Initial data commit

Task/Sorting-algorithms-Merge-sort/PL-I/sorting-algorithms-merge-sort.pli

@@ -0,0 +1,49 @@
+MERGE: PROCEDURE (A,LA,B,LB,C);
+
+/* Merge A(1:LA) with B(1:LB), putting the result in C
+   B and C may share the same memory, but not with A.
+*/
+   DECLARE (A(*),B(*),C(*)) BYADDR POINTER;
+   DECLARE (LA,LB) BYVALUE NONASGN FIXED BIN(31);
+   DECLARE (I,J,K) FIXED BIN(31);
+   DECLARE (SX) CHAR(58) VAR BASED (PX);
+   DECLARE (SY) CHAR(58) VAR BASED (PY);
+   DECLARE (PX,PY) POINTER;
+
+   I=1; J=1; K=1;
+   DO WHILE ((I <= LA) & (J <= LB));
+      PX=A(I); PY=B(J);
+      IF(SX <= SY) THEN
+         DO; C(K)=A(I); K=K+1; I=I+1; END;
+      ELSE
+         DO; C(K)=B(J); K=K+1; J=J+1; END;
+   END;
+   DO WHILE (I <= LA);
+      C(K)=A(I); I=I+1; K=K+1;
+   END;
+   RETURN;
+END MERGE;
+
+MERGESORT: PROCEDURE (AP,N) RECURSIVE ;
+
+/* Sort the array AP containing N pointers to strings */
+
+     DECLARE (AP(*))              BYADDR POINTER;
+     DECLARE (N)                  BYVALUE NONASGN FIXED BINARY(31);
+     DECLARE (M,I)                FIXED BINARY;
+     DECLARE AMP1(1)              POINTER BASED(PAM);
+     DECLARE (pX,pY,PAM) POINTER;
+     DECLARE SX CHAR(58) VAR BASED(pX);
+     DECLARE SY CHAR(58) VAR BASED(pY);
+
+   IF (N=1) THEN RETURN;
+   M = trunc((N+1)/2);
+   IF (M>1) THEN CALL MERGESORT(AP,M);
+   PAM=ADDR(AP(M+1));
+   IF (N-M > 1) THEN CALL MERGESORT(AMP1,N-M);
+   pX=AP(M); pY=AP(M+1);
+   IF SX <= SY then return;     /* Skip Merge */
+   DO I=1 to M; TP(I)=AP(I); END;
+   CALL MERGE(TP,M,AMP1,N-M,AP);
+   RETURN;
+END MERGESORT;