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cobol/source/covrly.mac
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; UPD ID= 639 on 12/14/77 at 5:04 PM
TITLE COVRLY FOR LIBOL V12C
SUBTTL OVERLAY ROUTINE AL BLACKINGTON/CAM
SEARCH COPYRT
SALL
;COPYRIGHT (C) DIGITAL EQUIPMENT CORPORATION 1974, 1985
;ALL RIGHTS RESERVED.
;
;THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY BE USED AND COPIED
;ONLY IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE.
; EDIT 342 USE CHANNEL 0 AS LAST RESORT, SO OVERLAY ON 1.
HISEG
.COPYRIGHT ;Put COPYRIGHT statement in .REL file.
;THIS ROUTINE IS CALLED BY A PUSHJ PP,OVLAY.
;IT ASSUMES THAT A FILE HAS BEEN INITIALIZED ON CHANNEL 1
; CONTAINING THE FOLLOWING DATA:
; THE FIRST TWO BLOCKS CONTAIN FINE-TABLE INFO FOR
;THE SEGMENTS. BLOCK 1 AND THE FIRST 72 WORDS OF BLOCK 2
;CONTAIN 2-WORD ENTRIES, ONE FOR EACH SEGMENT (0-99):
; WORD1, BITS 0-28 - RELATIVE BLOCK # FOR SEGMENT.
; BITS 29-35 - RELATIVE WORD # WITHIN BLOCK FOR
; FIRST WORD OF SEGMENT.
; WORD2, BITS 18-35 - SIZE OF THE SEGMENT (NEGATIVE)
;THE NEXT 50 WORDS OF BLOCK 2 CONTAIN "ALTER" INFORMATION
;FOR SEGMENTS 50-99:
; BITS 0-17 - LOCATION (RELATIVE TO BEGINNING OF
; NON-RESIDENT SEGMENT) OF A LIST OF
; ADDRESSES USED TO PRESET "ALTER" TABLE.
; BITS 18-35 - SIZE OF "ALTER" TABLE FOR THIS SEGMENT
;
;THE DATA IS GROUPED IN BLOCKS OF 19 WORDS. THE FIRST
; WORD CONTAINS RELOCATION INFO FOR THE NEXT 18
; DATA WORDS, IN 2-BIT BYTES:
; BIT 1 - RELOCATE LH
; 2 - RELOCATE RH
;THE FOLLOWING LOCATIONS ARE USED BY THIS ROUTINE:
EXTERNAL SEGWD. ;LH IS ADDRESS OF FIRST WORD IN RESIDENT
;AREA, RH IS ADDRESS OF FIRST WORD IN
;OVERLAY AREA.
EXTERNAL ALTER. ;XWD <ADDRESS OF IMPURE BASE>,<ADDRESS OF "ALTER" TABLE>
EXTERNAL SEGNO. ;SEGMENT NUMBER OF SEGMENT CURRENTLY IN CORE
EXTERNAL AINFO. ;CONTAINS INFO FOR THIS SEGMENT TAKEN
;FROM FINE-TABLE
EXTERNAL OVRBF. ;3-WORD BUFFER HEADER USED BY OVERLAY FILE
EXTERNAL OVRIX. ;POINTER TO THE INDEX TABLE, SET UP BY "RESET"
EXTERNAL KILL. ;ROUTINE WHICH TERMINATES RUN ON ERROR
;CONDITION
ENTRY OVLAY.
OVLAY.: MOVS TA,0(PA) ;SET RETURN ADDRESS
HRRM TA,(PP)
LDB TA,CURSEG ;CURRENT SEGMENT AND OVERLAY SEGMENT THE SAME?
LDB TB,OVRSEG
CAMN TA,TB
POPJ PP, ;YES
JUMPE TB,CPOPJ ;NO--IS NEXT SEGMENT RESIDENT?
CAMN TB,SEGNO. ;CURRENT SEGMENT?
JRST LOADED ;YES--NO I/O REQUIRED
;GET INFORMATION FROM INDEX TABLE
OVLY.9: MOVEM TB,SEGNO. ;RESET CURRENT SEGMENT NUMBER
LSH TB,1 ;MULTIPLY SEGMENT NUMBER BY 2
ADD TB,OVRIX. ;ADD IN BASE OF INDEX
LDB WD,[POINT 7,0(TB),35] ;PICK UP RELATIVE WORD#
LDB BL,[POINT 29,0(TB),28] ;PICK UP RELATIVE BLOCK#
MOVS LC,1(TB) ;PICK UP SEGMENT SIZE
JUMPGE LC,NOSEGM ;IF EMPTY--TROUBLE
MOVE TB,SEGNO. ;SEGMENT > 49?
CAIG TB,^D49
JRST LOADIT ;NO--DO NOT NEED MORE INFO
ADD TB,OVRIX. ;ADD IN BASE
MOVE TB,^D200-^D50(TB)
MOVEM TB,AINFO.
