| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.iapi.services.io.FormatableBitSet |
| 4 | |
| 5 | Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.iapi.services.io; |
| 22 | |
| 23 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 24 | |
| 25 | import java.io.InputStream; |
| 26 | import java.io.ObjectOutput; |
| 27 | import java.io.ObjectInput; |
| 28 | import java.io.IOException; |
| 29 | |
| 30 | /** |
| 31 | * FormatableBitSet is implemented as a packed array of bytes. |
| 32 | * |
| 33 | * @author Jamie -- originally coded by Jeff |
| 34 | */ |
| 35 | |
| 36 | public final class FormatableBitSet implements Formatable, Cloneable |
| 37 | { |
| 38 | |
| 39 | /******************************************************** |
| 40 | ** |
| 41 | ** This class implements Formatable. That means that it |
| 42 | ** can write itself to and from a formatted stream. If |
| 43 | ** you add more fields to this class, make sure that you |
| 44 | ** also write/read them with the writeExternal()/readExternal() |
| 45 | ** methods. |
| 46 | ** |
| 47 | ** If, inbetween releases, you add more fields to this class, |
| 48 | ** then you should bump the version number emitted by the getTypeFormatId() |
| 49 | ** method. |
| 50 | ** |
| 51 | ********************************************************/ |
| 52 | |
| 53 | /** |
| 54 | ** Bits are stored as an array of bytes. |
| 55 | ** Bits are numbered starting at 0. Bits |
| 56 | ** 0..7 go in byte[0], 8..15 in byte[1] and so on. |
| 57 | ** The number of bytes is tracked as part |
| 58 | ** of the byte array. The number of bits |
| 59 | ** being used is derived by the number of |
| 60 | ** bytes being used and the number of bits |
| 61 | ** being used by the last byte. The partially |
| 62 | ** unused byte is always byte[byte.length] with the |
| 63 | ** lowest bits being unused. |
| 64 | ** |
| 65 | ** Zero length bits are stored using a |
| 66 | ** zero length byte array, with all bits |
| 67 | ** marked as unused. |
| 68 | */ |
| 69 | private byte[] value; |
| 70 | private short bitsInLastByte; |
| 71 | |
| 72 | private transient int lengthAsBits; |
| 73 | |
| 74 | /** |
| 75 | * Niladic Constructor |
| 76 | */ |
| 77 | public FormatableBitSet() |
| 78 | { |
| 79 | } |
| 80 | |
| 81 | /** |
| 82 | * Constructs a Bit with the initial number of bits |
| 83 | */ |
| 84 | public FormatableBitSet(int numBits) |
| 85 | { |
| 86 | initializeBits(numBits); |
| 87 | } |
| 88 | |
| 89 | private void initializeBits(int numBits) |
| 90 | { |
| 91 | int numBytes = numBytesFromBits(numBits); |
| 92 | |
| 93 | // the byte array is zero'ed out by the new operator |
| 94 | value = new byte[numBytes]; |
| 95 | bitsInLastByte = numBitsInLastByte(numBits); |
| 96 | lengthAsBits = numBits; |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Constructs a Bit from an array of bytes. Assume |
| 101 | * bytes are all being used. |
| 102 | * |
| 103 | * @param newValue The array of bytes to make up the new Bit |
| 104 | */ |
| 105 | public FormatableBitSet(byte[] newValue) |
| 106 | { |
| 107 | value = newValue; |
| 108 | bitsInLastByte = 8; |
| 109 | lengthAsBits = calculateLength(newValue.length); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Constructs a Bit from an array of bytes. |
| 114 | * |
| 115 | * @param newValue The array of bytes to make up the new Bit |
| 116 | * @param numBits The number of bits |
| 117 | */ |
| 118 | public FormatableBitSet(byte[] newValue, int numBits) |
| 119 | { |
| 120 | bitsInLastByte = numBitsInLastByte(numBits); |
| 121 | lengthAsBits = numBits; |
| 122 | |
| 123 | int lenInBytes = numBytesFromBits(numBits); |
| 124 | |
| 125 | if (lenInBytes == newValue.length) { |
| 126 | value = newValue; |
| 127 | } else { |
| 128 | value = new byte[lenInBytes]; |
| 129 | System.arraycopy(newValue, 0, value, 0, newValue.length); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | /** |
| 134 | * Copy constructor |
| 135 | * |
| 136 | * @param original the FormatableBitSet to make a copy from |
| 137 | */ |
| 138 | public FormatableBitSet (FormatableBitSet original) |
| 139 | { |
| 140 | if (SanityManager.DEBUG) |
| 141 | SanityManager.ASSERT( |
| 142 | original != null, "cannot make copy from a null FormatableBitSet"); |
| 143 | |
| 144 | bitsInLastByte = original.bitsInLastByte; |
| 145 | lengthAsBits = original.lengthAsBits; |
| 146 | |
| 147 | int lenInBytes = FormatableBitSet.numBytesFromBits(original.lengthAsBits); |
| 148 | value = new byte[lenInBytes]; |
| 149 | if (lenInBytes > 0) |
