ptinit.c

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#include <xinu.h>

struct ptnode *ptfree;
struct ptentry porttab[NPORTS];
int32 ptnextid;

syscall ptinit(int32 maxmsgs)
{
    int32 i;                    /* Runs through the port table  */
    struct ptnode *next, *curr; /* Used to build a free list    */

    /* Allocate memory for all messages on all ports */

    ptfree = (struct ptnode *)getmem(maxmsgs * sizeof(struct ptnode));
    if (ptfree == (struct ptnode *)SYSERR)
    {
        panic("ptinit - insufficient memory");
    }

    /* Initialize all port table entries to free */

    for (i = 0; i < NPORTS; i++)
    {
        porttab[i].ptstate = PT_FREE;
        porttab[i].ptseq = 0;
    }
    ptnextid = 0;

    /* Create a free list of message nodes linked together */

    for (curr = next = ptfree; --maxmsgs > 0; curr = next)
    {
        curr->ptnext = ++next;
    }

    /* Set the pointer in the final node to NULL */

    curr->ptnext = NULL;
    return OK;
}