1 /* 2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.internal.misc; 27 28 import java.lang.reflect.Field; 29 import java.security.ProtectionDomain; 30 31 import sun.reflect.CallerSensitive; 32 import sun.reflect.Reflection; 33 import jdk.internal.misc.VM; 34 35 import jdk.internal.HotSpotIntrinsicCandidate; 36 37 38 /** 39 * A collection of methods for performing low-level, unsafe operations. 40 * Although the class and all methods are public, use of this class is 41 * limited because only trusted code can obtain instances of it. 42 * 43 * @author John R. Rose 44 * @see #getUnsafe 45 */ 46 47 public final class Unsafe { 48 49 private static native void registerNatives(); 50 static { 51 registerNatives(); 52 sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe"); 53 } 54 55 private Unsafe() {} 56 57 private static final Unsafe theUnsafe = new Unsafe(); 58 59 /** 60 * Provides the caller with the capability of performing unsafe 61 * operations. 62 * 63 * <p>The returned {@code Unsafe} object should be carefully guarded 64 * by the caller, since it can be used to read and write data at arbitrary 65 * memory addresses. It must never be passed to untrusted code. 66 * 67 * <p>Most methods in this class are very low-level, and correspond to a 68 * small number of hardware instructions (on typical machines). Compilers 69 * are encouraged to optimize these methods accordingly. 70 * 71 * <p>Here is a suggested idiom for using unsafe operations: 72 * 73 * <pre> {@code 74 * class MyTrustedClass { 75 * private static final Unsafe unsafe = Unsafe.getUnsafe(); 76 * ... 77 * private long myCountAddress = ...; 78 * public int getCount() { return unsafe.getByte(myCountAddress); } 79 * }}</pre> 80 * 81 * (It may assist compilers to make the local variable {@code final}.) 82 * 83 * @throws SecurityException if a security manager exists and its 84 * {@code checkPropertiesAccess} method doesn't allow 85 * access to the system properties. 86 */ 87 @CallerSensitive 88 public static Unsafe getUnsafe() { 89 Class<?> caller = Reflection.getCallerClass(); 90 if (!VM.isSystemDomainLoader(caller.getClassLoader())) 91 throw new SecurityException("Unsafe"); 92 return theUnsafe; 93 } 94 95 /// peek and poke operations 96 /// (compilers should optimize these to memory ops) 97 98 // These work on object fields in the Java heap. 99 // They will not work on elements of packed arrays. 100 101 /** 102 * Fetches a value from a given Java variable. 103 * More specifically, fetches a field or array element within the given 104 * object {@code o} at the given offset, or (if {@code o} is null) 105 * from the memory address whose numerical value is the given offset. 106 * <p> 107 * The results are undefined unless one of the following cases is true: 108 * <ul> 109 * <li>The offset was obtained from {@link #objectFieldOffset} on 110 * the {@link java.lang.reflect.Field} of some Java field and the object 111 * referred to by {@code o} is of a class compatible with that 112 * field's class. 113 * 114 * <li>The offset and object reference {@code o} (either null or 115 * non-null) were both obtained via {@link #staticFieldOffset} 116 * and {@link #staticFieldBase} (respectively) from the 117 * reflective {@link Field} representation of some Java field. 118 * 119 * <li>The object referred to by {@code o} is an array, and the offset 120 * is an integer of the form {@code B+N*S}, where {@code N} is 121 * a valid index into the array, and {@code B} and {@code S} are 122 * the values obtained by {@link #arrayBaseOffset} and {@link 123 * #arrayIndexScale} (respectively) from the array's class. The value 124 * referred to is the {@code N}<em>th</em> element of the array. 125 * 126 * </ul> 127 * <p> 128 * If one of the above cases is true, the call references a specific Java 129 * variable (field or array element). However, the results are undefined 130 * if that variable is not in fact of the type returned by this method. 131 * <p> 132 * This method refers to a variable by means of two parameters, and so 133 * it provides (in effect) a <em>double-register</em> addressing mode 134 * for Java variables. When the object reference is null, this method 135 * uses its offset as an absolute address. This is similar in operation 136 * to methods such as {@link #getInt(long)}, which provide (in effect) a 137 * <em>single-register</em> addressing mode for non-Java variables. 138 * However, because Java variables may have a different layout in memory 139 * from non-Java variables, programmers should not assume that these 140 * two addressing modes are ever equivalent. Also, programmers should 141 * remember that offsets from the double-register addressing mode cannot 142 * be portably confused with longs used in the single-register addressing 143 * mode. 144 * 145 * @param o Java heap object in which the variable resides, if any, else 146 * null 147 * @param offset indication of where the variable resides in a Java heap 148 * object, if any, else a memory address locating the variable 149 * statically 150 * @return the value fetched from the indicated Java variable 151 * @throws RuntimeException No defined exceptions are thrown, not even 152 * {@link NullPointerException} 153 */ 154 @HotSpotIntrinsicCandidate 155 public native int getInt(Object o, long offset); 156 157 /** 158 * Stores a value into a given Java variable. 159 * <p> 160 * The first two parameters are interpreted exactly as with 161 * {@link #getInt(Object, long)} to refer to a specific 162 * Java variable (field or array element). The given value 163 * is stored into that variable. 164 * <p> 165 * The variable must be of the same type as the method 166 * parameter {@code x}. 167 * 168 * @param o Java heap object in which the variable resides, if any, else 169 * null 170 * @param offset indication of where the variable resides in a Java heap 171 * object, if any, else a memory address locating the variable 172 * statically 173 * @param x the value to store into the indicated Java variable 174 * @throws RuntimeException No defined exceptions are thrown, not even 175 * {@link NullPointerException} 176 */ 177 @HotSpotIntrinsicCandidate 178 public native void putInt(Object o, long offset, int x); 179 180 /** 181 * Fetches a reference value from a given Java variable. 182 * @see #getInt(Object, long) 183 */ 184 @HotSpotIntrinsicCandidate 185 public native Object getObject(Object o, long offset); 186 187 /** 188 * Stores a reference value into a given Java variable. 189 * <p> 190 * Unless the reference {@code x} being stored is either null 191 * or matches the field type, the results are undefined. 192 * If the reference {@code o} is non-null, card marks or 193 * other store barriers for that object (if the VM requires them) 194 * are updated. 