| 1 | /*******************************************************************************. |
| 2 | * Copyright (c) 2011-2012 Ericsson, Ecole Polytechnique de Montreal and others |
| 3 | * |
| 4 | * All rights reserved. This program and the accompanying materials are made |
| 5 | * available under the terms of the Eclipse Public License v1.0 which |
| 6 | * accompanies this distribution, and is available at |
| 7 | * http://www.eclipse.org/legal/epl-v10.html |
| 8 | * |
| 9 | * Contributors: Matthew Khouzam - Initial Design and implementation |
| 10 | * Contributors: Francis Giraldeau - Initial API and implementation |
| 11 | *******************************************************************************/ |
| 12 | |
| 13 | package org.eclipse.linuxtools.internal.ctf.core.event.io; |
| 14 | |
| 15 | import java.nio.BufferOverflowException; |
| 16 | import java.nio.ByteBuffer; |
| 17 | import java.nio.ByteOrder; |
| 18 | |
| 19 | /** |
| 20 | * <b><u>BitBuffer</u></b> |
| 21 | * <p> |
| 22 | * A bitwise buffer capable of accessing fields with bit offsets. |
| 23 | */ |
| 24 | public class BitBuffer { |
| 25 | |
| 26 | // ------------------------------------------------------------------------ |
| 27 | // Constants |
| 28 | // ------------------------------------------------------------------------ |
| 29 | |
| 30 | /* default bit width */ |
| 31 | /** 8 bits to a char */ |
| 32 | public static final int BIT_CHAR = 8; |
| 33 | /** 16 bits to a short */ |
| 34 | public static final int BIT_SHORT = 16; |
| 35 | /** 32 bits to an int */ |
| 36 | public static final int BIT_INT = 32; |
| 37 | /** 32 bits to a float */ |
| 38 | public static final int BIT_FLOAT = 32; |
| 39 | /** 64 bits to a long */ |
| 40 | public static final int BIT_LONG = 64; |
| 41 | |
| 42 | // ------------------------------------------------------------------------ |
| 43 | // Attributes |
| 44 | // ------------------------------------------------------------------------ |
| 45 | |
| 46 | private ByteBuffer buf; |
| 47 | private int pos; |
| 48 | private ByteOrder byteOrder; |
| 49 | |
| 50 | // ------------------------------------------------------------------------ |
| 51 | // Constructors |
| 52 | // ------------------------------------------------------------------------ |
| 53 | /** |
| 54 | * Default constructor, makes a bigendian buffer |
| 55 | */ |
| 56 | public BitBuffer() { |
| 57 | this(null, ByteOrder.BIG_ENDIAN); |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * Constructor, makes a bigendian buffer |
| 62 | * |
| 63 | * @param buf |
| 64 | * the bytebuffer to read |
| 65 | */ |
| 66 | public BitBuffer(ByteBuffer buf) { |
| 67 | this(buf, ByteOrder.BIG_ENDIAN); |
| 68 | } |
| 69 | |
| 70 | /** |
| 71 | * Constructor that is fully parametrisable |
| 72 | * |
| 73 | * @param buf |
| 74 | * the buffer to read |
| 75 | * @param order |
| 76 | * the byte order (big endian, little endian, network?) |
| 77 | */ |
| 78 | public BitBuffer(ByteBuffer buf, ByteOrder order) { |
| 79 | setByteBuffer(buf); |
| 80 | order(order); |
| 81 | position(0); |
| 82 | } |
| 83 | |
| 84 | // ------------------------------------------------------------------------ |
| 85 | // 'Get' operations on buffer |
| 86 | // ------------------------------------------------------------------------ |
