
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3391 | Serge | 133 | for (k = lim - off - 1; k >= 0; --k) { |
134 | unsigned long upper, lower; |
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135 | |||
136 | /* |
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137 | * If shift is not word aligned, take upper rem bits of |
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138 | * word below and make them the bottom rem bits of result. |
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139 | */ |
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140 | if (rem && k > 0) |
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6082 | serge | 141 | lower = src[k - 1] >> (BITS_PER_LONG - rem); |
3391 | Serge | 142 | else |
143 | lower = 0; |
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6082 | serge | 144 | upper = src[k] << rem; |
145 | dst[k + off] = lower | upper; |
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3391 | Serge | 146 | } |
147 | if (off) |
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148 | memset(dst, 0, off*sizeof(unsigned long)); |
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149 | } |
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150 | EXPORT_SYMBOL(__bitmap_shift_left); |
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151 | |||
152 | int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1, |
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5056 | serge | 153 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 154 | { |
5056 | serge | 155 | unsigned int k; |
156 | unsigned int lim = bits/BITS_PER_LONG; |
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3391 | Serge | 157 | unsigned long result = 0; |
158 | |||
5056 | serge | 159 | for (k = 0; k < lim; k++) |
3391 | Serge | 160 | result |= (dst[k] = bitmap1[k] & bitmap2[k]); |
5056 | serge | 161 | if (bits % BITS_PER_LONG) |
162 | result |= (dst[k] = bitmap1[k] & bitmap2[k] & |
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163 | BITMAP_LAST_WORD_MASK(bits)); |
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3391 | Serge | 164 | return result != 0; |
165 | } |
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166 | EXPORT_SYMBOL(__bitmap_and); |
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167 | |||
168 | void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1, |
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5056 | serge | 169 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 170 | { |
5056 | serge | 171 | unsigned int k; |
172 | unsigned int nr = BITS_TO_LONGS(bits); |
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3391 | Serge | 173 | |
174 | for (k = 0; k < nr; k++) |
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175 | dst[k] = bitmap1[k] | bitmap2[k]; |
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176 | } |
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177 | EXPORT_SYMBOL(__bitmap_or); |
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178 | |||
179 | void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1, |
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5056 | serge | 180 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 181 | { |
5056 | serge | 182 | unsigned int k; |
183 | unsigned int nr = BITS_TO_LONGS(bits); |
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3391 | Serge | 184 | |
185 | for (k = 0; k < nr; k++) |
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186 | dst[k] = bitmap1[k] ^ bitmap2[k]; |
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187 | } |
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188 | EXPORT_SYMBOL(__bitmap_xor); |
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189 | |||
190 | int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, |
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5056 | serge | 191 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 192 | { |
5056 | serge | 193 | unsigned int k; |
194 | unsigned int lim = bits/BITS_PER_LONG; |
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3391 | Serge | 195 | unsigned long result = 0; |
196 | |||
5056 | serge | 197 | for (k = 0; k < lim; k++) |
3391 | Serge | 198 | result |= (dst[k] = bitmap1[k] & ~bitmap2[k]); |
5056 | serge | 199 | if (bits % BITS_PER_LONG) |
200 | result |= (dst[k] = bitmap1[k] & ~bitmap2[k] & |
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201 | BITMAP_LAST_WORD_MASK(bits)); |
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3391 | Serge | 202 | return result != 0; |
203 | } |
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204 | EXPORT_SYMBOL(__bitmap_andnot); |
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205 | |||
206 | int __bitmap_intersects(const unsigned long *bitmap1, |
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5056 | serge | 207 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 208 | { |