195 * @see #putInt(Object, long, int) 196 */ 197 @HotSpotIntrinsicCandidate 198 public native void putObject(Object o, long offset, Object x); 199 200 /** @see #getInt(Object, long) */ 201 @HotSpotIntrinsicCandidate 202 public native boolean getBoolean(Object o, long offset); 203 /** @see #putInt(Object, long, int) */ 204 @HotSpotIntrinsicCandidate 205 public native void putBoolean(Object o, long offset, boolean x); 206 /** @see #getInt(Object, long) */ 207 @HotSpotIntrinsicCandidate 208 public native byte getByte(Object o, long offset); 209 /** @see #putInt(Object, long, int) */ 210 @HotSpotIntrinsicCandidate 211 public native void putByte(Object o, long offset, byte x); 212 /** @see #getInt(Object, long) */ 213 @HotSpotIntrinsicCandidate 214 public native short getShort(Object o, long offset); 215 /** @see #putInt(Object, long, int) */ 216 @HotSpotIntrinsicCandidate 217 public native void putShort(Object o, long offset, short x); 218 /** @see #getInt(Object, long) */ 219 @HotSpotIntrinsicCandidate 220 public native char getChar(Object o, long offset); 221 /** @see #putInt(Object, long, int) */ 222 @HotSpotIntrinsicCandidate 223 public native void putChar(Object o, long offset, char x); 224 /** @see #getInt(Object, long) */ 225 @HotSpotIntrinsicCandidate 226 public native long getLong(Object o, long offset); 227 /** @see #putInt(Object, long, int) */ 228 @HotSpotIntrinsicCandidate 229 public native void putLong(Object o, long offset, long x); 230 /** @see #getInt(Object, long) */ 231 @HotSpotIntrinsicCandidate 232 public native float getFloat(Object o, long offset); 233 /** @see #putInt(Object, long, int) */ 234 @HotSpotIntrinsicCandidate 235 public native void putFloat(Object o, long offset, float x); 236 /** @see #getInt(Object, long) */ 237 @HotSpotIntrinsicCandidate 238 public native double getDouble(Object o, long offset); 239 /** @see #putInt(Object, long, int) */ 240 @HotSpotIntrinsicCandidate 241 public native void putDouble(Object o, long offset, double x); 242 243 // These read VM internal data. 244 245 /** 246 * Fetches an uncompressed reference value from a given native variable 247 * ignoring the VM's compressed references mode. 248 * 249 * @param address a memory address locating the variable 250 * @return the value fetched from the indicated native variable 251 */ 252 public native Object getUncompressedObject(long address); 253 254 /** 255 * Fetches the {@link java.lang.Class} Java mirror for the given native 256 * metaspace {@code Klass} pointer. 257 * 258 * @param metaspaceKlass a native metaspace {@code Klass} pointer 259 * @return the {@link java.lang.Class} Java mirror 260 */ 261 public native Class<?> getJavaMirror(long metaspaceKlass); 262 263 /** 264 * Fetches a native metaspace {@code Klass} pointer for the given Java 265 * object. 266 * 267 * @param o Java heap object for which to fetch the class pointer 268 * @return a native metaspace {@code Klass} pointer 269 */ 270 public native long getKlassPointer(Object o); 271 272 // These work on values in the C heap. 273 274 /** 275 * Fetches a value from a given memory address. If the address is zero, or 276 * does not point into a block obtained from {@link #allocateMemory}, the 277 * results are undefined. 278 * 279 * @see #allocateMemory 280 */ 281 @HotSpotIntrinsicCandidate 282 public native byte getByte(long address); 283 284 /** 285 * Stores a value into a given memory address. If the address is zero, or 286 * does not point into a block obtained from {@link #allocateMemory}, the 287 * results are undefined. 288 * 289 * @see #getByte(long) 290 */ 291 @HotSpotIntrinsicCandidate 292 public native void putByte(long address, byte x); 293 294 /** @see #getByte(long) */ 295 @HotSpotIntrinsicCandidate 296 public native short getShort(long address); 297 /** @see #putByte(long, byte) */ 298 @HotSpotIntrinsicCandidate 299 public native void putShort(long address, short x); 300 /** @see #getByte(long) */ 301 @HotSpotIntrinsicCandidate 302 public native char getChar(long address); 303 /** @see #putByte(long, byte) */ 304 @HotSpotIntrinsicCandidate 305 public native void putChar(long address, char x); 306 /** @see #getByte(long) */ 307 @HotSpotIntrinsicCandidate 308 public native int getInt(long address); 309 /** @see #putByte(long, byte) */ 310 @HotSpotIntrinsicCandidate 311 public native void putInt(long address, int x); 312 /** @see #getByte(long) */ 313 @HotSpotIntrinsicCandidate 314 public native long getLong(long address); 315 /** @see #putByte(long, byte) */ 316 @HotSpotIntrinsicCandidate 317 public native void putLong(long address, long x); 318 /** @see #getByte(long) */ 319 @HotSpotIntrinsicCandidate 320 public native float getFloat(long address); 321 /** @see #putByte(long, byte) */ 322 @HotSpotIntrinsicCandidate 323 public native void putFloat(long address, float x); 324 /** @see #getByte(long) */ 325 @HotSpotIntrinsicCandidate 326 public native double getDouble(long address); 327 /** @see #putByte(long, byte) */ 328 @HotSpotIntrinsicCandidate 329 public native void putDouble(long address, double x); 330 331 /** 332 * Fetches a native pointer from a given memory address. If the address is 333 * zero, or does not point into a block obtained from {@link 334 * #allocateMemory}, the results are undefined. 335 * 336 * <p>If the native pointer is less than 64 bits wide, it is extended as 337 * an unsigned number to a Java long. The pointer may be indexed by any 338 * given byte offset, simply by adding that offset (as a simple integer) to 339 * the long representing the pointer. The number of bytes actually read 340 * from the target address may be determined by consulting {@link 341 * #addressSize}. 342 * 343 * @see #allocateMemory 344 */ 345 @HotSpotIntrinsicCandidate 346 public native long getAddress(long address); 347 348 /** 349 * Stores a native pointer into a given memory address. If the address is 350 * zero, or does not point into a block obtained from {@link 351 * #allocateMemory}, the results are undefined. 352 * 353 * <p>The number of bytes actually written at the target address may be 354 * determined by consulting {@link #addressSize}. 355 * 356 * @see #getAddress(long) 357 */ 358 @HotSpotIntrinsicCandidate 359 public native void putAddress(long address, long x); 360 361 /// wrappers for malloc, realloc, free: 362 363 /** 364 * Allocates a new block of native memory, of the given size in bytes. The 365 * contents of the memory are uninitialized; they will generally be 366 * garbage. The resulting native pointer will never be zero, and will be 367 * aligned for all value types. Dispose of this memory by calling {@link 368 * #freeMemory}, or resize it with {@link #reallocateMemory}. 