| 87 | |
| 88 | /** |
| 89 | * Relative <i>get</i> method for reading 32-bit integer. |
| 90 | * |
| 91 | * Reads next four bytes from the current bit position according to current |
| 92 | * byte order. |
| 93 | * |
| 94 | * @return The int value read from the buffer |
| 95 | */ |
| 96 | public int getInt() { |
| 97 | int val = getInt(BIT_INT, true); |
| 98 | pos += BIT_INT; |
| 99 | return val; |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Relative <i>get</i> method for reading integer of <i>length</i> bits. |
| 104 | * |
| 105 | * Reads <i>length</i> bits starting at the current position. The result is |
| 106 | * signed extended if <i>signed</i> is true. The current position is |
| 107 | * increased of <i>length</i> bits. |
| 108 | * |
| 109 | * @param length |
| 110 | * The length in bits of this integer |
| 111 | * @param signed |
| 112 | * The sign extended flag |
| 113 | * @return The int value read from the buffer |
| 114 | */ |
| 115 | public int getInt(int length, boolean signed) { |
| 116 | int val; |
| 117 | if (!canRead(pos, length)) { |
| 118 | throw new BufferOverflowException(); |
| 119 | } |
| 120 | if (length == 0) { |
| 121 | val = 0; |
| 122 | } |
| 123 | if (byteOrder == ByteOrder.LITTLE_ENDIAN) { |
| 124 | val = getIntLE(pos, length, signed); |
| 125 | } else { |
| 126 | val = getIntBE(pos, length, signed); |
| 127 | } |
| 128 | pos += length; |
| 129 | return val; |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * Absolute <i>get</i> method for reading integer of <i>length</i> bits. |
| 134 | * |
| 135 | * Reads <i>length</i> bits starting from position <i>index</i>. The result |
| 136 | * is signed extended if <i>signed</i> is true. The current position is |
| 137 | * increased of <i>length</i> bits. |
| 138 | * |
| 139 | * @param index |
| 140 | * The start index in bits |
| 141 | * @param length |
| 142 | * The length in bits to read |
| 143 | * @param signed |
| 144 | * The sign extended flag |
| 145 | * @return The int value read from the buffer |
| 146 | */ |
| 147 | public int getInt(int index, int length, boolean signed) { |
| 148 | if (!canRead(index, length)) { |
| 149 | throw new BufferOverflowException(); |
| 150 | } |
| 151 | if (length == 0) { |
| 152 | return 0; |
| 153 | } |
| 154 | if (byteOrder == ByteOrder.LITTLE_ENDIAN) { |
| 155 | return getIntLE(index, length, signed); |
| 156 | } |
| 157 | return getIntBE(index, length, signed); |
| 158 | } |
| 159 | |
| 160 | private int getIntBE(int index, int length, boolean signed) { |
| 161 | assert ((length > 0) && (length <= BIT_INT)); |
| 162 | int end = index + length; |
| 163 | int startByte = index / BIT_CHAR; |
| 164 | int endByte = (end + (BIT_CHAR - 1)) / BIT_CHAR; |
| 165 | int currByte, lshift, cshift, mask, cmask, cache; |
| 166 | int value = 0; |
| 167 | |
| 168 | currByte = startByte; |
| 169 | cache = buf.get(currByte) & 0xFF; |
| 170 | boolean isNeg = (cache & (1 << (BIT_CHAR - (index % BIT_CHAR) - 1))) != 0; |
| 171 | if (signed && isNeg) { |
| 172 | value = ~0; |
| 173 | } |
| 174 | if (startByte == (endByte - 1)) { |
| 175 | cmask = cache >>> ((BIT_CHAR - (end % BIT_CHAR)) % BIT_CHAR); |
| 176 | if (((length) % BIT_CHAR) > 0) { |
| 177 | mask = ~((~0) << length); |
| 178 | cmask &= mask; |
| 179 | } |
| 180 | value <<= length; |
