Comparing the Assembler source to the Cobol target program

Transcription

1 Comparing the Assembler source to the Cobol target program Subject, issue Assembler program Cobol program source code lines source code lines. Reduction by 45%! branch instructions 25 No (0) GO TO instructions! VSAM macros Self-modifying code OPEN, CLOSE, GET, ACB, RPL, SHOWCB (2) Converted to one VSAM file declaration replaced by ordinary switch logic z/os macros SAVE, RETURN, WTO (2), CALL (2) No z/os macro needed to be emulated Dead code sequences Significant portions turn out to be never referenced Redundant operations Non-symbolic coding like clearing a register and then loading it with a value e.g. 36(R2) instead of working with symbolic names Detected and removed Detected and removed Replaced by artificial symbols The assembler program is a typical example for lethal maintenance : the work of the past 30 years was done so awful that the program became almost unreadable. The program is part of a productive customer application package. To keep privacy, it has been manually encrypted. The New Cobol Program (Result of the Transformation) * Program SAMPLE02 * Converted :25:13 * Using Njema V4.2 * Revised esc * Encrypted esc * **************************************************************** * MODULE NAME SAMPLE02 * FUNKTION xxx xxx xxx xxx xxx xxx * READ VSAM FILE (MYFILE) LOCATE MODUS * RECORD = VSAM SCH = 20 BYTE * 1. 4 BYTE FOR xxxxxx * 1. O/C OPEN/CLOSE xxxxxx * S/U/G, ZERO,BM * 3 4. VSAM ERROR RETURN CODE * 2. 4 BYTE FOR xxxxxx * 3. 8 BYTE FOR yyyyyy * 4. 4 BYTE * 1. U = OVERFLOW MODE * 2 4. EMPTY * 5. 4 BYTE MYFILE ADDR * 6. 4 BYTE xxfile ADDR * = PL 33 DATA = 53 BYTE * = PL 34 REC CNT = 2 COMP BYTE * = PL 34 TAB = 2004 BYTE * AUTHOR author IT Modernisation Services GmbH Page 1

2 * DATE * **************************************************************** * ID DIVISION. PROGRAM ID. SAMPLE02. ENVIRONMENT DIVISION. CONFIGURATION SECTION. DECIMAL POINT IS COMMA. INPUT OUTPUT SECTION. FILE CONTROL. SELECT MYFILE ASSIGN TO AS MYFILE ORGANIZATION IS INDEXED ACCESS MODE IS RANDOM RECORD KEY IS VSAMKEY FILE STATUS IS MYFILE FILE STATUS. Derived from the ACB and RPL macros DATA DIVISION. FILE SECTION. FD MYFILE. 01 MYFILE RECORD PIC X(10000). 01 FILLER REDEFINES MYFILE RECORD. 02 FILLER PIC X(54). 02 MYFILE RECORD 55B2 PIC S9(4) COMP. 02 FILLER PIC X(9944). WORKING STORAGE SECTION. * DATA AREA 01 RECAA PIC S9(8) COMP VALUE ZERO. 01 RECAA PTR REDEFINES RECAA POINTER. * HALFWORD NUMBERS * FULLWORD NUMBERS 77 H1754 PIC S9(4) VALUE H2004 PIC S9(4) VALUE F56 PIC S9(4) VALUE 56. * Definitions added by Njema 77 MYFILE FILE STATUS PIC XX. Status field automatically generated 01 VSAMKEY PIC X(9). 01 FILLER REDEFINES VSAMKEY. 02 VSAMKEY 1C1 PIC X. 02 VSAMKEY 2C8 PIC X(8). LINKAGE SECTION. COPY VSAM SCH. COPY VPL33A. * Definitions added by Njema 01 MVCL01 SOURCE PIC X(10000). 01 MVCL01 TARGET PIC X(10000). Record size is yet unknwn, hence set to a fictional value of 10,000 Artifical Cobol names are created to avoid reference modifiers. These comments are a leftover after the fields below them were removed, because they are unused. Such comments can only be removed manually. Two new COPY books were established for the whole application to allow for symbolic reference of fields. These two fields were inserted by the assembler MVCL replacement rule. IT Modernisation Services GmbH Page 2

