422 lines
11 KiB
C
422 lines
11 KiB
C
/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: sort.c *
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* Last rev: *
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* mods: *
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* comments: sorting in Prolog *
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* *
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*************************************************************************/
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/* for the moment, follow Prolog's traditional mergesort */
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#include "Yap.h"
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#include "Yatom.h"
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#include "YapHeap.h"
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#ifndef NULL
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#define NULL (void *)0
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#endif
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/* fill in the even or the odd elements */
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#define M_EVEN 0
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#define M_ODD 1
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static Int build_new_list(CELL *, Term CACHE_TYPE);
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static void simple_mergesort(CELL *, Int, int);
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static Int compact_mergesort(CELL *, Int, int);
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static int key_mergesort(CELL *, Int, int, Functor);
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static void adjust_vector(CELL *, Int);
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static Int p_sort( USES_REGS1 );
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static Int p_msort( USES_REGS1 );
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static Int p_ksort( USES_REGS1 );
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/* copy to a new list of terms */
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static Int
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build_new_list(CELL *pt, Term t USES_REGS)
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{
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Int out = 0;
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if (IsVarTerm(t))
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return(-1);
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if (t == TermNil)
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return(0);
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restart:
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while (IsPairTerm(t)) {
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out++;
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pt[0] = HeadOfTerm(t);
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t = TailOfTerm(t);
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if (IsVarTerm(t))
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return(-1);
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if (t == TermNil) {
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return(out);
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}
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pt += 2;
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if (pt > ASP - 4096) {
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if (!Yap_gcl((ASP-HR)*sizeof(CELL), 2, ENV, gc_P(P,CP))) {
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Yap_Error(OUT_OF_STACK_ERROR, TermNil, LOCAL_ErrorMessage);
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return(FALSE);
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}
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t = Deref(ARG1);
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pt = HR;
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out = 0;
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goto restart;
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}
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}
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return(-1);
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}
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/* copy to a new list of terms */
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static
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void simple_mergesort(CELL *pt, Int size, int my_p)
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{
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if (size > 2) {
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Int half_size = size / 2;
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CELL *pt_left, *pt_right, *end_pt, *end_pt_left;
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int left_p, right_p;
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pt_right = pt + half_size*2;
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left_p = my_p^1;
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right_p = my_p;
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simple_mergesort(pt, half_size, left_p);
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simple_mergesort(pt_right, size-half_size, right_p);
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/* now implement a simple merge routine */
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/* pointer to after the end of the list */
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end_pt = pt + 2*size;
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/* pointer to the element after the last element to the left */
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end_pt_left = pt+half_size*2;
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/* where is left list */
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pt_left = pt+left_p;
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/* where is right list */
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pt_right += right_p;
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/* where is new list */
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pt += my_p;
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/* while there are elements in the left or right vector do compares */
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while (pt_left < end_pt_left && pt_right < end_pt) {
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/* if the element to the left is larger than the one to the right */
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if (Yap_compare_terms(pt_left[0], pt_right[0]) <= 0) {
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/* copy the one to the left */
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pt[0] = pt_left[0];
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/* and avance the two pointers */
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pt += 2;
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pt_left += 2;
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} else {
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/* otherwise, copy the one to the right */
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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/* if any elements were left in the left vector just copy them */
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while (pt_left < end_pt_left) {
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pt[0] = pt_left[0];
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pt += 2;
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pt_left += 2;
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}
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/* if any elements were left in the right vector
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and they are in the wrong place, just copy them */
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if (my_p != right_p) {
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while(pt_right < end_pt) {
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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} else {
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if (size > 1 && (Yap_compare_terms(pt[0],pt[2]) > 0)) {
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CELL t = pt[2];
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pt[2+my_p] = pt[0];
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pt[my_p] = t;
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} else if (my_p) {
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pt[1] = pt[0];
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if (size > 1)
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pt[3] = pt[2];
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}
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}
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}
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/* copy to a new list of terms */
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static
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int key_mergesort(CELL *pt, Int size, int my_p, Functor FuncDMinus)
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{
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if (size > 2) {
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Int half_size = size / 2;
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CELL *pt_left, *pt_right, *end_pt, *end_pt_left;
