AllocNode
Synopsis
node = AllocNode(list, string, type, pri)
D0 A0 A1 D0 D1C Prototype
struct Node *AllocNode(struct List *list, STRPTR string, ULONG type, LONG pri);Description
Allocates and initializes a Node structure. If list is not NULL, the node is inserted into the list taking the pri (priority) parameter into account. The insertion is performed using the ENQUEUE macro defined in assembly/asmmacros.i, which performs the same function as exec/Enqueue().
If list is NULL, the node is only allocated and no insertion into a list is performed. In this case, the task is responsible for inserting the node into a list as it sees fit.
Inputs
- list — Address of a
Liststructure. If NULL, the node will only be allocated and NOT inserted into a list. - string — Address to place in
LN_NAME. Can be NULL. - type — Value to place in
LN_TYPE. Can be NULL. - pri — Priority to place in
LN_PRI. Can be NULL. This parameter is only considered whenlistis not NULL, and allows priority-based insertion of nodes. See alsoexec/Enqueue().
Result
- node — Address of the allocated
Nodestructure. If NULL, an error occurred.
Example
/* Simple usage of AllocNewList() and AllocNode() */
/* to create a label list for a LISTVIEW, using and */
/* not using the priority (pri) parameter */
struct List *list;
struct Node *node;
list = AllocNewList(); /* Create the list */
node = AllocNode(list, "Last Element", NULL, -5);
node = AllocNode(list, "I Element", NULL, 1);
node = AllocNode(list, "II Element", NULL, 2);
node = AllocNode(list, "IV Element", NULL, 4);
/*** this one I manage myself ***/
node = AllocNode(NULL, "???? Element", NULL, 0);
/** here you can call whichever function you prefer **/
/** the node has been allocated, but not inserted **/
/** into the list... for example you could use **/
/** AddTail() or AddHead(), etc... **/
node = AllocNode(list, "III Element", NULL, 3);
/* etc... as you can see, the priority determines the */
/* position of the node in the list, as long as */
/* list != NULL */See Also
AllocNewList, FreeNode, FreeList
exec/Enqueue()
Implementation
The original 68020 assembly implementation:
; (13-Jan-1995) --- AllocNode(List,name,type,pri) (a0/a1/d0/d1)
_LVOAllocNode
movem.l d2-d4/a2-a6,-(sp)
move.l a0,a3 ; Save struct List *
move.l a1,a2 ; Save STRPTR string
move.b d0,d2 ; type
move.b d1,d3 ; pri
moveq #4+LN_SIZE,d0 ; D0 = SIZEOF
move.l d0,d4 ; Save for PackAlloc()
moveq #1,d1
swap d1
move.l ab_ExecBase(a6),a6 ; Exec...
jsr _LVOAllocMem(a6)
tst.l d0
beq.s ANFail ; Can't Alloc Memory...
move.l d0,a5 ; A5 = (struct Node *)
move.l d4,(a5)+ ; A5 = True address to return...
move.b d2,LN_TYPE(a5) ; INITIALIZE THE NODE
move.b d3,LN_PRI(a5)
move.l a2,LN_NAME(a5)
move.l a3,d0 ; Does a List exist??
beq.s ANExit ; No then exit
move.l d0,a0 ; List
ENQUEUE a5
ANExit move.l a5,d0 ; Result...
ANFail movem.l (sp)+,d2-d4/a2-a6
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