DB0FHN

SQ6BOT > PSBBS    02.07.96 17:12l 110 Lines 2875 Bytes #-10324 (0) @ WW
BID : 276SR6BOX007
Read: GUEST
Subj: Loopback is almost ready!
Path: DB0AAB<DB0MFG<DB0PV<DB0WGS<OE3XSR<OE3XZR<OK0PBX<SP6KBL<SR6BOX
Sent: 960702/0344z @:SR6BOX.#WRO.POL.EU [BayCom-Mailbox [Wroclaw]] BCM1.37b
From: SQ6BOT @ SR6BOX.#WRO.POL.EU  (Zipu)
To  : PSBBS @ WW

Hi,

    I was too unpatient and I sent these sources with lots of temporary
things. I just (5:30 AM ;-) ) finished rebuilding, separating and
cleaning up sources. Now it looks as follows:

    BBS user level
     ^ |
     | v
    (buffer)  (I haven't made any range checking here yet - filling
     ^ |      this buffer up should cause sending RNR)
     | v
    AX.25 level (or just protocol level)
    (buffer)
     ^ |
     | v
    Hardware level

and there is no such mess as there was before.
Here is an example - hardware level functions that support loopback.

Loopback_Tx() is called by AX.25 level function, that prepares whole
frame. It can be also called by, say, TCP/IP level function, or
any else.

Loopback_Rx() is running as a process (forked while attaching interface)
and checks if there is data available. If there is - it calls upper level
function (AX.25 interpreter - or anything else).

For each hardware it's enough to substitute only these two functions.
For example - for KISS TNC: KISS_Tx will send data through RS232 ( :-( )
instead of memcpy'ing and KISS_Rx will check whether TNC has some
data available. If it has - function will create axframe structure,
fill it and call upper level routine.

So you can try to write hardware drivers (when I send rest of sources
with definitions of structures like axframe, etc.)

Loopback functions follow this message.

73 de Peter

-------------------------------------------------------------------

/*
 *  This is ONLY for loopback - send frame immediately
 */

int Loopback_Tx(struct interface *i,struct axframe *axf)
{
    int k;
    struct axframe *in;

    /*
     *  This is done by simple copying to loopback's input buffer.
     *  If there's no place then frame is discarded :-(
     */

    /* Count waiting frames */
    k=0;
    in=i->Frame;
    while(in!=NULL){
        in=in->next;
        k++;
    }
    if(k>=10)
        /* There's no place for adding new frame - Goodbye! */
        return(-1);
    /* There IS place for new frame */
    disable(); /* It should be atomic */
    /* Create axframe structure */
    in=calloc(1,sizeof(struct session));
    if(i->Frame==NULL){
        in->next=NULL;
        i->Frame=in;
    }else{
        in->next=i->Frame->next;
        i->Frame->next=in;
    }
    in->size=axf->size;
    in->S=axf->S;
    /* Create buffer */
    in->buf=calloc(1,axf->size);

    /* Following line contains the whole loopback idea ;-) */
    memcpy(in->buf,axf->buf,axf->size);

    enable();
}


/*
 *  Read from loopback
 */

int Loopback_Rx()
{
    while(1){
        if(CurProc->iface->Frame==NULL)
            ForceSwitch(); /* Don't overload CPU if it's not necessary */
        while(CurProc->iface->Frame!=NULL)
            /* There is a frame in receive queue */
            ReceiveAX25();
    }
}



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