52 lines
1.5 KiB
Plaintext
52 lines
1.5 KiB
Plaintext
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IDENTIFICATION DIVISION.
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PROGRAM-ID. SIEVE.
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* REMARKS. BYTE magazine benchmark.
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ENVIRONMENT DIVISION.
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CONFIGURATION SECTION.
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DATA DIVISION.
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WORKING-STORAGE SECTION.
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01 MISC.
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03 I PIC 9(4) COMP.
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03 PRIME PIC 9(5) COMP.
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03 K PIC 9(4) COMP.
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03 TOTAL-PRIME-COUNT PIC 9(4) COMP.
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02 SIEVETABLE.
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04 FLAGS PIC 9 COMP OCCURS 8191 TIMES.
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01 NUM-DISP PIC 9999.
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PROCEDURE DIVISION.
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MAIN.
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PERFORM ITER-ROUTINE 10 TIMES.
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MOVE TOTAL-PRIME-COUNT TO NUM-DISP.
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DISPLAY NUM-DISP ' primes'.
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STOP RUN.
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ITER-ROUTINE.
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MOVE ZEROES TO TOTAL-PRIME-COUNT.
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PERFORM TFR VARYING I FROM 1 BY 1 UNTIL I = 8191.
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PERFORM DCP THRU DCE VARYING I FROM 0 BY 1 UNTIL I = 8190.
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TFR.
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MOVE 1 TO FLAGS(I).
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DCP.
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IF FLAGS( I + 1 ) = 0
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GO TO DCE.
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COMPUTE PRIME = I + I + 3.
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COMPUTE K = I + PRIME.
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FIRST1.
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IF K > 8190 GO TO NEXT1.
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MOVE 0 TO FLAGS( K + 1 ).
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COMPUTE K = PRIME + K.
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GO TO FIRST1.
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NEXT1.
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ADD 1 TO TOTAL-PRIME-COUNT.
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* MOVE PRIME TO NUM-DISP.
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* DISPLAY 'FOUND PRIME = ' NUM-DISP.
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DCE.
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EXIT.
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