| 181 | value |= cmask; |
| 182 | return value; |
| 183 | } |
| 184 | cshift = index % BIT_CHAR; |
| 185 | if (cshift > 0) { |
| 186 | mask = ~((~0) << (BIT_CHAR - cshift)); |
| 187 | cmask = cache & mask; |
| 188 | lshift = BIT_CHAR - cshift; |
| 189 | value <<= lshift; |
| 190 | value |= cmask; |
| 191 | // index += lshift; |
| 192 | currByte++; |
| 193 | } |
| 194 | for (; currByte < (endByte - 1); currByte++) { |
| 195 | value <<= BIT_CHAR; |
| 196 | value |= buf.get(currByte) & 0xFF; |
| 197 | } |
| 198 | lshift = end % BIT_CHAR; |
| 199 | if (lshift > 0) { |
| 200 | mask = ~((~0) << lshift); |
| 201 | cmask = buf.get(currByte) & 0xFF; |
| 202 | cmask >>>= BIT_CHAR - lshift; |
| 203 | cmask &= mask; |
| 204 | value <<= lshift; |
| 205 | value |= cmask; |
| 206 | } else { |
| 207 | value <<= BIT_CHAR; |
| 208 | value |= buf.get(currByte) & 0xFF; |
| 209 | } |
| 210 | return value; |
| 211 | } |
| 212 | |
| 213 | private int getIntLE(int index, int length, boolean signed) { |
| 214 | assert ((length > 0) && (length <= BIT_INT)); |
| 215 | int end = index + length; |
| 216 | int startByte = index / BIT_CHAR; |
| 217 | int endByte = (end + (BIT_CHAR - 1)) / BIT_CHAR; |
| 218 | int currByte, lshift, cshift, mask, cmask, cache, mod; |
| 219 | int value = 0; |
| 220 | |
| 221 | currByte = endByte - 1; |
| 222 | cache = buf.get(currByte) & 0xFF; |
| 223 | mod = end % BIT_CHAR; |
| 224 | lshift = (mod > 0) ? mod : BIT_CHAR; |
| 225 | boolean isNeg = (cache & (1 << (lshift - 1))) != 0; |
| 226 | if (signed && isNeg) { |
| 227 | value = ~0; |
| 228 | } |
| 229 | if (startByte == (endByte - 1)) { |
| 230 | cmask = cache >>> (index % BIT_CHAR); |
| 231 | if (((length) % BIT_CHAR) > 0) { |
| 232 | mask = ~((~0) << length); |
| 233 | cmask &= mask; |
| 234 | } |
| 235 | value <<= length; |
| 236 | value |= cmask; |
| 237 | return value; |
| 238 | } |
| 239 | cshift = end % BIT_CHAR; |
| 240 | if (cshift > 0) { |
| 241 | mask = ~((~0) << cshift); |
| 242 | cmask = cache & mask; |
| 243 | value <<= cshift; |
| 244 | value |= cmask; |
| 245 | // end -= cshift; |
| 246 | currByte--; |
| 247 | } |
| 248 | for (; currByte >= (startByte + 1); currByte--) { |
| 249 | value <<= BIT_CHAR; |
| 250 | value |= buf.get(currByte) & 0xFF; |
| 251 | } |
| 252 | lshift = index % BIT_CHAR; |
| 253 | if (lshift > 0) { |
| 254 | mask = ~((~0) << (BIT_CHAR - lshift)); |
| 255 | cmask = buf.get(currByte) & 0xFF; |
| 256 | cmask >>>= lshift; |
| 257 | cmask &= mask; |
| 258 | value <<= (BIT_CHAR - lshift); |
| 259 | value |= cmask; |
| 260 | } else { |
| 261 | value <<= BIT_CHAR; |
| 262 | value |= buf.get(currByte) & 0xFF; |
| 263 | } |
| 264 | return value; |
| 265 | } |
| 266 | |
| 267 | // ------------------------------------------------------------------------ |
| 268 | // 'Put' operations on buffer |
| 269 | // ------------------------------------------------------------------------ |
| 270 | |
| 271 | /** |
| 272 | * Relative <i>put</i> method to write signed 32-bit integer. |
| 273 | * |
| 274 | * Write four bytes starting from current bit position in the buffer |
| 275 | * according to the current byte order. The current position is increased of |
| 276 | * <i>length</i> bits. |
| 277 | * |
| 278 | * @param value |
| 279 | * The int value to write |
| 280 | */ |