| 150 | System.arraycopy(original.value, 0, value, 0, lenInBytes); |
| 151 | } |
| 152 | |
| 153 | /* |
| 154 | * Cloneable |
| 155 | */ |
| 156 | public Object clone() |
| 157 | { |
| 158 | return new FormatableBitSet(this); |
| 159 | } |
| 160 | |
| 161 | |
| 162 | /** |
| 163 | * Get the length in bytes of a Bit value |
| 164 | * |
| 165 | * @return The length in bytes of this value |
| 166 | */ |
| 167 | public int getLengthInBytes() |
| 168 | { |
| 169 | if (value == null) |
| 170 | { |
| 171 | return 0; |
| 172 | } |
| 173 | |
| 174 | return FormatableBitSet.numBytesFromBits(lengthAsBits); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | ** Get the length in bits |
| 179 | ** |
| 180 | ** @return The length in bits for this value |
| 181 | ** |
| 182 | ** NOTE: could possibly be changed to a long. As is |
| 183 | ** we are restricted to 2^(31-3) -> 256meg instead |
| 184 | ** of 2^31 (Integer.MAX_VALUE) like other datatypes |
| 185 | ** (or 2 gig). If it is ever changed to a long |
| 186 | ** be sure to change read/writeExternal which write |
| 187 | ** out the length in bits. |
| 188 | */ |
| 189 | public int getLength() { |
| 190 | return lengthAsBits; |
| 191 | } |
| 192 | |
| 193 | private int calculateLength(int realByteLength) |
| 194 | { |
| 195 | if (realByteLength == 0) |
| 196 | { |
| 197 | return 0; |
| 198 | } |
| 199 | |
| 200 | return ((realByteLength - 1) * 8) + bitsInLastByte; |
| 201 | } |
| 202 | |
| 203 | /** |
| 204 | * Get the length in bits -- alias for getLength() |
| 205 | * |
| 206 | * @return The length in bits for this value |
| 207 | */ |
| 208 | public int size() |
| 209 | { |
| 210 | return getLength(); |
| 211 | } |
| 212 | |
| 213 | /** |
| 214 | * Get the value of the byte array |
| 215 | * |
| 216 | * @return The value of the byte array |
| 217 | */ |
| 218 | |
| 219 | public byte[] getByteArray() |
| 220 | { |
| 221 | if (value == null) |
| 222 | return null; |
| 223 | |
| 224 | // In some cases the array is bigger than the actual number |
| 225 | // of valid bytes. |
| 226 | int realByteLength = getLengthInBytes(); |
| 227 | |
| 228 | // Currently the case is that the return from this |
| 229 | // call only includes the valid bytes. |
| 230 | if (value.length != realByteLength) { |
| 231 | byte[] data = new byte[realByteLength]; |
| 232 | System.arraycopy(value, 0, data, 0, realByteLength); |
| 233 | |
| 234 | value = data; |
| 235 | } |
| 236 | |
| 237 | return value; |
| 238 | } |
| 239 | |
| 240 | /** |
| 241 | * Set the value of the byte array |
| 242 | * |
| 243 | * @return The value of the byte array |
| 244 | */ |
| 245 | public boolean isNull() |
| 246 | { |
| 247 | return this.value == null; |
| 248 | } |
| 249 | |
| 250 | /** |
| 251 | * Grow (widen) a FormatableBitSet to N bis |
| 252 | * |
| 253 | * @param n The number of bits you want. The bits are |
| 254 | * always added as 0 and are appended to the |
| 255 | * least significant end of the bit array. |
| 256 | * |
| 257 | * ASSUMPTIONS: that all extra bits in the last byte |
| 258 | * are zero. |
| 259 | */ |
| 260 | public void grow(int n) |
| 261 | { |
| 262 | if (n <= this.getLength()) |
| 263 | return; |
| 264 | |
| 265 | if (value == null) |
| 266 | { |
| 267 | initializeBits(n); |
| 268 | return; |
| 269 | } |
| 270 | |
| 271 | int delta = n - this.getLength(); |
| 272 | |
| 273 | |
| 274 | int oldNumBytes = getLengthInBytes(); |
| 275 | |
| 276 | /* |
| 277 | ** If we have enough space in the left over bits, |
| 278 | ** then all we need to do is change the modulo. |
| 279 | */ |
| 280 | if ((oldNumBytes != 0) && |
| 281 | (8 - this.bitsInLastByte) >= delta) |
| 282 | { |
| 283 | this.bitsInLastByte += delta; |
| 284 | lengthAsBits = n; |
| 285 | return; |
| 286 | } |
| 287 | |
| 288 | int newNumBytes = FormatableBitSet.numBytesFromBits(n); |
| 289 | |
| 290 | // is there enough room in the existing array |
| 291 | if (newNumBytes <= value.length) { |
| 292 | // ensure the bits are zeroed |
| 293 | for (int i = oldNumBytes; i < newNumBytes; i++) |
| 294 | value[i] = 0; |
| 295 | } else { |
| 296 | |
| 297 | |
| 298 | /* |
| 299 | ** We didn't have enough bytes in value, so we need |
| 300 | ** to create a bigger byte array and use that. |
| 301 | */ |
| 302 | byte[] newValue = new byte[newNumBytes]; |
| 303 | |
| 304 | System.arraycopy(value, 0, newValue, 0, oldNumBytes); |
| 305 | |
| 306 | value = newValue; |
| 307 | } |
| 308 | bitsInLastByte = numBitsInLastByte(n); |
| 309 | lengthAsBits = n; |
| 310 | } |
| 311 | |
| 312 | /** |
