First of all,I'm sorry about asking so many questions over the last few days.
My question is as below.
In the program below,
After the LTR instruction in GETSEM routine,there is a BP NEXTSEM instruction.Now in NEXTSEM routine,there is BCT R8,GETSEM.
My question is when R8 becomes zero which instruction would be executed next ? Would the control come back to instruction after BP NEXTSEM which is PERLOOP BR RC or would the NEXTMEET AH R8,SIX instruction be executed ?
I'm trying to understand when PERLOOP BR RC instruction is executed.
PUNCH ' ALIAS XXXQ71S2' 00001100
XXXQ71S1 START 0 00001200
ENTRY XXXQ71S2 00001300
EXTRN XXXQVLST 00001400
USING *,15 00001500
B COIBMEND 00001600
* 00001700
* 00002000
R0 EQU 0 00002100
R1 EQU 1 ADDR OF STUDENT ARRAY -- 00002200
* ASSIGNED DAYS 00002300
R2 EQU 2 ADDR OF MEETING TIME TABLE 00002400
R3 EQU 3 ADDR OF LOOP CONTROL DATA 00002500
R4 EQU 4 ADDR OF CLASS RECORD 00002600
R5 EQU 5 00002700
R6 EQU 6 00002800
R7 EQU 7 00002900
R8 EQU 8 00003000
R9 EQU 9 00003100
RA EQU 10 00003200
RB EQU 11 00003300
RC EQU 12 BR REG FOR BIT OPERATION 00003400
RD EQU 13 00003500
RE EQU 14 BR REG FOR NEXT INSTRUCTION 00003600
RF EQU 15 00003700
* 00003800
COIBMEND EQU * 00003900
SAVE (14,12) 00004000
L RA,=A(XXXQVLST) LOAD ADDR OF PARAMETER LIST 00004100
LM R1,R4,0(RA) 00004200
LA RF,XXXQ71S2 00004300
USING XXXQ71S2,RF 00004400
LA RC,TESTBITS POINT BR REG TO TM INST 00004500
LA RE,ASGNBITS 00004600
B STARTOP 00004700
XXXQ71S2 SAVE (14,12) 00004800
L RA,=A(XXXQVLST) LOAD ADDR OF PARAMETER LIST 00004900
LM R1,R4,0(RA) 00005000
LA RC,XORBITS POINT BR REQ TO XOR INST 00005100
LA RE,RETURNIT 00005200
STARTOP LA R6,1 R6 = CONSTANT 1 00005300
LH R8,2(R3) LOAD LAST SEM BIT VALUE 00005400
AR R8,R6 INCR LAST VALUE BY 1 00005500
LH RA,0(R3) LOAD FIRST SEM BIT VALUE 00005600
SR R8,RA SUBT FIRST FROM LAST 00005700
STH R8,HLDSEMS SAVE NUMB SEMS TO BE 00005800
* PROCESSED 00005900
* 00006000
* 00006100
* INIT SUBROUTINE FOR EACH BIT OPER 00006200
* 00006300
INIT LH RB,12(R4) LOAD INDEX TO MT TABLE 00006400
* ENTRY 00006500
MH RB,SIX MULT INDEX BY SIX 00006600
AR RB,R2 ADD ADDR OF MT TABLE 00006700
LH R0,14(R4) LOAD NUMB OF MT ENTRIES 00006800
* 00006900
* PROCESS EACH MT ENTRY CLASS MEETS 00007000
* 00007100
NEWMEET MVC TESTBITS+1(1),1(RB) INSERT DAYS MET IN BIT 00007200
* INSTRUCTIONS 00007400
MVC ORBITS+1(1),1(RB) 00007400
MVC XORBITS+1(1),1(RB) 00007500
LH R8,HLDSEMS R8 = NUMD SEMS TO PROCESS 00007600
LH RA,0(R3) 00007700
IC R9,0(RB) INSERT SEM BITS IN REG 9 00007800
SLL R9,23(RA) SHIFT TO FIRST SEM BIT 00007900
LR RA,R1 LOAD ADDR OF STUDN ARRAY 00008000
LH R7,4(RB) LOAD END PER OF MT ENTRY 00008100
AR R7,RA ADD ARRAY ADDR 00008200
* 00008205
* PROCESS EACH SEM MT ENTRY MEETS 00008210
* 00008215
GETSEM LH R5,2(RB) LOAD START PER OF MT ENTRY 00008220
AR R5,RA ADD ARRAY ADDR 00008225
SLL R9,1 SHIFT SEM BIT TO SIGN 00008230
* POSITION 00008235
LTR R9,R9 TEST SEM BIT VALUE 00008240
BZ NEXTMEET NO SEM BITS LEFT 00008245
BP NEXTSEM SEM BIT = 0 00008250
* 00008300
* PROCESS ALL PERIODS FOR EACH SEM 00008400
* 00008500
PERLOOP BR RC BRANCH TO BIT INSTRUCTIONS 00008600
* TESTBITS - CHECK CONFLICTS 00008605
* ORBITS - ASSIGN SECTION 00008610
* XORBITS - UNASSIGN SECTION 00008615
TESTBITS TM 0(R5),X'00' TEST ARRAY FOR CONFLICT 00008700
BC 5,SETCONFL 00008800
LOOPCTL BXLE R5,R6,PERLOOP INCR TO NEXT PERIOD 00008900
* 00009000
* INCR TO NEXT SEM MT ENTRY MEETS 00009100
* 00009200
NEXTSEM AH RA,4(R3) 00009300
AH R7,4(R3) 00009400
BCT R8,GETSEM ARE ALL SEMESTERS PROCESSED 00009500
* 00009600
* INCR TO NEXT MT ENTRY CLASS MEETS 00009700
* 00009800
NEXTMEET AH RB,SIX 00009900
BCT R0,NEWMEET ARE ALL MT ENTRIES PROCESSD 00010000
BR RE 00010100
SETCONFL MVI 16(R4),C'Y' TURN ON CONFLICT SWCH 00010200
RETURNIT RETURN (14,12),RC=0 RETURN TO MAIN LINE 1-5 00010300
* 00010400
* PROCESS NON CONFLICTING CLASS 00010500
* 00010600
ASGNBITS LA RC,ORBITS POINT BR REG TO OR INSTR 00010700
LA RE,RETURNIT 00010800
B INIT 00010900
ORBITS OI 0(R5),X'00' ASSIGN MT ENTRY TO STUDN 00011000
* ARRAY 00011100
B LOOPCTL 00011200
* 00011300
* BACK OUT PERVIOUS ASSIGNMENTS 00011400
* 00011500
XORBITS XI 0(R5),X'00' UNASSIGN MT ENTRY FROM 00011600
* ARRAY 00011700
B LOOPCTL 00011800
SIX DC H'6' 00012000
HLDSEMS DC H'0' 00012100
END 00012200
/*
