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zmr.c
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C/C++ Source or Header
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1993-10-23
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4KB
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173 lines
/*
* File: zmr.c 12-04-1988
* Copyright 1988 Omen Technology Inc All Rights Reserved
*
*
* This code implements ZMODEM Run Length Encoding, not funded
* by the original Telenet development contract. This software,
* including these features, may be freely used for non
* commercial and educational purposes. This software may also
* be freely used to support file transfer operations to or from
* licensed Omen Technology products. Contact Omen Technology
* for licensing for other uses. 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.
*
* 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;
}