## Presentation Device Driver Reference for OS/2

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### Default_Primary Parameter - dsp_stuc_ptr

dsp_stuc_ptr (PDSPINSTL_DATA) - input

The global DSPINSTL data structure is defined as follows:

    struct dspinstl_global_data

    {

    ULONG rev_num;                   /* Global DSPINSTL data structure       */

                                     /*   revision number                    */

    PFN Link_Chain_Element_Ptr;      /* Address of the Link_Chain_Element    */

                                     /*   service function                   */

    PFN Unlink_Chain_Element_Ptr;    /* Address of the Unlink_Chain_Element  */

                                     /*   service function                   */

    PFN Next_Chain_Element_Ptr;      /* Address of the Next_Chain_Element    */

                                     /*   service function                   */

    PFN Reserved_PTR1;               /* Reserved                             */

    PFN Select_Display_Resolutions_Ptr;/* Address of Select_Display_Resolutions*/

                                     /*   service function                   */

    PFN Reserved_PTR2;               /* Reserved                             */

    PFN Reserved_PTR3;               /* Reserved                             */

    PFN Reserved_PTR4;               /* Reserved                             */

    PDSPINSTL_GLOBAL_DATA            /* Pointer to head of data element chain*/

    PDSPINSTL_CHAIN_head             /* Pointer to head of data element chain*/

    BOOL Reserved_Book               /* Reserved                             */

    PSZ pszSourceDirectory           /* Source directory name (ASCIIZ string)*/

    ULONG ulSizeSource               /* Size of source directory name buffer */

    };

The source directory name string is the string that will be displayed in the Specify Source Directory PM panel that allows the user to override the default source directory for a given DSPINSTL step. The source directory name string, therefore, acts as the default source directory for that step. The string's inclusion in the global data structure provides the ability to modify the default source directory name to all action routines.

There are three service routines that are provided to manipulate the data element chain. The following data structure characterizes a DSPINSTL data element:

    struct dspinstl_chain_element

    {

     ULONG rev_num;        /* DSPINSTL data chain element revision number    */

     PDSPINSTL_CHAIN next; /* Pointer to next DSPINSTL data chain element    */

     PSZ key;              /* Pointer to keyword string associated with this */

                           /*   chain element                                */

     PSZ general_prompt;   /* Pointer to the prompt string to be written in  */

                           /*   the Specify Source Directory panel when this */

                           /*   chain element is interpreted.  A NULL value  */

                           /*   indicates that the previous source directory */

                           /*   should be used again and that this panel     */

                           /*   should be bypassed for this chain element.   */

     PSZ diskette_prompt;  /* Pointer to the prompt string to be written in  */

                           /*   the Insert Diskette prompt panel             */

     PSZ volume_label;     /* Pointer to the (optional) diskette volume      */

                           /*   label string that is used to verify the      */

                           /*   correct identity of a DSP diskette           */

     PSZ resolution_string;/* Optional string that indicates a display driver*/

                           /*   resolution.  The string can be passed to     */

                           /*   Select_Display_Resolutions or left NULL      */

    };

Note: The various strings that are found in DSPINSTL data elements are typically initialized from string values found in DSPINSTL configuration file entries.