;LOAD THE SEGMENT
LOADIT: SETSTS OVR,14 ;CLEAR "SYNCHRONOUS" BIT
USETI OVR,(BL) ;SET UP BLOCK # FOR READ
WAIT OVR, ;WAIT FOR ALL I/O TO CEASE
MOVE TA,OVRBF. ;IF THERE IS
MOVE TA,(TA) ; SOMETHING IN
SKIPGE (TA) ; NEXT BUFFER ALREADY,
INPUT OVR, ; SKIP OVER IT
PUSHJ PP,GETOVR ;GET FIRST DATA BLOCK
ADDM WD,OVRBF.+1 ;START AT CORRECT WORD
SUBI WD,1
MOVNS WD
ADDM WD,OVRBF.+2
HRR LC,SEGWD.
HLRZ PR,SEGWD. ;GET PURE RELOCATOR
HLRZ IR,ALTER. ;GET IMPURE RELOCATOR
;LOAD AN 18-WORD BLOCK
BLOKIN: MOVEI CT,^D18 ;SET COUNT
PUSHJ PP,GETWRD ;PICK UP RELOCATION
MOVE RW,WD
WORDIN: PUSHJ PP,GETWRD ;PICK UP A DATA WORD
JUMPGE RW,WORDI1 ;DOES LEFT-HALF NEED RELOCATION?
TLZE WD,(1B0) ;BY PURE BASE?
SKIPA TA,PR ;YES
MOVEI TA,(IR) ;NO
MOVSI TA,(TA) ;TO LEFT HALF
ADD WD,TA ;RELOCATE LEFT HALF
WORDI1: TLNN RW,1B19 ;IS RIGHT HALF RELOCATABLE?
JRST WORDI2 ;NO
TRZE WD,1B18 ;BY PURE BASE?
SKIPA TA,PR ;YES
MOVEI TA,(IR) ;NO
ADDI WD,(TA) ;RELOCATE RIGHT HALF
WORDI2: MOVEM WD,(LC) ;STORE IT
LSH RW,2
AOBJP LC,NEWSEG ;JUMP WHEN DONE
SOJG CT,WORDIN ;LOOP
JRST BLOKIN
;SEGMENT IS IN CORE
NEWSEG: PUSHJ PP, @SNRBP.## ;GO SEE IF WE HAVE TO SET ANY BREAK POINTS.
LOADED: MOVE TA,SEGNO. ;SEGMENT # > 49?
CAIG TA,^D49
POPJ PP, ;NO--EXIT
;RESET THE ALTER TABLE
MOVE TA,ALTER. ;PICK UP ADDRESS OF ALTER TABLE
HLLZ TB,AINFO. ;PICK UP RELOCATION LOC OF RESET INFO
ADD TA,TB ;ADD IN LOC OF NON-RESIDENT
HRRZ TB,AINFO. ;SET TB TO # OF WORDS
JUMPE TB,CPOPJ ;IF NONE--FORGET IT
ADDI TB,(TA) ;RELOCATE TB
BLT TA,-1(TB) ;MOVE INFO
CPOPJ: POPJ PP, ;RETURN
;GET A DATA WORD
GETWRD: SOSG OVRBF.+2
PUSHJ PP,GETOVR
ILDB WD,OVRBF.+1
POPJ PP,
;GET A BUFFER FULL
GETOVR: IN OVR,
POPJ PP,
GETSTS OVR,ER ;ERROR--GET STATUS
TRNN ER,$ERAS ;END--FILE?
JRST ERROR1 ;YES
OUTSTR [ASCIZ "Read error on overlay device"]
JRST KILL.
ERROR1: OUTSTR [ASCIZ "End-of-file on overlay device"]
ERROR2: OUTSTR [ASCIZ " -- compiler error"]
JRST KILL.
;EMPTY SEGMENT (COUNT WAS NOT NEGATIVE)
NOSEGM: OUTSTR [ASCIZ "No segment to load"]
JRST ERROR2
;BYTE POINTERS TO SEGMENT NUMBERS IN PARAMETERS
CURSEG: POINT 7,0(PA),26 ;CURRENT SEGMENT
OVRSEG: POINT 7,0(PA),35 ;DESIRED SEGMENT
;ACCUMULATORS
LC=1 ;CONTAINS IN RH, THE NEXT LOCATION FOR DATA
; IN LH, NUMBER OF WORDS TO GO (NEGATIVE)
WD=2 ;WORD # FROM FINE TABLE, OR NEW INPUT WORD
BL=3 ;BLOCK # FROM FINE TABLE
CT=4 ;COUNTER
RW=5 ;TO HOLD RELOCATION BITS
TA=6 ;TEMPORARY
TB=7 ;TEMPORARY
ER=10 ;ERROR BITS FOR INPUT FILE
IR=13 ;IMPURE RELOCATION
PR=14 ;RESIDENT RELOCATION
PA=16 ;SEGMENT NUMBER IN RH
PP=17 ;PUSH-DOWN POINTER
;INPUT DEVICE
OVR=1 ;[342]
;MONITOR INTERFACE
$ERAS=17B21 ;ERROR FLAGS FOR I/O
END