workbench/fs/pipe/pipelists.c

   1 /****************************************************************************
   2 **  File:       pipelists.c
   3 **  Program:    pipe-handler - an AmigaDOS handler for named pipes
   4 **  Version:    1.1
   5 **  Author:     Ed Puckett      qix@mit-oz
   6 **
   7 **  Copyright 1987 by EpAc Software.  All Rights Reserved.
   8 **
   9 **  History:    05-Jan-87       Original Version (1.0)
  10 */
  11
  12 #include   <exec/types.h>
  13
  14 #include   "pipelists.h"
  15
  16
  17
  18 /*---------------------------------------------------------------------------
  19 ** pipelists.c
  20 ** -----------
  21 ** This module contains functions and macros for list manipulation.
  22 ** To use its functions, a PIPELISTNODE must be part of the structure to be
  23 ** inserted in a list.  A list is identified by a PIPELISTHEADER (not a
  24 ** pointer to, but an actual PIPELISTHEADER structure).
  25 **      These routines, as implemented, use the fact that a PIPELISTHEADER
  26 ** and a PIPELISTNODE have the same struture.  Loops are started with the
  27 ** scanning pointer referencing the header.  This makes processing uniform,
  28 ** even when  the list is empty.
  29 **
  30 ** Visible Functions
  31 ** -----------------
  32 **      void  InsertHead (headerp, nodep)
  33 **      void  InsertTail (headerp, nodep)
  34 **      void  Delete     (headerp, nodep)
  35 **
  36 ** Macros (in pipelists.h)
  37 ** -----------------------
  38 **      InitList  (headerp)
  39 **      FirstItem (headerp)
  40 **      NextItem  (nodep)
  41 **
  42 ** Local Functions
  43 ** ---------------
  44 **      - none -
  45 */
  46
  47
  48
  49 /*---------------------------------------------------------------------------
  50 ** Insert the node pointed to by "nodep" at the head (front) of the list
  51 ** identified by "headerp".
  52 */
  53
  54 void  InsertHead (headerp, nodep)
  55
  56 PIPELISTHEADER  *headerp;
  57 PIPELISTNODE    *nodep;
  58
  59 { nodep->next= headerp->head;
  60   headerp->head= nodep;
  61 }
  62
  63
  64
  65 /*---------------------------------------------------------------------------
  66 ** Insert the node pointed to by "nodep" at the tail (end) of the list
  67 ** identified by "headerp".
  68 */
  69
  70 void  InsertTail (headerp, nodep)
  71
  72 PIPELISTHEADER  *headerp;
  73 PIPELISTNODE    *nodep;
  74
  75 { register PIPELISTNODE  *l;
  76
  77
  78   for (l= (PIPELISTNODE *) headerp; l->next != NULL; l= l->next)
  79     ;
  80
  81   l->next= nodep;
  82   nodep->next= NULL;
  83 }
  84
  85
  86
  87 /*---------------------------------------------------------------------------
  88 ** Delete the node pointed to by "nodep" from the list identified by
  89 ** "headerp".  If the node is not found in the list, nothing is done.
  90 */
  91
  92 void  Delete (headerp, nodep)
  93
  94 PIPELISTHEADER  *headerp;
  95 PIPELISTNODE    *nodep;
  96
  97 { PIPELISTNODE  *l;
  98
  99
 100   for (l= (PIPELISTNODE *) headerp; l->next != NULL; l= l->next)
 101     if (l->next == nodep)
 102       { l->next= l->next->next;
 103         break;
 104       }
 105 }