| 281 | public void putInt(int value) { |
| 282 | putInt(BIT_INT, value); |
| 283 | } |
| 284 | |
| 285 | /** |
| 286 | * Relative <i>put</i> method to write <i>length</i> bits integer. |
| 287 | * |
| 288 | * Writes <i>length</i> lower-order bits from the provided <i>value</i>, |
| 289 | * starting from current bit position in the buffer. Sequential bytes are |
| 290 | * written according to the current byte order. The sign bit is carried to |
| 291 | * the MSB if signed is true. The sign bit is included in <i>length</i>. The |
| 292 | * current position is increased of <i>length</i>. |
| 293 | * |
| 294 | * @param length |
| 295 | * The number of bits to write |
| 296 | * @param value |
| 297 | * The value to write |
| 298 | */ |
| 299 | public void putInt(int length, int value) { |
| 300 | putInt(this.pos, length, value); |
| 301 | } |
| 302 | |
| 303 | /** |
| 304 | * Absolute <i>put</i> method to write <i>length</i> bits integer. |
| 305 | * |
| 306 | * Writes <i>length</i> lower-order bits from the provided <i>value</i>, |
| 307 | * starting from <i>index</i> position in the buffer. Sequential bytes are |
| 308 | * written according to the current byte order. The sign bit is carried to |
| 309 | * the MSB if signed is true. The sign bit is included in <i>length</i>. The |
| 310 | * current position is increased of <i>length</i>. |
| 311 | * |
| 312 | * @param index |
| 313 | * The start position to write the value |
| 314 | * @param value |
| 315 | * The value to write |
| 316 | * @param length |
| 317 | * The number of bits to write |
| 318 | */ |
| 319 | public void putInt(int index, int length, int value) { |
| 320 | if (!canRead(index, length)) { |
| 321 | throw new BufferOverflowException(); |
| 322 | } |
| 323 | if (length == 0) { |
| 324 | return; |
| 325 | } |
| 326 | if (byteOrder == ByteOrder.LITTLE_ENDIAN) { |
| 327 | putIntLE(index, length, value); |
| 328 | } else { |
| 329 | putIntBE(index, length, value); |
| 330 | } |
| 331 | } |
| 332 | |
| 333 | private void putIntBE(int index, int length, int value) { |
| 334 | assert ((length > 0) && (length <= BIT_INT)); |
| 335 | int end = index + length; |
| 336 | int startByte = index / BIT_CHAR; |
| 337 | int endByte = (end + (BIT_CHAR - 1)) / BIT_CHAR; |
| 338 | int currByte, lshift, cshift, mask, cmask; |
| 339 | int correctedValue = value; |
| 340 | |
| 341 | /* |
| 342 | * mask v high bits. Works for unsigned and two complement signed |
| 343 | * numbers which value do not overflow on length bits. |
| 344 | */ |
| 345 | |
| 346 | if (length < BIT_INT) { |
| 347 | correctedValue &= ~(~0 << length); |
| 348 | } |
| 349 | |
| 350 | /* sub byte */ |
| 351 | if (startByte == (endByte - 1)) { |
| 352 | lshift = (BIT_CHAR - (end % BIT_CHAR)) % BIT_CHAR; |
| 353 | mask = ~((~0) << lshift); |
| 354 | if ((index % BIT_CHAR) > 0) { |
| 355 | mask |= (~(0)) << (BIT_CHAR - (index % BIT_CHAR)); |
| 356 | } |
| 357 | cmask = correctedValue << lshift; |
| 358 | /* |
| 359 | * low bits are cleared because of lshift and high bits are already |
| 360 | * cleared |
| 361 | */ |
| 362 | cmask &= ~mask; |
| 363 | int b = buf.get(startByte) & 0xFF; |
| 364 | buf.put(startByte, (byte) ((b & mask) | cmask)); |
| 365 | return; |
| 366 | } |
| 367 | |
| 368 | /* head byte contains MSB */ |
| 369 | currByte = endByte - 1; |
