Type ASSEMBLE
Source Lines : 2,116
Fixes Applied : 15
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [HRC309DS]
Module
DMSLDR (LDR)
Function
THIS MODULE CONSISTS OF THE FOLLOWING LOADER ROUTINES:
DMSLDRA, DMSLDRB
Attributes
REENTRANT, NUCLEUS RESIDENT
Operation
THE START EXECUTION ROUTINE RECEIVES CONTROL FROM THE
START COMMAND OR THE LDT CARD ROUTINE IF THE START OPTION
WAS SPECIFIED. THE START EXECUTION ROUTINE:
1. INITIALIZES FREE STORAGE.
2. CALLS THE DISK AND TYPE OUTPUT PROGRAM (DMSLIO) TO
PRINT A STORAGE MAP HEADER FOR COMMON, IF THE
REFTBL CONTAINS ANY COMMON ENTRIES.
3. SEARCHES THE REFTBL FOR ENTRIES WITH A NONZERO
FLAG (COMMON, CXD, PR, AND REFERENCES TO UNDEFINED
SYMBOLS).
A. A POINTER TO PR ENTRY IS PLACED IN A SEPARATE
TABLE DEPENDING UPON PR ALIGNMENT: BYTE,
HALFWORD, FULLWORD, OR DOUBLEWORD.
B. A CXD ENTRY IS MARKED "UNDEFINED" FOR LATER
PROCESSING AND A POINTER PLACED IN SPECIAL
CXD TABLE.
C. A COMMON IS DEFINED AT THE NEXT AVAILABLE
LOAD LOCATION AND THE LOCATION COUNTER
(LOCCNT) IS INCREASED BY THE LENGTH OF THE
COMMON. REFERENCES TO THE COMMON ARE
PROCESSED BY CALLED ADDEF. THE NAME,
ADDRESS, AND LENGTH OF THE COMMON ARE PRINTED
BY CALLING DMSLIO VIA CMVAL.
D. A REFERENCE TO AN UNDEFINED SYMBOL IS
REPLACED BY A VALUE OF ZERO BY CALLING ADDEF.
4. AFTER SCANNING ENTIRE REFTBL, THE DISK AND TYPE
OUTPUT PROGRAM (DMSLIO) IS CALLED TO PRINT A
STORAGE MAP HEADER FOR PR'S, IF THERE ARE ANY
PSEUDO-REGISTER ENTRIES IN THE REFTBL. THE NAME,
VALUE, AND LENGTH OF EACH PR (THEY WERE DEFINED
EARLIER WHEN ESD WAS FIRST ENCOUNTERED) ARE
PRINTED AS WELL AS THE CXD REQUEST, WHICH CAN ONLY
BE DETERMINED AFTER ALL PR'S HAVE BEEN ASSIGNED.
5. THE STARTING ADDRESS FOR EXECUTION IS THEN
DETERMINED: BY ENTRY-POINT NAME IS SUPPLIED, BY
START COMMAND OR BY THE START EXECUTION ADDRESS
(IN BRAD) SET BY FIRST PROGRAM LOADED, END CARD,
LDT CARD, OR ENTRY CONTROL CARD.
6. A. IF ACTUAL EXECUTION IS SUPPRESSED, FOR
EXAMPLE, BY SPECIFYING START (NO) COMMAND,
THE LIBRARY IS CLOSED, LOAD MAP CLOSED, FREE
STORAGE RELEASED, AND CONTROL RETURNED TO
CALLER. OTHERWISE, EXECUTION IS PERFORMED BY
SETP 6B.
B. THE MESSAGE "EXECUTION BEGINS" IS PRINTED,
IF THE CMS/DOS ENVIRONMENT IS NOT ACTIVE
( DOSCOMP+DOSSVC ). THE GETMAIN/FREEMAIN
STORAGE IS INITIALIZED (STRINIT). IF THE
CMS/DOS ENVIRONMENT IS ACTIVE ( DOSSVC),
A CALL IS MADE TO DMSSMNAT TO INITIALIZE
THE CMS/DOS PARTITION.
THE SAVE AREA ADDRESS IS SET IN REGISTER
13, THE ENTRY POINT OF THE PROGRAM IS SET
IN REGISTER 15, THE RETURN ADDRESS IS SET
IN REGISTER 14, AND THE ADDRESS TO THE
PROGRAM'S PLIST IS SET IN REGISTER 1.
An extended PLIST is supplied in R0. HRC309DS
IF THE CMS/DOS ENVIRONMENT IS ACTIVE
( DOSCOMP+DOSSVC ), REGISTER 1 WILL THEN
CONTAIN THE ENTRY POINT ADDRESS OF THE
PROGRAM TO BE EXECUTED.
CONTROL IS THEN TRANSFERRED TO THE LOADED
PROGRAM VIA 'LPSW' INSTRUCTION.
@VA04695
NOTE: ANY CHANGES MADE TO THIS MODULE SHOULD ALSO @VA04695
BE CONSIDERED FOR DMSOLD. @VA04695
Calls to Other Routines
DMSLIO - TO PRINT MESSAGES
DMSLSBC - TO DEFINE UNDEFINED ENTRIES AT ZERO
SERCH1 - IN DMSLDRB TO FIND STARTING NAME'S LOCATION