File: OVRDRV.MA of Tape: Sources/RTS/macrel-1a-rts8-src-2
(Source file text)
/OVRDRV - OVERLAY DRIVER / / / / / / / / / /COPYRIGHT (C) 1977 BY DIGITAL EQUIPMENT CORPORATION / / / / / / / / / / /THE INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE /AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT /CORPORATION. DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY /FOR ANY ERRORS THAT MAY APPEAR IN THIS DOCUMENT. / /THE SOFTWARE DESCRIBED IN THIS DOCUMENT IS FURNISHED TO THE PURCHASER /UNDER A LICENSE FOR USE ON A SINGLE COMPUTER SYSTEM AND CAN BE COPIED /(WITH INCLUSION OF DIGITAL'S COPYRIGHT NOTICE) ONLY FOR USE IN SUCH /SYSTEM, EXCEPT AS MAY OTHERWISE BE PROVIDED IN WRITING BY DIGITAL. / /DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY FOR THE USE /OR RELIABILITY OF ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY /DIGITAL. / / / / / / / / / / /OVERLAY DRIVER /FOR LINKER PROGRAM MODULES /V1A /THIS SECT IS TWO LOCATIONS AND CONTAINS THE TRANSFER VECTOR TO SWAPER /AND A FLAG THAT INDICATES WHETHER A JMP (1) OR JMS (0) WAS PERFORMED /TO THE TRANSFER VECTOR .SECT XFERV,Z 0 /FLAG, 1=JMP, 0=JMS SWAPER /TRANSFER VECTOR TO SWAP ROUTINE /THIS IS THE MAIN DRIVER SECTION .SECT SWAPER,R .GLOBAL SWPTAB,TRANVC FIELD XFERV SWAP, 6101 /VERSION NUMBER DCA AC /SAVE CALLING AC RAL DCA LINK /AND LINK RDF /GET CALLING DF TAD (CDF /FORM CDF SWAP0, JMP ONCE /DO ONCE ONLY CODE - REPLACED BY DCA EXIT CDF . /CHANGE TO THIS DATA FIELD TAD I SWAP /GET OVERLAY,LEVEL,FIELD DCA BINDAT /SAVE ISZ SWAP /BUMP POINTER TAD I SWAP /GET SUBROUTINE ADDRESS DCA XITLOC /SAVE TAD BINDAT /FORM CDF TO CALLED SUBROUTINE AND (7 RAL CLL RTL TAD (CDF DCA SWAP1A /SAVE TAD SWAP1A /FORM CIF TO CALLED SUBROUTINE IAC DCA EXIT+1 /SAVE FOR EXIT /LOAD OVERLAY OF CALLED SUBROUTINE LOAD, TAD BINDAT AND (1600 /EXTRACT LEVEL OF CALLED SUBROUTINE RTR CLL /5 RIGHT RTR RAR DCA PNTR /SAVE TAD PNTR TAD (SWPTAB /COMPUTE ENTRY INTO SWAP TABLE DCA FLD /POINTS TO FIELD OF OVERLAY TAD PNTR /COMPUTE ENTRY INTO CURRENT OVERLAY TABLE RTR CLL TAD (CURTAB DCA PNTR TAD BINDAT /EXTRACT DESIRED OVERLAY NUMBER AND (170 RTR CLL /RIGHT 3 RAR CIA /NEGATE DCA TEMP TAD TEMP TAD I PNTR /COMPARE WITH CURRENT OVERLAY NUMBER FOR LEVEL SNA CLA /SAME? JMP SWAP1 /YES, NO READING NEEDED LOAD1, TAD TEMP /NO, SET TO NEW CIA DCA I PNTR /OVERLAY NUMBER TAD FLD /SET UP POINTERS TO IAC DCA ADDRES /ADDRESS TAD ADDRES IAC DCA RELBLK /RELATIVE BLOCK NUMBER TAD RELBLK IAC DCA LENGTH /LENGTH OF OVERLAY TAD TEMP /TEST OVERLAY NUMBER SNA CLA /0? JMP LOAD2 /YES, NO MULTIPLICATION NEEDED TAD I LENGTH /BLOCK NUMBER = (LENGTH OF OVERLAY) ISZ TEMP /TIMES (THE NUMBER OF THE OVERLAY) JMP .