rtlbitmap.c 28.3 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115
/*
 * NTDLL bitmap functions
 *
 * Copyright 2002 Jon Griffiths
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 *
 * NOTES
 *  Bitmaps are an efficient type for manipulating large arrays of bits. They
 *  are commonly used by device drivers (e.g. For holding dirty/free blocks),
 *  but are also available to applications that need this functionality.
 *
 *  Bits are set LSB to MSB in each consecutive byte, making this implementation
 *  binary compatible with Win32.
 *
 *  Note that to avoid unexpected behaviour, the size of a bitmap should be set
 *  to a multiple of 32.
 */
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include "windef.h"
#include "winternl.h"
#include "wine/debug.h"

WINE_DEFAULT_DEBUG_CHANNEL(ntdll);

/* Bits set from LSB to MSB; used as mask for runs < 8 bits */
static const BYTE NTDLL_maskBits[8] = { 0, 1, 3, 7, 15, 31, 63, 127 };

/* Number of set bits for each value of a nibble; used for counting */
static const BYTE NTDLL_nibbleBitCount[16] = {
  0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4
};

/* First set bit in a nibble; used for determining least significant bit */
static const BYTE NTDLL_leastSignificant[16] = {
  0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
};

/* Last set bit in a nibble; used for determining most significant bit */
static const signed char NTDLL_mostSignificant[16] = {
  -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
};

/*************************************************************************
 * RtlInitializeBitMap	[NTDLL.@]
 *
 * Initialise a new bitmap.
 *
 * PARAMS
 *  lpBits [I] Bitmap pointer
 *  lpBuff [I] Memory for the bitmap
 *  ulSize [I] Size of lpBuff in bits
 *
 * RETURNS
 *  Nothing.
 *
 * NOTES
 *  lpBuff must be aligned on a ULONG suitable boundary, to a multiple of 32 bytes
 *  in size (irrespective of ulSize given).
 */
VOID WINAPI RtlInitializeBitMap(PRTL_BITMAP lpBits, PULONG lpBuff, ULONG ulSize)
{
  TRACE("(%p,%p,%u)\n", lpBits,lpBuff,ulSize);
  lpBits->SizeOfBitMap = ulSize;
  lpBits->Buffer = lpBuff;
}

/*************************************************************************
 * RtlSetAllBits	[NTDLL.@]
 *
 * Set all bits in a bitmap.
 *
 * PARAMS
 *  lpBits [I] Bitmap pointer
 *
 * RETURNS
 *  Nothing.
 */
VOID WINAPI RtlSetAllBits(PRTL_BITMAP lpBits)
{
  TRACE("(%p)\n", lpBits);
  memset(lpBits->Buffer, 0xff, ((lpBits->SizeOfBitMap + 31) & ~31) >> 3);
}

/*************************************************************************
 * RtlClearAllBits	[NTDLL.@]
 *
 * Clear all bits in a bitmap.
 *
 * PARAMS
 *  lpBit [I] Bitmap pointer
 *
 * RETURNS
 *  Nothing.
 */
VOID WINAPI RtlClearAllBits(PRTL_BITMAP lpBits)
{
  TRACE("(%p)\n", lpBits);
  memset(lpBits->Buffer, 0, ((lpBits->SizeOfBitMap + 31) & ~31) >> 3);
}

/*************************************************************************
 * RtlSetBits	[NTDLL.@]
 *
 * Set a range of bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] First bit to set
 *  ulCount [I] Number of consecutive bits to set
 *
 * RETURNS
 *  Nothing.
 */
VOID WINAPI RtlSetBits(PRTL_BITMAP lpBits, ULONG ulStart, ULONG ulCount)
{
  LPBYTE lpOut;

  TRACE("(%p,%u,%u)\n", lpBits, ulStart, ulCount);

  if (!lpBits || !ulCount ||
      ulStart >= lpBits->SizeOfBitMap ||
      ulCount > lpBits->SizeOfBitMap - ulStart)
    return;

  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
   * at a time. But beware of the pointer arithmetics...
   */
  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);