3 PROCEDURE DIVISION USING VSAM SCH, PL EVALUATE MYFILE OPEN WHEN 'O' PERFORM GETIT WHEN 'C' PERFORM XXX CLOSE WHEN 'E' PERFORM XXX CLOSE WHEN SPACE PERFORM XXX OPEN END EVALUATE PERFORM ENDE. * Subroutines created by Njema ENDE SECTION. ******** REG. PROGRAM END SET RETURN CODE TO 0 GOBACK. If the Assembler program contains symbols, which are Reserved XXX CLOSE SECTION. Words in Cobol, they are prefixed with an arbitrary string, here XXX- ******** CLOSE MYFILE IF MYFILE OPEN NOT = 'E' CLOSE MYFILE MOVE 'C' TO MYFILE O C MOVE 'C' TO MYFILE OPEN IF VSAM22 OPEN NOT = 'E' CALL 'SUBPROG2' USING VSAM SCH IF VSAM24 OPEN NOT = 'E' CALL 'SUBPROG1' USING VSAM SCH PERFORM ENDE. GET2 SECTION. MOVE '3' TO MYFILE O C MOVE VSAM22 PL35 KEY TO VSAMKEY 1C1 MOVE VSAM22 PL36 PRUEF ID TO VSAMKEY 2C8 READ MYFILE INVALID KEY DISPLAY 'Error reading MYFILE, Status = ' MYFILE FILE STATUS UPON CONSOLE SET RETURN CODE TO 8 NOT INVALID KEY MOVE ZERO TO MYFILE O C MOVE MYFILE RECORD TO PL 33 MOVE MYFILE RECORD 55B2 TO PL34 SATZ ANZ SET RECAA PTR TO ADDRESS OF MYFILE RECORD SET RECAA PTR UP BY F56 END READ ******** ERRROR HANDLING GOBACK. The re-engineering process, applied after the conversion to Cobol, carves out the main control logic clearly. IT Modernisation Services GmbH Page 3

4 XXX OPEN SECTION. ******** OPEN MYFILE KEY LOC MODE OPEN INPUT MYFILE MOVE 'O' TO MYFILE O C MOVE 'O' TO MYFILE OPEN MOVE ZERO TO PL34 SATZ ANZ PERFORM GETIT1. GETIT SECTION. ******** READ MYFILE WHEN PL34 REC COUNT = ZERO IF PL34 SATZ ANZ NOT = ZERO *MVCL *MVCL SET ADDRESS OF MVCL01 TARGET TO ADDRESS OF PL 34 TAB SET ADDRESS OF MVCL01 SOURCE TO RECAA PTR MOVE MVCL01 SOURCE (1:H2004) TO MVCL01 TARGET SET RECAA PTR UP BY H2004 SET MYFILE ADR PTR UP BY H1754 SUBTRACT 1 FROM PL34 SATZ ANZ PERFORM ENDE. GETIT1 SECTION. MOVE ZERO TO VSAM22 STATUS MOVE ZERO TO VSAM24 STATUS IF VSAM22 PL35 KEY = 'S' CALL 'SUBPROG1' USING VSAM SCH IF VSAM24 STATUS > ZERO PERFORM ENDE PERFORM GET2 CALL 'SUBPROG2' USING VSAM SCH IF VSAM22 STATUS > ZERO PERFORM ENDE PERFORM GET2. This is the only remaining situation, where pointers are still needed. The logic of the MOVE LONG instruction requires it. IT Modernisation Services GmbH Page 4

