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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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5 | * Tlhis source code is licensed under the GNU General Public License, |
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6 | * Version 2. See the file COPYING for more details. |
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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_empty(const unsigned long *bitmap, int bits) |
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45 | { |
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46 | int k, lim = bits/BITS_PER_LONG; |
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47 | for (k = 0; k < lim; ++k) |
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48 | if (bitmap[k]) |
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49 | return 0; |
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50 | |||
51 | if (bits % BITS_PER_LONG) |
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52 | if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) |
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53 | return 0; |
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54 | |||
55 | return 1; |
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56 | } |
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57 | EXPORT_SYMBOL(__bitmap_empty); |
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58 | |||
59 | int __bitmap_full(const unsigned long *bitmap, int bits) |
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60 | { |
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61 | int k, lim = bits/BITS_PER_LONG; |
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62 | for (k = 0; k < lim; ++k) |
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63 | if (~bitmap[k]) |
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64 | return 0; |
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65 | |||
66 | if (bits % BITS_PER_LONG) |
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67 | if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) |
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68 | return 0; |
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69 | |||
70 | return 1; |
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71 | } |
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72 | EXPORT_SYMBOL(__bitmap_full); |
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73 | |||
74 | int __bitmap_equal(const unsigned long *bitmap1, |
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75 | const unsigned long *bitmap2, int bits) |
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76 | { |
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77 | int k, lim = bits/BITS_PER_LONG; |
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78 | for (k = 0; k < lim; ++k) |
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79 | if (bitmap1[k] != bitmap2[k]) |
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80 | return 0; |
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81 | |||
82 | if (bits % BITS_PER_LONG) |
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83 | if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) |
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84 | return 0; |
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85 | |||
86 | return 1; |
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87 | } |
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88 | EXPORT_SYMBOL(__bitmap_equal); |
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89 | |||
90 | void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits) |
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91 | { |
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92 | int k, lim = bits/BITS_PER_LONG; |
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93 | for (k = 0; k < lim; ++k) |
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94 | dst[k] = ~src[k]; |
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95 | |||
96 | if (bits % BITS_PER_LONG) |
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97 | dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits); |
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98 | } |
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99 | EXPORT_SYMBOL(__bitmap_complement); |
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100 | |||
101 | /** |
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102 | * __bitmap_shift_right - logical right shift of the bits in a bitmap |
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103 | * @dst : destination bitmap |
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104 | * @src : source bitmap |
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105 | * @shift : shift by this many bits |
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106 | * @bits : bitmap size, in bits |
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107 | * |
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108 | * Shifting right (dividing) means moving bits in the MS -> LS bit |
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109 | * direction. Zeros are fed into the vacated MS positions and the |
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110 | * LS bits shifted off the bottom are lost. |
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111 | */ |
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112 | void __bitmap_shift_right(unsigned long *dst, |
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113 | const unsigned long *src, int shift, int bits) |
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114 | { |
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115 | int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG; |
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116 | int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; |
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117 | unsigned long mask = (1UL << left) - 1; |
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118 | for (k = 0; off + k < lim; ++k) { |
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119 | unsigned long upper, lower; |
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120 | |||
121 | /* |
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122 | * If shift is not word aligned, take lower rem bits of |
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123 | * word above and make them the top rem bits of result. |
