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BitUtils.php
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BitArray.php
373 lines
| 1 | <?php |
| 2 | declare(strict_types = 1); |
| 3 | |
| 4 | namespace BaconQrCode\Common; |
| 5 | |
| 6 | use BaconQrCode\Exception\InvalidArgumentException; |
| 7 | use SplFixedArray; |
| 8 | |
| 9 | /** |
| 10 | * A simple, fast array of bits. |
| 11 | */ |
| 12 | final class BitArray |
| 13 | { |
| 14 | /** |
| 15 | * Bits represented as an array of integers. |
| 16 | * |
| 17 | * @var SplFixedArray<int> |
| 18 | */ |
| 19 | private $bits; |
| 20 | |
| 21 | /** |
| 22 | * Size of the bit array in bits. |
| 23 | * |
| 24 | * @var int |
| 25 | */ |
| 26 | private $size; |
| 27 | |
| 28 | /** |
| 29 | * Creates a new bit array with a given size. |
| 30 | */ |
| 31 | public function __construct(int $size = 0) |
| 32 | { |
| 33 | $this->size = $size; |
| 34 | $this->bits = SplFixedArray::fromArray(array_fill(0, ($this->size + 31) >> 3, 0)); |
| 35 | } |
| 36 | |
| 37 | /** |
| 38 | * Gets the size in bits. |
| 39 | */ |
| 40 | public function getSize() : int |
| 41 | { |
| 42 | return $this->size; |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Gets the size in bytes. |
| 47 | */ |
| 48 | public function getSizeInBytes() : int |
| 49 | { |
| 50 | return ($this->size + 7) >> 3; |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * Ensures that the array has a minimum capacity. |
| 55 | */ |
| 56 | public function ensureCapacity(int $size) : void |
| 57 | { |
| 58 | if ($size > count($this->bits) << 5) { |
| 59 | $this->bits->setSize(($size + 31) >> 5); |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | /** |
| 64 | * Gets a specific bit. |
| 65 | */ |
| 66 | public function get(int $i) : bool |
| 67 | { |
| 68 | return 0 !== ($this->bits[$i >> 5] & (1 << ($i & 0x1f))); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Sets a specific bit. |
| 73 | */ |
| 74 | public function set(int $i) : void |
| 75 | { |
| 76 | $this->bits[$i >> 5] = $this->bits[$i >> 5] | 1 << ($i & 0x1f); |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * Flips a specific bit. |
| 81 | */ |
| 82 | public function flip(int $i) : void |
| 83 | { |
| 84 | $this->bits[$i >> 5] ^= 1 << ($i & 0x1f); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Gets the next set bit position from a given position. |
| 89 | */ |
| 90 | public function getNextSet(int $from) : int |
| 91 | { |
| 92 | if ($from >= $this->size) { |
| 93 | return $this->size; |
| 94 | } |
| 95 | |
| 96 | $bitsOffset = $from >> 5; |
| 97 | $currentBits = $this->bits[$bitsOffset]; |
| 98 | $bitsLength = count($this->bits); |
| 99 | $currentBits &= ~((1 << ($from & 0x1f)) - 1); |
| 100 | |
| 101 | while (0 === $currentBits) { |
| 102 | if (++$bitsOffset === $bitsLength) { |
| 103 | return $this->size; |
| 104 | } |
| 105 | |
| 106 | $currentBits = $this->bits[$bitsOffset]; |
| 107 | } |
| 108 | |
| 109 | $result = ($bitsOffset << 5) + BitUtils::numberOfTrailingZeros($currentBits); |
| 110 | return $result > $this->size ? $this->size : $result; |
| 111 | } |
| 112 | |
| 113 | /** |
| 114 | * Gets the next unset bit position from a given position. |
| 115 | */ |
| 116 | public function getNextUnset(int $from) : int |
| 117 | { |
| 118 | if ($from >= $this->size) { |
| 119 | return $this->size; |
| 120 | } |
| 121 | |
| 122 | $bitsOffset = $from >> 5; |
| 123 | $currentBits = ~$this->bits[$bitsOffset]; |
| 124 | $bitsLength = count($this->bits); |
| 125 | $currentBits &= ~((1 << ($from & 0x1f)) - 1); |