369 * 370 * @throws IllegalArgumentException if the size is negative or too large 371 * for the native size_t type 372 * 373 * @throws OutOfMemoryError if the allocation is refused by the system 374 * 375 * @see #getByte(long) 376 * @see #putByte(long, byte) 377 */ 378 public native long allocateMemory(long bytes); 379 380 /** 381 * Resizes a new block of native memory, to the given size in bytes. The 382 * contents of the new block past the size of the old block are 383 * uninitialized; they will generally be garbage. The resulting native 384 * pointer will be zero if and only if the requested size is zero. The 385 * resulting native pointer will be aligned for all value types. Dispose 386 * of this memory by calling {@link #freeMemory}, or resize it with {@link 387 * #reallocateMemory}. The address passed to this method may be null, in 388 * which case an allocation will be performed. 389 * 390 * @throws IllegalArgumentException if the size is negative or too large 391 * for the native size_t type 392 * 393 * @throws OutOfMemoryError if the allocation is refused by the system 394 * 395 * @see #allocateMemory 396 */ 397 public native long reallocateMemory(long address, long bytes); 398 399 /** 400 * Sets all bytes in a given block of memory to a fixed value 401 * (usually zero). 402 * 403 * <p>This method determines a block's base address by means of two parameters, 404 * and so it provides (in effect) a <em>double-register</em> addressing mode, 405 * as discussed in {@link #getInt(Object,long)}. When the object reference is null, 406 * the offset supplies an absolute base address. 407 * 408 * <p>The stores are in coherent (atomic) units of a size determined 409 * by the address and length parameters. If the effective address and 410 * length are all even modulo 8, the stores take place in 'long' units. 411 * If the effective address and length are (resp.) even modulo 4 or 2, 412 * the stores take place in units of 'int' or 'short'. 413 * 414 * @since 1.7 415 */ 416 public native void setMemory(Object o, long offset, long bytes, byte value); 417 418 /** 419 * Sets all bytes in a given block of memory to a fixed value 420 * (usually zero). This provides a <em>single-register</em> addressing mode, 421 * as discussed in {@link #getInt(Object,long)}. 422 * 423 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}. 424 */ 425 public void setMemory(long address, long bytes, byte value) { 426 setMemory(null, address, bytes, value); 427 } 428 429 /** 430 * Sets all bytes in a given block of memory to a copy of another 431 * block. 432 * 433 * <p>This method determines each block's base address by means of two parameters, 434 * and so it provides (in effect) a <em>double-register</em> addressing mode, 435 * as discussed in {@link #getInt(Object,long)}. When the object reference is null, 436 * the offset supplies an absolute base address. 437 * 438 * <p>The transfers are in coherent (atomic) units of a size determined 439 * by the address and length parameters. If the effective addresses and 440 * length are all even modulo 8, the transfer takes place in 'long' units. 441 * If the effective addresses and length are (resp.) even modulo 4 or 2, 442 * the transfer takes place in units of 'int' or 'short'. 443 * 444 * @since 1.7 445 */ 446 @HotSpotIntrinsicCandidate 447 public native void copyMemory(Object srcBase, long srcOffset, 448 Object destBase, long destOffset, 449 long bytes); 450 /** 451 * Sets all bytes in a given block of memory to a copy of another 452 * block. This provides a <em>single-register</em> addressing mode, 453 * as discussed in {@link #getInt(Object,long)}. 454 * 455 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}. 456 */ 457 public void copyMemory(long srcAddress, long destAddress, long bytes) { 458 copyMemory(null, srcAddress, null, destAddress, bytes); 459 } 460 461 /** 462 * Disposes of a block of native memory, as obtained from {@link 463 * #allocateMemory} or {@link #reallocateMemory}. The address passed to 464 * this method may be null, in which case no action is taken. 465 * 466 * @see #allocateMemory 467 */ 468 public native void freeMemory(long address); 469 470 /// random queries 471 472 /** 473 * This constant differs from all results that will ever be returned from 474 * {@link #staticFieldOffset}, {@link #objectFieldOffset}, 475 * or {@link #arrayBaseOffset}. 476 */ 477 public static final int INVALID_FIELD_OFFSET = -1; 478 479 /** 480 * Reports the location of a given field in the storage allocation of its 481 * class. Do not expect to perform any sort of arithmetic on this offset; 482 * it is just a cookie which is passed to the unsafe heap memory accessors. 483 * 484 * <p>Any given field will always have the same offset and base, and no 485 * two distinct fields of the same class will ever have the same offset 486 * and base. 487 * 488 * <p>As of 1.4.1, offsets for fields are represented as long values, 489 * although the Sun JVM does not use the most significant 32 bits. 490 * However, JVM implementations which store static fields at absolute 491 * addresses can use long offsets and null base pointers to express 492 * the field locations in a form usable by {@link #getInt(Object,long)}. 493 * Therefore, code which will be ported to such JVMs on 64-bit platforms 494 * must preserve all bits of static field offsets. 495 * @see #getInt(Object, long) 496 */ 497 public native long objectFieldOffset(Field f); 498 499 /** 500 * Reports the location of a given static field, in conjunction with {@link 501 * #staticFieldBase}. 502 * <p>Do not expect to perform any sort of arithmetic on this offset; 503 * it is just a cookie which is passed to the unsafe heap memory accessors. 504 * 505 * <p>Any given field will always have the same offset, and no two distinct 506 * fields of the same class will ever have the same offset. 507 * 508 * <p>As of 1.4.1, offsets for fields are represented as long values, 509 * although the Sun JVM does not use the most significant 32 bits. 510 * It is hard to imagine a JVM technology which needs more than 511 * a few bits to encode an offset within a non-array object, 512 * However, for consistency with other methods in this class, 513 * this method reports its result as a long value. 514 * @see #getInt(Object, long) 515 */ 516 public native long staticFieldOffset(Field f); 517 518 /** 519 * Reports the location of a given static field, in conjunction with {@link 520 * #staticFieldOffset}. 521 * <p>Fetch the base "Object", if any, with which static fields of the 522 * given class can be accessed via methods like {@link #getInt(Object, 523 * long)}. This value may be null. This value may refer to an object 524 * which is a "cookie", not guaranteed to be a real Object, and it should 525 * not be used in any way except as argument to the get and put routines in 526 * this class. 