5056 | serge | 209 | unsigned int k, lim = bits/BITS_PER_LONG; |
3391 | Serge | 210 | for (k = 0; k < lim; ++k) |
211 | if (bitmap1[k] & bitmap2[k]) |
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212 | return 1; |
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213 | |||
214 | if (bits % BITS_PER_LONG) |
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215 | if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) |
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216 | return 1; |
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217 | return 0; |
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218 | } |
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219 | EXPORT_SYMBOL(__bitmap_intersects); |
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220 | |||
221 | int __bitmap_subset(const unsigned long *bitmap1, |
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5056 | serge | 222 | const unsigned long *bitmap2, unsigned int bits) |
3391 | Serge | 223 | { |
5056 | serge | 224 | unsigned int k, lim = bits/BITS_PER_LONG; |
3391 | Serge | 225 | for (k = 0; k < lim; ++k) |
226 | if (bitmap1[k] & ~bitmap2[k]) |
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227 | return 0; |
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228 | |||
229 | if (bits % BITS_PER_LONG) |
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230 | if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) |
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231 | return 0; |
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232 | return 1; |
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233 | } |
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234 | EXPORT_SYMBOL(__bitmap_subset); |
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235 | |||
5056 | serge | 236 | int __bitmap_weight(const unsigned long *bitmap, unsigned int bits) |
3391 | Serge | 237 | { |
5056 | serge | 238 | unsigned int k, lim = bits/BITS_PER_LONG; |
239 | int w = 0; |
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3391 | Serge | 240 | |
241 | for (k = 0; k < lim; k++) |
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242 | w += hweight_long(bitmap[k]); |
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243 | |||
244 | if (bits % BITS_PER_LONG) |
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245 | w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); |
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246 | |||
247 | return w; |
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248 | } |
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249 | EXPORT_SYMBOL(__bitmap_weight); |
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250 | |||
5056 | serge | 251 | void bitmap_set(unsigned long *map, unsigned int start, int len) |
3391 | Serge | 252 | { |
253 | unsigned long *p = map + BIT_WORD(start); |
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5056 | serge | 254 | const unsigned int size = start + len; |
3391 | Serge | 255 | int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); |
256 | unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); |
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257 | |||
5056 | serge | 258 | while (len - bits_to_set >= 0) { |
3391 | Serge | 259 | *p |= mask_to_set; |
5056 | serge | 260 | len -= bits_to_set; |
3391 | Serge | 261 | bits_to_set = BITS_PER_LONG; |
262 | mask_to_set = ~0UL; |
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263 | p++; |
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264 | } |
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5056 | serge | 265 | if (len) { |
3391 | Serge | 266 | mask_to_set &= BITMAP_LAST_WORD_MASK(size); |
267 | *p |= mask_to_set; |
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268 | } |
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269 | } |
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270 | EXPORT_SYMBOL(bitmap_set); |
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271 | |||
5056 | serge | 272 | void bitmap_clear(unsigned long *map, unsigned int start, int len) |
3391 | Serge | 273 | { |
274 | unsigned long *p = map + BIT_WORD(start); |
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5056 | serge | 275 | const unsigned int size = start + len; |
3391 | Serge | 276 | int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); |
277 | unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); |
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278 | |||
5056 | serge | 279 | while (len - bits_to_clear >= 0) { |
3391 | Serge | 280 | *p &= ~mask_to_clear; |
5056 | serge | 281 | len -= bits_to_clear; |
3391 | Serge | 282 | bits_to_clear = BITS_PER_LONG; |
283 | mask_to_clear = ~0UL; |
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284 | p++; |
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285 | } |
