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最新推荐文章于 2024-02-03 17:01:58 发布

原创最新推荐文章于 2024-02-03 17:01:58 发布 · 428 阅读

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#integer #function #destructor #string #constructor #class

本文介绍了一个名为 TBuffer 的类的实现细节，该类用于处理缓冲区操作，包括内存分配、扩大缓冲区大小及读写操作。文章详细解释了构造函数、析构函数、扩大缓冲区的方法以及如何将缓冲区内容转换为字符串等功能。

type
TBuffer = class
private
    FBuffer: PChar;
    FMaxBufSize: integer;
    FIncreasement: integer;
    FContentSize: integer;
    FCapacity: integer;
    function GetAsString: string;
    function Enlarge(NewLen: integer): Boolean;
public
    OnBufFull: procedure;
    property MaxBufSize: integer read FMaxBufSize;
    property ContentSize: integer read FContentSize;
    property Capacity: integer read FCapacity;
    property Increasement: integer read FIncreasement;
    property AsString: string read GetAsString;
    function WriteBuf(P: PChar; Len: integer): Boolean;
    procedure ClearBuf(FreeMemory: Boolean = true);
    constructor Create(MaxSize: integer = 0; IncreaseSize: integer = 32768); //È±Ê¡ÈÝÁ¿ÉÏÏÞÎªÎÞÏÞ´ó£¬ÔöÁ¿Îª32K
    destructor Destroy; override;
end;

procedure HexStrToBuf(HexStr: string; var Buf: TReceiveBuffers);
function BufToHexStr(Buf: TReceiveBuffers): string;
function StrToHexStr(const s: string): string;
procedure ChangeAlarmBuffers(var Buf: TReceiveBuffers); overload;
procedure ChangeAlarmBuffers(var Buf: T2096ReceiveBuffers); overload;

implementation
uses UMain;
{ TBuffer }

procedure TBuffer.ClearBuf(FreeMemory: Boolean);
begin
if FreeMemory then begin
    FreeMem(FBuffer);
    FBuffer := nil;
    FCapacity := 0;
end;
FContentSize := 0;
end;

constructor TBuffer.Create(MaxSize: integer; IncreaseSize: integer);
begin
FBuffer := nil;
if IncreaseSize > 0 then
    FIncreasement := IncreaseSize
else
    FIncreasement := 32768;
if MaxSize < 0 then
    FMaxBufSize := 0
else
    FMaxBufSize := MaxSize;
FContentSize := 0;
FCapacity := 0;
OnBufFull := nil;
end;

destructor TBuffer.Destroy;
begin
FreeMem(FBuffer);
inherited;
end;

function TBuffer.Enlarge(NewLen: integer): Boolean;
var
P: PChar;
Len, IncNum: integer;
begin
Result := false;
if NewLen < FContentSize then //ÐÂµÄ³¤¶ÈÎÞ·¨ÈÝÄÉÒÑÓÐµÄÄÚÈÝ
    exit;
if (FMaxBufSize > 0) and (NewLen > FMaxBufSize) then begin
    if Assigned(OnBufFull) then begin
      IncNum := NewLen - FCapacity; //±£´æÔöÁ¿
      OnBufFull;
      if FContentSize = 0 then //Èç¹ûÓÃ»§ÔÚ OnBufFull ÊÂ¼þÖÐÒÑ¾Çå¿ÕÁË»º³åÇø
        Result := Enlarge(IncNum);
    end;
    exit;
end;
Len := FIncreasement * ((NewLen + FIncreasement - 1) div FIncreasement);
if (FMaxBufSize > 0) and (Len > FMaxBufSize) then
    Len := FMaxBufSize;
try
    GetMem(P, Len);
except
    if Assigned(OnBufFull) then begin
      IncNum := Len - FCapacity; //±£´æÔöÁ¿
      OnBufFull;
      if FContentSize = 0 then //...
        Result := Enlarge(IncNum);
    end;
    exit;
end;
Result := true;
Move(FBuffer^, P^, FContentSize);
FreeMem(FBuffer);
FCapacity := Len;
FBuffer := P;
end;

function TBuffer.GetAsString: string;
begin
SetLength(Result, FContentSize);
Move(FBuffer^, Result[1], FContentSize);
end;

function TBuffer.WriteBuf(P: PChar; Len: integer): Boolean;
var
PC: PChar;
begin
if FContentSize + Len > FCapacity then
    Result := Enlarge(FContentSize + Len)
else
    Result := true;
if Result then begin
    PC := FBuffer + FContentSize;
    Move(P^, PC^, Len);
    Inc(FContentSize, Len);
end;
end;