  /* Set bits in first byte, if ulStart isn't a byte boundary */
  if (ulStart & 7)
  {
    if (ulCount > 7)
    {
      /* Set from start bit to the end of the byte */
      *lpOut++ |= 0xff << (ulStart & 7);
      ulCount -= (8 - (ulStart & 7));
    }
    else
    {
      /* Set from the start bit, possibly into the next byte also */
      USHORT initialWord = NTDLL_maskBits[ulCount] << (ulStart & 7);

      *lpOut |= (initialWord & 0xff);
      if (initialWord >> 8) lpOut[1] |= (initialWord >> 8);
      return;
    }
  }

  /* Set bits up to complete byte count */
  if (ulCount >> 3)
  {
    memset(lpOut, 0xff, ulCount >> 3);
    lpOut = lpOut + (ulCount >> 3);
  }

  /* Set remaining bits, if any */
  if (ulCount & 0x7)
    *lpOut |= NTDLL_maskBits[ulCount & 0x7];
}

/*************************************************************************
 * RtlClearBits	[NTDLL.@]
 *
 * Clear bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] First bit to set
 *  ulCount [I] Number of consecutive bits to clear
 *
 * RETURNS
 *  Nothing.
 */
VOID WINAPI RtlClearBits(PRTL_BITMAP lpBits, ULONG ulStart, ULONG ulCount)
{
  LPBYTE lpOut;

  TRACE("(%p,%u,%u)\n", lpBits, ulStart, ulCount);

  if (!lpBits || !ulCount ||
      ulStart >= lpBits->SizeOfBitMap ||
      ulCount > lpBits->SizeOfBitMap - ulStart)
    return;

  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
   * at a time. But beware of the pointer arithmetics...
   */
  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);

  /* Clear bits in first byte, if ulStart isn't a byte boundary */
  if (ulStart & 7)
  {
    if (ulCount > 7)
    {
      /* Clear from start bit to the end of the byte */
      *lpOut++ &= ~(0xff << (ulStart & 7));
      ulCount -= (8 - (ulStart & 7));
    }
    else
    {
      /* Clear from the start bit, possibly into the next byte also */
      USHORT initialWord = ~(NTDLL_maskBits[ulCount] << (ulStart & 7));

      *lpOut &= (initialWord & 0xff);
      if ((initialWord >> 8) != 0xff) lpOut[1] &= (initialWord >> 8);
      return;
    }
  }

  /* Clear bits (in blocks of 8) on whole byte boundaries */
  if (ulCount >> 3)
  {
    memset(lpOut, 0, ulCount >> 3);
    lpOut = lpOut + (ulCount >> 3);
  }

  /* Clear remaining bits, if any */
  if (ulCount & 0x7)
    *lpOut &= ~NTDLL_maskBits[ulCount & 0x7];
}

/*************************************************************************
 * RtlAreBitsSet	[NTDLL.@]
 *
 * Determine if part of a bitmap is set.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] First bit to check from
 *  ulCount [I] Number of consecutive bits to check
 *
 * RETURNS
 *  TRUE,  If ulCount bits from ulStart are set.
 *  FALSE, Otherwise.
 */
BOOLEAN WINAPI RtlAreBitsSet(PCRTL_BITMAP lpBits, ULONG ulStart, ULONG ulCount)
{
  LPBYTE lpOut;
  ULONG ulRemainder;

  TRACE("(%p,%u,%u)\n", lpBits, ulStart, ulCount);

  if (!lpBits || !ulCount ||
      ulStart >= lpBits->SizeOfBitMap ||
      ulCount > lpBits->SizeOfBitMap - ulStart)
    return FALSE;

  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
   * at a time. But beware of the pointer arithmetics...
   */
  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);

  /* Check bits in first byte, if ulStart isn't a byte boundary */
  if (ulStart & 7)
  {
    if (ulCount > 7)
    {
      /* Check from start bit to the end of the byte */
      if ((*lpOut &
          ((0xff << (ulStart & 7))) & 0xff) != ((0xff << (ulStart & 7) & 0xff)))
        return FALSE;
      lpOut++;
      ulCount -= (8 - (ulStart & 7));
    }
    else
    {
      /* Check from the start bit, possibly into the next byte also */
      USHORT initialWord = NTDLL_maskBits[ulCount] << (ulStart & 7);

      if ((*lpOut & (initialWord & 0xff)) != (initialWord & 0xff))
        return FALSE;
      if ((initialWord & 0xff00) &&
          ((lpOut[1] & (initialWord >> 8)) != (initialWord >> 8)))
        return FALSE;
      return TRUE;
    }
  }