527 */ 528 public native Object staticFieldBase(Field f); 529 530 /** 531 * Detects if the given class may need to be initialized. This is often 532 * needed in conjunction with obtaining the static field base of a 533 * class. 534 * @return false only if a call to {@code ensureClassInitialized} would have no effect 535 */ 536 public native boolean shouldBeInitialized(Class<?> c); 537 538 /** 539 * Ensures the given class has been initialized. This is often 540 * needed in conjunction with obtaining the static field base of a 541 * class. 542 */ 543 public native void ensureClassInitialized(Class<?> c); 544 545 /** 546 * Reports the offset of the first element in the storage allocation of a 547 * given array class. If {@link #arrayIndexScale} returns a non-zero value 548 * for the same class, you may use that scale factor, together with this 549 * base offset, to form new offsets to access elements of arrays of the 550 * given class. 551 * 552 * @see #getInt(Object, long) 553 * @see #putInt(Object, long, int) 554 */ 555 public native int arrayBaseOffset(Class<?> arrayClass); 556 557 /** The value of {@code arrayBaseOffset(boolean[].class)} */ 558 public static final int ARRAY_BOOLEAN_BASE_OFFSET 559 = theUnsafe.arrayBaseOffset(boolean[].class); 560 561 /** The value of {@code arrayBaseOffset(byte[].class)} */ 562 public static final int ARRAY_BYTE_BASE_OFFSET 563 = theUnsafe.arrayBaseOffset(byte[].class); 564 565 /** The value of {@code arrayBaseOffset(short[].class)} */ 566 public static final int ARRAY_SHORT_BASE_OFFSET 567 = theUnsafe.arrayBaseOffset(short[].class); 568 569 /** The value of {@code arrayBaseOffset(char[].class)} */ 570 public static final int ARRAY_CHAR_BASE_OFFSET 571 = theUnsafe.arrayBaseOffset(char[].class); 572 573 /** The value of {@code arrayBaseOffset(int[].class)} */ 574 public static final int ARRAY_INT_BASE_OFFSET 575 = theUnsafe.arrayBaseOffset(int[].class); 576 577 /** The value of {@code arrayBaseOffset(long[].class)} */ 578 public static final int ARRAY_LONG_BASE_OFFSET 579 = theUnsafe.arrayBaseOffset(long[].class); 580 581 /** The value of {@code arrayBaseOffset(float[].class)} */ 582 public static final int ARRAY_FLOAT_BASE_OFFSET 583 = theUnsafe.arrayBaseOffset(float[].class); 584 585 /** The value of {@code arrayBaseOffset(double[].class)} */ 586 public static final int ARRAY_DOUBLE_BASE_OFFSET 587 = theUnsafe.arrayBaseOffset(double[].class); 588 589 /** The value of {@code arrayBaseOffset(Object[].class)} */ 590 public static final int ARRAY_OBJECT_BASE_OFFSET 591 = theUnsafe.arrayBaseOffset(Object[].class); 592 593 /** 594 * Reports the scale factor for addressing elements in the storage 595 * allocation of a given array class. However, arrays of "narrow" types 596 * will generally not work properly with accessors like {@link 597 * #getByte(Object, long)}, so the scale factor for such classes is reported 598 * as zero. 599 * 600 * @see #arrayBaseOffset 601 * @see #getInt(Object, long) 602 * @see #putInt(Object, long, int) 603 */ 604 public native int arrayIndexScale(Class<?> arrayClass); 605 606 /** The value of {@code arrayIndexScale(boolean[].class)} */ 607 public static final int ARRAY_BOOLEAN_INDEX_SCALE 608 = theUnsafe.arrayIndexScale(boolean[].class); 609 610 /** The value of {@code arrayIndexScale(byte[].class)} */ 611 public static final int ARRAY_BYTE_INDEX_SCALE 612 = theUnsafe.arrayIndexScale(byte[].class); 613 614 /** The value of {@code arrayIndexScale(short[].class)} */ 615 public static final int ARRAY_SHORT_INDEX_SCALE 616 = theUnsafe.arrayIndexScale(short[].class); 617 618 /** The value of {@code arrayIndexScale(char[].class)} */ 619 public static final int ARRAY_CHAR_INDEX_SCALE 620 = theUnsafe.arrayIndexScale(char[].class); 621 622 /** The value of {@code arrayIndexScale(int[].class)} */ 623 public static final int ARRAY_INT_INDEX_SCALE 624 = theUnsafe.arrayIndexScale(int[].class); 625 626 /** The value of {@code arrayIndexScale(long[].class)} */ 627 public static final int ARRAY_LONG_INDEX_SCALE 628 = theUnsafe.arrayIndexScale(long[].class); 629 630 /** The value of {@code arrayIndexScale(float[].class)} */ 631 public static final int ARRAY_FLOAT_INDEX_SCALE 632 = theUnsafe.arrayIndexScale(float[].class); 633 634 /** The value of {@code arrayIndexScale(double[].class)} */ 635 public static final int ARRAY_DOUBLE_INDEX_SCALE 636 = theUnsafe.arrayIndexScale(double[].class); 637 638 /** The value of {@code arrayIndexScale(Object[].class)} */ 639 public static final int ARRAY_OBJECT_INDEX_SCALE 640 = theUnsafe.arrayIndexScale(Object[].class); 641 642 /** 643 * Reports the size in bytes of a native pointer, as stored via {@link 644 * #putAddress}. This value will be either 4 or 8. Note that the sizes of 645 * other primitive types (as stored in native memory blocks) is determined 646 * fully by their information content. 647 */ 648 public native int addressSize(); 649 650 /** The value of {@code addressSize()} */ 651 public static final int ADDRESS_SIZE = theUnsafe.addressSize(); 652 653 /** 654 * Reports the size in bytes of a native memory page (whatever that is). 655 * This value will always be a power of two. 656 */ 657 public native int pageSize(); 658 659 660 /// random trusted operations from JNI: 661 662 /** 663 * Tells the VM to define a class, without security checks. By default, the 664 * class loader and protection domain come from the caller's class. 665 */ 666 public native Class<?> defineClass(String name, byte[] b, int off, int len, 667 ClassLoader loader, 668 ProtectionDomain protectionDomain); 669 670 /** 671 * Defines a class but does not make it known to the class loader or system dictionary. 672 * <p> 673 * For each CP entry, the corresponding CP patch must either be null or have 674 * the a format that matches its tag: 675 * <ul> 676 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang 677 * <li>Utf8: a string (must have suitable syntax if used as signature or name) 678 * <li>Class: any java.lang.Class object 679 * <li>String: any object (not just a java.lang.String) 680 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments 681 * </ul> 682 * @param hostClass context for linkage, access control, protection domain, and class loader 683 * @param data bytes of a class file 684 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data 685 */ 686 public native Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches); 687 688 /** 689 * Allocates an instance but does not run any constructor. 690 * Initializes the class if it has not yet been. 691 */ 692 @HotSpotIntrinsicCandidate 693 public native Object allocateInstance(Class<?