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5056 | serge | 286 | if (len) { |
3391 | Serge | 287 | mask_to_clear &= BITMAP_LAST_WORD_MASK(size); |
288 | *p &= ~mask_to_clear; |
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289 | } |
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290 | } |
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291 | EXPORT_SYMBOL(bitmap_clear); |
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292 | |||
5270 | serge | 293 | /** |
294 | * bitmap_find_next_zero_area_off - find a contiguous aligned zero area |
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3391 | Serge | 295 | * @map: The address to base the search on |
296 | * @size: The bitmap size in bits |
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297 | * @start: The bitnumber to start searching at |
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298 | * @nr: The number of zeroed bits we're looking for |
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299 | * @align_mask: Alignment mask for zero area |
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5270 | serge | 300 | * @align_offset: Alignment offset for zero area. |
3391 | Serge | 301 | * |
302 | * The @align_mask should be one less than a power of 2; the effect is that |
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5270 | serge | 303 | * the bit offset of all zero areas this function finds plus @align_offset |
304 | * is multiple of that power of 2. |
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3391 | Serge | 305 | */ |
5270 | serge | 306 | unsigned long bitmap_find_next_zero_area_off(unsigned long *map, |
3391 | Serge | 307 | unsigned long size, |
308 | unsigned long start, |
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309 | unsigned int nr, |
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5270 | serge | 310 | unsigned long align_mask, |
311 | unsigned long align_offset) |
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3391 | Serge | 312 | { |
313 | unsigned long index, end, i; |
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314 | again: |
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315 | index = find_next_zero_bit(map, size, start); |
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316 | |||
317 | /* Align allocation */ |
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5270 | serge | 318 | index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset; |
3391 | Serge | 319 | |
320 | end = index + nr; |
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321 | if (end > size) |
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322 | return end; |
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323 | i = find_next_bit(map, end, index); |
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324 | if (i < end) { |
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325 | start = i + 1; |
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326 | goto again; |
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327 | } |
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328 | return index; |
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329 | } |
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5270 | serge | 330 | EXPORT_SYMBOL(bitmap_find_next_zero_area_off); |
3391 | Serge | 331 | |
332 | /* |
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333 | * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers, |
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334 | * second version by Paul Jackson, third by Joe Korty. |
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335 | */ |
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336 | |||
337 | #define CHUNKSZ 32 |
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338 | #define nbits_to_hold_value(val) fls(val) |
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339 | #define BASEDEC 10 /* fancier cpuset lists input in decimal */ |
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340 | |||
341 | |||
342 | |||
343 | |||
344 | |||
345 | /** |
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346 | * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap |
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347 | * @buf: pointer to a bitmap |
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6082 | serge | 348 | * @pos: a bit position in @buf (0 <= @pos < @nbits) |
349 | * @nbits: number of valid bit positions in @buf |
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3391 | Serge | 350 | * |
6082 | serge | 351 | * Map the bit at position @pos in @buf (of length @nbits) to the |
3391 | Serge | 352 | * ordinal of which set bit it is. If it is not set or if @pos |
353 | * is not a valid bit position, map to -1. |
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354 | * |
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355 | * If for example, just bits 4 through 7 are set in @buf, then @pos |
