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Function 440Ch (68-12)    IOCTL: Code Page Switching                . DOS 3.3

     Handles Code Pages.

        On entry:      AH         44h
                       AL         0Ch
                       BX         Device/file handle
                       CH         Category: set device type
                                        0 . device unknown
                                        1 . COMx device
                                        3 . CON
                                        5 . LPTx
                       CL         Function:
                                     For categories 3 and 5:
                                        4Ah . select code page
                                        4Ch . prepare start
                                        4Dh . prepare end
                                        6Ah . get code page
                                        6Bh . query prepare list
                                     For category 3 only:
                                        5Fh . set display information (DOS 4+)
                                        7Fh . get display information (DOS 4+)
                       DS:DX      Parameter packet address (see below)

        Returns:       AX        Error code (if CF is set)


     Parameter packet (as required by each of the above subfunctions):

   --------------------------------------------------------------------------
     CL = 4Ch           Prepare Start Packet

     PS_FLAGS   DW      0       ;Bit 0 = 0 . Download prepare
                                       = 1 . Cartridge prepare
     PS_LENGTH  DW      2*(n+1) ;Length of rest of packet. n is the
                                ; number of additional code pages
                                ; specified in CONFIG.SYS.
     PS_NUMCP   DW      n       ;Number of code pages
     PS_CP1     DW      ?       ;Code page 1
                        :
                        :
     PS_CPn     DW      ?       ;Code page n

     Prepare Start Error Codes:

     01         Invalid function number
     22         Unknown command
     27         Code page conflict
     29         Device error
     31         Device driver does not have a copy of the code page

     Write Error Codes:

     27         Device or code page not found in file
     29         Device error
     31         File not a font file, or file structure damaged

   --------------------------------------------------------------------------
     CL = 4Dh           Prepare End Packet

     PE_LENGTH  DW      2       ;Prepare end packet
     PE_RSRVED  DW      0       ;Must be 0

     Prepare End Error Codes:

     19         Bad data from font file
     31         No prepare start

   --------------------------------------------------------------------------
     CL = 4AH or 6AH     Select/Query Selected Code Page Packet

     CP_LENGTH  DW      2+2*(n+1)       ;Packet length
     CP_CPID    DW      ?               ;Code page ID
     CP_VECTOR1 DW      ?,?             ;DBCS vector 1
                        :
                        :
     CP_VECTORn         ?,?             ;DBCS vector n
                DB      0,0             ;End marker

     Select Code Page Error Codes

     26         Code page not prepared
     27         Current keyboard does not support this code page
     29         Device error

     Query Selected Code Page Error Codes

     26         No code page has been selected
     27         Device error

   --------------------------------------------------------------------------
     CL = 6Bh            Query Prepared List Packet

     QL_LENGTH  DW 2*((m+1)+(n+1))      ;Packet length
     QL_NUMHDCP DW      n               ;Number of hardware code pages
     QL_HWCP1   DW      ?               ;Hardware code page 1
                        :
                        :
     QL_HWCPn   DW      ?               ;Hardware code page n
     QL_NUMCP   DW      m               ;Number of prepared code pages
     QL_CP1     DW      ?               ;Prepared code page 1
                        :
                        :
     QL_CPm     DW      ?               ;Prepared code page m

     Query Prepared List Error Codes

     26         No code pages have been selected
     29         Device error

   --------------------------------------------------------------------------
     CL = 5Fh or 7FH     Get/Set Display Information Packet

     VP_LEVEL   DB      0               ;Video parameters packet
     VP_RESRVD  DW      0               ;Reserved, must be 0
     VP_LENGTH  DW      14              ;Packet Length
     VP_FLAGS   DW      0               ;Control flags: bit 0 = 0 . Intense
                                        ;                       1 . Blink
     VP_MODE    DB      ?               ;Video mode 1 . text, 2 . APA
     VP_RESRVD  DB      0               ;Reserved, must be 0
     VP_COLORS  DW      ?               ;Number of colors, mono = 0
     VP_WIDTH   DW      ?               ;APA display width in pixels
     VP_LENG    DW      ?               ;APA display length in pixels
     VP_COLS    DW      ?               ;Display width in characters
     VP_ROWS    DW      ?               ;Display length in characters

   --------------------------------------------------------------------------

     This function uses an open device handle to request a device driver to
     switch code pages or get/set device information.

     Use the Prepare Start function to prepare a code page, followed by
     one of the IOCTL write control string calls (such as 4403h) to write the
     code page. End the stream with a Prepare End function call.

     You can select other functions by setting CL appropriately. The other
     functions are: Query Selected Code Page, Select Code Page, and
     Query Prepared List. See the information above for the information
     contained in the corresponding parameter packets.

     In addition, under DOS 4+, you can get or set display settings with the
     Get/Set Display Information functions as shown above. This
     information includes the video mode, text or APA (All Points
     Addressable), and the size of the display in characters.