> cls) 694 throws InstantiationException; 695 696 /** Throws the exception without telling the verifier. */ 697 public native void throwException(Throwable ee); 698 699 /** 700 * Atomically updates Java variable to {@code x} if it is currently 701 * holding {@code expected}. 702 * 703 * <p>This operation has memory semantics of a {@code volatile} read 704 * and write. Corresponds to C11 atomic_compare_exchange_strong. 705 * 706 * @return {@code true} if successful 707 */ 708 @HotSpotIntrinsicCandidate 709 public final native boolean compareAndSwapObject(Object o, long offset, 710 Object expected, 711 Object x); 712 713 /** 714 * Atomically updates Java variable to {@code x} if it is currently 715 * holding {@code expected}. 716 * 717 * <p>This operation has memory semantics of a {@code volatile} read 718 * and write. Corresponds to C11 atomic_compare_exchange_strong. 719 * 720 * @return {@code true} if successful 721 */ 722 @HotSpotIntrinsicCandidate 723 public final native boolean compareAndSwapInt(Object o, long offset, 724 int expected, 725 int x); 726 727 /** 728 * Atomically updates Java variable to {@code x} if it is currently 729 * holding {@code expected}. 730 * 731 * <p>This operation has memory semantics of a {@code volatile} read 732 * and write. Corresponds to C11 atomic_compare_exchange_strong. 733 * 734 * @return {@code true} if successful 735 */ 736 @HotSpotIntrinsicCandidate 737 public final native boolean compareAndSwapLong(Object o, long offset, 738 long expected, 739 long x); 740 741 /** 742 * Fetches a reference value from a given Java variable, with volatile 743 * load semantics. Otherwise identical to {@link #getObject(Object, long)} 744 */ 745 @HotSpotIntrinsicCandidate 746 public native Object getObjectVolatile(Object o, long offset); 747 748 /** 749 * Stores a reference value into a given Java variable, with 750 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)} 751 */ 752 @HotSpotIntrinsicCandidate 753 public native void putObjectVolatile(Object o, long offset, Object x); 754 755 /** Volatile version of {@link #getInt(Object, long)} */ 756 @HotSpotIntrinsicCandidate 757 public native int getIntVolatile(Object o, long offset); 758 759 /** Volatile version of {@link #putInt(Object, long, int)} */ 760 @HotSpotIntrinsicCandidate 761 public native void putIntVolatile(Object o, long offset, int x); 762 763 /** Volatile version of {@link #getBoolean(Object, long)} */ 764 @HotSpotIntrinsicCandidate 765 public native boolean getBooleanVolatile(Object o, long offset); 766 767 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */ 768 @HotSpotIntrinsicCandidate 769 public native void putBooleanVolatile(Object o, long offset, boolean x); 770 771 /** Volatile version of {@link #getByte(Object, long)} */ 772 @HotSpotIntrinsicCandidate 773 public native byte getByteVolatile(Object o, long offset); 774 775 /** Volatile version of {@link #putByte(Object, long, byte)} */ 776 @HotSpotIntrinsicCandidate 777 public native void putByteVolatile(Object o, long offset, byte x); 778 779 /** Volatile version of {@link #getShort(Object, long)} */ 780 @HotSpotIntrinsicCandidate 781 public native short getShortVolatile(Object o, long offset); 782 783 /** Volatile version of {@link #putShort(Object, long, short)} */ 784 @HotSpotIntrinsicCandidate 785 public native void putShortVolatile(Object o, long offset, short x); 786 787 /** Volatile version of {@link #getChar(Object, long)} */ 788 @HotSpotIntrinsicCandidate 789 public native char getCharVolatile(Object o, long offset); 790 791 /** Volatile version of {@link #putChar(Object, long, char)} */ 792 @HotSpotIntrinsicCandidate 793 public native void putCharVolatile(Object o, long offset, char x); 794 795 /** Volatile version of {@link #getLong(Object, long)} */ 796 @HotSpotIntrinsicCandidate 797 public native long getLongVolatile(Object o, long offset); 798 799 /** Volatile version of {@link #putLong(Object, long, long)} */ 800 @HotSpotIntrinsicCandidate 801 public native void putLongVolatile(Object o, long offset, long x); 802 803 /** Volatile version of {@link #getFloat(Object, long)} */ 804 @HotSpotIntrinsicCandidate 805 public native float getFloatVolatile(Object o, long offset); 806 807 /** Volatile version of {@link #putFloat(Object, long, float)} */ 808 @HotSpotIntrinsicCandidate 809 public native void putFloatVolatile(Object o, long offset, float x); 810 811 /** Volatile version of {@link #getDouble(Object, long)} */ 812 @HotSpotIntrinsicCandidate 813 public native double getDoubleVolatile(Object o, long offset); 814 815 /** Volatile version of {@link #putDouble(Object, long, double)} */ 816 @HotSpotIntrinsicCandidate 817 public native void putDoubleVolatile(Object o, long offset, double x); 818 819 /** 820 * Version of {@link #putObjectVolatile(Object, long, Object)} 821 * that does not guarantee immediate visibility of the store to 822 * other threads. This method is generally only useful if the 823 * underlying field is a Java volatile (or if an array cell, one 824 * that is otherwise only accessed using volatile accesses). 825 * 826 * Corresponds to C11 atomic_store_explicit(..., memory_order_release). 827 */ 828 @HotSpotIntrinsicCandidate 829 public native void putOrderedObject(Object o, long offset, Object x); 830 831 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */ 832 @HotSpotIntrinsicCandidate 833 public native void putOrderedInt(Object o, long offset, int x); 834 835 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */ 836 @HotSpotIntrinsicCandidate 837 public native void putOrderedLong(Object o, long offset, long x); 838 839 /** 840 * Unblocks the given thread blocked on {@code park}, or, if it is 841 * not blocked, causes the subsequent call to {@code park} not to 842 * block. Note: this operation is "unsafe" solely because the 843 * caller must somehow ensure that the thread has not been 844 * destroyed. Nothing special is usually required to ensure this 845 * when called from Java (in which there will ordinarily be a live 846 * reference to the thread) but this is not nearly-automatically 847 * so when calling from native code. 848 * 849 * @param thread the thread to unpark. 850 */ 851 @HotSpotIntrinsicCandidate 852 public native void unpark(Object thread); 853 854 /** 855 * Blocks current thread, returning when a balancing 856 * {@code unpark} occurs, or a balancing {@code unpark} has 857 * already occurred, or the thread is interrupted, or, if not 858 * absolute and time is not zero, the given time nanoseconds have 859 * elapsed, or if absolute, the given deadline in milliseconds 860 * since Epoch has passed, or spuriously (i.e., returning for no 861 * "reason"). Note: This operation is in the Unsafe class only 862 * because {@code unpark} is, so it would be strange to place it 863 * elsewhere. 