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int left_p, right_p;
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pt_right = pt + half_size*2;
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left_p = my_p^1;
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right_p = my_p;
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if (!key_mergesort(pt, half_size, left_p, FuncDMinus))
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return(FALSE);
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if (!key_mergesort(pt_right, size-half_size, right_p, FuncDMinus))
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return(FALSE);
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/* now implement a simple merge routine */
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/* pointer to after the end of the list */
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end_pt = pt + 2*size;
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/* pointer to the element after the last element to the left */
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end_pt_left = pt+half_size*2;
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/* where is left list */
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pt_left = pt+left_p;
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/* where is right list */
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pt_right += right_p;
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/* where is new list */
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pt += my_p;
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/* while there are elements in the left or right vector do compares */
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while (pt_left < end_pt_left && pt_right < end_pt) {
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/* if the element to the left is larger than the one to the right */
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Term t0 = pt_left[0] , t1 = pt_right[0];
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if (IsVarTerm(t0) || !IsApplTerm(t0) || FunctorOfTerm(t0) != FuncDMinus)
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return(FALSE);
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t0 = ArgOfTerm(1,t0);
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if (IsVarTerm(t1) || !IsApplTerm(t1) || FunctorOfTerm(t1) != FuncDMinus)
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return(FALSE);
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t1 = ArgOfTerm(1,t1);
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if (Yap_compare_terms(t0, t1) <= 0) {
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/* copy the one to the left */
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pt[0] = pt_left[0];
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/* and avance the two pointers */
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pt += 2;
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pt_left += 2;
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} else {
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/* otherwise, copy the one to the right */
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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/* if any elements were left in the left vector just copy them */
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while (pt_left < end_pt_left) {
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pt[0] = pt_left[0];
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pt += 2;
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pt_left += 2;
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}
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/* if any elements were left in the right vector
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and they are in the wrong place, just copy them */
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if (my_p != right_p) {
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while(pt_right < end_pt) {
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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}
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}
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} else {
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if (size > 1) {
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Term t0 = pt[0], t1 = pt[2];
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if (IsVarTerm(t0) || !IsApplTerm(t0) || FunctorOfTerm(t0) != FuncDMinus)
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return(FALSE);
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t0 = ArgOfTerm(1,t0);
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if (IsVarTerm(t1) || !IsApplTerm(t1) || FunctorOfTerm(t1) != FuncDMinus)
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return(FALSE);
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t1 = ArgOfTerm(1,t1);
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if (Yap_compare_terms(t0,t1) > 0) {
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CELL t = pt[2];
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pt[2+my_p] = pt[0];
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pt[my_p] = t;
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} else if (my_p) {
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pt[1] = pt[0];
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pt[3] = pt[2];
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}
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} else {
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if (my_p)
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pt[1] = pt[0];
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}
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}
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return(TRUE);
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}
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/* copy to a new list of terms and compress duplicates */
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static
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Int compact_mergesort(CELL *pt, Int size, int my_p)
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{
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if (size > 2) {
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Int half_size = size / 2;
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CELL *pt_left, *pt_right, *end_pt_right, *end_pt_left;
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int left_p, right_p;
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Int lsize, rsize;
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pt_right = pt + half_size*2;
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left_p = my_p^1;
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right_p = my_p;
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lsize = compact_mergesort(pt, half_size, left_p);
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rsize = compact_mergesort(pt_right, size-half_size, right_p);
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/* now implement a simple merge routine */
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/* where is left list */
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pt_left = pt+left_p;
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/* pointer to the element after the last element to the left */
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end_pt_left = pt+2*lsize;
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/* where is right list */
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pt_right += right_p;
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/* pointer to after the end of the list */
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end_pt_right = pt_right + 2*rsize;
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/* where is new list */
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pt += my_p;
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size = 0;
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/* while there are elements in the left or right vector do compares */
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while (pt_left < end_pt_left && pt_right < end_pt_right) {
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/* if the element to the left is larger than the one to the right */
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Int cmp = Yap_compare_terms(pt_left[0], pt_right[0]);
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if (cmp < (Int)0) {
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/* copy the one to the left */
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pt[0] = pt_left[0];
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/* and avance the two pointers */
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pt += 2;
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size ++;
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pt_left += 2;
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} else if (cmp == (Int)0) {
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/* otherwise, just skip one of them, anyone */
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pt_left += 2;
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} else {
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/* otherwise, copy the one to the right */
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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size++;
