stbits.pas

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(* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is TurboPower SysTools
 *
 * The Initial Developer of the Original Code is
 * TurboPower Software
 *
 * Portions created by the Initial Developer are Copyright (C) 1996-2002
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * ***** END LICENSE BLOCK ***** *)

{*********************************************************}
{* SysTools: StBits.pas 4.03                             *}
{*********************************************************}
{* SysTools: Bit set class                               *}
{*********************************************************}

{$I StDefine.inc}

{Notes:
  CopyBits, OrBits, AndBits, and SubBits require that the parameter B have
  the same Max value as the current object, or an exception is generated.

  Use the inherited Count property to get the number of bits currently set.

  TStBits takes advantage of the suballocator whenever the bit set is
  small enough to allow it. Changing the Max property of the class
  allocates a new data area, copies the old data into it, and then
  deallocates the old data area.

  Supports up to 2**34 bits, if they will fit into memory.

  When Windows 3.1 is used, it requires enhanced mode operation.
}

unit StBits;

interface

uses
  Windows, Classes, SysUtils,
  
  StBase, StConst;

type
  TStBits = class;

  TBitIterateFunc =
    function(Container : TStBits; N : LongInt; OtherData : Pointer) : Boolean;

  TStBits = class(TStContainer)
  {.Z+}
  protected
    {property instance variables}
    FMax : LongInt;          {highest element number}

    {private instance variables}
    btBlockSize : LongInt;   {bytes allocated to data area}
    btBits : PByte;          {pointer to data area}

    {undocumented protected methods}
    procedure btSetMax(Max : LongInt);
    procedure btRecount;
    function btByte(I : LongInt) : PByte;

  {.Z-}
  public
    constructor Create(Max : LongInt); virtual;
      {-Initialize an empty bitset with highest element number Max}
    destructor Destroy; override;
      {-Free a bitset}

    procedure LoadFromStream(S : TStream); override;
      {-Read a bitset from a stream}
    procedure StoreToStream(S : TStream); override;
      {-Write a bitset to a stream}

    procedure Clear; override;
      {-Clear all bits in set but leave instance intact}

    procedure CopyBits(B : TStBits);
      {-Copy all bits in B to this bitset}
    procedure SetBits;
      {-Set all bits}
    procedure InvertBits;
      {-Invert all bits}
    procedure OrBits(B : TStBits);
      {-Or the specified bitset into this one (create the union)}
    procedure AndBits(B : TStBits);
      {-And the specified bitset with this one (create the intersection)}
    procedure SubBits(B : TStBits);
      {-Subtract the specified bitset from this one (create the difference)}

    procedure SetBit(N : LongInt);
      {-Set bit N}
    procedure ClearBit(N : LongInt);
      {-Clear bit N}
    procedure ToggleBit(N : LongInt);
      {-Toggle bit N}
    procedure ControlBit(N : LongInt; State : Boolean);
      {-Set or clear bit N according to State}
    function BitIsSet(N : LongInt) : Boolean;
      {-Return True if bit N is set}

    function FirstSet : LongInt;
      {-Return the index of the first set bit, -1 if none}
    function LastSet : LongInt;
      {-Return the index of the last set bit, -1 if none}
    function FirstClear : LongInt;
      {-Return the index of the first clear bit, -1 if none}
    function LastClear : LongInt;
      {-Return the index of the last clear bit, -1 if none}
    function NextSet(N : LongInt) : LongInt;
      {-Return the index of the next set bit after N, -1 if none}
    function PrevSet(N : LongInt) : LongInt;
      {-Return the index of the previous set bit after N, -1 if none}
    function NextClear(N : LongInt) : LongInt;
      {-Return the index of the next set bit after N, -1 if none}
    function PrevClear(N : LongInt) : LongInt;
      {-Return the index of the previous set bit after N, -1 if none}

    function Iterate(Action : TBitIterateFunc;
                     UseSetBits, Up : Boolean;
                     OtherData : Pointer) : LongInt;
      {-Call Action for all the matching bits, returning the last bit visited}
    function IterateFrom(Action : TBitIterateFunc;
                         UseSetBits, Up : Boolean;
                         OtherData : Pointer;
                         From : LongInt) : LongInt;
      {-Call Action for all the matching bits starting with bit From}

    property Max : LongInt
      {-Read or write the maximum element count in the bitset}
      read FMax
      write btSetMax;

    property Items[N : LongInt] : Boolean
      {-Read or write Nth bit in set}
      read BitIsSet
      write ControlBit;
      default;
  end;


{======================================================================}


implementation

{$IFDEF ThreadSafe}
var
  ClassCritSect : TRTLCriticalSection;
{$ENDIF}

procedure EnterClassCS;
begin
{$IFDEF ThreadSafe}
  EnterCriticalSection(ClassCritSect);
{$ENDIF}
end;

procedure LeaveClassCS;
begin
{$IFDEF ThreadSafe}
  LeaveCriticalSection(ClassCritSect);
{$ENDIF}
end;

function MinLong(A, B : LongInt) : LongInt;
begin
  if A < B then
    Result := A
  else
    Result := B;
end;

function MaxLong(A, B : LongInt) : LongInt;
begin
  if A > B then
    Result := A
  else
    Result := B;
end;

