Programmer 7500

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Text File | 1986-12-06 | 14.4 KB | 365 lines

DESQview Technical Notes Revised: April 18, 1986 Page 1 --------------------------------------------------------------------- RUNNING YOUR PROGRAM IN A SMALL WINDOW Programs that call DOS or the ROM BIOS to display information on the screen run in a small window with no modifications. These programs are referred to as "well-behaved". "Misbehaved" programs are programs that write directly into the hardware video buffer and/or move the cursor by directly manipulating the hardware. These programs can only be run in a full-screen window and cannot be run in background. "Misbehaved" programs can be made to behave using the following techniques: Programs the write directly to the video buffer typically determine during initialization whether they should run on a monochrome or color monitor. They select a video buffer address of B000:0000H for monochrome or B800:0000H for color displays. DESQview provides a new BIOS call that supplies the caller with an alternate video buffer address. The program can write into this buffer exactly as if it were the hardware video buffer. DESQview will automatically take care of displaying only the information that falls within the current window area. The following code sequence checks for DESQview's presence and then requests the alternate buffer address: MOV AX,2B01H ; set date & check DV version MOV CX,'DE' ; set CX DX to DESQ MOV DX,'SQ' ; for the date (invalid) INT 21H ; call DOS CMP AL,FFH ; check for invalid JZ NO_DESQVIEW ; DESQview is not running MOV MAJOR_VERSION,BH ; DV Version number MOV MINOR_VERSION,BL ; (no real need to store these) ; Since DESQview is running, get the alternate buffer MOV AX,0B800H ; load hardware buffer address MOV ES,AX ; into ES:DI (0B000H for monochrome) MOV DI,0 MOV AH,0FEH ; load function code into AH INT 10H ; ask for alternate buffer address ; ES:DI now has alternate buffer address The first section of this code checks to be sure that DESQview is run- ning. If it is not, then there is no need to check for an alternate buffer address. If DESQview is running, then ES:DI contains the al- ternate buffer address after the INT 10 call. There is no need to synchronize with video retrace when writing into this buffer; DESQview will automatically synchronize when the information is writ- ten to the "real" screen. Users familiar with IBM's TopView program will note that TopView supports an equivalent call to find an alter- nate screen buffer. TopView requires, however, that another call be made every time you write into the buffer to tell TopView that some- thing changed (the 0FFH function code). DESQview supports these calls but DOES NOT require them. Note that if TopView or DESQview is not running, ES:DI are returned unchanged. DESQview Technical Notes Revised: April 18, 1986 Page 2 --------------------------------------------------------------------- MANAGING THE CURSOR Programs that manipulate the hardware to move the cursor must be modified so that all cursor movement is done through the ROM BIOS. The following code sequence moves the cursor to row 5, column 30: MOV DH,5 ; specify row 5 MOV DL,30 ; specify column 30 MOV BH,0 ; specify display page 0 MOV AH,2 ; load function code INT 10H ; move the cursor Coordinates are zero based starting in the upper left corner of the screen. The display page is almost always 0 unless your program makes special use of the extra text pages on a color graphics adapter. DESQview will insure that the current cursor position will always be visible in the window. Please note that this function is very easy to use and is actually quite fast. That's all it takes to make a program run in a small window. The various loader programs that Quarterdeck supplies with DESQview per- form these modifications automatically for several popular software packages. Let us know if you have any problems converting your program. DESQview Technical Notes Revised: April 18, 1986 Page 3 --------------------------------------------------------------------- LINKABLE INTERFACE The following routines can be assembled with the IBM or Microsoft Assembler and then linked into your program. We believe they will work as-is when linked to Assembler and MS Pascal programs. They may also work with "C". We know that they are not linkable as-is to Turbo Pascal or Compiled BASIC although you may be able to adapt them by studying the code. Perhaps we can provide examples for other lan- guages in the future. This source is also available as an ASM and OBJ file on the Quarterdeck Bulletin Board System. Contact Quarterdeck for information on the Bulletin Board. Functions provided: DV_GET_VERSION - Allows a program to determine if it is run- ning in DESQview and returns the DESQview version number. DV_PAUSE - Allows application to give up the rest of its time slice when engaged in processor intensive, but non-critical activity (Example: testing for keyboard input on menus). Users of this call are eligible for the Multi-tasker's Good Citizen Award. DV_BEGIN_CRITICAL - When used with the DV_END_CRITICAL call, defines a section of code that DESQview will not slice out of. Use for timing critical operations. DV_END_CRITICAL - See DV_BEGIN_CRITICAL. DV_GET_VIDEO_BUFFER - If your program writes directly to screen buffer, use this routine in the module where you determine screen address. Put the address on the stack and call the routine. Routine determines if DESQview is running and if so, returns in AX the address to use in DESQview. (code begins next page) DESQview Technical Notes Revised: April 18, 1986 Page 4 --------------------------------------------------------------------- NAME DVINT TITLE DESQview Interfaces PAGE 66,132 DVINT_SEG SEGMENT 'CODE' ASSUME CS:DVINT_SEG PUBLIC DV_GET_VERSION PUBLIC DV_PAUSE PUBLIC DV_BEGIN_CRITICAL PUBLIC DV_END_CRITICAL PUBLIC DV_GET_VIDEO_BUFFER IN_DV DB 1 GET_VERSION PROC PUSH BX PUSH CX PUSH DX MOV AX,2B01H ; DV get version ; request MOV CX,'DE' MOV DX,'SQ' INT 21H CMP AL,0FFH ; Are we in DV? JE NO_DV ; Jump if not MOV AX,BX ; We are; put ; the version ; number in AX MOV CS:IN_DV,1 ; Set the local IN_DV flag JMP SHORT DVGV_EXIT NO_DV: SUB AX,AX ; Clear AX MOV CS:IN_DV,AL ; And the local ; flag DVGV_EXIT: POP DX POP CX POP BX RET GET_VERSION ENDP ; DV_GET_VERSION returns the DV version number in AX, or 0 if not ;in DV. This should be called before any other DV functions. DV_GET_VERSION PROC FAR CALL GET_VERSION RET DV_GET_VERSION ENDP DESQview Technical Notes Revised: April 18, 1986 Page 5 --------------------------------------------------------------------- ; API_CALL is a local routine that goes on stack, does whatever ;call is passed it in BX, and then goes off stack API_CALL PROC PUSH AX MOV AX,101AH INT 15H ; OSTACK MOV AX,BX INT 15H ; Parameter MOV AX,1025H INT 15H ; USTACK POP AX RET API_CALL ENDP ; DV_PAUSE gives up the rest of its time slice when called. DV_PAUSE PROC FAR CMP CS:IN_DV,1 ; Are we in DV? JNE DVP_END ; Jump if not PUSH BX MOV BX,1000H ; PAUSE function ; call CALL API_CALL POP BX DVP_END: RET DV_PAUSE ENDP ; Begins a critical region. This is a section of code which DV ;will not slice out of. It MUST be ended with a DV_END_CRITICAL ;call. DV_BEGIN_CRITICAL PROC FAR CMP CS:IN_DV,1 ; Are we in DV? JNE DVBC_END ; Jump if not PUSH BX MOV BX,101BH ; BEGINC CALL API_CALL POP BX DVBC_END: RET DV_BEGIN_CRITICAL ENDP DESQview Technical Notes Revised: April 18, 1986 Page 6 --------------------------------------------------------------------- ; Ends a critical region. DV_END_CRITICAL PROC FAR CMP CS:IN_DV,1 ; Are we in DV? JNE DVEC_END ; Jump if not PUSH BX MOV BX,101CH ; ENDC CALL API_CALL POP BX DVEC_END: RET DV_END_CRITICAL ENDP ; Passed on the stack the video buffer address to use outside of ; DV. Returns the video buffer address to use instead. ; If what it returns is different, then video synching is not ; necessary. Also, this call does a DV_GET_VERSION call itself, ; so if you get the video buffer, it is not required that you get ; the version. DV_GET_VIDEO_BUFFER PROC FAR PUSH BP MOV BP,SP PUSH BX PUSH DI PUSH ES MOV ES,[BP+6] ; Put the starting ; segment in ES CALL GET_VERSION TEST AX,AX ; Are we in ; DESQview? JZ DVGVB_END ; Jump if not SUB DI,DI ; Clear DI MOV AH,0FEH ; Get video buffer ; function call INT 10H DVGVB_END: MOV AX,ES POP ES POP DI POP BX POP BP RET 2 DV_GET_VIDEO_BUFFER ENDP DVINT_SEG ENDS END ;(end of file) DESQview Technical Notes Revised: April 18, 1986 Page 7 --------------------------------------------------------------------- Use of DESQview .DVP files Once a program has been installed in DESQview. DESQview creates a file which is loaded in the \DV directory that has the filename ??-PIF.DVP where "??" represents the two keys used to open the window. After installing your program, you will find a file in the \DV directory that corresponds to the keys you chose to open your program window. This file contains all of the configuration parameters necessary to run your program properly in DESQview. It is important for you to know that Quarterdeck holds no copyright to these .DVP files and that you are free to distribute them with your software. In fact, we encourage you to do so. If one of these files is present in the drive and subdirectory in which your program is installed and a user is adding the program to DESQview, DESQview will automatically find the .DVP file and allow the user to install the program by selecting it from the Add Program menu. If you are planning to include both a DESQview .DVP file and a TopView PIF, you may want to add a (DV) to the program name field in the DVP so that the DESQview user will know which file to select. The DESQview "Add a Program" utility will find both the DVP and the PIF and display the program name from each, so it is important that the program name distinguish which is which. When programs are added in this fashion, it ensures that the user will get them installed right the first time. This makes users happy and eliminates a lot of support calls, which I'm sure will make both of our companies happy. The file is only 416 bytes in size. All that is necessary on your part is to include it on your distribution disk. Then when your install program transfers your program to the user's floppy or hard drive be sure that the .DVP file is also transferred. If you have any questions or need help in setting up your program in DESQview, don't hesitate to call us at Quarterdeck.