| 313 | * Shrink (narrow) a FormatableBitSet to N bits |
| 314 | * |
| 315 | * @param n The number of bits the caller wants. The |
| 316 | * bits are always removed from the |
| 317 | * least significant end of the bit array. |
| 318 | */ |
| 319 | public FormatableBitSet shrink(int n) |
| 320 | { |
| 321 | int numBytes; |
| 322 | int lastByteNum; |
| 323 | |
| 324 | /* |
| 325 | ** Sanity check: we shouldn't shrink down to |
| 326 | ** nothing. |
| 327 | */ |
| 328 | if (SanityManager.DEBUG) |
| 329 | { |
| 330 | if (value == null) |
| 331 | { |
| 332 | SanityManager.THROWASSERT("Attempt to shrink a null Bit"+ |
| 333 | " -- caller should have known better probably"); |
| 334 | return null; |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | if (n >= this.getLength()) |
| 339 | { |
| 340 | return this; |
| 341 | } |
| 342 | |
| 343 | |
| 344 | lastByteNum = numBytesFromBits(n) - 1; |
| 345 | bitsInLastByte = numBitsInLastByte(n); |
| 346 | lengthAsBits = n; |
| 347 | |
| 348 | /* |
| 349 | ** Mask out any left over bits in the |
| 350 | ** last byte. Retain the highest bits. |
| 351 | */ |
| 352 | if (bitsInLastByte != 8) |
| 353 | { |
| 354 | value[lastByteNum] &= 0xFF00 >> bitsInLastByte; |
| 355 | } |
| 356 | |
| 357 | return this; |
| 358 | } |
| 359 | |
| 360 | /* |
| 361 | ** Some of the operators required by SQL. These could alternatively |
| 362 | ** be in SQLBit, but since they are so tightly bound to the implementation |
| 363 | ** rather than return something that undermines the encapsulation |
| 364 | ** of this type, i have chosen to put them in here. |
| 365 | */ |
| 366 | |
| 367 | /** |
| 368 | * Bit equivalence. Compare this with other. |
| 369 | * If the length is different, then cannot be |
| 370 | * equal so short circuit. Otherwise, rely on |
| 371 | * compare(). Note that two zero length bits are |
| 372 | * considered equal. |
| 373 | * |
| 374 | * @param other the other bit to compare to |
| 375 | * |
| 376 | * @return TRUE|FALSE |
| 377 | */ |
| 378 | public boolean equals(FormatableBitSet other) |
| 379 | { |
| 380 | if (this.getLength() != other.getLength()) |
| 381 | { |
| 382 | return false; |
| 383 | } |
| 384 | |
| 385 | return (this.compare(other) == 0); |
| 386 | } |
| 387 | |
| 388 | /** |
| 389 | * Bit comparison. Compare this with other. |
| 390 | * Will always do a byte by byte compare. |
| 391 | * |
| 392 | * Given 2 similar bits of unequal lengths (x and y), |
| 393 | * where x.getLength() < y.getLength() but where: |
| 394 | * |
| 395 | * x[0..x.getLength()] == y[0..x.getLength()] |
| 396 | * |
| 397 | * then x < y. |
| 398 | * |
| 399 | * |
| 400 | * @param other the other bit to compare to |
| 401 | * |
| 402 | * @return -1 - if other < this |
| 403 | * 0 - if other == this |
| 404 | * 1 - if other > this |
| 405 | * |
| 406 | */ |
| 407 | public int compare(FormatableBitSet other) |
| 408 | { |
| 409 | |
| 410 | int otherCount, thisCount; |
| 411 | int otherLen, thisLen; |
| 412 | byte[] otherb; |
| 413 | |
| 414 | otherb = other.value; |
| 415 | /* |
| 416 | ** By convention, nulls sort low, and null == null |
| 417 | */ |
| 418 | if (this.value == null || otherb == null) |
| 419 | { |
| 420 | if (this.value != null) // otherb == null |
| 421 | return 1; |
| 422 | if (otherb != null) // this.value == null |
| 423 | return -1; |
| 424 | return 0; // both null |
| 425 | } |
| 426 | |
| 427 | otherLen = other.getLengthInBytes(); |
| 428 | thisLen = getLengthInBytes(); |
| 429 | for (otherCount = 0, thisCount = 0; |
| 430 | otherCount < otherLen && thisCount < thisLen; |
| 431 | otherCount++, thisCount++) |
| 432 | { |
| 433 | if (otherb[otherCount] != this.value[thisCount]) |
| 434 | break; |
| 435 | } |
| 436 | |
| 437 | /* |
| 438 | ** '==' if byte by byte comparison is identical and |
| 439 | ** exact same length in bits (not bytes). |
| 440 | */ |
| 441 | if ((otherCount == otherLen) && (thisCount == thisLen)) |
| 442 | { |
| 443 | if (this.getLength() == other.getLength()) |
| 444 | { |
| 445 | return 0; |
| 446 | } |
| 447 | |
| 448 | /* |
| 449 | ** If subset of bits is identical, return 1 |
| 450 | ** if other.getLength() > this.getLength(); otherwise, |
| 451 | ** -1 |
| 452 | */ |
| 453 | return (other.getLength() < this.getLength()) ? 1 : -1; |
| 454 | } |
| 455 | |
| 456 | if (otherCount == otherLen) |
| 457 | { |
| 458 | return 1; |
| 459 | } |
| 460 | else if (thisCount == thisLen) |
| 461 | { |
| 462 | return -1; |
| 463 | } |
| 464 | else |
| 465 | { |
| 466 | /* |
| 467 | ** Ok, we have a difference somewhere. Now |