5 The original Assembler Program * Encrypted esc * ******************************************************************* * MODULE NAME SAMPLE02 * * FUNKTION xxx xxx xxx xxx xxx xxx * * READ VSAM FILE (MYFILE) LOCATE MODUS * * RECORD = VSAM SCH = 20 BYTE * * 1. 4 BYTE FOR xxxxxx * * 1. O/C OPEN/CLOSE xxxxxx * * S/U/G, ZERO,BM * * 3 4. VSAM ERROR RETURN CODE * * 2. 4 BYTE FOR xxxxxx * * 3. 8 BYTE FOR yyyyyy * * 4. 4 BYTE * * 1. U = OVERFLOW MODE * * 2 4. EMPTY * * 5. 4 BYTE MYFILE ADDR * * 6. 4 BYTE xxfile ADDR * * = PL 33 DATA = 53 BYTE * * = PL 34 REC CNT = 2 COMP BYTE * * = PL 34 TAB = 2004 BYTE * * AUTHOR author * * DATE * * ******************************************************************* * FRAME FOR ASSEMBLER SUBROUTINES WITH PARAMETERS * * ******************************************************************* SPACE R0 EQU R1 EQU R2 EQU R3 EQU R4 EQU R5 EQU R6 EQU R7 EQU R8 EQU R9 EQU R10 EQU R11 EQU R12 EQU R13 EQU R14 EQU R15 EQU * SAMPLE02 CSECT SAMPLE02 RMODE ANY SAMPLE02 AMODE DS 0H * SAVE (14,12) STM R14,R12,12(R13) USING SAMPLE02,11, LR R11,R LA R10,4095(R11) CONNECT SAVE AREAS LA R10,1(R10) CONNECT SAVE AREAS ST R13,SAVEAREA LR R12,R LA R13,SAVEAREA ST R13,8(R12) * * * ANFANG DS 0H * LM R2,R5,0(R1) SWAP PARAMETER ADDRESSES STM R2,R5,VSSCH IT Modernisation Services GmbH Page 5

6 CLI 36(R2),C'O' MYFILE = OPEN? BE GETIT YES CLI 36(R2),C'C' CLOSE MYFILE/22/ BE CLOSE YES CLI 36(R2),C'E' CLOSE SYS022/ BE CLOSE YES CLI 36(R2),C' ' OPEN MYFILE/22/ BE OPEN YES B ENDE YES * ******** OPEN MYFILE KEY LOC MODE * OPEN DS 0H * * OPEN (MYFILE),MODE= LTR R15,R * BP ERRORX BP ERRORX MVI 0(R2),C'O' MYFILE OPEN OK MVI 36(R2),C'O' MYFILE OPEN OK SR R7,R STH R7,0(0,R4) PL34 REC COUNT = ZERO * B GETIT * ******** CLOSE MYFILE * CLOSE DS 0H * * WTO ('CLOSE MYFILE',D),('*',DE),ROUTCDE=(11),DESC=(7) CLI 36(R2),C'E' CLOSE MYFILE? BE CLO22 YES CLOSE (MYFILE),MODE= * LTR R15,R * BP ERRORX MVI 0(R2),C'C' MYFILE CLOSE OK MVI 36(R2),C'C' MYFILE CLOSE OK * * WTO ('CALLC 10=>20',D),('*',DE),ROUTCDE=(11),DESC=(7) CLO22 DS 0H CLI 37(R2),C'E' CLOSE SYS022? BE CLO23 YES CALL SUBPROG2,((R2)) * WTO ('CALLC 10=>30',D),('*',DE),ROUTCDE=(11),DESC=(7) CLO23 DS 0H CLI 38(R2),C'E' CLOSE SYS024? BE ENDE YES CALL SUBPROG1,((R2)) B ENDE * ******** READ MYFILE WHEN PL34 REC COUNT = ZERO * GETIT DS 0H * SR R8,R CH R8,0(0,R4) PL34 REC COUNT = ZERO? BNE GETIT2 NEXT PL 34 TAB * GETIT1 DS 0H * MVC 6(2,R2),C MVC 22(2,R2),C * CLI 8(R2),C'S' S CODE? BE GET * WTO ('CALLG 10=>20',D),('*',DE),ROUTCDE=(11),DESC=(7) CALL SUBPROG2,((R2)) V CODE * IT Modernisation Services GmbH Page 6