| 126 | |
| 127 | while (0 === $currentBits) { |
| 128 | if (++$bitsOffset === $bitsLength) { |
| 129 | return $this->size; |
| 130 | } |
| 131 | |
| 132 | $currentBits = ~$this->bits[$bitsOffset]; |
| 133 | } |
| 134 | |
| 135 | $result = ($bitsOffset << 5) + BitUtils::numberOfTrailingZeros($currentBits); |
| 136 | return $result > $this->size ? $this->size : $result; |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * Sets a bulk of bits. |
| 141 | */ |
| 142 | public function setBulk(int $i, int $newBits) : void |
| 143 | { |
| 144 | $this->bits[$i >> 5] = $newBits; |
| 145 | } |
| 146 | |
| 147 | /** |
| 148 | * Sets a range of bits. |
| 149 | * |
| 150 | * @throws InvalidArgumentException if end is smaller than start |
| 151 | */ |
| 152 | public function setRange(int $start, int $end) : void |
| 153 | { |
| 154 | if ($end < $start) { |
| 155 | throw new InvalidArgumentException('End must be greater or equal to start'); |
| 156 | } |
| 157 | |
| 158 | if ($end === $start) { |
| 159 | return; |
| 160 | } |
| 161 | |
| 162 | --$end; |
| 163 | |
| 164 | $firstInt = $start >> 5; |
| 165 | $lastInt = $end >> 5; |
| 166 | |
| 167 | for ($i = $firstInt; $i <= $lastInt; ++$i) { |
| 168 | $firstBit = $i > $firstInt ? 0 : $start & 0x1f; |
| 169 | $lastBit = $i < $lastInt ? 31 : $end & 0x1f; |
| 170 | |
| 171 | if (0 === $firstBit && 31 === $lastBit) { |
| 172 | $mask = 0x7fffffff; |
| 173 | } else { |
| 174 | $mask = 0; |
| 175 | |
| 176 | for ($j = $firstBit; $j < $lastBit; ++$j) { |
| 177 | $mask |= 1 << $j; |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | $this->bits[$i] = $this->bits[$i] | $mask; |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * Clears the bit array, unsetting every bit. |
| 187 | */ |
| 188 | public function clear() : void |
| 189 | { |
| 190 | $bitsLength = count($this->bits); |
| 191 | |
| 192 | for ($i = 0; $i < $bitsLength; ++$i) { |
| 193 | $this->bits[$i] = 0; |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | /** |
| 198 | * Checks if a range of bits is set or not set. |
| 199 | |
| 200 | * @throws InvalidArgumentException if end is smaller than start |
| 201 | */ |
| 202 | public function isRange(int $start, int $end, bool $value) : bool |
| 203 | { |
| 204 | if ($end < $start) { |
| 205 | throw new InvalidArgumentException('End must be greater or equal to start'); |
| 206 | } |
| 207 | |
| 208 | if ($end === $start) { |
| 209 | return true; |
| 210 | } |
| 211 | |
| 212 | --$end; |
| 213 | |
| 214 | $firstInt = $start >> 5; |
| 215 | $lastInt = $end >> 5; |
| 216 | |
| 217 | for ($i = $firstInt; $i <= $lastInt; ++$i) { |
| 218 | $firstBit = $i > $firstInt ? 0 : $start & 0x1f; |
| 219 | $lastBit = $i < $lastInt ? 31 : $end & 0x1f; |
| 220 | |
| 221 | if (0 === $firstBit && 31 === $lastBit) { |
| 222 | $mask = 0x7fffffff; |
| 223 | } else { |
| 224 | $mask = 0; |
| 225 | |
| 226 | for ($j = $firstBit; $j <= $lastBit; ++$j) { |
| 227 | $mask |= 1 << $j; |
| 228 | } |
| 229 | } |
| 230 | |
| 231 | if (($this->bits[$i] & $mask) !== ($value ? $mask : 0)) { |
| 232 | return false; |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | return true; |
| 237 | } |
| 238 | |
| 239 | /** |
| 240 | * Appends a bit to the array. |
| 241 | */ |
| 242 | public function appendBit(bool $bit) : void |
| 243 | { |
| 244 | $this->ensureCapacity($this->size + 1); |
| 245 | |
| 246 | if ($bit) { |
| 247 | $this->bits[$this->size >> 5] = $this->bits[$this->size >> 5] | (1 << ($this->size & 0x1f)); |
| 248 | } |
| 249 | |