-2 LOAD2, TAD I RELBLK /PLUS (RELATIVE BLOCK OF LEVEL) TAD STRBLK /PLUS (STARTING BLOCK OF PROGRAM) DCA REDBLK /SAVE IN CALL LOCATION TAD I ADDRES /GET ADDRESS TO LOAD DCA REDADD /SAVE IN CALL LOCATION TAD I FLD /GET FIELD AND (7 /MASK RTR CLL RTR /POSITION TAD I LENGTH /GET LENGTH RTR RTR RTR DCA REDCNT /FORM CONTROL WORD CIF 0 JMS I (7607 /CALL SYSTEM HANDLER TO READ IN OVERLAY REDCNT, 7756 /FUNCTION CONTROL WORD (POINTS TO MREAD-1 FOR "ONCE" REDADD, -7607 /BUFFER ADDRESS (CONTAINS SYS: ENTRY POINT FOR "ONCE" REDBLK, 0 /STARTING BLOCK NUMBER HLT /ERROR RETURN ADDRESS SWAP1, TAD XFERV /GET JMP-JMS FLAG SZA CLA /SET? JMP SWAP2 /YES, EXECUTE A JMP CLA CLL CMA RTL /-3 TAD SWAP /BACK UP TO CALLER'S PC DCA SWAP TAD I SWAP SWAP1A, 0 /CDF TO CALLED SUBROUTINE DCA I XITLOC /SAVE IN CALLED SUBROUTINE ISZ XITLOC /BUMP TRANSFER ADDRESS CDF . TAD (ISZ XFERV DCA I SWAP /SET BACK UP ENTRY IN XFER VECTOR TABLE SWAP2, DCA XFERV /CLEAR FLAG TAD LINK /RESTORE LINK AND AC RAR CLL TAD AC EXIT, 0 /SET DF TO CALLING FIELD 0 /SET IF TO CALLED FIELD JMP I XITLOC /GO TO CALLED SUBROUTINE /VARIABLE LOCATIONS /SOME OF THE FOLLOWING LOCATIONS CONTAIN /ONCE ONLY CODE TO SET UP STARTING BLOCK /AND CHECK THAT FILE CAME FROM SYS: CURTAB=. /CURRENT OVERLAY IN LEVEL TABLE (8 ENTRIES) STRBLK=. /ENTRY 0 IS USED TO HOLD STARTING BLOCK OF FILE ONCE, DCA EXIT /SAVE CALLING FIELD /ALSO ENTRY 0 TAD .-1 /SET UP SO WON'T BE EXECUTED AGAIN /ALSO ENTRY 1 DCA SWAP0 /ALSO ENTRY 2 CDF 0 /ALSO ENTRY 3 TAD I FLD /GET STARTING BLOCK FROM "SOFSET" /ALSO ENTRY 4 SNA /ALSO ENTRY 5 HLT /ERROR, K.M. PATCHES NOT IN /ALSO ENTRY 6 DCA STRBLK /SAVE /ALSO ENTRY 7 TAD I REDCNT /CHECK FILE CAME FROM SYS: TAD REDADD BINDAT, /CONTAINS OVERLAY,LEVEL,FIELD OF DESIRED SUBROUTINE SNA CLA /FROM SYS: ? XITLOC, /CONTAINS LOCATION TO GO TO IN DESIRED SUBROUTINE JMP SWAP0+1 /YES, OK PNTR, /POINTS INTO CURTAB HLT /NO, ERROR TEMP, /TEMP STORAGE JMP .-1 /DON'T ALLOW CONTINUE FLD, /POINTS TO FIELD WORD IN SWPTAB 7747 /POINTER TO "SOFSET" ADDRES=REDADD /POINTS TO ADDRESS WORD IN SWPTAB RELBLK=REDBLK /POINTS TO RELATIVE BLOCK WORD IN SWPTAB LENGTH=REDCNT /POINTS TO LENGTH WORD IN SWPTAB AC, 0 /SAVED AC LINK, 0 /SAVED LINK PAGE /THIS AREA CONTAINS OVERLAY DATA FOR MAIN AND THE 7 LEVELS /THE FORMAT OF EACH ENTRY IS: /WORD1: FIELD OF LEVEL /WORD2: ADDRESS OF LEVEL /WORD3: RELATIVE BLOCK OF 1ST OVERLAY IN LEVEL /WORD4: LENGTH OF THE LEVEL (ANY AND ALL OVERLAYS-EACH) / (ALL OVERLAYS IN A LEVEL ARE THE SAME LENGTH) SWPTAB, *.+40 /THIS AREA CONTAINS THE TRANSFER VECTORS FOR EACH ENTRY POINT /IN ALL THE OVERLAYS IN ALL THE LEVELS /ITS SIZE SHOULD BE MODIFIED BY THE USER /TO FIT THE MAXIMUM NUMBER OF TRANSFER VECTORS NEEDED /EACH TRANSFER VECTOR OCCUPIES 4 LOCATIONS /THE TABLE IS INITIALLY SET UP FOR 24(DEC) (30(OCT)) VECTORS /THE MAXIMUM SIZE THIS TABLE CAN BE IS 3774 (OCT) LOCATIONS FOR /511 (DEC) (777 (OCT)) VECTORS /THE FORMAT OF EACH VECTOR ENTRY IS: /WORD1: ISZ XFERV /WORD2: JMS I XFERV+1 /WORD3: LEVEL/OVERLAY/FIELD /WORD4: ADDRESS TRANVC, SIZE=^D24 /MODIFY THIS LINE TO CHANGE THE SIZE OF THE TABLE /SET FOR 24(DEC) *SIZE^4+.