最佳性能版：

function Swap16(const Value: Word): Word; inline;begin  Result := Swap(Value);end;function Swap32(const Value: LongWord): LongWord; inline;begin  Result := Swap(Word(Value)) shl 16 + Swap(Word(Value shr 16));end;function Swap64(const Value: Int64): Int64;{
    $IFDEF WIN32}asm  mov     edx, [ebp + $08]  mov     eax, [ebp + $0c]  bswap   edx  bswap   eax{
    $ELSE}{
    $IFDEF WIN64}asm  mov     rax, rcx  bswap   rax{
    $ELSE}begin  Result := Swap32(LongWord(Value));  Result := (Result shl 32) or Swap32(LongWord(Value shr 32));{
    $ENDIF}{
    $ENDIF}end;function SwapFloat(const Value: Single): Single; overload; inline;var  R: LongWord absolute Result;  V: LongWord absolute Value;begin  R := Swap32(V);end;function SwapFloat(const Value: Double): Double; overload; inline;var  R: Int64 absolute Result;  V: Int64 absolute Value;begin  R := Swap64(V);end;

 

其它版本：

function ExchangeByteOrderDouble(const PV: PAnsiChar): Double;var  pd: PAnsiChar;begin  pd := @Result;  pd[0] := pv[7];  pd[1] := pv[6];  pd[2] := pv[5];  pd[3] := pv[4];  pd[4] := pv[3];  pd[5] := pv[2];  pd[6] := pv[1];  pd[7] := pv[0];end;

 

好吧，这个最慢

function SwapByteOrder(const Value: Double): Double; overload;var  V: Int64 absolute Result;  VV: Int64 absolute Value;begin  V :=    ((((VV and $00000000000000ff) shl 56) or    ((VV and $000000000000ff00) shl 40) or    ((VV and $0000000000ff0000) shl 24) or    ((VV and $00000000ff000000) shl 8) or    ((VV and $000000ff00000000) shr 8) or    ((VV and $0000ff0000000000) shr 24) or    ((VV and $00ff000000000000) shr 40) or    ((VV and $ff00000000000000) shr 56)));end;

 

感谢 网友

@[合肥]全能地图