/*
 * 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 */
void	zsdar32(char *buf, int length, int frameend)
{
	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 */
int		zrdatr32(register char *buf, int length)
{
	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;
}