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356 | * values 4 through 7 will get mapped to 0 through 3, respectively, |
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5056 | serge | 357 | * and other @pos values will get mapped to -1. When @pos value 7 |
3391 | Serge | 358 | * gets mapped to (returns) @ord value 3 in this example, that means |
359 | * that bit 7 is the 3rd (starting with 0th) set bit in @buf. |
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360 | * |
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361 | * The bit positions 0 through @bits are valid positions in @buf. |
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362 | */ |
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6082 | serge | 363 | static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits) |
3391 | Serge | 364 | { |
6082 | serge | 365 | if (pos >= nbits || !test_bit(pos, buf)) |
3391 | Serge | 366 | return -1; |
367 | |||
6082 | serge | 368 | return __bitmap_weight(buf, pos); |
3391 | Serge | 369 | } |
370 | |||
371 | /** |
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372 | * bitmap_ord_to_pos - find position of n-th set bit in bitmap |
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373 | * @buf: pointer to bitmap |
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374 | * @ord: ordinal bit position (n-th set bit, n >= 0) |
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6082 | serge | 375 | * @nbits: number of valid bit positions in @buf |
3391 | Serge | 376 | * |
377 | * Map the ordinal offset of bit @ord in @buf to its position in @buf. |
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6082 | serge | 378 | * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord |
379 | * >= weight(buf), returns @nbits. |
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3391 | Serge | 380 | * |
381 | * If for example, just bits 4 through 7 are set in @buf, then @ord |
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382 | * values 0 through 3 will get mapped to 4 through 7, respectively, |
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6082 | serge | 383 | * and all other @ord values returns @nbits. When @ord value 3 |
3391 | Serge | 384 | * gets mapped to (returns) @pos value 7 in this example, that means |
385 | * that the 3rd set bit (starting with 0th) is at position 7 in @buf. |
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386 | * |
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6082 | serge | 387 | * The bit positions 0 through @nbits-1 are valid positions in @buf. |
3391 | Serge | 388 | */ |
6082 | serge | 389 | unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits) |
3391 | Serge | 390 | { |
6082 | serge | 391 | unsigned int pos; |
3391 | Serge | 392 | |
6082 | serge | 393 | for (pos = find_first_bit(buf, nbits); |
394 | pos < nbits && ord; |
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395 | pos = find_next_bit(buf, nbits, pos + 1)) |
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3391 | Serge | 396 | ord--; |
397 | |||
398 | return pos; |
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399 | } |
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400 | |||
401 | /** |
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402 | * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap |
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403 | * @dst: remapped result |
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404 | * @src: subset to be remapped |
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405 | * @old: defines domain of map |
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406 | * @new: defines range of map |
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6082 | serge | 407 | * @nbits: number of bits in each of these bitmaps |
3391 | Serge | 408 | * |
409 | * Let @old and @new define a mapping of bit positions, such that |
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410 | * whatever position is held by the n-th set bit in @old is mapped |
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411 | * to the n-th set bit in @new. In the more general case, allowing |
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412 | * for the possibility that the weight 'w' of @new is less than the |
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413 | * weight of @old, map the position of the n-th set bit in @old to |
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414 | * the position of the m-th set bit in @new, where m == n % w. |
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415 | * |
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416 | * If either of the @old and @new bitmaps are empty, or if @src and |
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417 | * @dst point to the same location, then this routine copies @src |