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}
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}
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/* if any elements were left in the left vector just copy them */
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while (pt_left < end_pt_left) {
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pt[0] = pt_left[0];
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pt += 2;
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pt_left += 2;
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size++;
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}
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/* if any elements were left in the right vector
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and they are in the wrong place, just copy them */
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while(pt_right < end_pt_right) {
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pt[0] = pt_right[0];
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pt += 2;
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pt_right += 2;
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size++;
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}
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return(size);
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} else if (size == 2) {
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Int cmp = Yap_compare_terms(pt[0],pt[2]);
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if (cmp > 0) {
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/* swap */
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CELL t = pt[2];
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pt[2+my_p] = pt[0];
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pt[my_p] = t;
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return(2);
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} else if (cmp == 0) {
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if (my_p)
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pt[1] = pt[0];
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return(1);
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} else {
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if (my_p) {
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pt[1] = pt[0];
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pt[3] = pt[2];
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}
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return(2);
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}
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} else {
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/* size = 1 */
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if (my_p)
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pt[1] = pt[0];
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return(1);
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}
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}
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static void
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adjust_vector(CELL *pt, Int size)
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{
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/* the elements are where they should be */
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CELL *ptf = pt + 2*(size-1);
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pt ++;
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while (pt < ptf) {
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pt[0] = AbsPair(pt+1);
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pt += 2;
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}
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/* close the list */
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pt[0] = TermNil;
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}
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static Int
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p_sort( USES_REGS1 )
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{
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/* use the heap to build a new list */
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CELL *pt = HR;
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Term out;
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/* list size */
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Int size;
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size = build_new_list(pt, Deref(ARG1) PASS_REGS);
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if (size < 0)
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return(FALSE);
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if (size < 2)
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return(Yap_unify(ARG1, ARG2));
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pt = HR; /* because of possible garbage collection */
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/* make sure no one writes on our temp data structure */
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HR += size*2;
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/* reserve the necessary space */
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size = compact_mergesort(pt, size, M_EVEN);
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/* reajust space */
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HR = pt+size*2;
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adjust_vector(pt, size);
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out = AbsPair(pt);
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return(Yap_unify(out, ARG2));
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}
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static Int
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p_msort( USES_REGS1 )
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{
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/* use the heap to build a new list */
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CELL *pt = HR;
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Term out;
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/* list size */
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Int size;
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size = build_new_list(pt, Deref(ARG1) PASS_REGS);
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if (size < 0)
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return(FALSE);
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if (size < 2)
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return(Yap_unify(ARG1, ARG2));
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pt = HR; /* because of possible garbage collection */
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/* reserve the necessary space */
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HR += size*2;
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simple_mergesort(pt, size, M_EVEN);
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adjust_vector(pt, size);
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out = AbsPair(pt);
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return(Yap_unify(out, ARG2));
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}
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static Int
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p_ksort( USES_REGS1 )
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{
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/* use the heap to build a new list */
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CELL *pt = HR;
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Term out;
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/* list size */
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Int size;
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size = build_new_list(pt, Deref(ARG1) PASS_REGS);
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if (size < 0)
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return(FALSE);
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if (size < 2)
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return(Yap_unify(ARG1, ARG2));
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/* reserve the necessary space */
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pt = HR; /* because of possible garbage collection */
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HR += size*2;
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if (!key_mergesort(pt, size, M_EVEN, FunctorMinus))
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return(FALSE);
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adjust_vector(pt, size);
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out = AbsPair(pt);
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return(Yap_unify(out, ARG2));
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}
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void
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Yap_InitSortPreds(void)
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{
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Yap_InitCPred("$sort", 2, p_sort, 0);
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Yap_InitCPred("$msort", 2, p_msort, 0);
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Yap_InitCPred("$keysort", 2, p_ksort, 0);
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}
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