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124 | */ |
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125 | if (!rem || off + k + 1 >= lim) |
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126 | upper = 0; |
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127 | else { |
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128 | upper = src[off + k + 1]; |
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129 | if (off + k + 1 == lim - 1 && left) |
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130 | upper &= mask; |
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131 | } |
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132 | lower = src[off + k]; |
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133 | if (left && off + k == lim - 1) |
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134 | lower &= mask; |
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135 | dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem; |
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136 | if (left && k == lim - 1) |
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137 | dst[k] &= mask; |
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138 | } |
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139 | if (off) |
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140 | memset(&dst[lim - off], 0, off*sizeof(unsigned long)); |
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141 | } |
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142 | EXPORT_SYMBOL(__bitmap_shift_right); |
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143 | |||
144 | |||
145 | /** |
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146 | * __bitmap_shift_left - logical left shift of the bits in a bitmap |
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147 | * @dst : destination bitmap |
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148 | * @src : source bitmap |
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149 | * @shift : shift by this many bits |
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150 | * @bits : bitmap size, in bits |
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151 | * |
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152 | * Shifting left (multiplying) means moving bits in the LS -> MS |
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153 | * direction. Zeros are fed into the vacated LS bit positions |
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154 | * and those MS bits shifted off the top are lost. |
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155 | */ |
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156 | |||
157 | void __bitmap_shift_left(unsigned long *dst, |
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158 | const unsigned long *src, int shift, int bits) |
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159 | { |
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160 | int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG; |
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161 | int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; |
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162 | for (k = lim - off - 1; k >= 0; --k) { |
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163 | unsigned long upper, lower; |
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164 | |||
165 | /* |
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166 | * If shift is not word aligned, take upper rem bits of |
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167 | * word below and make them the bottom rem bits of result. |
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168 | */ |
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169 | if (rem && k > 0) |
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170 | lower = src[k - 1]; |
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171 | else |
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172 | lower = 0; |
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173 | upper = src[k]; |
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174 | if (left && k == lim - 1) |
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175 | upper &= (1UL << left) - 1; |
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176 | dst[k + off] = lower >> (BITS_PER_LONG - rem) | upper << rem; |
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177 | if (left && k + off == lim - 1) |
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178 | dst[k + off] &= (1UL << left) - 1; |
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179 | } |
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180 | if (off) |
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181 | memset(dst, 0, off*sizeof(unsigned long)); |
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182 | } |
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183 | EXPORT_SYMBOL(__bitmap_shift_left); |
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184 | |||
185 | int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1, |
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186 | const unsigned long *bitmap2, int bits) |
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187 | { |
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188 | int k; |
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189 | int nr = BITS_TO_LONGS(bits); |
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190 | unsigned long result = 0; |
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191 | |||
192 | for (k = 0; k < nr; k++) |
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193 | result |= (dst[k] = bitmap1[k] & bitmap2[k]); |
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194 | return result != 0; |
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195 | } |
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196 | EXPORT_SYMBOL(__bitmap_and); |
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197 | |||
198 | void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1, |
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199 | const unsigned long *bitmap2, int bits) |
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200 | { |
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201 | int k; |
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202 | int nr = BITS_TO_LONGS(bits); |
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203 | |||
204 | for (k = 0; k < nr; k++) |
