大小端交换

大小端交换

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{$IF RTLVersion<25}   IntPtr = Integer;   {$IFEND IntPtr}

　　

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function swap16(const v): Word; begin   // FF, EE : EE->1, FF->2   PByte(@result)^ := PByte(IntPtr(@v) + 1)^;   PByte(IntPtr(@result) + 1)^ := PByte(@v)^; end;   function swap32(const v): Cardinal; begin   // FF, EE, DD, CC : CC->1, DD->2, EE->3, FF->4   PByte(@result)^ := PByte(IntPtr(@v) + 3)^;   PByte(IntPtr(@result) + 1)^ := PByte(IntPtr(@v) + 2)^;   PByte(IntPtr(@result) + 2)^ := PByte(IntPtr(@v) + 1)^;   PByte(IntPtr(@result) + 3)^ := PByte(@v)^; end;   function swap64(const v): Int64; begin   // FF, EE, DD, CC, BB, AA, 99, 88 : 88->1 ,99->2 ....   PByte(@result)^ := PByte(IntPtr(@v) + 7)^;   PByte(IntPtr(@result) + 1)^ := PByte(IntPtr(@v) + 6)^;   PByte(IntPtr(@result) + 2)^ := PByte(IntPtr(@v) + 5)^;   PByte(IntPtr(@result) + 3)^ := PByte(IntPtr(@v) + 4)^;   PByte(IntPtr(@result) + 4)^ := PByte(IntPtr(@v) + 3)^;   PByte(IntPtr(@result) + 5)^ := PByte(IntPtr(@v) + 2)^;   PByte(IntPtr(@result) + 6)^ := PByte(IntPtr(@v) + 1)^;   PByte(IntPtr(@result) + 7)^ := PByte(@v)^; end;   // v and outVal is can't the same value procedure swap64Ex(const v; out outVal); begin   // FF, EE, DD, CC, BB, AA, 99, 88 : 88->1 ,99->2 ....   PByte(@outVal)^ := PByte(IntPtr(@v) + 7)^;   PByte(IntPtr(@outVal) + 1)^ := PByte(IntPtr(@v) + 6)^;   PByte(IntPtr(@outVal) + 2)^ := PByte(IntPtr(@v) + 5)^;   PByte(IntPtr(@outVal) + 3)^ := PByte(IntPtr(@v) + 4)^;   PByte(IntPtr(@outVal) + 4)^ := PByte(IntPtr(@v) + 3)^;   PByte(IntPtr(@outVal) + 5)^ := PByte(IntPtr(@v) + 2)^;   PByte(IntPtr(@outVal) + 6)^ := PByte(IntPtr(@v) + 1)^;   PByte(IntPtr(@outVal) + 7)^ := PByte(@v)^; end;   // v and outVal is can't the same value procedure swap32Ex(const v; out outVal); begin   // FF, EE, DD, CC : CC->1, DD->2, EE->3, FF->4   PByte(@outVal)^ := PByte(IntPtr(@v) + 3)^;   PByte(IntPtr(@outVal) + 1)^ := PByte(IntPtr(@v) + 2)^;   PByte(IntPtr(@outVal) + 2)^ := PByte(IntPtr(@v) + 1)^;   PByte(IntPtr(@outVal) + 3)^ := PByte(@v)^; end;   // v and outVal is can't the same value procedure swap16Ex(const v; out outVal); begin   // FF, EE : EE->1, FF->2   PByte(@outVal)^ := PByte(IntPtr(@v) + 1)^;   PByte(IntPtr(@outVal) + 1)^ := PByte(@v)^; end;   // overload swap, result type is integer, because single maybe NaN function swap(v: Single): Integer; overload; begin   swap32Ex(v, Result); end;   // overload swap function swap(v: word): Word; overload; begin   swap16Ex(v, Result); end;   // overload swap function swap(v: Cardinal): Cardinal; overload; begin   swap32Ex(v, Result); end;   // swap , result type is Int64, because Double maybe NaN function swap(v: Double): Int64; overload; begin   swap64Ex(v, Result); end;