summaryrefslogtreecommitdiff
path: root/src/lib/xmodem.c
blob: bcbe23274b459bfc196455e0c9c3d367d22c92ee (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
/*
        Copyright 2006 Arastra, Inc.
        Copyright 2001, 2002 Georges Menie (www.menie.org)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <string.h>
#include <delay.h>

extern void uart8250_tx_byte(unsigned, unsigned char);
extern int uart8250_can_rx_byte(unsigned);
extern unsigned char uart8250_rx_byte(unsigned);

static int _inbyte(int msec)
{
	while (!uart8250_can_rx_byte(CONFIG_TTYS0_BASE)) {
		udelay(1000);
		if (msec-- <= 0)
			return -1;
	}
	return uart8250_rx_byte(CONFIG_TTYS0_BASE);
}

static void _outbyte(unsigned char c)
{
	uart8250_tx_byte(CONFIG_TTYS0_BASE, c);
}

static unsigned short crc16_ccitt(const unsigned char *buf, int sz)
{
	unsigned short crc = 0;
	while (--sz >= 0) {
		int i;
		crc ^= (unsigned short) *buf++ << 8;
		for (i = 0; i < 8; i++)
			if (crc & 0x8000)
				crc = crc << 1 ^ 0x1021;
			else
				crc <<= 1;
	}
	return crc;
}

#define SOH  0x01
#define STX  0x02
#define EOT  0x04
#define ACK  0x06
#define NAK  0x15
#define CAN  0x18
#define CTRLZ 0x1A

#define DLY_1S 1000
#define MAXRETRANS 25

static int check(int crc, const unsigned char *buf, int sz)
{
	if (crc) {
		unsigned short crc = crc16_ccitt(buf, sz);
		unsigned short tcrc = (buf[sz]<<8)+buf[sz+1];
		if (crc == tcrc)
			return 1;
	}
	else {
		int i;
		unsigned char cks = 0;
		for (i = 0; i < sz; ++i) {
			cks += buf[i];
		}
		if (cks == buf[sz])
		return 1;
	}

	return 0;
}

static void flushinput(void)
{
	while (_inbyte(((DLY_1S)*3)>>1) >= 0)
		;
}

int xmodemReceive(unsigned char *dest, int destsz)
{
	unsigned char xbuff[1030]; /* 1024 for XModem 1k + 3 head chars + 2 crc + nul */
	unsigned char *p;
	int bufsz, crc = 0;
	unsigned char trychar = 'C';
	unsigned char packetno = 1;
	int i, c, len = 0;
	int retry, retrans = MAXRETRANS;

	for(;;) {
		for( retry = 0; retry < 16; ++retry) {
			if (trychar) _outbyte(trychar);
			if ((c = _inbyte((DLY_1S)<<1)) >= 0) {
				switch (c) {
				case SOH:
					bufsz = 128;
					goto start_recv;
				case STX:
					bufsz = 1024;
					goto start_recv;
				case EOT:
					flushinput();
					_outbyte(ACK);
					return len; /* normal end */
				case CAN:
					if ((c = _inbyte(DLY_1S)) == CAN) {
						flushinput();
						_outbyte(ACK);
						return -1; /* canceled by remote */
					}
					break;
				default:
					break;
				}
			}
		}
		if (trychar == 'C') { trychar = NAK; continue; }
		flushinput();
		_outbyte(CAN);
		_outbyte(CAN);
		_outbyte(CAN);
		return -2; /* sync error */

	start_recv:
		if (trychar == 'C') crc = 1;
		trychar = 0;
		p = xbuff;
		*p++ = c;
		for (i = 0;  i < (bufsz+(crc?1:0)+3); ++i) {
			if ((c = _inbyte(DLY_1S)) < 0) goto reject;
			*p++ = c;
		}

		if (xbuff[1] == (unsigned char)(~xbuff[2]) && 
			(xbuff[1] == packetno || xbuff[1] == (unsigned char)packetno-1) &&
			check(crc, &xbuff[3], bufsz)) {
			if (xbuff[1] == packetno)	{
				register int count = destsz - len;
				if (count > bufsz) count = bufsz;
				if (count > 0) {
					memcpy (&dest[len], &xbuff[3], count);
					len += count;
				}
				++packetno;
				retrans = MAXRETRANS+1;
			}
			if (--retrans <= 0) {
				flushinput();
				_outbyte(CAN);
				_outbyte(CAN);
				_outbyte(CAN);
				return -3; /* too many retry error */
			}
			_outbyte(ACK);
			continue;
		}
	reject:
		flushinput();
		_outbyte(NAK);
	}
}