  /* Check bits in blocks of 8 bytes */
  ulRemainder = ulCount & 7;
  ulCount >>= 3;
  while (ulCount--)
  {
    if (*lpOut++ != 0xff)
      return FALSE;
  }

  /* Check remaining bits, if any */
  if (ulRemainder &&
      (*lpOut & NTDLL_maskBits[ulRemainder]) != NTDLL_maskBits[ulRemainder])
    return FALSE;
  return TRUE;
}

/*************************************************************************
 * RtlAreBitsClear	[NTDLL.@]
 *
 * Determine if part of a bitmap is clear.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] First bit to check from
 *  ulCount [I] Number of consecutive bits to check
 *
 * RETURNS
 *  TRUE,  If ulCount bits from ulStart are clear.
 *  FALSE, Otherwise.
 */
BOOLEAN WINAPI RtlAreBitsClear(PCRTL_BITMAP lpBits, ULONG ulStart, ULONG ulCount)
{
  LPBYTE lpOut;
  ULONG ulRemainder;

  TRACE("(%p,%u,%u)\n", lpBits, ulStart, ulCount);

  if (!lpBits || !ulCount ||
      ulStart >= lpBits->SizeOfBitMap ||
      ulCount > lpBits->SizeOfBitMap - ulStart)
    return FALSE;

  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
   * at a time. But beware of the pointer arithmetics...
   */
  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);

  /* Check bits in first byte, if ulStart isn't a byte boundary */
  if (ulStart & 7)
  {
    if (ulCount > 7)
    {
      /* Check from start bit to the end of the byte */
      if (*lpOut & ((0xff << (ulStart & 7)) & 0xff))
        return FALSE;
      lpOut++;
      ulCount -= (8 - (ulStart & 7));
    }
    else
    {
      /* Check from the start bit, possibly into the next byte also */
      USHORT initialWord = NTDLL_maskBits[ulCount] << (ulStart & 7);

      if (*lpOut & (initialWord & 0xff))
        return FALSE;
      if ((initialWord & 0xff00) && (lpOut[1] & (initialWord >> 8)))
        return FALSE;
      return TRUE;
    }
  }

  /* Check bits in blocks of 8 bytes */
  ulRemainder = ulCount & 7;
  ulCount >>= 3;
  while (ulCount--)
  {
    if (*lpOut++)
      return FALSE;
  }

  /* Check remaining bits, if any */
  if (ulRemainder && *lpOut & NTDLL_maskBits[ulRemainder])
    return FALSE;
  return TRUE;
}

/*************************************************************************
 * RtlFindSetBits	[NTDLL.@]
 *
 * Find a block of set bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulCount [I] Number of consecutive set bits to find
 *  ulHint  [I] Suggested starting position for set bits
 *
 * RETURNS
 *  The bit at which the match was found, or -1 if no match was found.
 */
ULONG WINAPI RtlFindSetBits(PCRTL_BITMAP lpBits, ULONG ulCount, ULONG ulHint)
{
  ULONG ulPos, ulEnd;

  TRACE("(%p,%u,%u)\n", lpBits, ulCount, ulHint);

  if (!lpBits || !ulCount || ulCount > lpBits->SizeOfBitMap)
    return ~0U;

  ulEnd = lpBits->SizeOfBitMap;

  if (ulHint + ulCount > lpBits->SizeOfBitMap)
    ulHint = 0;

  ulPos = ulHint;

  while (ulPos < ulEnd)
  {
    /* FIXME: This could be made a _lot_ more efficient */
    if (RtlAreBitsSet(lpBits, ulPos, ulCount))
      return ulPos;

    /* Start from the beginning if we hit the end and had a hint */
    if (ulPos == ulEnd - 1 && ulHint)
    {
      ulEnd = ulHint;
      ulPos = ulHint = 0;
    }
    else
      ulPos++;
  }
  return ~0U;
}

