Function 57h (87)        Get or Set a File's Date and Time

    Gets or sets a file's date and time.

    To get a file's date and time:

       On entry:      AH         57h
                      AL         00h
                      BX         File handle

       Returns:       AX         Error code   if CF is set
                      CX         Time
                      DX         Date

    To set a file's date and time:

       On entry:      AH         57h
                      AL         01h
                      BX         File handle
                      CX         Time
                      DX         Date

       Returns:       AX         Error code   if CF is set

       Error codes:   1          Invalid function number in AL
                      6          Invalid handle

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    Function 57h gets or sets the date and time for a file that has been
    opened with a file handle (such as with function 3Dh).

    The date and time are defined as follows:

           CX = Time = Hour * 2048 + Minute * 32 + Second / 2
           DX = Date = (Year - 1980) * 512 + Month * 32 + Day

                 CX Bits           Description
                 11 - 15           Hours (0..23)
                  5 - 10           Minutes (0..59)
                  0 - 4            Seconds/2 (0..30)

                 DX Bits           Description
                  9 - 15           Year since 1980 (0..119)
                  5 - 8            Month (1..12)
                  0 - 4            Day (1..31)

       Notes:         Contrary to what some DOS documentation says, the
                      date and time are returned in the conventional
                      format, with the high-order part in CH and DH and
                      the low-order part in CL and DL.