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vdr/libdtv/liblx/xListFuncs.c

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/*
*
* xListFuncs.c: list handling functions of liblx
*
*
* $Revision: 1.1 $
* $Date: 2001/08/15 10:00:00 $
* $Author: hakenes $
*
* (C) 1992-2001 Rolf Hakenes <hakenes@hippomi.de>, under the GNU GPL.
*
* liblx is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* liblx is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You may have received a copy of the GNU General Public License
* along with liblx; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
*/
#include <string.h>
#include "liblx.h"
/*************************************************************************
* *
* function : xHashKey *
* *
* arguments : Name - character pointer *
* *
* return : 16 Bit CRC checksum as hashkey *
* *
*************************************************************************/
unsigned short xHashKey (Name)
char *Name;
{
unsigned short Key = 0;
unsigned long Value;
char *Ptr;
if (!Name) return (0);
for (Ptr = Name; *Ptr; Ptr++) {
Value = ((Key >> 8) ^ (*Ptr)) & 0xFF;
Value = Value ^ (Value >> 4);
Key = 0xFFFF & ((Key << 8) ^ Value ^ (Value << 5) ^ (Value << 12));
}
return (Key);
}
/*************************************************************************
* *
* function : xNewNode *
* *
* arguments : Name - character pointer to the node's name *
* *
* Size - size of the surrounding structure in bytes *
* *
* return : pointer to a correct initialized NODE structure *
* *
*-----------------------------------------------------------------------*
* *
* xNewNode() allocates memory for a NODE structure and initializes *
* it properly. If argument Name points to a string, it copies that *
* into a new allocated memory area and assigns Node->Name to it. *
* Because NODE's are often part of bigger structures, the size of *
* the surrounding structure could be specified to allocate it. *
* *
*************************************************************************/
struct NODE *xNewNode (Name, Size)
char *Name;
unsigned long Size;
{
struct NODE *Node;
if (Size < sizeof(struct NODE)) Size = sizeof(struct NODE);
xMemAlloc (Size, &Node);
Node->Succ = NULL;
Node->Pred = NULL;
if (Name == NULL)
{
Node->Name = NULL;
Node->HashKey = 0;
}
else
{
xMemAlloc (strlen (Name) + 1, &(Node->Name));
strcpy (Node->Name, Name);
Node->HashKey = xHashKey (Name);
}
return (Node);
}
/*************************************************************************
* *
* function : xNewList *
* *
* arguments : Name - character pointer to the list's name *
* *
* return : pointer to a correct initialized LIST structure *
* *
*-----------------------------------------------------------------------*
* *
* xNewList() allocates memory for a LIST structure and initializes *
* it properly. If argument Name points to a string, it copies that *
* into a new allocated memory area and assigns List->Name to it. *
* *
*************************************************************************/
struct LIST *xNewList (Name)
char *Name;
{
struct LIST *List;
xMemAlloc (sizeof(struct LIST), &List);
List->Head = NULL;
List->Tail = NULL;
List->Size = 0;
if (Name == NULL)
{
List->Name = NULL;
}
else
{
xMemAlloc (strlen (Name) + 1, &(List->Name));
strcpy (List->Name, Name);
}
return (List);
}
/*************************************************************************
* *
* function : xFindName *
* *
* arguments : List - pointer to a LIST structure *
* *
* Name - pointer to a name string *
* *
* return : pointer to a NODE structure *
* *
*-----------------------------------------------------------------------*
* *
* xFindName() looks for element with name 'Name' in list 'List' and *
* returns its NODE structure. *
* *
*************************************************************************/
struct NODE *xFindName (List, Name)
struct LIST *List;
char *Name;
{
struct NODE *Node;
unsigned short HashKey;
if (!Name || !List) return (NULL);
HashKey = xHashKey (Name);
for (Node = List->Head; Node; Node = Node->Succ)
if (HashKey == Node->HashKey)
if (Node->Name)
if (strcmp (Node->Name, Name) == 0) return (Node);
return (NULL);
}