| 468 | ** we have to go to the trouble of converting |
| 469 | ** to a int and masking out the sign to get |
| 470 | ** a valid comparision because bytes are signed. |
| 471 | */ |
| 472 | int otherInt, thisInt; |
| 473 | |
| 474 | otherInt = (int)otherb[otherCount]; |
| 475 | otherInt &= (0x100 - 1); |
| 476 | |
| 477 | thisInt = (int)this.value[thisCount]; |
| 478 | thisInt &= (0x100 - 1); |
| 479 | |
| 480 | return (thisInt > otherInt) ? 1 : -1; |
| 481 | |
| 482 | } |
| 483 | } |
| 484 | |
| 485 | /** |
| 486 | * Bit concatenation. |
| 487 | * |
| 488 | * @param other the other bit to append to this |
| 489 | * |
| 490 | * @return Bit -- the newly concatenated bit |
| 491 | * |
| 492 | */ |
| 493 | public FormatableBitSet concatenate(FormatableBitSet other) |
| 494 | { |
| 495 | int newLen; |
| 496 | int otherLen; |
| 497 | int prevLen; |
| 498 | int prevLenBytes; |
| 499 | int newLenBytes; |
| 500 | int otherLenBytes; |
| 501 | int i, j; |
| 502 | byte[] newValue; |
| 503 | byte[] otherValue; |
| 504 | int shiftBits; |
| 505 | int inByte; |
| 506 | |
| 507 | |
| 508 | prevLen = this.getLength(); |
| 509 | prevLenBytes = this.getLengthInBytes(); |
| 510 | otherLen = other.getLength(); |
| 511 | otherValue = other.getByteArray(); |
| 512 | otherLenBytes = other.getLengthInBytes(); |
| 513 | newLen = prevLen + otherLen; |
| 514 | newLenBytes = numBytesFromBits(newLen); |
| 515 | newValue = new byte[newLenBytes]; |
| 516 | |
| 517 | |
| 518 | /* |
| 519 | ** Copy over the entire array in this.value |
| 520 | ** to newLenBytes. |
| 521 | */ |
| 522 | for (i = 0; i < prevLenBytes; i++) |
| 523 | { |
| 524 | newValue[i] = this.value[i]; |
| 525 | } |
| 526 | |
| 527 | /* |
| 528 | ** Now if we have any bits left over |
| 529 | ** we need to shift them, and keep |
| 530 | ** shifting everything down. Be careful |
| 531 | ** to handle the case where the bit |
| 532 | ** used to have length 0. |
| 533 | */ |
| 534 | shiftBits = (prevLen == 0) ? 8 : this.bitsInLastByte; |
| 535 | for (j = 0; j < otherLenBytes; j++, i++) |
| 536 | { |
| 537 | if (shiftBits == 8) |
| 538 | { |
| 539 | newValue[i] = otherValue[j]; |
| 540 | } |
| 541 | else |
| 542 | { |
| 543 | /* |
| 544 | ** Convert to an int because it will get converted |
| 545 | ** on the shift anyway. |
| 546 | */ |
| 547 | inByte = (int)otherValue[j]; |
| 548 | |
| 549 | /* |
| 550 | ** Mask off the high bits in case they are now |
| 551 | ** turned on if we had the sign bit on. |
| 552 | */ |
| 553 | inByte &= (0x100 - 1); |
| 554 | |
| 555 | /* |
| 556 | ** Use the high order bits to finish off |
| 557 | ** the last byte |
| 558 | */ |
| 559 | newValue[i-1] |= (inByte >>> shiftBits); |
| 560 | |
| 561 | /* |
| 562 | ** Start the next one with whatever is left, unless |
| 563 | ** there is nothing left. |
| 564 | */ |
| 565 | if (i < newLenBytes) |
| 566 | { |
| 567 | newValue[i] |= (inByte << (8 - shiftBits)); |
| 568 | } |
| 569 | } |
| 570 | } |
| 571 | |
| 572 | return new FormatableBitSet(newValue, newLen); |
| 573 | } |
| 574 | |
| 575 | /** |
| 576 | * Produce a hash code by putting the value bytes into an int, exclusive OR'ing |
| 577 | * if there are more than 4 bytes. |
| 578 | * |
| 579 | * @return the hash code |
| 580 | */ |
| 581 | public int hashCode() |
| 582 | { |
| 583 | if( null == value) |
| 584 | return 0; |
| 585 | |
| 586 | int code = 0; |
| 587 | int i; |
| 588 | int shift = 0; |
| 589 | |
| 590 | int byteLength = getLengthInBytes(); |
| 591 | for( i = 0; i < byteLength; i++) |
| 592 | { |
| 593 | code ^= (value[i] & 0xff)<<shift; |
| 594 | shift += 8; |
| 595 | if( 32 <= shift) |
| 596 | shift = 0; |
| 597 | } |
| 598 | return code; |
| 599 | } |
| 600 | |
| 601 | /** |
| 602 | * Bit isSet |
| 603 | * |
| 604 | * @param position the bit to check |
| 605 | * |
| 606 | */ |
| 607 | public final boolean isSet(int position) |
| 608 | { |
| 609 | if (SanityManager.DEBUG) |
| 610 | { |
| 611 | if (position >= this.getLength()) |
| 612 | { |
| 613 | SanityManager.THROWASSERT( |
| 614 | "Attempt to get a bit position (" + position + |
| 615 | ")" + |
| 616 | "that exceeds the max length (" + this.getLength() + ")"); |
| 617 | } |
| 618 | } |
| 619 | |
| 620 | try { |
| 621 | |
| 622 | int bytepos = position / 8; |
| 623 | int bitpos = 7 - (position % 8); |
| 624 | |
| 625 | return ((value[bytepos] & (1 << bitpos)) != 0); |
| 626 | |
| 627 | } catch (ArrayIndexOutOfBoundsException e) { |
| 628 | // Should not happen, handle it just in case not all cases are tested |
