test/hyperoid/list.c

   1 //
   2 // LIST - list processing functions for orbiter
   3 //
   4 // Version: 1.0  Copyright (C) 1990, Hutchins Software
   5 // Author: Edward Hutchins
   6 // Revisions:
   7 //
   8
   9 #include "orbiter.h"
  10
  11 //
  12 // AddHead - add an object to the head of a list
  13 //
  14
  15 VOID FAR PASCAL AddHead( NPLIST npList, NPNODE npNode )
  16 {
  17         if (npList->npHead)
  18         {
  19                 npNode->npNext = npList->npHead;
  20                 npNode->npPrev = NULL;
  21                 npList->npHead = (npList->npHead->npPrev = npNode);
  22         }
  23         else // add to an empty list
  24         {
  25                 npList->npHead = npList->npTail = npNode;
  26                 npNode->npNext = npNode->npPrev = NULL;
  27         }
  28 }
  29
  30 //
  31 // RemHead - remove the first element in a list
  32 //
  33
  34 NPNODE FAR PASCAL RemHead( NPLIST npList )
  35 {
  36         if (npList->npHead)
  37         {
  38                 NPNODE npNode = npList->npHead;
  39                 if (npList->npTail != npNode)
  40                 {
  41                         npList->npHead = npNode->npNext;
  42                         npNode->npNext->npPrev = NULL;
  43                 }
  44                 else npList->npHead = npList->npTail = NULL;
  45                 return( npNode );
  46         }
  47         else return( NULL );
  48 }
  49
  50 //
  51 // Remove - remove an arbitrary element from a list
  52 //
  53
  54 VOID FAR PASCAL Remove( NPLIST npList, NPNODE npNode )
  55 {
  56         if (npNode->npPrev) npNode->npPrev->npNext = npNode->npNext;
  57         else npList->npHead = npNode->npNext;
  58         if (npNode->npNext) npNode->npNext->npPrev = npNode->npPrev;
  59         else npList->npTail = npNode->npPrev;
  60 }
  61