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418 | * to @dst. |
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419 | * |
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420 | * The positions of unset bits in @old are mapped to themselves |
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421 | * (the identify map). |
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422 | * |
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423 | * Apply the above specified mapping to @src, placing the result in |
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424 | * @dst, clearing any bits previously set in @dst. |
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425 | * |
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426 | * For example, lets say that @old has bits 4 through 7 set, and |
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427 | * @new has bits 12 through 15 set. This defines the mapping of bit |
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428 | * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other |
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429 | * bit positions unchanged. So if say @src comes into this routine |
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430 | * with bits 1, 5 and 7 set, then @dst should leave with bits 1, |
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431 | * 13 and 15 set. |
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432 | */ |
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433 | void bitmap_remap(unsigned long *dst, const unsigned long *src, |
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434 | const unsigned long *old, const unsigned long *new, |
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6082 | serge | 435 | unsigned int nbits) |
3391 | Serge | 436 | { |
6082 | serge | 437 | unsigned int oldbit, w; |
3391 | Serge | 438 | |
439 | if (dst == src) /* following doesn't handle inplace remaps */ |
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440 | return; |
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6082 | serge | 441 | bitmap_zero(dst, nbits); |
3391 | Serge | 442 | |
6082 | serge | 443 | w = bitmap_weight(new, nbits); |
444 | for_each_set_bit(oldbit, src, nbits) { |
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445 | int n = bitmap_pos_to_ord(old, oldbit, nbits); |
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3391 | Serge | 446 | |
447 | if (n < 0 || w == 0) |
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448 | set_bit(oldbit, dst); /* identity map */ |
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449 | else |
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6082 | serge | 450 | set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst); |
3391 | Serge | 451 | } |
452 | } |
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453 | EXPORT_SYMBOL(bitmap_remap); |
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454 | |||
455 | /** |
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456 | * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit |
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457 | * @oldbit: bit position to be mapped |
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458 | * @old: defines domain of map |
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459 | * @new: defines range of map |
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460 | * @bits: number of bits in each of these bitmaps |
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461 | * |
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462 | * Let @old and @new define a mapping of bit positions, such that |
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463 | * whatever position is held by the n-th set bit in @old is mapped |
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464 | * to the n-th set bit in @new. In the more general case, allowing |
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465 | * for the possibility that the weight 'w' of @new is less than the |
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466 | * weight of @old, map the position of the n-th set bit in @old to |
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467 | * the position of the m-th set bit in @new, where m == n % w. |
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468 | * |
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469 | * The positions of unset bits in @old are mapped to themselves |
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470 | * (the identify map). |
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471 | * |
||
472 | * Apply the above specified mapping to bit position @oldbit, returning |
||
473 | * the new bit position. |
||
474 | * |
||
475 | * For example, lets say that @old has bits 4 through 7 set, and |
||
476 | * @new has bits 12 through 15 set. This defines the mapping of bit |