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205 | dst[k] = bitmap1[k] | bitmap2[k]; |
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206 | } |
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207 | EXPORT_SYMBOL(__bitmap_or); |
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208 | |||
209 | void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1, |
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210 | const unsigned long *bitmap2, int bits) |
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211 | { |
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212 | int k; |
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213 | int nr = BITS_TO_LONGS(bits); |
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214 | |||
215 | for (k = 0; k < nr; k++) |
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216 | dst[k] = bitmap1[k] ^ bitmap2[k]; |
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217 | } |
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218 | EXPORT_SYMBOL(__bitmap_xor); |
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219 | |||
220 | int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1, |
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221 | const unsigned long *bitmap2, int bits) |
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222 | { |
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223 | int k; |
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224 | int nr = BITS_TO_LONGS(bits); |
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225 | unsigned long result = 0; |
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226 | |||
227 | for (k = 0; k < nr; k++) |
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228 | result |= (dst[k] = bitmap1[k] & ~bitmap2[k]); |
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229 | return result != 0; |
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230 | } |
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231 | EXPORT_SYMBOL(__bitmap_andnot); |
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232 | |||
233 | int __bitmap_intersects(const unsigned long *bitmap1, |
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234 | const unsigned long *bitmap2, int bits) |
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235 | { |
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236 | int k, lim = bits/BITS_PER_LONG; |
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237 | for (k = 0; k < lim; ++k) |
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238 | if (bitmap1[k] & bitmap2[k]) |
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239 | return 1; |
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240 | |||
241 | if (bits % BITS_PER_LONG) |
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242 | if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) |
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243 | return 1; |
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244 | return 0; |
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245 | } |
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246 | EXPORT_SYMBOL(__bitmap_intersects); |
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247 | |||
248 | int __bitmap_subset(const unsigned long *bitmap1, |
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249 | const unsigned long *bitmap2, int bits) |
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250 | { |
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251 | int k, lim = bits/BITS_PER_LONG; |
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252 | for (k = 0; k < lim; ++k) |
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253 | if (bitmap1[k] & ~bitmap2[k]) |
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254 | return 0; |
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255 | |||
256 | if (bits % BITS_PER_LONG) |
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257 | if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) |
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258 | return 0; |
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259 | return 1; |
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260 | } |
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261 | EXPORT_SYMBOL(__bitmap_subset); |
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262 | |||
263 | int __bitmap_weight(const unsigned long *bitmap, int bits) |
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264 | { |
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265 | int k, w = 0, lim = bits/BITS_PER_LONG; |
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266 | |||
267 | for (k = 0; k < lim; k++) |
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268 | w += hweight_long(bitmap[k]); |
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269 | |||
270 | if (bits % BITS_PER_LONG) |
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271 | w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); |
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272 | |||
273 | return w; |
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274 | } |
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275 | EXPORT_SYMBOL(__bitmap_weight); |
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276 | |||
277 | void bitmap_set(unsigned long *map, int start, int nr) |
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278 | { |
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279 | unsigned long *p = map + BIT_WORD(start); |
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280 | const int size = start + nr; |
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281 | int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG); |
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282 | unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); |
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283 | |||
284 | while (nr - bits_to_set >= 0) { |
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285 | *p |= mask_to_set; |
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286 | nr -= bits_to_set; |
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287 | bits_to_set = BITS_PER_LONG; |
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288 | mask_to_set = ~0UL; |
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289 | p++; |
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290 | } |
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291 | if (nr) { |
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292 | mask_to_set &= BITMAP_LAST_WORD_MASK(size); |