| 370 | cshift = end % BIT_CHAR; |
| 371 | if (cshift > 0) { |
| 372 | lshift = BIT_CHAR - cshift; |
| 373 | mask = ~((~0) << lshift); |
| 374 | cmask = correctedValue << lshift; |
| 375 | cmask &= ~mask; |
| 376 | int b = buf.get(currByte) & 0xFF; |
| 377 | buf.put(currByte, (byte) ((b & mask) | cmask)); |
| 378 | correctedValue >>>= cshift; |
| 379 | // end -= cshift; |
| 380 | currByte--; |
| 381 | } |
| 382 | |
| 383 | /* middle byte(s) */ |
| 384 | for (; currByte >= (startByte + 1); currByte--) { |
| 385 | buf.put(currByte, (byte) correctedValue); |
| 386 | correctedValue >>>= BIT_CHAR; |
| 387 | } |
| 388 | /* end byte contains LSB */ |
| 389 | if ((index % BIT_CHAR) > 0) { |
| 390 | mask = (~0) << (BIT_CHAR - (index % BIT_CHAR)); |
| 391 | cmask = correctedValue & ~mask; |
| 392 | int b = buf.get(currByte) & 0xFF; |
| 393 | buf.put(currByte, (byte) ((b & mask) | cmask)); |
| 394 | } else { |
| 395 | buf.put(currByte, (byte) correctedValue); |
| 396 | } |
| 397 | } |
| 398 | |
| 399 | private void putIntLE(int index, int length, int value) { |
| 400 | assert ((length > 0) && (length <= BIT_INT)); |
| 401 | int end = index + length; |
| 402 | int startByte = index / BIT_CHAR; |
| 403 | int endByte = (end + (BIT_CHAR - 1)) / BIT_CHAR; |
| 404 | int currByte, lshift, cshift, mask, cmask; |
| 405 | int correctedValue = value; |
| 406 | |
| 407 | /* |
| 408 | * mask v high bits. Works for unsigned and two complement signed |
| 409 | * numbers which value do not overflow on length bits. |
| 410 | */ |
| 411 | |
| 412 | if (length < BIT_INT) { |
| 413 | correctedValue &= ~(~0 << length); |
| 414 | } |
| 415 | |
| 416 | /* sub byte */ |
| 417 | if (startByte == (endByte - 1)) { |
| 418 | lshift = index % BIT_CHAR; |
| 419 | mask = ~((~0) << lshift); |
| 420 | if ((end % BIT_CHAR) > 0) { |
| 421 | mask |= (~(0)) << (end % BIT_CHAR); |
| 422 | } |
| 423 | cmask = correctedValue << lshift; |
| 424 | /* |
| 425 | * low bits are cleared because of lshift and high bits are already |
| 426 | * cleared |
| 427 | */ |
| 428 | cmask &= ~mask; |
| 429 | int b = buf.get(startByte) & 0xFF; |
| 430 | buf.put(startByte, (byte) ((b & mask) | cmask)); |
| 431 | return; |
| 432 | } |
| 433 | |
| 434 | /* head byte */ |
| 435 | currByte = startByte; |
| 436 | cshift = index % BIT_CHAR; |
| 437 | if (cshift > 0) { |
| 438 | mask = ~((~0) << cshift); |
| 439 | cmask = correctedValue << cshift; |
| 440 | cmask &= ~mask; |
| 441 | int b = buf.get(currByte) & 0xFF; |
| 442 | buf.put(currByte, (byte) ((b & mask) | cmask)); |
| 443 | correctedValue >>>= BIT_CHAR - cshift; |
| 444 | // index += BIT_CHAR - cshift; |
| 445 | currByte++; |
| 446 | } |
| 447 | |
| 448 | /* middle byte(s) */ |
| 449 | for (; currByte < (endByte - 1); currByte++) { |
| 450 | buf.put(currByte, (byte) correctedValue); |
| 451 | correctedValue >>>= BIT_CHAR; |
| 452 | } |
| 453 | /* end byte */ |
| 454 | if ((end % BIT_CHAR) > 0) { |
| 455 | mask = (~0) << (end % BIT_CHAR); |
| 456 | cmask = correctedValue & ~mask; |
| 457 | int b = buf.get(currByte) & 0xFF; |
| 458 | buf.put(currByte, (byte) ((b & mask) | cmask)); |
| 459 | } else { |
| 460 | buf.put(currByte, (byte) correctedValue); |
| 461 | } |
| 462 | } |
| 463 | |
| 464 | // ------------------------------------------------------------------------ |