7 CLC 6(2,R2),C00 16=REC NOT THERE, 99=COUNT = ZERO BH ENDE B GET * GET1 DS 0H * * WTO ('CALLG 10=>30',D),('*',DE),ROUTCDE=(11),DESC=(7) CALL SUBPROG1,((R2)) S CODE * CLC 22(2,R2),C00 16=REC NOT THERE, 99=COUNT = ZERO BH ENDE * GET2 DS 0H * MVI 0(R2),C'3' VSSCH = 3 (GET MODUS) * MVC VSAMKEY(1),8(R2) MVC VSAMKEY+1(8),12(R2) GET RPL=MYRPL READ MYFILE LTR R15,R * BP ERRORX BP ERRORX * MVI 0(R2),C'O' MYFILE GET OK (OPEN MODUS) L R6,AR2 START REC ADDR. IN MYFILE REC MVC 0(54,R3),0(R6) MVC 0(2,R4),54(R6) L R9,F56 R9 = AR R6,R ST R6,RECAA * GETIT2 DS 0H *MVCL LR R8,R L R6,RECAA XR R7,R XR R9,R LH R7,H LH R9,H * ICM R7,B'1000',=X'40' * LR R9,R MVCL R8,R L R6,RECAA AH R6,H ST R6,RECAA AH R5,H ST R5,ST5 R5 = MVC 24(4,R2),ST *MVCL * L R6,RECAA * MVC 0(254,R5),0(R6) BYTE TO 1. PL 34 TAB * L R9,F254 R9 = * AR R5,R * AR R6,R * L R9,F250 R9 = * LA R7,GETIT3 R7 = ADDR. GETIT * L R8,F7 R8 = * GETIT3 DS 0H * * MVC 0(250,R5),0(R6) * ST R5,ST5 R5 = * MVC 24(4,R2),ST * AR R5,R * AR R6,R * BCTR R8,R7 BRANCH TO GETIT * ST R6,RECAA * L R5,PL34T R5 = START TAB AREA IT Modernisation Services GmbH Page 7

8 LH R8,0(0,R4) SH R8,H STH R8,0(0,R4) B ENDE * ******** ERRROR HANDLING * ERRORX DS 0H ERROR HANDLING * MVC LAUS+27(18),=C'10 R15/ERROR/MESS=' CVD R15,DWORT UNPK HILF(16),DWORT(8) MVZ HILF+15(1),FF ZONES MVC LAUS+47(4),HILF * CLI 0(R2),C'3' MYFILE GET ERROR BE ERRORX3 YES * SHOWCB ACB=MYFILE,AREA=AR1,LENGTH=12,FIELDS=(ERROR,MAREA,MLEN) * L R9,AR1 ADDR. OF AR CVD R9,DWORT UNPK HILF(16),DWORT(8) MVZ HILF+15(1),FF MVC LAUS+52(4),HILF+12 ERROR TO LISTING * L R9,AR1+4 MESSAGE ADDRESS L R10,AR1+8 MESSAGE LENGTH BCTR R10,0 MESSAGE LENGTH STC R10,MVC1+1 MESSAGE LENGTH TO MVC MVC1 MVC LAUS+57(0),0(R9) * * CLI AR1+7,X'01' MYFILE OPEN ERROR? CLI AR1+7,X'02' MYFILE CLOSE ERROR? BE ERRORX2 YES * ERRORX1 DS 0H MYFILE OPEN ERROR * MVC LAUS+1(24),=C'OPEN ERROR IN MYFILE ' B ERRORX9 YES * ERRORX2 DS 0H MYFILE CLOSE ERROR * MVC LAUS+1(24),=C'CLOSE ERROR IN MYFILE ' B ERRORX9 YES * ERRORX3 DS 0H MYFILE GET ERROR * MVC 2(2,R2),C16 REC NOT FOUND => VSAM SCH MVC LAUS+1(24),=C'GET ERROR IN MYFILE ' MVC LAUS+27(15),=C'R15/FDBK/FTNCD=' * SHOWCB RPL=RPL21,AREA=AR1,LENGTH=8,FIELDS=(FDBK,FTNCD) * L R9,AR1 ADDR. OF FDBK CVD R9,DWORT UNPK HILF(16),DWORT(8) MVZ HILF+15(1),FF MVC LAUS+52(4),HILF * L R9,AR1+4 ADDR. OF FTNCD CVD R9,DWORT UNPK HILF(16),DWORT(8) MVZ HILF+15(1),FF MVC LAUS+57(4),HILF B ERRORX9 YES * ERRORX9 DS 0H EXIT SUBROUTINE IF ERROR * IT Modernisation Services GmbH Page 8