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293 | *p |= mask_to_set; |
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294 | } |
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295 | } |
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296 | EXPORT_SYMBOL(bitmap_set); |
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297 | |||
298 | void bitmap_clear(unsigned long *map, int start, int nr) |
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299 | { |
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300 | unsigned long *p = map + BIT_WORD(start); |
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301 | const int size = start + nr; |
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302 | int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); |
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303 | unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); |
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304 | |||
305 | while (nr - bits_to_clear >= 0) { |
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306 | *p &= ~mask_to_clear; |
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307 | nr -= bits_to_clear; |
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308 | bits_to_clear = BITS_PER_LONG; |
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309 | mask_to_clear = ~0UL; |
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310 | p++; |
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311 | } |
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312 | if (nr) { |
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313 | mask_to_clear &= BITMAP_LAST_WORD_MASK(size); |
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314 | *p &= ~mask_to_clear; |
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315 | } |
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316 | } |
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317 | EXPORT_SYMBOL(bitmap_clear); |
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318 | |||
319 | /* |
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320 | * bitmap_find_next_zero_area - find a contiguous aligned zero area |
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321 | * @map: The address to base the search on |
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322 | * @size: The bitmap size in bits |
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323 | * @start: The bitnumber to start searching at |
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324 | * @nr: The number of zeroed bits we're looking for |
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325 | * @align_mask: Alignment mask for zero area |
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326 | * |
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327 | * The @align_mask should be one less than a power of 2; the effect is that |
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328 | * the bit offset of all zero areas this function finds is multiples of that |
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329 | * power of 2. A @align_mask of 0 means no alignment is required. |
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330 | */ |
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331 | unsigned long bitmap_find_next_zero_area(unsigned long *map, |
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332 | unsigned long size, |
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333 | unsigned long start, |
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334 | unsigned int nr, |
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335 | unsigned long align_mask) |
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336 | { |
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337 | unsigned long index, end, i; |
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338 | again: |
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339 | index = find_next_zero_bit(map, size, start); |
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340 | |||
341 | /* Align allocation */ |
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342 | index = __ALIGN_MASK(index, align_mask); |
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343 | |||
344 | end = index + nr; |
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345 | if (end > size) |
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346 | return end; |
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347 | i = find_next_bit(map, end, index); |
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348 | if (i < end) { |
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349 | start = i + 1; |
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350 | goto again; |
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351 | } |
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352 | return index; |
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353 | } |
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354 | EXPORT_SYMBOL(bitmap_find_next_zero_area); |
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355 | |||
356 | /* |
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357 | * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers, |
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358 | * second version by Paul Jackson, third by Joe Korty. |
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359 | */ |
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360 | |||
361 | #define CHUNKSZ 32 |
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362 | #define nbits_to_hold_value(val) fls(val) |
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363 | #define BASEDEC 10 /* fancier cpuset lists input in decimal */ |
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364 | |||
365 | |||
366 | |||
367 | |||
368 | |||
369 | /** |
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370 | * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap |
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371 | * @buf: pointer to a bitmap |
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372 | * @pos: a bit position in @buf (0 <= @pos < @bits) |
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373 | * @bits: number of valid bit positions in @buf |
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374 | * |
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375 | * Map the bit at position @pos in @buf (of length @bits) to the |