| 629 | // by insane server. |
| 630 | return false; |
| 631 | } |
| 632 | } |
| 633 | |
| 634 | /** |
| 635 | * Bit get -- alias for isSet() |
| 636 | * |
| 637 | * @param position the bit to check |
| 638 | * |
| 639 | */ |
| 640 | public final boolean get(int position) |
| 641 | { |
| 642 | return isSet(position); |
| 643 | } |
| 644 | |
| 645 | /** |
| 646 | * Bit set |
| 647 | * |
| 648 | * @param position the bit to set |
| 649 | * |
| 650 | */ |
| 651 | public void set(int position) |
| 652 | { |
| 653 | |
| 654 | if (SanityManager.DEBUG) |
| 655 | { |
| 656 | if (position >= this.getLength()) |
| 657 | { |
| 658 | SanityManager.THROWASSERT( |
| 659 | "Attempt to set a bit position that exceeds the max length (" |
| 660 | + this.getLength() + ")"); |
| 661 | } |
| 662 | } |
| 663 | |
| 664 | // Should not happen, handle it just in case not all cases are tested |
| 665 | // by insane server. |
| 666 | if (position >= getLength()) |
| 667 | grow(position); |
| 668 | |
| 669 | int bytepos = position / 8; |
| 670 | int bitpos = 7 - (position % 8); |
| 671 | |
| 672 | value[bytepos] |= (1 << bitpos); |
| 673 | } |
| 674 | |
| 675 | /** |
| 676 | * Bit clear |
| 677 | * |
| 678 | * @param position the bit to clear |
| 679 | * |
| 680 | */ |
| 681 | public void clear(int position) |
| 682 | { |
| 683 | int bytepos; |
| 684 | int bitpos; |
| 685 | |
| 686 | if (SanityManager.DEBUG) |
| 687 | { |
| 688 | if (position >= this.getLength()) |
| 689 | { |
| 690 | SanityManager.THROWASSERT( |
| 691 | "Attempt to set a bit position that exceeds the max length (" |
| 692 | + this.getLength() + ")"); |
| 693 | } |
| 694 | } |
| 695 | |
| 696 | // Should not happen, handle it just in case not all cases are tested |
| 697 | // by insane server. |
| 698 | if (position >= getLength()) |
| 699 | grow(position); |
| 700 | |
| 701 | bytepos = position / 8; |
| 702 | bitpos = 7 - (position % 8); |
| 703 | |
| 704 | value[bytepos] &= ~(1 << bitpos); |
| 705 | } |
| 706 | |
| 707 | /** |
| 708 | Clear all the bits in this FormatableBitSet |
| 709 | */ |
| 710 | public void clear() |
| 711 | { |
| 712 | if (value == null) |
| 713 | return; |
| 714 | |
| 715 | int byteLength = getLengthInBytes(); |
| 716 | for (int ix=0; ix < byteLength; ix++) |
| 717 | value[ix] = 0; |
| 718 | } |
| 719 | |
| 720 | |
| 721 | /** |
| 722 | * Figure out how many bytes are needed to |
| 723 | * store the input number of bits. |
| 724 | * |
| 725 | * @param bits bits |
| 726 | * |
| 727 | * @return the number of bytes |
| 728 | */ |
| 729 | protected static int |
| 730 | numBytesFromBits(int bits) |
| 731 | { |
| 732 | return (bits == 0) ? 0 : ((bits - 1) / 8) + 1; |
| 733 | } |
| 734 | |
| 735 | /** |
| 736 | * Figure out how many bits are in the last |
| 737 | * byte from the total number of bits. |
| 738 | * |
| 739 | * @param bits bits |
| 740 | * |
| 741 | * @return the number of bits |
| 742 | */ |
| 743 | private static short |
| 744 | numBitsInLastByte(int bits) |
| 745 | { |
| 746 | int modulo = bits % 8; |
| 747 | return (short)((modulo == 0) ? |
| 748 | ((bits == 0) ? 0 : 8) : |
| 749 | modulo); |
| 750 | } |
| 751 | |
| 752 | /** |
| 753 | * Translate a hex character to a byte. |
| 754 | * |
| 755 | * @param hexChar A character with the value [0-9a-fA-F]. |
| 756 | * |
| 757 | * @return A byte with the numeric value corresponding to the hex character |
| 758 | */ |
| 759 | private static byte |
| 760 | hexCharToByte(char hexChar) |
| 761 | { |
| 762 | byte byteValue; |
| 763 | |
| 764 | switch (hexChar) |
| 765 | { |
| 766 | case '0': |
| 767 | byteValue = 0; |
| 768 | break; |
| 769 | |
| 770 | case '1': |
| 771 | byteValue = 1; |
| 772 | break; |
| 773 | |
| 774 | case '2': |
| 775 | byteValue = 2; |
| 776 | break; |
| 777 | |
| 778 | case '3': |
| 779 | byteValue = 3; |
| 780 | break; |
| 781 | |
| 782 | case '4': |
| 783 | byteValue = 4; |
| 784 | break; |
| 785 | |
| 786 | case '5': |
| 787 | byteValue = 5; |
| 788 | break; |
| 789 | |
| 790 | case '6': |
| 791 | byteValue = 6; |
| 792 | break; |
| 793 | |
| 794 | case '7': |
| 795 | byteValue = 7; |
| 796 | break; |
| 797 | |
| 798 | case '8': |
| 799 | byteValue = 8; |
| 800 | break; |
| 801 | |
| 802 | case '9': |
| 803 | byteValue = 9; |
| 804 | break; |
| 805 | |
| 806 | case 'a': |
| 807 | case 'A': |
| 808 | byteValue = 0xA; |
| 809 | break; |
| 810 | |
| 811 | case 'b': |
| 812 | case 'B': |
| 813 | byteValue = 0xB; |
| 814 | break; |
| 815 | |
| 816 | case 'c': |
| 817 | case 'C': |
| 818 | byteValue = 0xC; |
