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Task/Sorting-algorithms-Shell-sort/COBOL/sorting-algorithms-shell-sort.cobol

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+       C-PROCESS SECTION.
+       C-000.
+           DISPLAY "SORT STARTING".
+
+           DIVIDE WC-SIZE BY 2 GIVING WC-GAP.
+
+           PERFORM E-PROCESS-GAP UNTIL WC-GAP = 0.
+
+           DISPLAY "SORT FINISHED".
+
+       C-999.
+           EXIT.
+
+
+       E-PROCESS-GAP SECTION.
+       E-000.
+           PERFORM F-SELECTION VARYING WB-IX-1 FROM WC-GAP BY 1
+                               UNTIL WB-IX-1 > WC-SIZE.
+
+           DIVIDE WC-GAP BY 2.2 GIVING WC-GAP.
+
+       E-999.
+           EXIT.
+
+       F-SELECTION SECTION.
+       F-000.
+           SET WB-IX-2            TO WB-IX-1.
+           MOVE WB-ENTRY(WB-IX-1) TO WC-TEMP.
+
+           SET WB-IX-3 TO WB-IX-2.
+           SET WB-IX-3 DOWN BY WC-GAP.
+           PERFORM G-PASS UNTIL WB-IX-2 NOT > WC-GAP
+      * The next line logically reads :
+      *                   or wb-entry(wb-ix-2 - wc-gap) not > wc-temp.
+                          OR WB-ENTRY(WB-IX-3) NOT > WC-TEMP.
+
+           IF WB-IX-1 NOT = WB-IX-2
+              MOVE WC-TEMP TO WB-ENTRY(WB-IX-2).
+
+       F-999.
+           EXIT.
+
+       G-PASS SECTION.
+      * Note that WB-IX-3 is WC-GAP less than WB-IX-2.
+      * Logically this should be :
+      *    move wb-entry(wb-ix-2 - wc-gap) to wb-entry(wb-ix-2).
+      *    set wb-ix-2 down by wc-gap.
+      * Unfortunately wb-entry(wb-ix-2 - wc-gap) is not legal in C2 cobol
+       G-000.
+           MOVE WB-ENTRY(WB-IX-3) TO WB-ENTRY(WB-IX-2).
+           SET WB-IX-2            DOWN BY WC-GAP.
+           SET WB-IX-3            DOWN BY WC-GAP.
+
+       G-999.
+           EXIT.