864 */ 865 @HotSpotIntrinsicCandidate 866 public native void park(boolean isAbsolute, long time); 867 868 /** 869 * Gets the load average in the system run queue assigned 870 * to the available processors averaged over various periods of time. 871 * This method retrieves the given {@code nelem} samples and 872 * assigns to the elements of the given {@code loadavg} array. 873 * The system imposes a maximum of 3 samples, representing 874 * averages over the last 1, 5, and 15 minutes, respectively. 875 * 876 * @param loadavg an array of double of size nelems 877 * @param nelems the number of samples to be retrieved and 878 * must be 1 to 3. 879 * 880 * @return the number of samples actually retrieved; or -1 881 * if the load average is unobtainable. 882 */ 883 public native int getLoadAverage(double[] loadavg, int nelems); 884 885 // The following contain CAS-based Java implementations used on 886 // platforms not supporting native instructions 887 888 /** 889 * Atomically adds the given value to the current value of a field 890 * or array element within the given object {@code o} 891 * at the given {@code offset}. 892 * 893 * @param o object/array to update the field/element in 894 * @param offset field/element offset 895 * @param delta the value to add 896 * @return the previous value 897 * @since 1.8 898 */ 899 @HotSpotIntrinsicCandidate 900 public final int getAndAddInt(Object o, long offset, int delta) { 901 int v; 902 do { 903 v = getIntVolatile(o, offset); 904 } while (!compareAndSwapInt(o, offset, v, v + delta)); 905 return v; 906 } 907 908 /** 909 * Atomically adds the given value to the current value of a field 910 * or array element within the given object {@code o} 911 * at the given {@code offset}. 912 * 913 * @param o object/array to update the field/element in 914 * @param offset field/element offset 915 * @param delta the value to add 916 * @return the previous value 917 * @since 1.8 918 */ 919 @HotSpotIntrinsicCandidate 920 public final long getAndAddLong(Object o, long offset, long delta) { 921 long v; 922 do { 923 v = getLongVolatile(o, offset); 924 } while (!compareAndSwapLong(o, offset, v, v + delta)); 925 return v; 926 } 927 928 /** 929 * Atomically exchanges the given value with the current value of 930 * a field or array element within the given object {@code o} 931 * at the given {@code offset}. 932 * 933 * @param o object/array to update the field/element in 934 * @param offset field/element offset 935 * @param newValue new value 936 * @return the previous value 937 * @since 1.8 938 */ 939 @HotSpotIntrinsicCandidate 940 public final int getAndSetInt(Object o, long offset, int newValue) { 941 int v; 942 do { 943 v = getIntVolatile(o, offset); 944 } while (!compareAndSwapInt(o, offset, v, newValue)); 945 return v; 946 } 947 948 /** 949 * Atomically exchanges the given value with the current value of 950 * a field or array element within the given object {@code o} 951 * at the given {@code offset}. 952 * 953 * @param o object/array to update the field/element in 954 * @param offset field/element offset 955 * @param newValue new value 956 * @return the previous value 957 * @since 1.8 958 */ 959 @HotSpotIntrinsicCandidate 960 public final long getAndSetLong(Object o, long offset, long newValue) { 961 long v; 962 do { 963 v = getLongVolatile(o, offset); 964 } while (!compareAndSwapLong(o, offset, v, newValue)); 965 return v; 966 } 967 968 /** 969 * Atomically exchanges the given reference value with the current 970 * reference value of a field or array element within the given 971 * object {@code o} at the given {@code offset}. 972 * 973 * @param o object/array to update the field/element in 974 * @param offset field/element offset 975 * @param newValue new value 976 * @return the previous value 977 * @since 1.8 978 */ 979 @HotSpotIntrinsicCandidate 980 public final Object getAndSetObject(Object o, long offset, Object newValue) { 981 Object v; 982 do { 983 v = getObjectVolatile(o, offset); 984 } while (!compareAndSwapObject(o, offset, v, newValue)); 985 return v; 986 } 987 988 989 /** 990 * Ensures that loads before the fence will not be reordered with loads and 991 * stores after the fence; a "LoadLoad plus LoadStore barrier". 992 * 993 * Corresponds to C11 atomic_thread_fence(memory_order_acquire) 994 * (an "acquire fence"). 995 * 996 * A pure LoadLoad fence is not provided, since the addition of LoadStore 997 * is almost always desired, and most current hardware instructions that 998 * provide a LoadLoad barrier also provide a LoadStore barrier for free. 999 * @since 1.8 1000 */ 1001 @HotSpotIntrinsicCandidate 1002 public native void loadFence(); 1003 1004 /** 1005 * Ensures that loads and stores before the fence will not be reordered with 1006 * stores after the fence; a "StoreStore plus LoadStore barrier". 1007 * 1008 * Corresponds to C11 atomic_thread_fence(memory_order_release) 1009 * (a "release fence"). 1010 * 1011 * A pure StoreStore fence is not provided, since the addition of LoadStore 1012 * is almost always desired, and most current hardware instructions that 1013 * provide a StoreStore barrier also provide a LoadStore barrier for free. 1014 * @since 1.8 1015 */ 1016 @HotSpotIntrinsicCandidate 1017 public native void storeFence(); 1018 1019 /** 1020 * Ensures that loads and stores before the fence will not be reordered 1021 * with loads and stores after the fence. Implies the effects of both 1022 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad 1023 * barrier. 1024 * 1025 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst). 1026 * @since 1.8 1027 */ 1028 @HotSpotIntrinsicCandidate 1029 public native void fullFence(); 1030 1031 /** 1032 * Throws IllegalAccessError; for use by the VM for access control 1033 * error support. 1034 * @since 1.8 1035 */ 1036 private static void throwIllegalAccessError() { 1037 throw new IllegalAccessError(); 1038 } 1039 1040 /** 1041 * @return Returns true if the native byte ordering of this 1042 * platform is big-endian, false if it is little-endian. 1043 */ 1044 public final boolean isBigEndian() { return BE; } 1045 1046 /** 1047 * @return Returns true if this platform is capable of performing 1048 * accesses at addresses which are not aligned for the type of the 1049 * primitive type being accessed, false otherwise. 1050 */ 1051 public final boolean unalignedAccess() { return unalignedAccess; } 1052 1053 /** 1054 * Fetches a value at some byte offset into a given Java object. 