/*************************************************************************
 * RtlFindClearBits	[NTDLL.@]
 *
 * Find a block of clear bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulCount [I] Number of consecutive clear bits to find
 *  ulHint  [I] Suggested starting position for clear bits
 *
 * RETURNS
 *  The bit at which the match was found, or -1 if no match was found.
 */
ULONG WINAPI RtlFindClearBits(PCRTL_BITMAP lpBits, ULONG ulCount, ULONG ulHint)
{
  ULONG ulPos, ulEnd;

  TRACE("(%p,%u,%u)\n", lpBits, ulCount, ulHint);

  if (!lpBits || !ulCount || ulCount > lpBits->SizeOfBitMap)
    return ~0U;

  ulEnd = lpBits->SizeOfBitMap;

  if (ulHint + ulCount > lpBits->SizeOfBitMap)
    ulHint = 0;

  ulPos = ulHint;

  while (ulPos < ulEnd)
  {
    /* FIXME: This could be made a _lot_ more efficient */
    if (RtlAreBitsClear(lpBits, ulPos, ulCount))
      return ulPos;

    /* Start from the beginning if we hit the end and started from ulHint */
    if (ulPos == ulEnd - 1 && ulHint)
    {
      ulEnd = ulHint;
      ulPos = ulHint = 0;
    }
    else
      ulPos++;
  }
  return ~0U;
}

/*************************************************************************
 * RtlFindSetBitsAndClear	[NTDLL.@]
 *
 * Find a block of set bits in a bitmap, and clear them if found.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulCount [I] Number of consecutive set bits to find
 *  ulHint  [I] Suggested starting position for set bits
 *
 * RETURNS
 *  The bit at which the match was found, or -1 if no match was found.
 */
ULONG WINAPI RtlFindSetBitsAndClear(PRTL_BITMAP lpBits, ULONG ulCount, ULONG ulHint)
{
  ULONG ulPos;

  TRACE("(%p,%u,%u)\n", lpBits, ulCount, ulHint);

  ulPos = RtlFindSetBits(lpBits, ulCount, ulHint);
  if (ulPos != ~0U)
    RtlClearBits(lpBits, ulPos, ulCount);
  return ulPos;
}

/*************************************************************************
 * RtlFindClearBitsAndSet	[NTDLL.@]
 *
 * Find a block of clear bits in a bitmap, and set them if found.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulCount [I] Number of consecutive clear bits to find
 *  ulHint  [I] Suggested starting position for clear bits
 *
 * RETURNS
 *  The bit at which the match was found, or -1 if no match was found.
 */
ULONG WINAPI RtlFindClearBitsAndSet(PRTL_BITMAP lpBits, ULONG ulCount, ULONG ulHint)
{
  ULONG ulPos;

  TRACE("(%p,%u,%u)\n", lpBits, ulCount, ulHint);

  ulPos = RtlFindClearBits(lpBits, ulCount, ulHint);
  if (ulPos != ~0U)
    RtlSetBits(lpBits, ulPos, ulCount);
  return ulPos;
}

/*************************************************************************
 * RtlNumberOfSetBits	[NTDLL.@]
 *
 * Find the number of set bits in a bitmap.
 *
 * PARAMS
 *  lpBits [I] Bitmap pointer
 *
 * RETURNS
 *  The number of set bits.
 */
ULONG WINAPI RtlNumberOfSetBits(PCRTL_BITMAP lpBits)
{
  ULONG ulSet = 0;

  TRACE("(%p)\n", lpBits);

  if (lpBits)
  {
    LPBYTE lpOut = (BYTE *)lpBits->Buffer;
    ULONG ulCount, ulRemainder;
    BYTE bMasked;

    ulCount = lpBits->SizeOfBitMap >> 3;
    ulRemainder = lpBits->SizeOfBitMap & 0x7;

    while (ulCount--)
    {
      ulSet += NTDLL_nibbleBitCount[*lpOut >> 4];
      ulSet += NTDLL_nibbleBitCount[*lpOut & 0xf];
      lpOut++;
    }

    if (ulRemainder)
    {
      bMasked = *lpOut & NTDLL_maskBits[ulRemainder];
      ulSet += NTDLL_nibbleBitCount[bMasked >> 4];
      ulSet += NTDLL_nibbleBitCount[bMasked & 0xf];
    }
  }
  return ulSet;
}