| 819 | break; |
| 820 | |
| 821 | case 'd': |
| 822 | case 'D': |
| 823 | byteValue = 0xD; |
| 824 | break; |
| 825 | |
| 826 | case 'e': |
| 827 | case 'E': |
| 828 | byteValue = 0xE; |
| 829 | break; |
| 830 | |
| 831 | case 'f': |
| 832 | case 'F': |
| 833 | byteValue = 0xF; |
| 834 | break; |
| 835 | |
| 836 | default: |
| 837 | if (SanityManager.DEBUG) |
| 838 | { |
| 839 | SanityManager.THROWASSERT("illegal char = " + hexChar); |
| 840 | } |
| 841 | throw new IllegalArgumentException(); |
| 842 | } |
| 843 | |
| 844 | return byteValue; |
| 845 | } |
| 846 | |
| 847 | private static char[] decodeArray = {'0', '1', '2', '3', '4', '5', '6', '7', |
| 848 | '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; |
| 849 | |
| 850 | /** |
| 851 | * Format the string into BitSet format: {0, 2, 4, 8} if bits 0, 2, 4, 8 |
| 852 | * are set. |
| 853 | * |
| 854 | * @return A new String containing the formatted Bit value |
| 855 | */ |
| 856 | public String toString() |
| 857 | { |
| 858 | char[] outChars; |
| 859 | int inPosition; |
| 860 | int outPosition; |
| 861 | int inByte; |
| 862 | |
| 863 | if (value == null) |
| 864 | { |
| 865 | return null; |
| 866 | } |
| 867 | { |
| 868 | // give it a reasonable size |
| 869 | StringBuffer str = new StringBuffer(getLength()*8*3); |
| 870 | str.append("{"); |
| 871 | boolean first = true; |
| 872 | for (inPosition = 0; inPosition < getLength(); inPosition++) |
| 873 | { |
| 874 | if (isSet(inPosition)) |
| 875 | { |
| 876 | if (!first) |
| 877 | str.append(", "); |
| 878 | first = false; |
| 879 | str.append(inPosition); |
| 880 | } |
| 881 | } |
| 882 | str.append("}"); |
| 883 | return new String(str); |
| 884 | } |
| 885 | } |
| 886 | |
| 887 | |
| 888 | |
| 889 | /** |
| 890 | * Statically calculates how many bits can fit into the number of |
| 891 | * bytes if this Bit object is externalized. Only valid for this |
| 892 | * implementation of Bit. |
| 893 | */ |
| 894 | public static int maxBitsForSpace(int numBytes) |
| 895 | { |
| 896 | return (numBytes - 4)*8; |
| 897 | |
| 898 | } |
| 899 | |
| 900 | /** |
| 901 | * If any bit is set, return the bit number of a bit that is set. |
| 902 | * If no bit is set, return -1; |
| 903 | * |
| 904 | * @return the bit number of a bit that is set, or -1 if no bit is set |
| 905 | */ |
| 906 | public int anySetBit() |
| 907 | { |
| 908 | int numbytes = getLengthInBytes(); |
| 909 | int bitpos; |
| 910 | |
| 911 | for (int i = 0; i < numbytes-1; i++) |
| 912 | { |
| 913 | if (value[i] != 0) |
| 914 | { |
| 915 | for (int j = 0; j < 8; j++) |
| 916 | { |
| 917 | bitpos = 7-j; |
| 918 | if (((1 << bitpos) & value[i]) != 0) |
| 919 | return ((i*8)+j); |
| 920 | } |
| 921 | } |
| 922 | } |
| 923 | |
| 924 | |
| 925 | // only the top part of the last byte is relevant |
| 926 | byte mask = (byte)(0xFF << (8-bitsInLastByte)); |
| 927 | if ((value[numbytes-1] & mask) != 0) |
| 928 | { |
| 929 | for (int j = 0; j < bitsInLastByte; j++) |
| 930 | { |
| 931 | bitpos = 7-j; |
| 932 | if (((1 << bitpos) & value[numbytes-1]) != 0) |
| 933 | return ((numbytes-1)*8)+j; |
| 934 | } |
| 935 | } |
| 936 | |
| 937 | return -1; |
| 938 | } |
| 939 | |
| 940 | /** |
| 941 | * Like anySetBit(), but return any set bit whose number is bigger than |
| 942 | * beyondBit. If no bit is set after beyondBit, -1 is returned. |
| 943 | * By using anySetBit() and anySetBit(beyondBit), one can quickly go |
| 944 | * thru the entire bit array to return all set bit. |
| 945 | * |
| 946 | * @param beyondBit only look at bit that is greater than this bit number |
| 947 | * @return the bit number of a bit that is set, or -1 if no bit after |
| 948 | * beyondBit is set |
| 949 | */ |
| 950 | public int anySetBit(int beyondBit) |
| 951 | { |
| 952 | if (SanityManager.DEBUG) |
| 953 | { |
| 954 | if (beyondBit >= this.getLength()) |
| 955 | SanityManager.THROWASSERT( |
| 956 | "Attempt to access bit position that exceeds the max length (" |
| 957 | + this.getLength() + ")"); |
| 958 | } |
| 959 | |
| 960 | int startingBit = (beyondBit+1); |
| 961 | |
| 962 | // we have seen the last bit. |
| 963 | if (startingBit >= this.getLength()) |
| 964 | return -1; |
| 965 | |
| 966 | int numbytes = getLengthInBytes(); |
| 967 | int startingByte = startingBit / 8; |
| 968 | int startingBitpos = startingBit % 8; |
| 969 | int bitpos; |
| 970 | byte mask; |
| 971 | |
| 972 | // see if any bits in this byte is set, only the bottom part of the |
| 973 | // first byte is relevant |
| 974 | mask = (byte)(0xFF >> startingBitpos); |
