page 88,132 Comment ~ GIVEBACK (Version 3.1) Description and Source Code Kurt Riegel, 3019 North Oakland Street, Arlington, VA 22207 ASTRO Bulletin Board, data 202-524-1837, voice 703-522-5427 (The description below is cast in terms of using GIVEBACK under DESQview or DoubleDos, in conjunction with the bulletin board program RBBS-PC, but the same procedure is usable from ANY calling program, for example using CALL GIVEBACK in compiled BASIC.) This small assembly language routine follows information provided in the DESQview (DV) 2.01 manual, and in the DoubleDos (DD) 4.0 manual. The idea is simple, but powerful. DESQview kindly terminates processing in a window if the computer pauses for a standard dos keyboard function, saving the rest of the time slice for jobs in other windows. But in other kinds of loops, for example the loop in RBBS bulletin board which watches for the telephone to ring, lots of time is wasted, uselessly looking for a phone ring every few milliseconds. Once a second would be quite enough! By calling this routine from the end of a wasteful loop in a program, DESQview will be forced to "give back" the rest of the time in that time slice, that is, you will execute the loop only once per time slice rather than many times. This greatly speeds up jobs in the other DV windows, without affecting the calling program at all. The most wasteful RBBS task is waiting for the telephone to ring; another is waiting for the user to select a command and hit the Return key. So we CALL this procedure at the end of these loops. The table below summarizes actual measurements made with DV on an AST Premium 286 (10 MHz, zero wait state), relative to speed on the same machine without DV, running a single job. DV SETUP default performance settings were 9 slices foreground, 3 slices background. This improvement would be larger and MUCH more noticeable on a slower machine. Similarly, DoubleDos normally allocates two thirds of the computing cycles to the Visible task, and the remaining third to the Invisible task (plenty for the RBBS bulletin board). The loss of cycles is sometimes noticeable, and this reclaims them when not really needed by RBBS. You can even use this to speed up both nodes of RBBS, when one is in the Visible section and the other is in the Invisible section (you would probably choose PRIORITY=EQUAL with 2 nodes). DD version 4.00 has a special interrupt that allows the programmer to "give back" up to 255 time slices of duration 55 milliseconds each. This procedure gives back 6 slices, about a third of a second at the old 4.77 MHz clock rate. The table below summarizes actual speed measurements with and without GIVEBACK, running under both DoubleDos and DESQview. The speedup is wonderful, about 65%. Once you use it, you'll never go back. Non-bbs speed ³ Waiting for Ring ³ Caller On ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ DV: Unmodified ³ 74% ³ 74% With GIVEBACK ³ 98% ³ variable, average 86% ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ DD: Unmodified ³ 57% ³ 57% With GIVEBACK ³ 94% ³ variable, average 80% ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ Challenge for multitasking RBBS enthusiasts: There are additional wasteful loops in RBBS--put on your best Sherlock outfit, and go snooping for places to CALL GIVEBACK. Please keep in touch with me on your progress through the telephone numbers or address posted at the top of this file. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ RBBS 16.1 ³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Starting with version 16.1, RBBS has the implementation for GIVEBACK ³ ³ already built in. The original release version omitted one call, ³ ³ the one within the loop waiting for the telephone to ring. It is ³ ³ repaired by making the small change below in RBBSSUB2.BAS ³ ³ ³ ³ 270 . . . ³ ³ call giveback:WEND ³ ³ ³ ³ Then compile the modified RBBSSUB2.BAS, and LINK RBBSSUB2.OBJ ³ ³ together with GIVEBK31.OBJ and the rest of the normal RBBS OBJect ³ ³ files package. ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ RBBS 15.1c ³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ To implement GIVEBACK, modify RBBSSUB1.BAS by the addition of the ³ ³ lower case letter portion) in 2 lines only: ³ ³ ³ ³ 270 IF RECYCLE.WAIT > 0 THEN _ ' CPC15-1C ³ ³ IF TI! > INACTIVE.DELAY! THEN _ ' CPC15-1C ³ ³ SUBROUTINE.PARAMETER = 8 : _ ' CPC15-1C ³ ³ EXIT SUB ' CPC15-1C ³ ³ call giveback:WEND ³ ³ . . . ³ ³ 1526 Y$ = KEY.PRESSED$ ³ ³ IF Y$ <> "" THEN _ ³ ³ GOTO 1545 ³ ³ call giveback:GOTO 1525 ³ ³ ³ ³ Then compile the modified RBBSSUB1.BAS, and LINK RBBSSUB1.OBJ ³ ³ together with GIVEBK31.OBJ and the rest of the normal RBBS OBJect ³ ³ files package. ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ RBBS 14.1d ³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ To implement GIVEBACK, modify RBBS-SUB.BAS version 14.1D (by the ³ ³ addition of the lower case letter portion) in 2 lines only: ³ ³ ³ ³ 270 call giveback : WEND ³ ³ . . . ³ ³ 1526 (actually, three lines after this line number . . .) ³ ³ call giveback : WEND ³ ³ ³ ³ Then compile the modified RBBS-SUB.BAS, and LINK RBBS-SUB.OBJ ³ ³ together with GIVEBK31.OBJ and the rest of the normal RBBS OBJect ³ ³ files package. ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ GIVEBACK Version history: 1.0 December 1986 was the first version, for RBBS-PC v14.1D and DoubleDos version 4.0 1.2 January 2, 1987 Added a second call to giveback in the WHILE..WEND loop which waits for user to enter a command. DoubleDos only. 1.3 May 20, 1987. Changed to prevent RBBS modified with GIVEBACK from crashing the system when run under naked Dos, that is, without the use of DoubleDos. Replaced direct INT FEh statement, with indirect AH=EEh, followed by normal Dos function INT 21h. DD and Dos obligingly work together like this: DD modifies the INT 21h function tables when it starts so as to recognize EEh, and naked Dos ignores functions like EEh which are unknown to it. Possible caution--DD is definitely non-standard in making this modification. This should cause no problem, UNLESS you use yet another non-standard program that also grabs AH=EEh under INT 21h for another purpose (unlikely). 2.0 Jan 1988. Version is for DESQview 2.01 (works fine in 2.0 too), together with RBBS 15.1c. It does not supersede GIVEBK13, required for operation under DoubleDos. Although it duplicates some lines of code found in RBBSDV.ASM, this is a simple, small, and cleanly independent addition. RBBS, modified to include this revision, will work under naked DOS alone, or under DESQview. (personal note--I run only a single node, and prefer to drop all the FILELOCK, RBBSDV, and multilink crap and related calls from my personal version of RBBS; shrinks the .EXE file and makes it more reliable) 3.0 Feb 1988. This version consolidates DoubleDos and DESQview routines into one that works equally well for RBBS running under either multitasker, or under naked DOS. Calling points are given for both RBBS 14.1d and 15.1c. My hope is that RBBS version 16.0 will incorporate this into the release version. 3.1 Apr 1988. Minor upgrade neatens code and also eliminates the former requirement for initializing GIVEBACK by calling GIVEINIT. It can be initialized explicitly as before; but if the user chooses to call GIVEBACK straight away, then the initialization will be taken care of automatically. (End of comments here-you do not have to remove these comments to assemble.) ~ GIVESEG SEGMENT 'CODE' ASSUME CS:GIVESEG PUBLIC GIVEINIT ;the initialization routine, optional PUBLIC GIVEBACK ;CALL GIVEBACK to give back time slice MultiTasker DB -1 ; will indicate which multitasker is running, if any ;-1 means this hasn't yet been called, and ; initialization is required using GIVEINIT ; 0 means no multitasker is present, only naked dos ; 1 means DESQview is running ; 2 means DoubleDos is running GIVEINIT PROC FAR PUSH AX ; save this stuff for safety PUSH BX PUSH CX PUSH DX MOV AX,2B01H ; DV get version request, result to AX MOV CX,'DE' ; Illegal MOV DX,'SQ' ; date, on purpose INT 21H ; An error indicates DV isn't running CMP AL,0FFH ; Are we in DV? JE NO_DV ; Jump if not MOV CS:MultiTasker,1 ; 1 will mean DV is present JMP SHORT InitExit NO_DV: ; DV isn't here, maybe DD is-let's check MOV AH,0E4h ; function E4h tests for presence of DoubleDos INT 21h ; does nothing at all if DD not present CMP AL,01 ; 1 indicates DD present, program visible JZ DDhere CMP AL,02 ; 2 indicates DD present, program invisible JZ DDhere JMP NoMultitsk ; anything else indicates not present, so quit DDhere: MOV CS:MultiTasker,2 ;this value indicates DD present JMP SHORT InitExit NoMultitsk: MOV CS:MultiTasker,0 ;Neither DV nor DD running InitExit: POP DX ;and put it all back POP CX POP BX POP AX RET GIVEINIT ENDP API_CALL PROC ; local DV routine that goes on stack, does whatever PUSH AX ; call is passed in BX, then goes off stack MOV AX,101AH INT 15H ; OSTACK MOV AX,BX INT 15H ; Parameter MOV AX,1025H INT 15H ; USTACK POP AX RET API_CALL ENDP GIVEBACK PROC FAR ;Gives up the rest of its time slice when called. ;GIVEINIT will be invoked automatically the first time ; that GIVEBACK is called; GIVEINIT can (optionally) ; be called explicitly to force initialization. CMP CS:MultiTasker,1 ;let's see what's running here JZ DVrunning ;1 means DESQview is running JG DDrunning ;2 means DoubleDos is running CMP CS:MultiTasker,0 ;only naked Dos or uninitialized state ; remain as possibilities JZ GetOutaHere ;0 means naked Dos CALL GIVEINIT ;last remaining possibility is -1 JMP GIVEBACK ;after initializing, try this again GetOutaHere: ;nothing else to do, so go back RET DVrunning: PUSH BX MOV BX,1000H ; DV_PAUSE function call CALL API_CALL POP BX JMP SHORT GetOutaHere DDrunning: push bp ;save caller's base pointer register mov bp,sp ;setup to address off of base pointer register push ax ;just in case this messes up something mov ax,0EE06h Comment ~ EEh in AH is special DoubleDos giveback interrupt. 06h in AL is six 55ms giveback intervals = 1/3 sec. ~ int 21h ;invokes special DoubleDos giveback interrupt pop ax ;puts it back POP BP ;restore callers base pointer register JMP SHORT GetOutaHere GIVEBACK ENDP GIVESEG ENDS END