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#include "slist.h"
#include "threads/malloc.h"
#include <stdio.h>
// #include <stdlib.h>
/* List structure */
struct Node
{
ListElement Element;
Position Next;
};
/* make empty list */
SList
MakeEmpty( SList L )
{
if( L != NULL )
DeleteList( L );
L = malloc( sizeof( struct Node ) );
if( L == NULL ) {
printf( "Out of memory!\n" );
return NULL;
}
L->Next = NULL;
return L;
}
/* Return true if L is empty */
int
IsEmpty( SList L )
{
return L->Next == NULL;
}
/* Return true if P is the last position in SList L */
/* Parameter L is unused in this implementation */
int IsLast( Position P, UNUSED SList L)
{
return P->Next == NULL;
}
/* Return Position of X in L; NULL if not found */
Position
Find( ListElement X, SList L )
{
Position P;
P = L->Next;
while( P != NULL && P->Element != X )
P = P->Next;
return P;
}
/* Delete from a SList */
/* Cell pointed to by P->Next is wiped out */
/* Assume that the position is legal */
/* Assume use of a header node */
void
Delete( ListElement X, SList L )
{
Position P, TmpCell;
P = FindPrevious( X, L );
if( !IsLast( P, L ) ) /* Assumption of header use */
{ /* X is found; delete it */
TmpCell = P->Next;
P->Next = TmpCell->Next; /* Bypass deleted cell */
free( TmpCell );
}
}
/* If X is not found, then Next field of returned value is NULL */
/* Assumes a header */
Position
FindPrevious( ListElement X, SList L )
{
Position P;
P = L;
while( P->Next != NULL && P->Next->Element != X )
P = P->Next;
return P;
}
/* Insert (after legal position P) */
/* Header implementation assumed */
/* Parameter L is unused in this implementation */
void
Insert( ListElement X, UNUSED SList L, Position P )
{
Position TmpCell;
TmpCell = malloc( sizeof( struct Node ) );
if( TmpCell == NULL ) {
printf( "Out of space!!!\n" );
return;
}
TmpCell->Element = X;
TmpCell->Next = P->Next;
P->Next = TmpCell;
}
/* DeleteSList algorithm */
void
DeleteList( SList L )
{
Position P, Tmp;
P = L->Next; /* Header assumed */
L->Next = NULL;
while( P != NULL )
{
Tmp = P->Next;
free( P );
P = Tmp;
}
}
Position
Header( SList L )
{
return L;
}
Position
First( SList L )
{
return L->Next;
}
Position
Advance( Position P )
{
return P->Next;
}
ListElement
Retrieve( Position P )
{
return P->Element;
}
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