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376 | * ordinal of which set bit it is. If it is not set or if @pos |
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377 | * is not a valid bit position, map to -1. |
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378 | * |
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379 | * If for example, just bits 4 through 7 are set in @buf, then @pos |
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380 | * values 4 through 7 will get mapped to 0 through 3, respectively, |
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381 | * and other @pos values will get mapped to 0. When @pos value 7 |
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382 | * gets mapped to (returns) @ord value 3 in this example, that means |
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383 | * that bit 7 is the 3rd (starting with 0th) set bit in @buf. |
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384 | * |
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385 | * The bit positions 0 through @bits are valid positions in @buf. |
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386 | */ |
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387 | static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits) |
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388 | { |
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389 | int i, ord; |
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390 | |||
391 | if (pos < 0 || pos >= bits || !test_bit(pos, buf)) |
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392 | return -1; |
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393 | |||
394 | i = find_first_bit(buf, bits); |
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395 | ord = 0; |
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396 | while (i < pos) { |
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397 | i = find_next_bit(buf, bits, i + 1); |
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398 | ord++; |
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399 | } |
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400 | BUG_ON(i != pos); |
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401 | |||
402 | return ord; |
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403 | } |
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404 | |||
405 | /** |
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406 | * bitmap_ord_to_pos - find position of n-th set bit in bitmap |
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407 | * @buf: pointer to bitmap |
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408 | * @ord: ordinal bit position (n-th set bit, n >= 0) |
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409 | * @bits: number of valid bit positions in @buf |
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410 | * |
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411 | * Map the ordinal offset of bit @ord in @buf to its position in @buf. |
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412 | * Value of @ord should be in range 0 <= @ord < weight(buf), else |
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413 | * results are undefined. |
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414 | * |
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415 | * If for example, just bits 4 through 7 are set in @buf, then @ord |
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416 | * values 0 through 3 will get mapped to 4 through 7, respectively, |
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417 | * and all other @ord values return undefined values. When @ord value 3 |
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418 | * gets mapped to (returns) @pos value 7 in this example, that means |
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419 | * that the 3rd set bit (starting with 0th) is at position 7 in @buf. |
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420 | * |
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421 | * The bit positions 0 through @bits are valid positions in @buf. |
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422 | */ |
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423 | int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits) |
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424 | { |
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425 | int pos = 0; |
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426 | |||
427 | if (ord >= 0 && ord < bits) { |
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428 | int i; |
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429 | |||
430 | for (i = find_first_bit(buf, bits); |
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431 | i < bits && ord > 0; |
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432 | i = find_next_bit(buf, bits, i + 1)) |
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433 | ord--; |
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434 | if (i < bits && ord == 0) |
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435 | pos = i; |
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436 | } |
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437 | |||
438 | return pos; |
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439 | } |
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440 | |||
441 | /** |
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442 | * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap |
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443 | * @dst: remapped result |
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444 | * @src: subset to be remapped |
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445 | * @old: defines domain of map |
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446 | * @new: defines range of map |
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447 | * @bits: number of bits in each of these bitmaps |
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448 | * |
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449 | * Let @old and @new define a mapping of bit positions, such that |
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450 | * whatever position is held by the n-th set bit in @old is mapped |
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451 | * to the n-th set bit in @new. In the more general case, allowing |
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452 | * for the possibility that the weight 'w' of @new is less than the |