/*************************************************************************
 * RtlNumberOfClearBits	[NTDLL.@]
 *
 * Find the number of clear bits in a bitmap.
 *
 * PARAMS
 *  lpBits [I] Bitmap pointer
 *
 * RETURNS
 *  The number of clear bits.
 */
ULONG WINAPI RtlNumberOfClearBits(PCRTL_BITMAP lpBits)
{
  TRACE("(%p)\n", lpBits);

  if (lpBits)
    return lpBits->SizeOfBitMap - RtlNumberOfSetBits(lpBits);
  return 0;
}

/*************************************************************************
 * RtlFindMostSignificantBit	[NTDLL.@]
 *
 * Find the most significant bit in a 64 bit integer.
 *
 * RETURNS
 *  The position of the most significant bit.
 */
CCHAR WINAPI RtlFindMostSignificantBit(ULONGLONG ulLong)
{
    signed char ret = 32;
    DWORD dw;

    if (!(dw = (ulLong >> 32)))
    {
        ret = 0;
        dw = (DWORD)ulLong;
    }
    if (dw & 0xffff0000)
    {
        dw >>= 16;
        ret += 16;
    }
    if (dw & 0xff00)
    {
        dw >>= 8;
        ret += 8;
    }
    if (dw & 0xf0)
    {
        dw >>= 4;
        ret += 4;
    }
    return ret + NTDLL_mostSignificant[dw];
}

/*************************************************************************
 * RtlFindLeastSignificantBit	[NTDLL.@]
 *
 * Find the least significant bit in a 64 bit integer.
 *
 * RETURNS
 *  The position of the least significant bit.
 */
CCHAR WINAPI RtlFindLeastSignificantBit(ULONGLONG ulLong)
{
    signed char ret = 0;
    DWORD dw;

    if (!(dw = (DWORD)ulLong))
    {
        ret = 32;
        if (!(dw = ulLong >> 32)) return -1;
    }
    if (!(dw & 0xffff))
    {
        dw >>= 16;
        ret += 16;
    }
    if (!(dw & 0xff))
    {
        dw >>= 8;
        ret += 8;
    }
    if (!(dw & 0x0f))
    {
        dw >>= 4;
        ret += 4;
    }
    return ret + NTDLL_leastSignificant[dw & 0x0f];
}

/*************************************************************************
 * NTDLL_RunSortFn
 *
 * Internal helper: qsort comparison function for RTL_BITMAP_RUN arrays
 */
static int __cdecl NTDLL_RunSortFn(const void *lhs, const void *rhs)
{
  if (((const RTL_BITMAP_RUN*)lhs)->NumberOfBits > ((const RTL_BITMAP_RUN*)rhs)->NumberOfBits)
    return -1;
  return 1;
}

/*************************************************************************
 * NTDLL_FindSetRun
 *
 * Internal helper: Find the next run of set bits in a bitmap.
 */
static ULONG NTDLL_FindSetRun(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpSize)
{
  LPBYTE lpOut;
  ULONG ulFoundAt = 0, ulCount = 0;

  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
   * at a time. But beware of the pointer arithmetics...
   */
  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);

  while (1)
  {
    /* Check bits in first byte */
    const BYTE bMask = (0xff << (ulStart & 7)) & 0xff;
    const BYTE bFirst = *lpOut & bMask;

    if (bFirst)
    {
      /* Have a set bit in first byte */
      if (bFirst != bMask)
      {
        /* Not every bit is set */
        ULONG ulOffset;