9 MVC WTO2+8(100),LAUS DS 0H WTO2 WTO (' ',D), ('*',DE),ROUTCDE=(11),DESC=(7) * CLI 0(R2),C'3' MYFILE GET ERROR BNE ERRORX MVC LAUS+1(8),=C'VSAMKEY=' MVC LAUS+9(9),VSAMKEY VSAMKEY MVC LAUS+18(16),=C' VSAM PL35 KEY=' MVC LAUS+34(4),8(R2) MVC WTO3+8(100),LAUS DS 0H WTO3 WTO (' ',D), ('*',DE),ROUTCDE=(11),DESC=(7) * ERRORX10 DS 0H EXIT SUBROUTINE IF ERROR L R13,4(R13) RETURN (14,12),RC= * ******** REG. PROGRAM END * ENDE DS 0H * L R13,4(R13) * RETURN (14,12),RC= LM R14,R12,12(R13) LA R15,0(0,0) BR R * * DATA AREA * DS 0F SAVEAREA DC 18F'0' SAVE AREAS DS 0F ST0 DS F R ST1 DS F R ST2 DS F R ST3 DS F R ST4 DS F R ST5 DS F R ST6 DS F R ST7 DS F R ST8 DS F R ST9 DS F R ST15 DS F R DS 0F VAR. ADDRESSES VSSCH DS F VSAM SWITCH (OPEN/CLOSE) PL33 DS F PL 33 DATA (53 BYTES) PL34A DS F PL34 REC CNT (S9999 COMP) PL34T DS F PL 34 TAB (2004 LANG) DS 0F SAVE INT.AREAS RECAA DS F ADDR. MYFILE RECORD * DS 0F P1 DC P'1' * HALFWORD NUMBERS * FULLWORD NUMBERS DS 0F BINARY REGISTER NUMBERS FULLWORD F1 DC F'1' H0 DC H'0' H1 DC H'1' H1754 DC H'1754' H2004 DC H'2004' DS 0F F7 DC F'7' F56 DC F'56' IT Modernisation Services GmbH Page 9

10 F250 DC F'250' FOR MOVE > F254 DC F'254' DS 0D DWORT DS D AR1 DS 10F AREA FOR SHOWCB AR2 DS CL VSAMKEY DS CL9 KEY FOR MYFILE HILF DS CL16 FOR UNPACK (SHOWCB) DS 0F FF DC X'FF' LAUS DC 120X'40' C00 DC C'00' OK STATUS C16 DC C'16' REC NOT FOUND C99 DC C'99' DS 0F DC C'SAMPLE02 CREATION : ,09.30 ' LTORG MYFILE ACB AM=VSAM,DDNAME=MYFILE,MACRF=(KEY,DIR,IN) MYRPL RPL ACB=MYFILE,AM=VSAM,AREA=AR2,AREALEN=4,ARG=VSAMKEY,KEYLEN =9,OPTCD=(KEY,DIR,SYN,NUP,KEQ,FKS,LOC) END SAMPLE IT Modernisation Services GmbH Page 10