Type ASSEMBLE
Source Lines : 860
Fixes Applied : 1
Most Recent Version : Friday, December 8, 1978
Last Fix ID : [R09878DM]
Module
DMMLOC (SUBROUTINE OF DUMPSCAN)
Function
LOCATE 'STRING' WITHIN THE LIMITS 'FROM' 'TO'
Attributes
REUSABLE
NON-REENTRANT
Operation
'LOCATE' ACCEPTS A COMMAND OF THE FORM:-
'LOCATE' 'STRING' 'FROM' 'TO'
WHERE 'STRING' MAY BE ANY CONTIGUOUS STRING
OF UP TO 16 HEXADECIMAL DIGITS. 'FROM' IS
THE ADDRESS AT WHICH THE SEARCH BEGINS,
AND 'TO' IS THE END ADDRESS. 'LOCATE' WILL
SEARCH THAT RANGE OF THE DUMP, SEARCHING
ON A HALF BYTE BOUNDARY, FOR THE GIVEN STRING.
SEARCH STOPS WHEN EITHER THE 'TO' ADDRESS IS
REACHED, OR THE STRING IS FOUND. 'LOCATE WILL
PASS OVER PAGES NOT IN THE DUMP.
M.O. IS AS FOLLOWS. THE INPUT STRING IS SCANNED
FOR VALID, CONTIGUOUS HEX CHARACTERS. EACH ONE
CAUSES A BIT TO BE SET IN A MASK HALF BYTE.
THERE ARE FOUR MASKS, ALLOWING A STRING LENGTH
OF 16 CHARACTERS. THEN THE PAGE CONTAINING THE
'FROM' ADDRESS IS BROUGHT INTO 'BUFF1' BY DMMGET.
THE HEX DATA IS THEN XLATED INTO EBCDIC IN 'LOCBUFF'
(IF THE 'FROM' ADDRESS IS LESS THAN 8 BYTES,
((16 HEX DIGITS)) FROM THE END OF THE PAGE,
THE LAST 8 BYTES ARE TRANSLATED INTO THE 16 BYTES
IMMEDIATELY PRECEDING 'LOCBUFF', AND THE NEXT PAGE
IS TRANSLATED. THIS IS BECAUSE THE STRING MIGHT
RUN ACROSS A PAGE BOUNDARY.) THE FIRST FOUR BYTES
OF THE STRING ARE LOADED INTO R4. THE MASK IS LOADED
INTO R2, AND R3 IS POINTED AT THE TRANSLATED
EQUIVALENT 'TO' LOCATION IN 'LOCBUFF'. AN EXECUTE
INSTRUCTION WITH A 'CLM' AS ITS OBJECT, IS USED
FOR THE COMPARE. IF NO MATCH OCCURS, THE PTR IN R3
IS UPDATED, THE LIMITS ARE CHECKED, AND ANOTHER
COMPARISON IS MADE UNTIL THE 'TO' EQUIVALENT
ADDRESS IS REACHED. IF THERE IS A MATCH, THE
MASK IS REPLACED BY THE NEXT ONE, THE R3 POINTER
IS UPDATED BY 4 AND THE NEXT WORD IN THE STRING IS
COMPARED AGAINST THE NEXT WORD IN THE TRANSLATED
BUFFER. THIS IS CONTINUED UNTIL ALL WORDS IN THE
STRING AGREE WITH THE BUFFER, SUBJECT TO THE MASKING.
THE MATCHING ADDRESS IN R3 FROM 'LOCBUFF', IS
CONVERTED BACK TO A REAL ADDRESS FROM THE DUMP.
THIS ADDRESS IS PASSED TO EITHER DMMFED, FOR
A TYPEWRITER TYPE DEVICE, OR DMMFEX FOR A GRAPHICS
DEVICE.
Calls to Other Routines
DMMGET TO FETCH DATA INTO CORE
DMMINT TO TRANSLATE HEX TO EBCDIC
DMMHEX TO TRANSLATE EBCDIC TO HEX
DMMFEX TO WRITE THE FOUND LOCATION TO A SCREEN
DMMFED TO WRITE THE FOUND LOCATION TO A TYPEWRITER