1055 * More specifically, fetches a value within the given object 1056 * <code>o</code> at the given offset, or (if <code>o</code> is 1057 * null) from the memory address whose numerical value is the 1058 * given offset. <p> 1059 * 1060 * The specification of this method is the same as {@link 1061 * #getLong(Object, long)} except that the offset does not need to 1062 * have been obtained from {@link #objectFieldOffset} on the 1063 * {@link java.lang.reflect.Field} of some Java field. The value 1064 * in memory is raw data, and need not correspond to any Java 1065 * variable. Unless <code>o</code> is null, the value accessed 1066 * must be entirely within the allocated object. The endianness 1067 * of the value in memory is the endianness of the native platform. 1068 * 1069 * <p> The read will be atomic with respect to the largest power 1070 * of two that divides the GCD of the offset and the storage size. 1071 * For example, getLongUnaligned will make atomic reads of 2-, 4-, 1072 * or 8-byte storage units if the offset is zero mod 2, 4, or 8, 1073 * respectively. There are no other guarantees of atomicity. 1074 * <p> 1075 * 8-byte atomicity is only guaranteed on platforms on which 1076 * support atomic accesses to longs. 1077 * 1078 * @param o Java heap object in which the value resides, if any, else 1079 * null 1080 * @param offset The offset in bytes from the start of the object 1081 * @return the value fetched from the indicated object 1082 * @throws RuntimeException No defined exceptions are thrown, not even 1083 * {@link NullPointerException} 1084 * @since 9 1085 */ 1086 @HotSpotIntrinsicCandidate 1087 public final long getLongUnaligned(Object o, long offset) { 1088 if ((offset & 7) == 0) { 1089 return getLong(o, offset); 1090 } else if ((offset & 3) == 0) { 1091 return makeLong(getInt(o, offset), 1092 getInt(o, offset + 4)); 1093 } else if ((offset & 1) == 0) { 1094 return makeLong(getShort(o, offset), 1095 getShort(o, offset + 2), 1096 getShort(o, offset + 4), 1097 getShort(o, offset + 6)); 1098 } else { 1099 return makeLong(getByte(o, offset), 1100 getByte(o, offset + 1), 1101 getByte(o, offset + 2), 1102 getByte(o, offset + 3), 1103 getByte(o, offset + 4), 1104 getByte(o, offset + 5), 1105 getByte(o, offset + 6), 1106 getByte(o, offset + 7)); 1107 } 1108 } 1109 /** 1110 * As {@link #getLongUnaligned(Object, long)} but with an 1111 * additional argument which specifies the endianness of the value 1112 * as stored in memory. 1113 * 1114 * @param o Java heap object in which the variable resides 1115 * @param offset The offset in bytes from the start of the object 1116 * @param bigEndian The endianness of the value 1117 * @return the value fetched from the indicated object 1118 * @since 9 1119 */ 1120 public final long getLongUnaligned(Object o, long offset, boolean bigEndian) { 1121 return convEndian(bigEndian, getLongUnaligned(o, offset)); 1122 } 1123 1124 /** @see #getLongUnaligned(Object, long) */ 1125 @HotSpotIntrinsicCandidate 1126 public final int getIntUnaligned(Object o, long offset) { 1127 if ((offset & 3) == 0) { 1128 return getInt(o, offset); 1129 } else if ((offset & 1) == 0) { 1130 return makeInt(getShort(o, offset), 1131 getShort(o, offset + 2)); 1132 } else { 1133 return makeInt(getByte(o, offset), 1134 getByte(o, offset + 1), 1135 getByte(o, offset + 2), 1136 getByte(o, offset + 3)); 1137 } 1138 } 1139 /** @see #getLongUnaligned(Object, long, boolean) */ 1140 public final int getIntUnaligned(Object o, long offset, boolean bigEndian) { 1141 return convEndian(bigEndian, getIntUnaligned(o, offset)); 1142 } 1143 1144 /** @see #getLongUnaligned(Object, long) */ 1145 @HotSpotIntrinsicCandidate 1146 public final short getShortUnaligned(Object o, long offset) { 1147 if ((offset & 1) == 0) { 1148 return getShort(o, offset); 1149 } else { 1150 return makeShort(getByte(o, offset), 1151 getByte(o, offset + 1)); 1152 } 1153 } 1154 /** @see #getLongUnaligned(Object, long, boolean) */ 1155 public final short getShortUnaligned(Object o, long offset, boolean bigEndian) { 1156 return convEndian(bigEndian, getShortUnaligned(o, offset)); 1157 } 1158 1159 /** @see #getLongUnaligned(Object, long) */ 1160 @HotSpotIntrinsicCandidate 1161 public final char getCharUnaligned(Object o, long offset) { 1162 return (char)getShortUnaligned(o, offset); 1163 } 1164 1165 /** @see #getLongUnaligned(Object, long, boolean) */ 1166 public final char getCharUnaligned(Object o, long offset, boolean bigEndian) { 1167 return convEndian(bigEndian, getCharUnaligned(o, offset)); 1168 } 1169 1170 /** 1171 * Stores a value at some byte offset into a given Java object. 1172 * <p> 1173 * The specification of this method is the same as {@link 1174 * #getLong(Object, long)} except that the offset does not need to 1175 * have been obtained from {@link #objectFieldOffset} on the 1176 * {@link java.lang.reflect.Field} of some Java field. The value 1177 * in memory is raw data, and need not correspond to any Java 1178 * variable. The endianness of the value in memory is the 1179 * endianness of the native platform. 1180 * <p> 1181 * The write will be atomic with respect to the largest power of 1182 * two that divides the GCD of the offset and the storage size. 1183 * For example, putLongUnaligned will make atomic writes of 2-, 4-, 1184 * or 8-byte storage units if the offset is zero mod 2, 4, or 8, 1185 * respectively. There are no other guarantees of atomicity. 1186 * <p> 1187 * 8-byte atomicity is only guaranteed on platforms on which 1188 * support atomic accesses to longs. 1189 * 1190 * @param o Java heap object in which the value resides, if any, else 1191 * null 1192 * @param offset The offset in bytes from the start of the object 1193 * @param x the value to store 1194 * @throws RuntimeException No defined exceptions are thrown, not even 1195 * {@link NullPointerException} 1196 * @since 9 1197 */ 1198 @HotSpotIntrinsicCandidate 1199 public final void putLongUnaligned(Object o, long offset, long x) { 1200 if ((offset & 7) == 0) { 1201 putLong(o, offset, x); 1202 } else if ((offset & 3) == 0) { 1203 putLongParts(o, offset, 1204 (int)(x >> 0), 1205 (int)(x >>> 32)); 1206 } else if ((offset & 1) == 0) { 1207 putLongParts(o, offset, 1208 (short)(x >>> 0), 1209 (short)(x >>> 16), 1210 (short)(x >>> 32), 1211 (short)(x >>> 48)); 1212 } else { 1213 putLongParts(o, offset, 1214 (byte)(x >>> 0), 1215 (byte)(x >>> 8), 1216 (byte)(x >>> 16), 1217 (byte)(x >>> 24), 1218 (byte)(x >>> 32), 1219 (byte)(x >>> 40), 1220 (byte)(x >>> 48), 1221 (byte)(x >>> 56)); 1222 } 1223 } 1224 1225 /** 1226 * As {@link #putLongUnaligned(Object, long, long)} but with an additional 1227 * argument which specifies the endianness of the value as stored in memory. 