||
477 | * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other |
||
478 | * bit positions unchanged. So if say @oldbit is 5, then this routine |
||
479 | * returns 13. |
||
480 | */ |
||
481 | int bitmap_bitremap(int oldbit, const unsigned long *old, |
||
482 | const unsigned long *new, int bits) |
||
483 | { |
||
484 | int w = bitmap_weight(new, bits); |
||
485 | int n = bitmap_pos_to_ord(old, oldbit, bits); |
||
486 | if (n < 0 || w == 0) |
||
487 | return oldbit; |
||
488 | else |
||
489 | return bitmap_ord_to_pos(new, n % w, bits); |
||
490 | } |
||
491 | EXPORT_SYMBOL(bitmap_bitremap); |
||
492 | |||
493 | /** |
||
494 | * bitmap_onto - translate one bitmap relative to another |
||
495 | * @dst: resulting translated bitmap |
||
496 | * @orig: original untranslated bitmap |
||
497 | * @relmap: bitmap relative to which translated |
||
498 | * @bits: number of bits in each of these bitmaps |
||
499 | * |
||
500 | * Set the n-th bit of @dst iff there exists some m such that the |
||
501 | * n-th bit of @relmap is set, the m-th bit of @orig is set, and |
||
502 | * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. |
||
503 | * (If you understood the previous sentence the first time your |
||
504 | * read it, you're overqualified for your current job.) |
||
505 | * |
||
506 | * In other words, @orig is mapped onto (surjectively) @dst, |
||
6082 | serge | 507 | * using the map { |
3391 | Serge | 508 | * m-th set bit of @relmap }. |
509 | * |
||
510 | * Any set bits in @orig above bit number W, where W is the |
||
511 | * weight of (number of set bits in) @relmap are mapped nowhere. |
||
512 | * In particular, if for all bits m set in @orig, m >= W, then |
||
513 | * @dst will end up empty. In situations where the possibility |
||
514 | * of such an empty result is not desired, one way to avoid it is |
||
515 | * to use the bitmap_fold() operator, below, to first fold the |
||
516 | * @orig bitmap over itself so that all its set bits x are in the |
||
517 | * range 0 <= x < W. The bitmap_fold() operator does this by |
||
518 | * setting the bit (m % W) in @dst, for each bit (m) set in @orig. |
||
519 | * |
||
520 | * Example [1] for bitmap_onto(): |
||
521 | * Let's say @relmap has bits 30-39 set, and @orig has bits |
||
522 | * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, |
||
523 | * @dst will have bits 31, 33, 35, 37 and 39 set. |
||
524 | * |
||
525 | * When bit 0 is set in @orig, it means turn on the bit in |
||
526 | * @dst corresponding to whatever is the first bit (if any) |
||
527 | * that is turned on in @relmap. Since bit 0 was off in the |
||
528 | * above example, we leave off that bit (bit 30) in @dst. |
||
529 | * |
||
530 | * When bit 1 is set in @orig (as in the above example), it |
||
531 | * means turn on the bit in @dst corresponding to whatever |
||
532 | * is the second bit that is turned on in @relmap. The second |
||
533 | * bit in @relmap that was turned on in the above example was |
||
534 | * bit 31, so we turned on bit 31 in @dst. |
||
535 | * |
||
536 | * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, |
||
537 | * because they were the 4th, 6th, 8th and 10th set bits |
||
538 | * set in @relmap, and the 4th, 6th, 8th and 10th bits of |
||
539 | * @orig (i.e. bits 3, 5, 7 and 9) were also set. |
||
540 | * |
||
541 | * When bit 11 is set in @orig, it means turn on the bit in |
||
542 | * @dst corresponding to whatever is the twelfth bit that is |
||
543 | * turned on in @relmap. In the above example, there were |
||
544 | * only ten bits turned on in @relmap (30..39), so that bit |
||
545 | * 11 was set in @orig had no affect on @dst. |
||
546 | * |
||
547 | * Example [2] for bitmap_fold() + bitmap_onto(): |
||
548 | * Let's say @relmap has these ten bits set: |
||
549 | * 40 41 42 43 45 48 53 61 74 95 |
||
550 | * (for the curious, that's 40 plus the first ten terms of the |
||
551 | * Fibonacci sequence.) |
||
552 | * |
||
553 | * Further lets say we use the following code, invoking |
||
554 | * bitmap_fold() then bitmap_onto, as suggested above to |
||
5270 | serge | 555 | * avoid the possibility of an empty @dst result: |
3391 | Serge | 556 | * |
557 | * unsigned long *tmp; // a temporary bitmap's bits |
||
558 | * |
||
559 | * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); |
||
560 | * bitmap_onto(dst, tmp, relmap, bits); |
||
561 | * |
||
562 | * Then this table shows what various values of @dst would be, for |
||
563 | * various @orig's. I list the zero-based positions of each set bit. |
||
564 | * The tmp column shows the intermediate result, as computed by |
||
565 | * using bitmap_fold() to fold the @orig bitmap modulo ten |
||
566 | * (the weight of @relmap). |
||
567 | * |
||
568 | * @orig tmp @dst |
||
569 | * 0 0 40 |
||
570 | * 1 1 41 |
||
571 | * 9 9 95 |
||
572 | * 10 0 40 (*) |
||
