/* This module implements the serial line framing method used by
 * net/rom nodes.  This allows the net/rom software to talk to
 * an actual net/rom over its serial interface, which is useful
 * if we want to do packet switching for multi-line wormholes.
 * Copyright 1989 Dan Frank, W9NK
 */
#include "global.h"
#ifdef NETROM
#ifdef NRS
#include "mbuf.h"
#include "iface.h"
#include "pktdrvr.h"
#include "ax25.h"
#include "nrs.h"
#include "asy.h"
#include "trace.h"
#include "commands.h"
  
static struct mbuf *nrs_encode __ARGS((struct mbuf *bp));
static struct mbuf *nrs_decode __ARGS((int dev,char c));
  
/* control structures, sort of overlayed on async control blocks */
struct nrs Nrs[ASY_MAX];
  
/* Send a raw net/rom serial frame */
int
nrs_raw(iface,bp)
struct iface *iface;
struct mbuf *bp;
{
    struct mbuf *bp1;
  
    dump(iface,IF_TRACE_OUT,CL_AX25,bp);
    iface->rawsndcnt++;
    iface->lastsent = secclock();
  
    if((bp1 = nrs_encode(bp)) == NULLBUF){
        free_p(bp);
        return -1;
    }
    return Nrs[iface->xdev].send(iface->dev,bp1);
}
  
/* Encode a packet in net/rom serial format */
static struct mbuf *
nrs_encode(bp)
struct mbuf *bp;
{
    struct mbuf *lbp;   /* Mbuf containing line-ready packet */
    register char *cp;
    int c;
    unsigned char csum = 0;
  
    /* Allocate output mbuf that's twice as long as the packet.
     * This is a worst-case guess (consider a packet full of STX's!)
     * Add five bytes for STX, ETX, checksum, and two nulls.
     */
    lbp = alloc_mbuf((int16)(2*len_p(bp) + 5));
    if(lbp == NULLBUF){
        /* No space; drop */
        free_p(bp);
        return NULLBUF;
    }
    cp = lbp->data;
  
    *cp++ = STX;
  
    /* Copy input to output, escaping special characters */
    while((c = PULLCHAR(&bp)) != -1){
        switch(c){
            case STX:
            case ETX:
            case DLE:
                *cp++ = DLE;
            /* notice drop through to default */
            default:
                *cp++ = c;
        }
        csum += c;
    }
    *cp++ = ETX;
    *cp++ = csum;
    *cp++ = NUL;
    *cp++ = NUL;
  
    lbp->cnt = cp - lbp->data;
    return lbp;
}
/* Process incoming bytes in net/rom serial format
 * When a buffer is complete, return it; otherwise NULLBUF
 */
static struct mbuf *
nrs_decode(dev,c)
int dev;    /* net/rom unit number */
char c;     /* Incoming character */
{
    struct mbuf *bp;
    register struct nrs *sp;
  
    sp = &Nrs[dev];
    switch(sp->state) {
        case NRS_INTER:
            if(uchar(c) == STX) {   /* look for start of frame */
                sp->state = NRS_INPACK; /* we're in a packet */
                sp->csum = 0;               /* reset checksum */
            }
            return NULLBUF;
        case NRS_CSUM:
            bp = sp->rbp;
            sp->rbp = NULLBUF;
            sp->rcnt = 0;
            sp->state = NRS_INTER;  /* go back to inter-packet state */
            if(sp->csum == uchar(c)) {
                sp->packets++;
            } else {
                free_p(bp); /* drop packet with bad checksum */
                bp = NULLBUF;
                sp->errors++;   /* increment error count */
            }
            return bp;
        case NRS_ESCAPE:
            sp->state = NRS_INPACK; /* end of escape */
            break;          /* this will drop through to char processing */
        case NRS_INPACK:
        switch(uchar(c)) {
            /* If we see an STX in a packet, assume that previous */
            /* packet was trashed, and start a new packet */
            case STX:
                free_p(sp->rbp);
                sp->rbp = NULLBUF;
                sp->rcnt = 0;
                sp->csum = 0;
                sp->errors++;
                return NULLBUF;
            case ETX:
                sp->state = NRS_CSUM;   /* look for checksum */
                return NULLBUF;
            case DLE:
                sp->state = NRS_ESCAPE;
                return NULLBUF;
        }
    }
    /* If we get to here, it's with a character that's part of the packet.
     * Make sure there's space for it.
     */
    if(sp->rbp == NULLBUF){
        /* Allocate first mbuf for new packet */
        if((sp->rbp1 = sp->rbp = alloc_mbuf(NRS_ALLOC)) == NULLBUF) {
            sp->state = NRS_INTER;
            return NULLBUF; /* No memory, drop */
        }
        sp->rcp = sp->rbp->data;
    } else if(sp->rbp1->cnt == NRS_ALLOC){
        /* Current mbuf is full; link in another */
        if((sp->rbp1->next = alloc_mbuf(NRS_ALLOC)) == NULLBUF){
            /* No memory, drop whole thing */
            free_p(sp->rbp);
            sp->rbp = NULLBUF;
            sp->rcnt = 0;
            sp->state = NRS_INTER;
            return NULLBUF;
        }
        sp->rbp1 = sp->rbp1->next;
        sp->rcp = sp->rbp1->data;
    }
    /* Store the character, increment fragment and total
     * byte counts
     */
    *sp->rcp++ = c;
    sp->rbp1->cnt++;
    sp->rcnt++;
    sp->csum += uchar(c);   /* add to checksum */
    return NULLBUF;
}
  
/* Process net/rom serial line I/O */
void
nrs_recv(dev,v1,v2)
int dev;
void *v1;
void *v2;
{
    char c;
    struct mbuf *bp,*nbp;
    struct phdr phdr;
  
    /* Process any pending input */
    for(;;){
        c = Nrs[dev].get(Nrs[dev].iface->dev);
        if((bp = nrs_decode(dev,c)) == NULLBUF)
            continue;
        if((nbp = pushdown(bp,sizeof(phdr))) == NULLBUF){
            free_p(bp);
            continue;
        }
        phdr.iface = Nrs[dev].iface;
        phdr.type = CL_AX25;
        memcpy(&nbp->data[0],(char *)&phdr,sizeof(phdr));
        enqueue(&Hopper,nbp);
    }
  
}
/* donrstat:  display status of active net/rom serial interfaces */
int
donrstat(argc,argv,p)
int argc;
char *argv[];
void *p;
{
    register struct nrs *np;
    register int i;
  
    tputs("Interface   RcvB  NumReceived  CSumErrors\n");
  
    for(i = 0, np = Nrs; i < ASY_MAX ; i++, np++)
        if(np->iface != NULLIF)
            if(tprintf(" %8s   %4d   %10lu  %10lu\n",
                np->iface->name, np->rcnt,
                np->packets, np->errors) == EOF)
                break;
  
    return 0;
}
#endif
  
#endif /* NETROM */