        if (bFirst & 0x0f)
          ulOffset = NTDLL_leastSignificant[bFirst & 0x0f];
        else
          ulOffset = 4 + NTDLL_leastSignificant[bFirst >> 4];
        ulStart += ulOffset;
        ulFoundAt = ulStart;
        for (;ulOffset < 8; ulOffset++)
        {
          if (!(bFirst & (1 << ulOffset)))
          {
            *lpSize = ulCount;
            return ulFoundAt; /* Set from start, but not until the end */
          }
          ulCount++;
          ulStart++;
        }
        /* Set to the end - go on to count further bits */
        lpOut++;
        break;
      }
      /* every bit from start until the end of the byte is set */
      ulFoundAt = ulStart;
      ulCount = 8 - (ulStart & 7);
      ulStart = (ulStart & ~7u) + 8;
      lpOut++;
      break;
    }
    ulStart = (ulStart & ~7u) + 8;
    lpOut++;
    if (ulStart >= lpBits->SizeOfBitMap)
      return ~0U;
  }

  /* Check if reached the end of bitmap */
  if (ulStart >= lpBits->SizeOfBitMap) {
    *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
    return ulFoundAt;
  }

  /* Count blocks of 8 set bits */
  while (*lpOut == 0xff)
  {
    ulCount += 8;
    ulStart += 8;
    if (ulStart >= lpBits->SizeOfBitMap)
    {
      *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
      return ulFoundAt;
    }
    lpOut++;
  }

  /* Count remaining contiguous bits, if any */
  if (*lpOut & 1)
  {
    ULONG ulOffset = 0;

    for (;ulOffset < 7u; ulOffset++)
    {
      if (!(*lpOut & (1 << ulOffset)))
        break;
      ulCount++;
    }
  }
  *lpSize = ulCount;
  return ulFoundAt;
}

/*************************************************************************
 * NTDLL_FindClearRun
 *
 * Internal helper: Find the next run of set bits in a bitmap.
 */
static ULONG NTDLL_FindClearRun(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpSize)
{
  LPBYTE lpOut;
  ULONG ulFoundAt = 0, ulCount = 0;

  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
   * at a time. But beware of the pointer arithmetics...
   */
  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);

  while (1)
  {
    /* Check bits in first byte */
    const BYTE bMask = (0xff << (ulStart & 7)) & 0xff;
    const BYTE bFirst = (~*lpOut) & bMask;

    if (bFirst)
    {
      /* Have a clear bit in first byte */
      if (bFirst != bMask)
      {
        /* Not every bit is clear */
        ULONG ulOffset;

        if (bFirst & 0x0f)
          ulOffset = NTDLL_leastSignificant[bFirst & 0x0f];
        else
          ulOffset = 4 + NTDLL_leastSignificant[bFirst >> 4];
        ulStart += ulOffset;
        ulFoundAt = ulStart;
        for (;ulOffset < 8; ulOffset++)
        {
          if (!(bFirst & (1 << ulOffset)))
          {
            *lpSize = ulCount;
            return ulFoundAt; /* Clear from start, but not until the end */
          }
          ulCount++;
          ulStart++;
        }
        /* Clear to the end - go on to count further bits */
        lpOut++;
        break;
      }
      /* Every bit from start until the end of the byte is clear */
      ulFoundAt = ulStart;
      ulCount = 8 - (ulStart & 7);
      ulStart = (ulStart & ~7u) + 8;
      lpOut++;
      break;
    }
    ulStart = (ulStart & ~7u) + 8;
    lpOut++;
    if (ulStart >= lpBits->SizeOfBitMap)
      return ~0U;
  }

  /* Check if reached the end of bitmap */
  if (ulStart >= lpBits->SizeOfBitMap) {
    *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
    return ulFoundAt;
  }

  /* Count blocks of 8 clear bits */
  while (!*lpOut)
  {
    ulCount += 8;
    ulStart += 8;
    if (ulStart >= lpBits->SizeOfBitMap)
    {
      *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
      return ulFoundAt;
    }
    lpOut++;
  }

  /* Count remaining contiguous bits, if any */
  if (!(*lpOut & 1))
  {
    ULONG ulOffset = 0;

    for (;ulOffset < 7u; ulOffset++)
    {
      if (*lpOut & (1 << ulOffset))
        break;
      ulCount++;
    }
  }
  *lpSize = ulCount;
  return ulFoundAt;
}