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453 | * weight of @old, map the position of the n-th set bit in @old to |
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454 | * the position of the m-th set bit in @new, where m == n % w. |
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455 | * |
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456 | * If either of the @old and @new bitmaps are empty, or if @src and |
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457 | * @dst point to the same location, then this routine copies @src |
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458 | * to @dst. |
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459 | * |
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460 | * The positions of unset bits in @old are mapped to themselves |
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461 | * (the identify map). |
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462 | * |
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463 | * Apply the above specified mapping to @src, placing the result in |
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464 | * @dst, clearing any bits previously set in @dst. |
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465 | * |
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466 | * For example, lets say that @old has bits 4 through 7 set, and |
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467 | * @new has bits 12 through 15 set. This defines the mapping of bit |
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468 | * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other |
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469 | * bit positions unchanged. So if say @src comes into this routine |
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470 | * with bits 1, 5 and 7 set, then @dst should leave with bits 1, |
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471 | * 13 and 15 set. |
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472 | */ |
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473 | void bitmap_remap(unsigned long *dst, const unsigned long *src, |
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474 | const unsigned long *old, const unsigned long *new, |
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475 | int bits) |
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476 | { |
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477 | int oldbit, w; |
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478 | |||
479 | if (dst == src) /* following doesn't handle inplace remaps */ |
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480 | return; |
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481 | bitmap_zero(dst, bits); |
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482 | |||
483 | w = bitmap_weight(new, bits); |
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484 | for_each_set_bit(oldbit, src, bits) { |
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485 | int n = bitmap_pos_to_ord(old, oldbit, bits); |
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486 | |||
487 | if (n < 0 || w == 0) |
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488 | set_bit(oldbit, dst); /* identity map */ |
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489 | else |
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490 | set_bit(bitmap_ord_to_pos(new, n % w, bits), dst); |
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491 | } |
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492 | } |
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493 | EXPORT_SYMBOL(bitmap_remap); |
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494 | |||
495 | /** |
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496 | * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit |
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497 | * @oldbit: bit position to be mapped |
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498 | * @old: defines domain of map |
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499 | * @new: defines range of map |
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500 | * @bits: number of bits in each of these bitmaps |
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501 | * |
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502 | * Let @old and @new define a mapping of bit positions, such that |
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503 | * whatever position is held by the n-th set bit in @old is mapped |
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504 | * to the n-th set bit in @new. In the more general case, allowing |
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505 | * for the possibility that the weight 'w' of @new is less than the |
||
506 | * weight of @old, map the position of the n-th set bit in @old to |
||
507 | * the position of the m-th set bit in @new, where m == n % w. |
||
508 | * |
||
509 | * The positions of unset bits in @old are mapped to themselves |
||
510 | * (the identify map). |
||
511 | * |
||
512 | * Apply the above specified mapping to bit position @oldbit, returning |
||
513 | * the new bit position. |
||
514 | * |
||
515 | * For example, lets say that @old has bits 4 through 7 set, and |
||
516 | * @new has bits 12 through 15 set. This defines the mapping of bit |
||
517 | * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other |
||
518 | * bit positions unchanged. So if say @oldbit is 5, then this routine |
||
519 | * returns 13. |
||
520 | */ |
||
521 | int bitmap_bitremap(int oldbit, const unsigned long *old, |
||
522 | const unsigned long *new, int bits) |
||
523 | { |
||
524 | int w = bitmap_weight(new, bits); |
||
525 | int n = bitmap_pos_to_ord(old, oldbit, bits); |
||
526 | if (n < 0 || w == 0) |
||
527 | return oldbit; |
||
528 | else |
||
529 | return bitmap_ord_to_pos(new, n % w, bits); |
||
530 | } |
||
531 | EXPORT_SYMBOL(bitmap_bitremap); |
||
532 | |||
533 | /** |
||
534 | * bitmap_onto - translate one bitmap relative to another |
||
535 | * @dst: resulting translated bitmap |
||
536 | * @orig: original untranslated bitmap |
||
537 | * @relmap: bitmap relative to which translated |
||
538 | * @bits: number of bits in each of these bitmaps |
||
539 | * |
||
540 | * Set the n-th bit of @dst iff there exists some m such that the |
||
541 | * n-th bit of @relmap is set, the m-th bit of @orig is set, and |
||