| 975 | |
| 976 | if (startingByte == numbytes-1) // starting byte == last byte |
| 977 | mask &= (byte)(0xFF << (8-bitsInLastByte)); |
| 978 | |
| 979 | if ((value[startingByte] & mask ) != 0) |
| 980 | { |
| 981 | // I know we will see the bit before bitsInLastByte even if we are |
| 982 | // at the last byte, no harm in going up to 8 in the loop |
| 983 | for (int j = startingBitpos; j < 8; j++) |
| 984 | { |
| 985 | if (SanityManager.DEBUG) |
| 986 | { |
| 987 | if (startingByte == numbytes-1) |
| 988 | SanityManager.ASSERT(j < bitsInLastByte, |
| 989 | "going beyond the last bit"); |
| 990 | } |
| 991 | bitpos = 7-j; |
| 992 | if (((1 << bitpos) & value[startingByte]) != 0) |
| 993 | { |
| 994 | return (startingByte*8+j); |
| 995 | } |
| 996 | } |
| 997 | } |
| 998 | |
| 999 | for (int i = (startingByte+1); i < numbytes-1; i++) |
| 1000 | { |
| 1001 | if (value[i] != 0) |
| 1002 | { |
| 1003 | for (int j = 0; j < 8; j++) |
| 1004 | { |
| 1005 | bitpos = 7-j; |
| 1006 | if (((1 << bitpos) & value[i]) != 0) |
| 1007 | { |
| 1008 | return ((i*8)+j); |
| 1009 | } |
| 1010 | } |
| 1011 | } |
| 1012 | } |
| 1013 | |
| 1014 | // Last byte if there are more than one bytes. Only the top part of |
| 1015 | // the last byte is relevant |
| 1016 | if (startingByte != numbytes-1) |
| 1017 | { |
| 1018 | mask = (byte)(0xFF << (8-bitsInLastByte)); |
| 1019 | |
| 1020 | if ((value[numbytes-1] & mask) != 0) |
| 1021 | { |
| 1022 | for (int j = 0; j < bitsInLastByte; j++) |
| 1023 | { |
| 1024 | bitpos = 7-j; |
| 1025 | if (((1 << bitpos) & value[numbytes-1]) != 0) |
| 1026 | { |
| 1027 | return ((numbytes-1)*8)+j; |
| 1028 | } |
| 1029 | } |
| 1030 | } |
| 1031 | } |
| 1032 | |
| 1033 | return -1; |
| 1034 | |
| 1035 | } |
| 1036 | |
| 1037 | /** |
| 1038 | * Bitwise OR this Bit with another Bit. |
| 1039 | * |
| 1040 | * @param otherBit the other Bit |
| 1041 | */ |
| 1042 | public void or(FormatableBitSet otherBit) |
| 1043 | { |
| 1044 | if (otherBit == null || otherBit.getLength() == 0) |
| 1045 | return; |
| 1046 | |
| 1047 | int otherLength = otherBit.getLength(); |
| 1048 | |
| 1049 | if (otherLength > getLength()) |
| 1050 | grow(otherLength); // expand this bit |
| 1051 | |
| 1052 | if (otherBit instanceof FormatableBitSet) |
| 1053 | { |
| 1054 | // we know the bit ordering, optimize this |
| 1055 | FormatableBitSet ob = (FormatableBitSet)otherBit; |
| 1056 | int obByteLen = ob.getLengthInBytes(); |
| 1057 | for (int i = 0; i < obByteLen-1; i++) |
| 1058 | value[i] |= ob.value[i]; |
| 1059 | |
| 1060 | // do the last byte bit by bit |
| 1061 | for (int i = (obByteLen-1)*8; i < otherLength; i++) |
| 1062 | if (otherBit.isSet(i)) |
| 1063 | set(i); |
| 1064 | } |
| 1065 | else |
| 1066 | { |
| 1067 | // we don't know the bit ordering, call thru the interface and go |
| 1068 | // thru bit by bit |
| 1069 | // this bit impl's length >= other bit's length |
| 1070 | |
| 1071 | for (int i = 0; i < otherLength; i++) |
| 1072 | { |
| 1073 | if (otherBit.isSet(i)) |
| 1074 | set(i); |
| 1075 | } |
| 1076 | } |
| 1077 | } |
| 1078 | |
| 1079 | /** |
| 1080 | * Bitwise AND this Bit with another Bit. |
| 1081 | * |
| 1082 | * @param otherBit the other Bit |
| 1083 | */ |
| 1084 | public void and(FormatableBitSet otherBit) |
| 1085 | { |
| 1086 | if (SanityManager.DEBUG) |
| 1087 | SanityManager.ASSERT(otherBit != null, "cannot AND null with a FormatableBitSet"); |
| 1088 | |
| 1089 | int otherLength = otherBit.getLength(); |
| 1090 | |
| 1091 | // Supposedly cannot happen, but handle it just in case. |
| 1092 | if (otherLength > getLength()) |
| 1093 | grow(otherLength); // expand this bit |
| 1094 | |
| 1095 | if (otherLength < getLength()) |
| 1096 | { |
| 1097 | // clear all bits that are not in the other bit |
| 1098 | int startingByte = (otherLength * 8) + 1; |
| 1099 | int len = getLengthInBytes(); |
| 1100 | for (int i = startingByte; i < len; i++) |
| 1101 | value[i] = 0; |
| 1102 | |
| 1103 | for (int i = otherLength; i < startingByte*8; i++) |
| 1104 | { |
| 1105 | if (i < getLength()) |
| 1106 | clear(i); |
| 1107 | else |
| 1108 | break; |
| 1109 | } |
| 1110 | } |
| 1111 | |
| 1112 | if (otherLength == 0) |
| 1113 | return; |
| 1114 | |
| 1115 | int length = otherBit.getLengthInBytes() < getLengthInBytes() ? |
| 1116 | otherBit.getLengthInBytes() : getLengthInBytes(); |
| 1117 | |
| 1118 | for (int i = 0; i < length; i++) |
| 1119 | value[i] &= otherBit.value[i]; |
| 1120 | } |
| 1121 | |
| 1122 | /** |