/*************************************************************************
 * RtlFindNextForwardRunSet	[NTDLL.@]
 *
 * Find the next run of set bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] Bit position to start searching from
 *  lpPos   [O] Start of run
 *
 * RETURNS
 *  Success: The length of the next set run in the bitmap. lpPos is set to
 *           the start of the run.
 *  Failure: 0, if no run is found or any parameters are invalid.
 */
ULONG WINAPI RtlFindNextForwardRunSet(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpPos)
{
  ULONG ulSize = 0;

  TRACE("(%p,%u,%p)\n", lpBits, ulStart, lpPos);

  if (lpBits && ulStart < lpBits->SizeOfBitMap && lpPos)
    *lpPos = NTDLL_FindSetRun(lpBits, ulStart, &ulSize);

  return ulSize;
}

/*************************************************************************
 * RtlFindNextForwardRunClear	[NTDLL.@]
 *
 * Find the next run of clear bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] Bit position to start searching from
 *  lpPos   [O] Start of run
 *
 * RETURNS
 *  Success: The length of the next clear run in the bitmap. lpPos is set to
 *           the start of the run.
 *  Failure: 0, if no run is found or any parameters are invalid.
 */
ULONG WINAPI RtlFindNextForwardRunClear(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpPos)
{
  ULONG ulSize = 0;

  TRACE("(%p,%u,%p)\n", lpBits, ulStart, lpPos);

  if (lpBits && ulStart < lpBits->SizeOfBitMap && lpPos)
    *lpPos = NTDLL_FindClearRun(lpBits, ulStart, &ulSize);

  return ulSize;
}

/*************************************************************************
 * RtlFindLastBackwardRunSet	[NTDLL.@]
 *
 * Find a previous run of set bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] Bit position to start searching from
 *  lpPos   [O] Start of run
 *
 * RETURNS
 *  Success: The length of the previous set run in the bitmap. lpPos is set to
 *           the start of the run.
 *  Failure: 0, if no run is found or any parameters are invalid.
 */
ULONG WINAPI RtlFindLastBackwardRunSet(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpPos)
{
  FIXME("(%p,%u,%p)-stub!\n", lpBits, ulStart, lpPos);
  return 0;
}

/*************************************************************************
 * RtlFindLastBackwardRunClear	[NTDLL.@]
 *
 * Find a previous run of clear bits in a bitmap.
 *
 * PARAMS
 *  lpBits  [I] Bitmap pointer
 *  ulStart [I] Bit position to start searching from
 *  lpPos   [O] Start of run
 *
 * RETURNS
 *  Success: The length of the previous clear run in the bitmap. lpPos is set
 *           to the start of the run.
 *  Failure: 0, if no run is found or any parameters are invalid.
 */
ULONG WINAPI RtlFindLastBackwardRunClear(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpPos)
{
  FIXME("(%p,%u,%p)-stub!\n", lpBits, ulStart, lpPos);
  return 0;
}

/*************************************************************************
 * NTDLL_FindRuns
 *
 * Internal implementation of RtlFindSetRuns/RtlFindClearRuns.
 */
static ULONG NTDLL_FindRuns(PCRTL_BITMAP lpBits, PRTL_BITMAP_RUN lpSeries,
                            ULONG ulCount, BOOLEAN bLongest,
                            ULONG (*fn)(PCRTL_BITMAP,ULONG,PULONG))
{
  BOOL bNeedSort = ulCount > 1;
  ULONG ulPos = 0, ulRuns = 0;

  TRACE("(%p,%p,%d,%d)\n", lpBits, lpSeries, ulCount, bLongest);

  if (!ulCount)
    return ~0U;

  while (ulPos < lpBits->SizeOfBitMap)
  {
    /* Find next set/clear run */
    ULONG ulSize, ulNextPos = fn(lpBits, ulPos, &ulSize);

    if (ulNextPos == ~0U)
      break;

    if (bLongest && ulRuns == ulCount)
    {
      /* Sort runs with shortest at end, if they are out of order */
      if (bNeedSort)
        qsort(lpSeries, ulRuns, sizeof(RTL_BITMAP_RUN), NTDLL_RunSortFn);