| 250 | ++$this->size; |
| 251 | } |
| 252 | |
| 253 | /** |
| 254 | * Appends a number of bits (up to 32) to the array. |
| 255 | |
| 256 | * @throws InvalidArgumentException if num bits is not between 0 and 32 |
| 257 | */ |
| 258 | public function appendBits(int $value, int $numBits) : void |
| 259 | { |
| 260 | if ($numBits < 0 || $numBits > 32) { |
| 261 | throw new InvalidArgumentException('Num bits must be between 0 and 32'); |
| 262 | } |
| 263 | |
| 264 | $this->ensureCapacity($this->size + $numBits); |
| 265 | |
| 266 | for ($numBitsLeft = $numBits; $numBitsLeft > 0; $numBitsLeft--) { |
| 267 | $this->appendBit((($value >> ($numBitsLeft - 1)) & 0x01) === 1); |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | /** |
| 272 | * Appends another bit array to this array. |
| 273 | */ |
| 274 | public function appendBitArray(self $other) : void |
| 275 | { |
| 276 | $otherSize = $other->getSize(); |
| 277 | $this->ensureCapacity($this->size + $other->getSize()); |
| 278 | |
| 279 | for ($i = 0; $i < $otherSize; ++$i) { |
| 280 | $this->appendBit($other->get($i)); |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | /** |
| 285 | * Makes an exclusive-or comparision on the current bit array. |
| 286 | * |
| 287 | * @throws InvalidArgumentException if sizes don't match |
| 288 | */ |
| 289 | public function xorBits(self $other) : void |
| 290 | { |
| 291 | $bitsLength = count($this->bits); |
| 292 | $otherBits = $other->getBitArray(); |
| 293 | |
| 294 | if ($bitsLength !== count($otherBits)) { |
| 295 | throw new InvalidArgumentException('Sizes don\'t match'); |
| 296 | } |
| 297 | |
| 298 | for ($i = 0; $i < $bitsLength; ++$i) { |
| 299 | $this->bits[$i] = $this->bits[$i] ^ $otherBits[$i]; |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | /** |
| 304 | * Converts the bit array to a byte array. |
| 305 | * |
| 306 | * @return SplFixedArray<int> |
| 307 | */ |
| 308 | public function toBytes(int $bitOffset, int $numBytes) : SplFixedArray |
| 309 | { |
| 310 | $bytes = new SplFixedArray($numBytes); |
| 311 | |
| 312 | for ($i = 0; $i < $numBytes; ++$i) { |
| 313 | $byte = 0; |
| 314 | |
| 315 | for ($j = 0; $j < 8; ++$j) { |
| 316 | if ($this->get($bitOffset)) { |
| 317 | $byte |= 1 << (7 - $j); |
| 318 | } |
| 319 | |
| 320 | ++$bitOffset; |
| 321 | } |
| 322 | |
| 323 | $bytes[$i] = $byte; |
| 324 | } |
| 325 | |
| 326 | return $bytes; |
| 327 | } |
| 328 | |
| 329 | /** |
| 330 | * Gets the internal bit array. |
| 331 | * |
| 332 | * @return SplFixedArray<int> |
| 333 | */ |
| 334 | public function getBitArray() : SplFixedArray |
| 335 | { |
| 336 | return $this->bits; |
| 337 | } |
| 338 | |
| 339 | /** |
| 340 | * Reverses the array. |
| 341 | */ |
| 342 | public function reverse() : void |
| 343 | { |
| 344 | $newBits = new SplFixedArray(count($this->bits)); |
| 345 | |
| 346 | for ($i = 0; $i < $this->size; ++$i) { |
| 347 | if ($this->get($this->size - $i - 1)) { |
| 348 | $newBits[$i >> 5] = $newBits[$i >> 5] | (1 << ($i & 0x1f)); |
| 349 | } |
| 350 | } |
| 351 | |
| 352 | $this->bits = $newBits; |
| 353 | } |
| 354 | |
| 355 | /** |
| 356 | * Returns a string representation of the bit array. |
| 357 | */ |
| 358 | public function __toString() : string |
| 359 | { |
| 360 | $result = ''; |
| 361 | |
| 362 | for ($i = 0; $i < $this->size; ++$i) { |
| 363 | if (0 === ($i & 0x07)) { |
| 364 | $result .= ' '; |
| 365 | } |
| 366 | |
| 367 | $result .= $this->get($i) ? 'X' : '.'; |
| 368 | } |
| 369 | |
| 370 | return $result; |
| 371 | } |
| 372 | } |
| 373 |