542 | * the n-th bit of @relmap is also the m-th _set_ bit of @relmap. |
||
543 | * (If you understood the previous sentence the first time your |
||
544 | * read it, you're overqualified for your current job.) |
||
545 | * |
||
546 | * In other words, @orig is mapped onto (surjectively) @dst, |
||
547 | * using the the map { |
||
548 | * m-th set bit of @relmap }. |
||
549 | * |
||
550 | * Any set bits in @orig above bit number W, where W is the |
||
551 | * weight of (number of set bits in) @relmap are mapped nowhere. |
||
552 | * In particular, if for all bits m set in @orig, m >= W, then |
||
553 | * @dst will end up empty. In situations where the possibility |
||
554 | * of such an empty result is not desired, one way to avoid it is |
||
555 | * to use the bitmap_fold() operator, below, to first fold the |
||
556 | * @orig bitmap over itself so that all its set bits x are in the |
||
557 | * range 0 <= x < W. The bitmap_fold() operator does this by |
||
558 | * setting the bit (m % W) in @dst, for each bit (m) set in @orig. |
||
559 | * |
||
560 | * Example [1] for bitmap_onto(): |
||
561 | * Let's say @relmap has bits 30-39 set, and @orig has bits |
||
562 | * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine, |
||
563 | * @dst will have bits 31, 33, 35, 37 and 39 set. |
||
564 | * |
||
565 | * When bit 0 is set in @orig, it means turn on the bit in |
||
566 | * @dst corresponding to whatever is the first bit (if any) |
||
567 | * that is turned on in @relmap. Since bit 0 was off in the |
||
568 | * above example, we leave off that bit (bit 30) in @dst. |
||
569 | * |
||
570 | * When bit 1 is set in @orig (as in the above example), it |
||
571 | * means turn on the bit in @dst corresponding to whatever |
||
572 | * is the second bit that is turned on in @relmap. The second |
||
573 | * bit in @relmap that was turned on in the above example was |
||
574 | * bit 31, so we turned on bit 31 in @dst. |
||
575 | * |
||
576 | * Similarly, we turned on bits 33, 35, 37 and 39 in @dst, |
||
577 | * because they were the 4th, 6th, 8th and 10th set bits |
||
578 | * set in @relmap, and the 4th, 6th, 8th and 10th bits of |
||
579 | * @orig (i.e. bits 3, 5, 7 and 9) were also set. |
||
580 | * |
||
581 | * When bit 11 is set in @orig, it means turn on the bit in |
||
582 | * @dst corresponding to whatever is the twelfth bit that is |
||
583 | * turned on in @relmap. In the above example, there were |
||
584 | * only ten bits turned on in @relmap (30..39), so that bit |
||
585 | * 11 was set in @orig had no affect on @dst. |
||
586 | * |
||
587 | * Example [2] for bitmap_fold() + bitmap_onto(): |
||
588 | * Let's say @relmap has these ten bits set: |
||
589 | * 40 41 42 43 45 48 53 61 74 95 |
||
590 | * (for the curious, that's 40 plus the first ten terms of the |
||
591 | * Fibonacci sequence.) |
||
592 | * |
||
593 | * Further lets say we use the following code, invoking |
||
594 | * bitmap_fold() then bitmap_onto, as suggested above to |
||
595 | * avoid the possitility of an empty @dst result: |
||
596 | * |
||
597 | * unsigned long *tmp; // a temporary bitmap's bits |
||
598 | * |
||
599 | * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits); |
||
600 | * bitmap_onto(dst, tmp, relmap, bits); |
||
601 | * |
||
602 | * Then this table shows what various values of @dst would be, for |
||
603 | * various @orig's. I list the zero-based positions of each set bit. |
||
604 | * The tmp column shows the intermediate result, as computed by |
||
605 | * using bitmap_fold() to fold the @orig bitmap modulo ten |
||
606 | * (the weight of @relmap). |
||
607 | * |
||
608 | * @orig tmp @dst |
||
609 | * 0 0 40 |
||
610 | * 1 1 41 |
||
611 | * 9 9 95 |
||
612 | * 10 0 40 (*) |
||
613 | * 1 3 5 7 1 3 5 7 41 43 48 61 |
||
614 | * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45 |
||
615 | * 0 9 18 27 0 9 8 7 40 61 74 95 |
||
616 | * 0 10 20 30 0 40 |
||
617 | * 0 11 22 33 0 1 2 3 40 41 42 43 |
||
618 | * 0 12 24 36 0 2 4 6 40 42 45 53 |
||
619 | * 78 102 211 1 2 8 41 42 74 (*) |
||
620 | * |
||
621 | * (*) For these marked lines, if we hadn't first done bitmap_fold() |
||
622 | * into tmp, then the @dst result would have been empty. |
||
623 | * |
||
624 | * If either of @orig or @relmap is empty (no set bits), then @dst |
||
625 | * will be returned empty. |
||
626 | * |
||
627 | * If (as explained above) the only set bits in @orig are in positions |
||
628 | * m where m >= W, (where W is the weight of @relmap) then @dst will |
||
629 | * once again be returned empty. |
||
630 | * |
||
631 | * All bits in @dst not set by the above rule are cleared. |
||
632 | */ |
||
633 | void bitmap_onto(unsigned long *dst, const unsigned long *orig, |
||
634 | const unsigned long *relmap, int bits) |
||
635 | { |
||
636 | int n, m; /* same meaning as in above comment */ |
||
637 | |||
638 | if (dst == orig) /* following doesn't handle inplace mappings */ |
||
639 | return; |
||
640 | bitmap_zero(dst, bits); |
||
641 | |||
642 | /* |
||
643 | * The following code is a more efficient, but less |
||
644 | * obvious, equivalent to the loop: |
||
645 | * for (m = 0; m < bitmap_weight(relmap, bits); m++) { |
||
646 | * n = bitmap_ord_to_pos(orig, m, bits); |
||
647 | * if (test_bit(m, orig)) |
||
648 | * set_bit(n, dst); |
||
649 | * } |
||
650 | */ |
||
651 | |||
652 | m = 0; |
||
653 | for_each_set_bit(n, relmap, bits) { |
||
654 | /* m == bitmap_pos_to_ord(relmap, n, bits) */ |
||
655 | if (test_bit(m, orig)) |
||
656 | set_bit(n, dst); |
||
657 | m++; |
||
658 | } |
||
659 | } |
||
660 | EXPORT_SYMBOL(bitmap_onto); |
||
661 | |||
662 | /** |
||
663 | * bitmap_fold - fold larger bitmap into smaller, modulo specified size |
||
664 | * @dst: resulting smaller bitmap |
||
665 | * @orig: original larger bitmap |
||
666 | * @sz: specified size |
||
667 | * @bits: number of bits in each of these bitmaps |
||
668 | * |
||
669 | * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst. |
||
670 | * Clear all other bits in @dst. See further the comment and |
||
671 | * Example [2] for bitmap_onto() for why and how to use this. |
||
672 | */ |
||
673 | void bitmap_fold(unsigned long *dst, const unsigned long *orig, |
||
674 | int sz, int bits) |
||
675 | { |
||
676 | int oldbit; |
||
677 | |||
678 | if (dst == orig) /* following doesn't handle inplace mappings */ |
||
679 | return; |
||
680 | bitmap_zero(dst, bits); |
||
681 | |||
682 | for_each_set_bit(oldbit, orig, bits) |
||
683 | set_bit(oldbit % sz, dst); |
||
684 | } |
||
685 | EXPORT_SYMBOL(bitmap_fold); |
