Category : C Source Code
Archive   : RZSZ317.ZIP
Filename : ZMR.C

/*
* File: zmr.c 07-30-1989
* Copyright 1988, 1989 Omen Technology Inc All Rights Reserved
*
*
*
* This module implements ZMODEM Run Length Encoding, an
* extension that was not funded by the original Telenet
* development contract.
*
* This software may be freely used for non commercial and
* educational (didactic only) purposes. This software may also
* be freely used to support file transfer operations to or from
* licensed Omen Technology products. Any programs which use
* part or all of this software must be provided in source form
* with this notice intact except by written permission from Omen
* Technology Incorporated.
*
* Use of this software for commercial or administrative purposes
* except when exclusively limited to interfacing Omen Technology
* products requires a per port license payment of $20.00 US per
* port (less in quantity). Use of this code by inclusion,
* decompilation, reverse engineering or any other means
* constitutes agreement to these conditions and acceptance of
* liability to license the materials and payment of reasonable
* legal costs necessary to enforce this license agreement.
*
*
* Omen Technology Inc FAX: 503-621-3745
* Post Office Box 4681
* Portland OR 97208
*
* This code is made available in the hope it will be useful,
* BUT WITHOUT ANY WARRANTY OF ANY KIND OR LIABILITY FOR ANY
* DAMAGES OF ANY KIND.
*
* ZMODEM RLE compression and decompression functions
*/

/* Send data subpacket RLE encoded with 32 bit FCS */
zsdar32(buf, length, frameend)
char *buf;
{
register int c, l, n;
register UNSL long crc;

crc = 0xFFFFFFFFL; l = *buf++ & 0377;
if (length == 1) {
zsendline(l); crc = UPDC32(l, crc);
if (l == ZRESC) {
zsendline(1); crc = UPDC32(1, crc);
}
} else {
for (n = 0; --length >= 0; ++buf) {
if ((c = *buf & 0377) == l && n < 126 && length>0) {
++n; continue;
}
switch (n) {
case 0:
zsendline(l);
crc = UPDC32(l, crc);
if (l == ZRESC) {
zsendline(0100); crc = UPDC32(0100, crc);
}
l = c; break;
case 1:
if (l != ZRESC) {
zsendline(l); zsendline(l);
crc = UPDC32(l, crc);
crc = UPDC32(l, crc);
n = 0; l = c; break;
}
/* **** FALL THRU TO **** */
default:
zsendline(ZRESC); crc = UPDC32(ZRESC, crc);
if (l == 040 && n < 34) {
n += 036;
zsendline(n); crc = UPDC32(n, crc);
}
else {
n += 0101;
zsendline(n); crc = UPDC32(n, crc);
zsendline(l); crc = UPDC32(l, crc);
}
n = 0; l = c; break;
}
}
}
xsendline(ZDLE); xsendline(frameend);
crc = UPDC32(frameend, crc);

crc = ~crc;
for (length=4; --length >= 0;) {
zsendline((int)crc); crc >>= 8;
}
}


/* Receive data subpacket RLE encoded with 32 bit FCS */
zrdatr32(buf, length)
register char *buf;
{
register int c;
register UNSL long crc;
register char *end;
register int d;

crc = 0xFFFFFFFFL; Rxcount = 0; end = buf + length;
d = 0; /* Use for RLE decoder state */
while (buf <= end) {
if ((c = zdlread()) & ~0377) {
crcfoo:
switch (c) {
case GOTCRCE:
case GOTCRCG:
case GOTCRCQ:
case GOTCRCW:
d = c; c &= 0377;
crc = UPDC32(c, crc);
if ((c = zdlread()) & ~0377)
goto crcfoo;
crc = UPDC32(c, crc);
if ((c = zdlread()) & ~0377)
goto crcfoo;
crc = UPDC32(c, crc);
if ((c = zdlread()) & ~0377)
goto crcfoo;
crc = UPDC32(c, crc);
if ((c = zdlread()) & ~0377)
goto crcfoo;
crc = UPDC32(c, crc);
if (crc != 0xDEBB20E3) {
zperr(badcrc);
return ERROR;
}
Rxcount = length - (end - buf);
#ifndef DSZ
vfile("zrdatr32: %d %s", Rxcount,
Zendnames[d-GOTCRCE&3]);
#endif
return d;
case GOTCAN:
zperr("Sender Canceled");
return ZCAN;
case TIMEOUT:
zperr("TIMEOUT");
return c;
default:
zperr("Bad data subpacket");
return c;
}
}
crc = UPDC32(c, crc);
switch (d) {
case 0:
if (c == ZRESC) {
d = -1; continue;
}
*buf++ = c; continue;
case -1:
if (c >= 040 && c < 0100) {
d = c - 035; c = 040; goto spaces;
}
if (c == 0100) {
d = 0;
*buf++ = ZRESC; continue;
}
d = c; continue;
default:
d -= 0100;
if (d < 1)
goto badpkt;
spaces:
if ((buf + d) > end)
goto badpkt;
while ( --d >= 0)
*buf++ = c;
d = 0; continue;
}
}
badpkt:
zperr("Data subpacket too long");
return ERROR;
}