{----------------------------------------------------------------------}

procedure TStBits.AndBits(B : TStBits);
var
  I : LongInt;
  P : PByte;
begin
{$IFDEF ThreadSafe}
  EnterClassCS;
  EnterCS;
  B.EnterCS;
  try
{$ENDIF}
    if (not Assigned(B)) or (B.Max <> FMax) then
      RaiseContainerError(stscBadType);
    for I := 0 to btBlockSize-1 do begin
      P := btByte(I);
      P^ := P^ and B.btByte(I)^;
    end;
    btRecount;
{$IFDEF ThreadSafe}
  finally
    B.LeaveCS;
    LeaveCS;
    LeaveClassCS;
  end;
{$ENDIF}
end;

function TStBits.BitIsSet(N : LongInt) : Boolean;
begin
{$IFDEF ThreadSafe}
  EnterCS;
  try
{$ENDIF}
{$IFOPT R+}
    if (N < 0) or (N > FMax) then
      RaiseContainerError(stscBadIndex);
{$ENDIF}
    Result := (btByte(N shr 3)^ and (1 shl (Byte(N) and 7)) <> 0);
{$IFDEF ThreadSafe}
  finally
    LeaveCS;
  end;
{$ENDIF}
end;

function TStBits.btByte(I : LongInt) : PByte;
begin
  Result := PByte(PChar(btBits)+I);
end;

procedure TStBits.btRecount;
const
  {number of bits set in every possible byte}
  BitCount : array[Byte] of Byte = (
  0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
  4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8);
var
  N : LongInt;
  P : PByte;
  B : Byte;
begin
{$IFDEF ThreadSafe}
  EnterCS;
  try
{$ENDIF}
    {Clear unused bits in last byte}
    B := Byte(FMax) and 7;
    if B < 7 then begin
      P := btByte(btBlockSize-1);
      P^ := P^ and ((1 shl (B+1))-1);
    end;

    {Add up the bits in each byte}
    FCount := 0;
    for N := 0 to btBlockSize-1 do
      inc(FCount, BitCount[btByte(N)^]);
{$IFDEF ThreadSafe}
  finally
    LeaveCS;
  end;
{$ENDIF}
end;

procedure TStBits.btSetMax(Max : LongInt);
var
  BlockSize, OldBlockSize, OldMax : LongInt;
  OldBits : PByte;
begin
{$IFDEF ThreadSafe}
  EnterCS;
  try
{$ENDIF}
    {Validate new size}
    if Max < 0 then
      RaiseContainerError(stscBadSize);
    BlockSize := (Max+8) div 8;

    {Save old size settings}
    OldBlockSize := btBlockSize;
    OldMax := FMax;

    {Assign new size settings}
    FMax := Max;
    btBlockSize := BlockSize;

    if BlockSize <> OldBlockSize then begin
      {Get new data area and transfer data}
      OldBits := btBits;
      try
        HugeGetMem(Pointer(btBits), btBlockSize);
      except
        btBlockSize := OldBlockSize;
        btBits := OldBits;
        FMax := OldMax;
        raise;
      end;

      if OldBlockSize < btBlockSize then begin
        HugeFillChar(btByte(OldBlockSize)^, btBlockSize-OldBlockSize, 0);
        BlockSize := OldBlockSize;
      end else
        BlockSize := btBlockSize;
      HugeMove(OldBits^, btBits^, BlockSize);

      {Free old data area}
      HugeFreeMem(Pointer(OldBits), OldBlockSize);
    end;
{$IFDEF ThreadSafe}
  finally
    LeaveCS;
  end;
{$ENDIF}
end;

procedure TStBits.Clear;
begin
{$IFDEF ThreadSafe}
  EnterCS;
  try
{$ENDIF}
    HugeFillChar(btBits^, btBlockSize, 0);
    FCount := 0;
{$IFDEF ThreadSafe}
  finally
    LeaveCS;
  end;
{$ENDIF}
end;

procedure TStBits.ClearBit(N : LongInt);
var
  P : PByte;
  M : Byte;
begin
{$IFDEF ThreadSafe}
  EnterCS;
  try
{$ENDIF}
{$IFOPT R+}
    if (N < 0) or (N > FMax) then
      RaiseContainerError(stscBadIndex);
{$ENDIF}
    P := btByte(N shr 3);
    M := 1 shl (Byte(N) and 7);
    if (P^ and M) <> 0 then begin
      P^ := P^ and not M;
      dec(FCount);
    end;
{$IFDEF ThreadSafe}
  finally
    LeaveCS;
  end;
{$ENDIF}
end;

procedure TStBits.ControlBit(N : LongInt; State : Boolean);
begin
{$IFDEF ThreadSafe}
  EnterCS;
  try
{$ENDIF}
    if State then
      SetBit(N)
    else
      ClearBit(N);
{$IFDEF ThreadSafe}
  finally
    LeaveCS;
  end;
{$ENDIF}
end;

procedure TStBits.CopyBits(B : TStBits);