| 465 | // Buffer attributes handling |
| 466 | // ------------------------------------------------------------------------ |
| 467 | |
| 468 | /** |
| 469 | * Can this buffer be read for thus amount of bits? |
| 470 | * |
| 471 | * @param length |
| 472 | * the length in bits to read |
| 473 | * @return does the buffer have enough room to read the next "length" |
| 474 | */ |
| 475 | public boolean canRead(int length) { |
| 476 | return canRead(pos, length); |
| 477 | } |
| 478 | |
| 479 | /** |
| 480 | * Can this buffer be read for thus amount of bits? |
| 481 | * |
| 482 | * @param index |
| 483 | * the position in the buffer to read |
| 484 | * @param length |
| 485 | * the length in bits to read |
| 486 | * @return does the buffer have enough room to read the next "length" |
| 487 | */ |
| 488 | public boolean canRead(int index, int length) { |
| 489 | if (buf == null) { |
| 490 | return false; |
| 491 | } |
| 492 | |
| 493 | if ((index + length) > (buf.capacity() * BIT_CHAR)) { |
| 494 | return false; |
| 495 | } |
| 496 | return true; |
| 497 | } |
| 498 | |
| 499 | /** |
| 500 | * Sets the order of the buffer. |
| 501 | * |
| 502 | * @param order |
| 503 | * The order of the buffer. |
| 504 | */ |
| 505 | public void order(ByteOrder order) { |
| 506 | this.byteOrder = order; |
| 507 | if (buf != null) { |
| 508 | buf.order(order); |
| 509 | } |
| 510 | } |
| 511 | |
| 512 | /** |
| 513 | * Sets the order of the buffer. |
| 514 | * |
| 515 | * @return The order of the buffer. |
| 516 | */ |
| 517 | public ByteOrder order() { |
| 518 | return byteOrder; |
| 519 | } |
| 520 | |
| 521 | /** |
| 522 | * Sets the position in the buffer. |
| 523 | * |
| 524 | * @param order |
| 525 | * The position of the buffer. |
| 526 | */ |
| 527 | public void position(int newPosition) { |
| 528 | this.pos = newPosition; |
| 529 | } |
| 530 | |
| 531 | /** |
| 532 | * |
| 533 | * Sets the position in the buffer. |
| 534 | * |
| 535 | * @return order The position of the buffer. |
| 536 | */ |
| 537 | public int position() { |
| 538 | return pos; |
| 539 | } |
| 540 | |
| 541 | /** |
| 542 | * Sets the byte buffer |
| 543 | * |
| 544 | * @param buf |
| 545 | * the byte buffer |
| 546 | */ |
| 547 | public void setByteBuffer(ByteBuffer buf) { |
| 548 | this.buf = buf; |
| 549 | if (buf != null) { |
| 550 | this.buf.order(byteOrder); |
| 551 | } |
| 552 | clear(); |
| 553 | } |
| 554 | |
| 555 | /** |
| 556 | * Gets the byte buffer |
| 557 | * |
| 558 | * @return The byte buffer |
| 559 | */ |
| 560 | public ByteBuffer getByteBuffer() { |
| 561 | return buf; |
| 562 | } |
| 563 | |
| 564 | /** |
| 565 | * Sets the byte order |
| 566 | * |
| 567 | * @param byteOrder |
| 568 | * The byte order |
| 569 | */ |
| 570 | public void setByteOrder(ByteOrder byteOrder) { |
| 571 | this.byteOrder = byteOrder; |
| 572 | } |
| 573 | |
| 574 | /** |
| 575 | * Gets the byte order |
| 576 | * |
| 577 | * @return The byte order |
| 578 | */ |
| 579 | public ByteOrder getByteOrder() { |
| 580 | return byteOrder; |
| 581 | } |
| 582 | |
| 583 | /** |
| 584 | * resets the bitbuffer. |
| 585 | */ |
| 586 | public void clear() { |
| 587 | position(0); |
| 588 | |
| 589 | if (buf == null) { |
| 590 | return; |
| 591 | } |
| 592 | buf.clear(); |
| 593 | } |
| 594 | |
| 595 | } |