573 | * 1 3 5 7 1 3 5 7 41 43 48 61 |
||
574 | * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 |
||
575 | * 0 9 18 27 0 9 8 7 40 61 74 95 |
||
576 | * 0 10 20 30 0 40 |
||
577 | * 0 11 22 33 0 1 2 3 40 41 42 43 |
||
578 | * 0 12 24 36 0 2 4 6 40 42 45 53 |
||
579 | * 78 102 211 1 2 8 41 42 74 (*) |
||
580 | * |
||
581 | * (*) For these marked lines, if we hadn't first done bitmap_fold() |
||
582 | * into tmp, then the @dst result would have been empty. |
||
583 | * |
||
584 | * If either of @orig or @relmap is empty (no set bits), then @dst |
||
585 | * will be returned empty. |
||
586 | * |
||
587 | * If (as explained above) the only set bits in @orig are in positions |
||
588 | * m where m >= W, (where W is the weight of @relmap) then @dst will |
||
589 | * once again be returned empty. |
||
590 | * |
||
591 | * All bits in @dst not set by the above rule are cleared. |
||
592 | */ |
||
593 | void bitmap_onto(unsigned long *dst, const unsigned long *orig, |
||
6082 | serge | 594 | const unsigned long *relmap, unsigned int bits) |
3391 | Serge | 595 | { |
6082 | serge | 596 | unsigned int n, m; /* same meaning as in above comment */ |
3391 | Serge | 597 | |
598 | if (dst == orig) /* following doesn't handle inplace mappings */ |
||
599 | return; |
||
600 | bitmap_zero(dst, bits); |
||
601 | |||
602 | /* |
||
603 | * The following code is a more efficient, but less |
||
604 | * obvious, equivalent to the loop: |
||
605 | * for (m = 0; m < bitmap_weight(relmap, bits); m++) { |
||
606 | * n = bitmap_ord_to_pos(orig, m, bits); |
||
607 | * if (test_bit(m, orig)) |
||
608 | * set_bit(n, dst); |
||
609 | * } |
||
610 | */ |
||
611 | |||
612 | m = 0; |
||
613 | for_each_set_bit(n, relmap, bits) { |
||
614 | /* m == bitmap_pos_to_ord(relmap, n, bits) */ |
||
615 | if (test_bit(m, orig)) |
||
616 | set_bit(n, dst); |
||
617 | m++; |
||
618 | } |
||
619 | } |
||
620 | EXPORT_SYMBOL(bitmap_onto); |
||
621 | |||
622 | /** |
||
623 | * bitmap_fold - fold larger bitmap into smaller, modulo specified size |
||
624 | * @dst: resulting smaller bitmap |
||
625 | * @orig: original larger bitmap |
||
626 | * @sz: specified size |
||
6082 | serge | 627 | * @nbits: number of bits in each of these bitmaps |
3391 | Serge | 628 | * |
629 | * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. |
||
630 | * Clear all other bits in @dst. See further the comment and |
||
631 | * Example [2] for bitmap_onto() for why and how to use this. |
||
632 | */ |
||
633 | void bitmap_fold(unsigned long *dst, const unsigned long *orig, |
||
6082 | serge | 634 | unsigned int sz, unsigned int nbits) |
3391 | Serge | 635 | { |
6082 | serge | 636 | unsigned int oldbit; |
3391 | Serge | 637 | |
638 | if (dst == orig) /* following doesn't handle inplace mappings */ |
||
639 | return; |
||
6082 | serge | 640 | bitmap_zero(dst, nbits); |
3391 | Serge | 641 | |
6082 | serge | 642 | for_each_set_bit(oldbit, orig, nbits) |
3391 | Serge | 643 | set_bit(oldbit % sz, dst); |
644 | } |
||
645 | EXPORT_SYMBOL(bitmap_fold); |
||
646 | |||
647 | /* |
||
648 | * Common code for bitmap_*_region() routines. |
||
649 | * bitmap: array of unsigned longs corresponding to the bitmap |
||
650 | * pos: the beginning of the region |
||
651 | * order: region size (log base 2 of number of bits) |
||
652 | * reg_op: operation(s) to perform on that region of bitmap |
||
653 | * |
||
654 | * Can set, verify and/or release a region of bits in a bitmap, |
||
655 | * depending on which combination of REG_OP_* flag bits is set. |
||
656 | * |
||
657 | * A region of a bitmap is a sequence of bits in the bitmap, of |
||
658 | * some size '1 << order' (a power of two), aligned to that same |
||
659 | * '1 << order' power of two. |
||
660 | * |
||
661 | * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). |
||
662 | * Returns 0 in all other cases and reg_ops. |
||
663 | */ |
||
664 | |||
665 | enum { |
||
666 | REG_OP_ISFREE, /* true if region is all zero bits */ |
||
667 | REG_OP_ALLOC, /* set all bits in region */ |
||
668 | REG_OP_RELEASE, /* clear all bits in region */ |
||
669 | }; |
||
670 | |||
5056 | serge | 671 | static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op) |
3391 | Serge | 672 | { |
673 | int nbits_reg; /* number of bits in region */ |
||
674 | int index; /* index first long of region in bitmap */ |
||
675 | int offset; /* bit offset region in bitmap[index] */ |
||
676 | int nlongs_reg; /* num longs spanned by region in bitmap */ |
||
677 | int nbitsinlong; /* num bits of region in each spanned long */ |
||
678 | unsigned long mask; /* bitmask for one long of region */ |
||
679 | int i; /* scans bitmap by longs */ |
||
680 | int ret = 0; /* return value */ |
||
681 | |||
682 | /* |
||
683 | * Either nlongs_reg == 1 (for small orders that fit in one long) |
||
684 | * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) |
||
685 | */ |
||
686 | nbits_reg = 1 << order; |