1228 * @param o Java heap object in which the value resides 1229 * @param offset The offset in bytes from the start of the object 1230 * @param x the value to store 1231 * @param bigEndian The endianness of the value 1232 * @throws RuntimeException No defined exceptions are thrown, not even 1233 * {@link NullPointerException} 1234 * @since 9 1235 */ 1236 public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) { 1237 putLongUnaligned(o, offset, convEndian(bigEndian, x)); 1238 } 1239 1240 /** @see #putLongUnaligned(Object, long, long) */ 1241 @HotSpotIntrinsicCandidate 1242 public final void putIntUnaligned(Object o, long offset, int x) { 1243 if ((offset & 3) == 0) { 1244 putInt(o, offset, x); 1245 } else if ((offset & 1) == 0) { 1246 putIntParts(o, offset, 1247 (short)(x >> 0), 1248 (short)(x >>> 16)); 1249 } else { 1250 putIntParts(o, offset, 1251 (byte)(x >>> 0), 1252 (byte)(x >>> 8), 1253 (byte)(x >>> 16), 1254 (byte)(x >>> 24)); 1255 } 1256 } 1257 /** @see #putLongUnaligned(Object, long, long, boolean) */ 1258 public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) { 1259 putIntUnaligned(o, offset, convEndian(bigEndian, x)); 1260 } 1261 1262 /** @see #putLongUnaligned(Object, long, long) */ 1263 @HotSpotIntrinsicCandidate 1264 public final void putShortUnaligned(Object o, long offset, short x) { 1265 if ((offset & 1) == 0) { 1266 putShort(o, offset, x); 1267 } else { 1268 putShortParts(o, offset, 1269 (byte)(x >>> 0), 1270 (byte)(x >>> 8)); 1271 } 1272 } 1273 /** @see #putLongUnaligned(Object, long, long, boolean) */ 1274 public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) { 1275 putShortUnaligned(o, offset, convEndian(bigEndian, x)); 1276 } 1277 1278 /** @see #putLongUnaligned(Object, long, long) */ 1279 @HotSpotIntrinsicCandidate 1280 public final void putCharUnaligned(Object o, long offset, char x) { 1281 putShortUnaligned(o, offset, (short)x); 1282 } 1283 /** @see #putLongUnaligned(Object, long, long, boolean) */ 1284 public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) { 1285 putCharUnaligned(o, offset, convEndian(bigEndian, x)); 1286 } 1287 1288 // JVM interface methods 1289 private native boolean unalignedAccess0(); 1290 private native boolean isBigEndian0(); 1291 1292 // BE is true iff the native endianness of this platform is big. 1293 private static final boolean BE = theUnsafe.isBigEndian0(); 1294 1295 // unalignedAccess is true iff this platform can perform unaligned accesses. 1296 private static final boolean unalignedAccess = theUnsafe.unalignedAccess0(); 1297 1298 private static int pickPos(int top, int pos) { return BE ? top - pos : pos; } 1299 1300 // These methods construct integers from bytes. The byte ordering 1301 // is the native endianness of this platform. 1302 private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) { 1303 return ((toUnsignedLong(i0) << pickPos(56, 0)) 1304 | (toUnsignedLong(i1) << pickPos(56, 8)) 1305 | (toUnsignedLong(i2) << pickPos(56, 16)) 1306 | (toUnsignedLong(i3) << pickPos(56, 24)) 1307 | (toUnsignedLong(i4) << pickPos(56, 32)) 1308 | (toUnsignedLong(i5) << pickPos(56, 40)) 1309 | (toUnsignedLong(i6) << pickPos(56, 48)) 1310 | (toUnsignedLong(i7) << pickPos(56, 56))); 1311 } 1312 private static long makeLong(short i0, short i1, short i2, short i3) { 1313 return ((toUnsignedLong(i0) << pickPos(48, 0)) 1314 | (toUnsignedLong(i1) << pickPos(48, 16)) 1315 | (toUnsignedLong(i2) << pickPos(48, 32)) 1316 | (toUnsignedLong(i3) << pickPos(48, 48))); 1317 } 1318 private static long makeLong(int i0, int i1) { 1319 return (toUnsignedLong(i0) << pickPos(32, 0)) 1320 | (toUnsignedLong(i1) << pickPos(32, 32)); 1321 } 1322 private static int makeInt(short i0, short i1) { 1323 return (toUnsignedInt(i0) << pickPos(16, 0)) 1324 | (toUnsignedInt(i1) << pickPos(16, 16)); 1325 } 1326 private static int makeInt(byte i0, byte i1, byte i2, byte i3) { 1327 return ((toUnsignedInt(i0) << pickPos(24, 0)) 1328 | (toUnsignedInt(i1) << pickPos(24, 8)) 1329 | (toUnsignedInt(i2) << pickPos(24, 16)) 1330 | (toUnsignedInt(i3) << pickPos(24, 24))); 1331 } 1332 private static short makeShort(byte i0, byte i1) { 1333 return (short)((toUnsignedInt(i0) << pickPos(8, 0)) 1334 | (toUnsignedInt(i1) << pickPos(8, 8))); 1335 } 1336 1337 private static byte pick(byte le, byte be) { return BE ? be : le; } 1338 private static short pick(short le, short be) { return BE ? be : le; } 1339 private static int pick(int le, int be) { return BE ? be : le; } 1340 1341 // These methods write integers to memory from smaller parts 1342 // provided by their caller. The ordering in which these parts 1343 // are written is the native endianness of this platform. 1344 private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) { 1345 putByte(o, offset + 0, pick(i0, i7)); 1346 putByte(o, offset + 1, pick(i1, i6)); 1347 putByte(o, offset + 2, pick(i2, i5)); 1348 putByte(o, offset + 3, pick(i3, i4)); 1349 putByte(o, offset + 4, pick(i4, i3)); 1350 putByte(o, offset + 5, pick(i5, i2)); 1351 putByte(o, offset + 6, pick(i6, i1)); 1352 putByte(o, offset + 7, pick(i7, i0)); 1353 } 1354 private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) { 1355 putShort(o, offset + 0, pick(i0, i3)); 1356 putShort(o, offset + 2, pick(i1, i2)); 1357 putShort(o, offset + 4, pick(i2, i1)); 1358 putShort(o, offset + 6, pick(i3, i0)); 1359 } 1360 private void putLongParts(Object o, long offset, int i0, int i1) { 1361 putInt(o, offset + 0, pick(i0, i1)); 1362 putInt(o, offset + 4, pick(i1, i0)); 1363 } 1364 private void putIntParts(Object o, long offset, short i0, short i1) { 1365 putShort(o, offset + 0, pick(i0, i1)); 1366 putShort(o, offset + 2, pick(i1, i0)); 1367 } 1368 private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) { 1369 putByte(o, offset + 0, pick(i0, i3)); 1370 putByte(o, offset + 1, pick(i1, i2)); 1371 putByte(o, offset + 2, pick(i2, i1)); 1372 putByte(o, offset + 3, pick(i3, i0)); 1373 } 1374 private void putShortParts(Object o, long offset, byte i0, byte i1) { 1375 putByte(o, offset + 0, pick(i0, i1)); 1376 putByte(o, offset + 1, pick(i1, i0)); 1377 } 1378 1379 // Zero-extend an integer 1380 private static int toUnsignedInt(byte n) { return n & 0xff; } 1381 private static int toUnsignedInt(short n) { return n & 0xffff; } 1382 private static long toUnsignedLong(byte n) { return n & 0xffl; } 1383 private static long toUnsignedLong(short n) { return n & 0xffffl; } 1384 private static long toUnsignedLong(int n) { return n & 0xffffffffl; } 1385 1386 // Maybe byte-reverse an integer 1387 private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); } 1388 private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; } 1389 private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; } 1390 private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; } 1391 }