      /* Replace last run if this one is bigger */
      if (ulSize > lpSeries[ulRuns - 1].NumberOfBits)
      {
        lpSeries[ulRuns - 1].StartingIndex = ulNextPos;
        lpSeries[ulRuns - 1].NumberOfBits = ulSize;

        /* We need to re-sort the array, _if_ we didn't leave it sorted */
        if (ulRuns > 1 && ulSize > lpSeries[ulRuns - 2].NumberOfBits)
          bNeedSort = TRUE;
      }
    }
    else
    {
      /* Append to found runs */
      lpSeries[ulRuns].StartingIndex = ulNextPos;
      lpSeries[ulRuns].NumberOfBits = ulSize;
      ulRuns++;

      if (!bLongest && ulRuns == ulCount)
        break;
    }
    ulPos = ulNextPos + ulSize;
  }
  return ulRuns;
}

/*************************************************************************
 * RtlFindSetRuns	[NTDLL.@]
 *
 * Find a series of set runs in a bitmap.
 *
 * PARAMS
 *  lpBits   [I] Bitmap pointer
 *  lpSeries [O] Array for each run found
 *  ulCount  [I] Number of runs to find
 *  bLongest [I] Whether to find the very longest runs or not
 *
 * RETURNS
 *  The number of set runs found.
 */
ULONG WINAPI RtlFindSetRuns(PCRTL_BITMAP lpBits, PRTL_BITMAP_RUN lpSeries,
                            ULONG ulCount, BOOLEAN bLongest)
{
  TRACE("(%p,%p,%u,%d)\n", lpBits, lpSeries, ulCount, bLongest);

  return NTDLL_FindRuns(lpBits, lpSeries, ulCount, bLongest, NTDLL_FindSetRun);
}

/*************************************************************************
 * RtlFindClearRuns	[NTDLL.@]
 *
 * Find a series of clear runs in a bitmap.
 *
 * PARAMS
 *  lpBits   [I] Bitmap pointer
 *  ulSeries [O] Array for each run found
 *  ulCount  [I] Number of runs to find
 *  bLongest [I] Whether to find the very longest runs or not
 *
 * RETURNS
 *  The number of clear runs found.
 */
ULONG WINAPI RtlFindClearRuns(PCRTL_BITMAP lpBits, PRTL_BITMAP_RUN lpSeries,
                              ULONG ulCount, BOOLEAN bLongest)
{
  TRACE("(%p,%p,%u,%d)\n", lpBits, lpSeries, ulCount, bLongest);

  return NTDLL_FindRuns(lpBits, lpSeries, ulCount, bLongest, NTDLL_FindClearRun);
}

/*************************************************************************
 * RtlFindLongestRunSet	[NTDLL.@]
 *
 * Find the longest set run in a bitmap.
 *
 * PARAMS
 *  lpBits   [I] Bitmap pointer
 *  pulStart [O] Destination for start of run
 *
 * RETURNS
 *  The length of the run found, or 0 if no run is found.
 */
ULONG WINAPI RtlFindLongestRunSet(PCRTL_BITMAP lpBits, PULONG pulStart)
{
  RTL_BITMAP_RUN br;

  TRACE("(%p,%p)\n", lpBits, pulStart);

  if (RtlFindSetRuns(lpBits, &br, 1, TRUE) == 1)
  {
    if (pulStart)
      *pulStart = br.StartingIndex;
    return br.NumberOfBits;
  }
  return 0;
}

/*************************************************************************
 * RtlFindLongestRunClear	[NTDLL.@]
 *
 * Find the longest clear run in a bitmap.
 *
 * PARAMS
 *  lpBits   [I] Bitmap pointer
 *  pulStart [O] Destination for start of run
 *
 * RETURNS
 *  The length of the run found, or 0 if no run is found.
 */
ULONG WINAPI RtlFindLongestRunClear(PCRTL_BITMAP lpBits, PULONG pulStart)
{
  RTL_BITMAP_RUN br;

  TRACE("(%p,%p)\n", lpBits, pulStart);

  if (RtlFindClearRuns(lpBits, &br, 1, TRUE) == 1)
  {
    if (pulStart)
      *pulStart = br.StartingIndex;
    return br.NumberOfBits;
  }
  return 0;
}