| 1123 | * Logically XORs this FormatableBitSet with the specified FormatableBitSet. |
| 1124 | * @param set The FormatableBitSet to be XORed with. |
| 1125 | */ |
| 1126 | public void xor(FormatableBitSet set) |
| 1127 | { |
| 1128 | if (SanityManager.DEBUG) |
| 1129 | { |
| 1130 | if (getLength() != set.getLength()) |
| 1131 | { |
| 1132 | SanityManager.THROWASSERT("getLength() (" + getLength() + |
| 1133 | ") and set.getLength() (" + |
| 1134 | set.getLength() + |
| 1135 | ") expected to be the same"); |
| 1136 | } |
| 1137 | } |
| 1138 | |
| 1139 | int setLength = set.getLength(); |
| 1140 | for (int i = setLength; i-- > 0; ) |
| 1141 | { |
| 1142 | if (isSet(i) && set.isSet(i)) |
| 1143 | { |
| 1144 | clear(i); |
| 1145 | } |
| 1146 | else if (isSet(i) || set.isSet(i)) |
| 1147 | { |
| 1148 | set(i); |
| 1149 | } |
| 1150 | } |
| 1151 | } |
| 1152 | |
| 1153 | /** |
| 1154 | * Get a count of the number of bits that are set. |
| 1155 | * |
| 1156 | * @return The number of bits that are set. |
| 1157 | */ |
| 1158 | public int getNumBitsSet() |
| 1159 | { |
| 1160 | int count = 0; |
| 1161 | |
| 1162 | for (int index = getLength() - 1; index >= 0; index--) |
| 1163 | { |
| 1164 | if (isSet(index)) |
| 1165 | { |
| 1166 | count++; |
| 1167 | } |
| 1168 | } |
| 1169 | |
| 1170 | return count; |
| 1171 | } |
| 1172 | |
| 1173 | ///////////////////////////////////////////////////////// |
| 1174 | // |
| 1175 | // EXTERNALIZABLE |
| 1176 | // |
| 1177 | ///////////////////////////////////////////////////////// |
| 1178 | /** |
| 1179 | * Format: <UL> |
| 1180 | * <LI>int length in bits </LI> |
| 1181 | * <LI>byte[] </LI></UL> |
| 1182 | * |
| 1183 | * @see java.io.Externalizable#writeExternal |
| 1184 | */ |
| 1185 | public void writeExternal(ObjectOutput out) throws IOException |
| 1186 | { |
| 1187 | // never called when value is null |
| 1188 | if (SanityManager.DEBUG) |
| 1189 | SanityManager.ASSERT(value != null); |
| 1190 | |
| 1191 | out.writeInt(getLength()); |
| 1192 | int byteLen = getLengthInBytes(); |
| 1193 | if (byteLen > 0) |
| 1194 | { |
| 1195 | out.write(value, 0, byteLen); |
| 1196 | } |
| 1197 | } |
| 1198 | |
| 1199 | /** |
| 1200 | * Note: gracefully handles zero length |
| 1201 | * bits -- will create a zero length array |
| 1202 | * with no bits being used. Fortunately |
| 1203 | * in.read() is ok with a zero length array |
| 1204 | * so no special code. |
| 1205 | * <p> |
| 1206 | * WARNING: this method cannot be changed w/o |
| 1207 | * changing SQLBit because SQLBit calls this |
| 1208 | * directly w/o calling read/writeObject(), so |
| 1209 | * the format id is not stored in that case. |
| 1210 | * |
| 1211 | * @see java.io.Externalizable#readExternal |
| 1212 | */ |
| 1213 | public void readExternal(ObjectInput in) throws IOException |
| 1214 | { |
| 1215 | int lenInBits; |
| 1216 | int lenInBytes; |
| 1217 | |
| 1218 | lenInBits = in.readInt(); |
| 1219 | |
| 1220 | lenInBytes = FormatableBitSet.numBytesFromBits(lenInBits); |
| 1221 | |
| 1222 | |
| 1223 | /* |
| 1224 | ** How can lenInBytes be zero? The implication is |
| 1225 | ** that lenInBits is zero. Well, the reason this can |
| 1226 | ** happen is that the store will reset our stream |
| 1227 | ** out from underneath us if we are a Bit column that |
| 1228 | ** overflows onto another page because it assumes that |
| 1229 | ** we want to stream it in specially. Because of this warped |
| 1230 | ** API, our readInt() will return 0 even though our |
| 1231 | ** writeExternal() did a writeInt(xxx). The upshot |
| 1232 | ** is that you should leave the following alone. |
| 1233 | */ |
| 1234 | |
| 1235 | value = new byte[lenInBytes]; |
| 1236 | |
| 1237 | in.readFully(value); |
| 1238 | |
| 1239 | bitsInLastByte = numBitsInLastByte(lenInBits); |
| 1240 | |
| 1241 | lengthAsBits = lenInBits; |
| 1242 | } |
| 1243 | |
| 1244 | public void readExternalFromArray(ArrayInputStream in) throws IOException |
| 1245 | { |
| 1246 | int lenInBits = in.readInt(); |
| 1247 | |
| 1248 | int lenInBytes = FormatableBitSet.numBytesFromBits(lenInBits); |
| 1249 | |
| 1250 | value = new byte[lenInBytes]; |
| 1251 | |
| 1252 | in.readFully(value); |
| 1253 | |
| 1254 | bitsInLastByte = numBitsInLastByte(lenInBits); |
| 1255 | |
| 1256 | lengthAsBits = lenInBits; |
| 1257 | } |
| 1258 | |
| 1259 | /** |
| 1260 | * Get the formatID which corresponds to this class. |
| 1261 | * |
| 1262 | * @return the formatID of this class |
| 1263 | */ |
| 1264 | public int getTypeFormatId() { return StoredFormatIds.BITIMPL_V01_ID; } |
| 1265 | } |