||
686 | |||
687 | /* |
||
688 | * Common code for bitmap_*_region() routines. |
||
689 | * bitmap: array of unsigned longs corresponding to the bitmap |
||
690 | * pos: the beginning of the region |
||
691 | * order: region size (log base 2 of number of bits) |
||
692 | * reg_op: operation(s) to perform on that region of bitmap |
||
693 | * |
||
694 | * Can set, verify and/or release a region of bits in a bitmap, |
||
695 | * depending on which combination of REG_OP_* flag bits is set. |
||
696 | * |
||
697 | * A region of a bitmap is a sequence of bits in the bitmap, of |
||
698 | * some size '1 << order' (a power of two), aligned to that same |
||
699 | * '1 << order' power of two. |
||
700 | * |
||
701 | * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). |
||
702 | * Returns 0 in all other cases and reg_ops. |
||
703 | */ |
||
704 | |||
705 | enum { |
||
706 | REG_OP_ISFREE, /* true if region is all zero bits */ |
||
707 | REG_OP_ALLOC, /* set all bits in region */ |
||
708 | REG_OP_RELEASE, /* clear all bits in region */ |
||
709 | }; |
||
710 | |||
711 | static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op) |
||
712 | { |
||
713 | int nbits_reg; /* number of bits in region */ |
||
714 | int index; /* index first long of region in bitmap */ |
||
715 | int offset; /* bit offset region in bitmap[index] */ |
||
716 | int nlongs_reg; /* num longs spanned by region in bitmap */ |
||
717 | int nbitsinlong; /* num bits of region in each spanned long */ |
||
718 | unsigned long mask; /* bitmask for one long of region */ |
||
719 | int i; /* scans bitmap by longs */ |
||
720 | int ret = 0; /* return value */ |
||
721 | |||
722 | /* |
||
723 | * Either nlongs_reg == 1 (for small orders that fit in one long) |
||
724 | * or (offset == 0 && mask == ~0UL) (for larger multiword orders.) |
||
725 | */ |
||
726 | nbits_reg = 1 << order; |
||
727 | index = pos / BITS_PER_LONG; |
||
728 | offset = pos - (index * BITS_PER_LONG); |
||
729 | nlongs_reg = BITS_TO_LONGS(nbits_reg); |
||
730 | nbitsinlong = min(nbits_reg, BITS_PER_LONG); |
||
731 | |||
732 | /* |
||
733 | * Can't do "mask = (1UL << nbitsinlong) - 1", as that |
||
734 | * overflows if nbitsinlong == BITS_PER_LONG. |
||
735 | */ |
||
736 | mask = (1UL << (nbitsinlong - 1)); |
||
737 | mask += mask - 1; |
||
738 | mask <<= offset; |
||
739 | |||
740 | switch (reg_op) { |
||
741 | case REG_OP_ISFREE: |
||
742 | for (i = 0; i < nlongs_reg; i++) { |
||
743 | if (bitmap[index + i] & mask) |
||
744 | goto done; |
||
745 | } |
||
746 | ret = 1; /* all bits in region free (zero) */ |
||
747 | break; |
||
748 | |||
749 | case REG_OP_ALLOC: |
||
750 | for (i = 0; i < nlongs_reg; i++) |
||
751 | bitmap[index + i] |= mask; |
||
752 | break; |
||
753 | |||
754 | case REG_OP_RELEASE: |
||
755 | for (i = 0; i < nlongs_reg; i++) |
||
756 | bitmap[index + i] &= ~mask; |
||
757 | break; |
||
758 | } |
||
759 | done: |
||
760 | return ret; |
||
761 | } |
||
762 | |||
763 | /** |
||
764 | * bitmap_find_free_region - find a contiguous aligned mem region |
||
765 | * @bitmap: array of unsigned longs corresponding to the bitmap |
||
766 | * @bits: number of bits in the bitmap |
||
767 | * @order: region size (log base 2 of number of bits) to find |
||
768 | * |
||
769 | * Find a region of free (zero) bits in a @bitmap of @bits bits and |
||
770 | * allocate them (set them to one). Only consider regions of length |
||
771 | * a power (@order) of two, aligned to that power of two, which |
||
772 | * makes the search algorithm much faster. |
||
773 | * |
||
774 | * Return the bit offset in bitmap of the allocated region, |
||
775 | * or -errno on failure. |
||
776 | */ |
||
777 | int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) |
||
778 | { |
||
779 | int pos, end; /* scans bitmap by regions of size order */ |
||
780 | |||
781 | for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) { |
||
782 | if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) |
||
783 | continue; |
||
784 | __reg_op(bitmap, pos, order, REG_OP_ALLOC); |
||
785 | return pos; |
||
786 | } |
||
787 | return -ENOMEM; |
||
788 | } |
||
789 | EXPORT_SYMBOL(bitmap_find_free_region); |
||
790 | |||
791 | /** |
||
792 | * bitmap_release_region - release allocated bitmap region |
||
793 | * @bitmap: array of unsigned longs corresponding to the bitmap |
||
794 | * @pos: beginning of bit region to release |
||
795 | * @order: region size (log base 2 of number of bits) to release |
||
796 | * |
||
797 | * This is the complement to __bitmap_find_free_region() and releases |
||
798 | * the found region (by clearing it in the bitmap). |
||
799 | * |
||
800 | * No return value. |
||
801 | */ |
||
802 | void bitmap_release_region(unsigned long *bitmap, int pos, int order) |
||
803 | { |
||
804 | __reg_op(bitmap, pos, order, REG_OP_RELEASE); |
||
805 | } |
||
806 | EXPORT_SYMBOL(bitmap_release_region); |
||
807 | |||
808 | /** |
||
809 | * bitmap_allocate_region - allocate bitmap region |
||
810 | * @bitmap: array of unsigned longs corresponding to the bitmap |
||
811 | * @pos: beginning of bit region to allocate |
||
812 | * @order: region size (log base 2 of number of bits) to allocate |
||
813 | * |
||
814 | * Allocate (set bits in) a specified region of a bitmap. |
||
815 | * |
||
816 | * Return 0 on success, or %-EBUSY if specified region wasn't |
||
817 | * free (not all bits were zero). |
||
818 | */ |
||
819 | int bitmap_allocate_region(unsigned long *bitmap, int pos, int order) |
||
820 | { |
||
821 | if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) |
||
822 | return -EBUSY; |
||
823 | __reg_op(bitmap, pos, order, REG_OP_ALLOC); |
||
824 | return 0; |
||
825 | } |
||
826 | EXPORT_SYMBOL(bitmap_allocate_region); |
||
827 | |||
828 | /** |
||
829 | * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order. |
||
830 | * @dst: destination buffer |
||
831 | * @src: bitmap to copy |
||
832 | * @nbits: number of bits in the bitmap |
||
833 | * |
||
834 | * Require nbits % BITS_PER_LONG == 0. |
||
835 | */ |
||
836 | void bitmap_copy_le(void *dst, const unsigned long *src, int nbits) |
||
837 | { |
||
838 | unsigned long *d = dst; |
||
839 | int i; |
||
840 | |||
841 | for (i = 0; i < nbits/BITS_PER_LONG; i++) { |
||
842 | if (BITS_PER_LONG == 64) |
||
843 | d[i] = cpu_to_le64(src[i]); |
||
844 | else |
||
845 | d[i] = cpu_to_le32(src[i]); |
||
846 | } |
||
847 | } |
||
848 | EXPORT_SYMBOL(bitmap_copy_le);>=>><>>>>=><=>><>><>><>><>><>>>=>>>>>>>=>>>>=>>>>>>>>>><>><>><>><>>><>>>>> |