||
687 | index = pos / BITS_PER_LONG; |
||
688 | offset = pos - (index * BITS_PER_LONG); |
||
689 | nlongs_reg = BITS_TO_LONGS(nbits_reg); |
||
690 | nbitsinlong = min(nbits_reg, BITS_PER_LONG); |
||
691 | |||
692 | /* |
||
693 | * Can't do "mask = (1UL << nbitsinlong) - 1", as that |
||
694 | * overflows if nbitsinlong == BITS_PER_LONG. |
||
695 | */ |
||
696 | mask = (1UL << (nbitsinlong - 1)); |
||
697 | mask += mask - 1; |
||
698 | mask <<= offset; |
||
699 | |||
700 | switch (reg_op) { |
||
701 | case REG_OP_ISFREE: |
||
702 | for (i = 0; i < nlongs_reg; i++) { |
||
703 | if (bitmap[index + i] & mask) |
||
704 | goto done; |
||
705 | } |
||
706 | ret = 1; /* all bits in region free (zero) */ |
||
707 | break; |
||
708 | |||
709 | case REG_OP_ALLOC: |
||
710 | for (i = 0; i < nlongs_reg; i++) |
||
711 | bitmap[index + i] |= mask; |
||
712 | break; |
||
713 | |||
714 | case REG_OP_RELEASE: |
||
715 | for (i = 0; i < nlongs_reg; i++) |
||
716 | bitmap[index + i] &= ~mask; |
||
717 | break; |
||
718 | } |
||
719 | done: |
||
720 | return ret; |
||
721 | } |
||
722 | |||
723 | /** |
||
724 | * bitmap_find_free_region - find a contiguous aligned mem region |
||
725 | * @bitmap: array of unsigned longs corresponding to the bitmap |
||
726 | * @bits: number of bits in the bitmap |
||
727 | * @order: region size (log base 2 of number of bits) to find |
||
728 | * |
||
729 | * Find a region of free (zero) bits in a @bitmap of @bits bits and |
||
730 | * allocate them (set them to one). Only consider regions of length |
||
731 | * a power (@order) of two, aligned to that power of two, which |
||
732 | * makes the search algorithm much faster. |
||
733 | * |
||
734 | * Return the bit offset in bitmap of the allocated region, |
||
735 | * or -errno on failure. |
||
736 | */ |
||
5056 | serge | 737 | int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order) |
3391 | Serge | 738 | { |
5056 | serge | 739 | unsigned int pos, end; /* scans bitmap by regions of size order */ |
3391 | Serge | 740 | |
5056 | serge | 741 | for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) { |
3391 | Serge | 742 | if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) |
743 | continue; |
||
744 | __reg_op(bitmap, pos, order, REG_OP_ALLOC); |
||
745 | return pos; |
||
746 | } |
||
747 | return -ENOMEM; |
||
748 | } |
||
749 | EXPORT_SYMBOL(bitmap_find_free_region); |
||
750 | |||
751 | /** |
||
752 | * bitmap_release_region - release allocated bitmap region |
||
753 | * @bitmap: array of unsigned longs corresponding to the bitmap |
||
754 | * @pos: beginning of bit region to release |
||
755 | * @order: region size (log base 2 of number of bits) to release |
||
756 | * |
||
757 | * This is the complement to __bitmap_find_free_region() and releases |
||
758 | * the found region (by clearing it in the bitmap). |
||
759 | * |
||
760 | * No return value. |
||
761 | */ |
||
5056 | serge | 762 | void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order) |
3391 | Serge | 763 | { |
764 | __reg_op(bitmap, pos, order, REG_OP_RELEASE); |
||
765 | } |
||
766 | EXPORT_SYMBOL(bitmap_release_region); |
||
767 | |||
768 | /** |
||
769 | * bitmap_allocate_region - allocate bitmap region |
||
770 | * @bitmap: array of unsigned longs corresponding to the bitmap |
||
771 | * @pos: beginning of bit region to allocate |
||
772 | * @order: region size (log base 2 of number of bits) to allocate |
||
773 | * |
||
774 | * Allocate (set bits in) a specified region of a bitmap. |
||
775 | * |
||
776 | * Return 0 on success, or %-EBUSY if specified region wasn't |
||
777 | * free (not all bits were zero). |
||
778 | */ |
||
5056 | serge | 779 | int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order) |
3391 | Serge | 780 | { |
781 | if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) |
||
782 | return -EBUSY; |
||
5056 | serge | 783 | return __reg_op(bitmap, pos, order, REG_OP_ALLOC); |
3391 | Serge | 784 | } |
785 | EXPORT_SYMBOL(bitmap_allocate_region); |
||
786 | |||
787 | /** |
||
788 | * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. |
||
789 | * @dst: destination buffer |
||
790 | * @src: bitmap to copy |
||
791 | * @nbits: number of bits in the bitmap |
||
792 | * |
||
793 | * Require nbits % BITS_PER_LONG == 0. |
||
794 | */ |
||
6082 | serge | 795 | #ifdef __BIG_ENDIAN |
796 | void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits) |
||
3391 | Serge | 797 | { |
6082 | serge | 798 | unsigned int i; |
3391 | Serge | 799 | |
800 | for (i = 0; i < nbits/BITS_PER_LONG; i++) { |
||
801 | if (BITS_PER_LONG == 64) |
||
6082 | serge | 802 | dst[i] = cpu_to_le64(src[i]); |
3391 | Serge | 803 | else |
6082 | serge | 804 | dst[i] = cpu_to_le32(src[i]); |
3391 | Serge | 805 | } |
806 | } |
||
807 | EXPORT_SYMBOL(bitmap_copy_le); |
||
6082 | serge | 808 | #endif>=>><>>>>=><=>><>><>><>><>><>>>=>>>>>=>>=>>>>>>>>>><>=><=>>>> |