summaryrefslogtreecommitdiffstats
path: root/drivers/misc/altera-stapl/altera-comp.c
blob: 49b103bedaafad04ca78f5dd2aa116537a4ad64f (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
/*
 * altera-comp.c
 *
 * altera FPGA driver
 *
 * Copyright (C) Altera Corporation 1998-2001
 * Copyright (C) 2010 NetUP Inc.
 * Copyright (C) 2010 Igor M. Liplianin <liplianin@netup.ru>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include "altera-exprt.h"

#define	SHORT_BITS		16
#define	CHAR_BITS		8
#define	DATA_BLOB_LENGTH	3
#define	MATCH_DATA_LENGTH	8192
#define ALTERA_REQUEST_SIZE	1024
#define ALTERA_BUFFER_SIZE	(MATCH_DATA_LENGTH + ALTERA_REQUEST_SIZE)

static u32 altera_bits_req(u32 n)
{
	u32 result = SHORT_BITS;

	if (n == 0)
		result = 1;
	else {
		/* Look for the highest non-zero bit position */
		while ((n & (1 << (SHORT_BITS - 1))) == 0) {
			n <<= 1;
			--result;
		}
	}

	return result;
}

static u32 altera_read_packed(u8 *buffer, u32 bits, u32 *bits_avail,
							u32 *in_index)
{
	u32 result = 0;
	u32 shift = 0;
	u32 databyte = 0;

	while (bits > 0) {
		databyte = buffer[*in_index];
		result |= (((databyte >> (CHAR_BITS - *bits_avail))
			& (0xff >> (CHAR_BITS - *bits_avail))) << shift);

		if (bits <= *bits_avail) {
			result &= (0xffff >> (SHORT_BITS - (bits + shift)));
			*bits_avail -= bits;
			bits = 0;
		} else {
			++(*in_index);
			shift += *bits_avail;
			bits -= *bits_avail;
			*bits_avail = CHAR_BITS;
		}
	}

	return result;
}

u32 altera_shrink(u8 *in, u32 in_length, u8 *out, u32 out_length, s32 version)
{
	u32 i, j, data_length = 0L;
	u32 offset, length;
	u32 match_data_length = MATCH_DATA_LENGTH;
	u32 bits_avail = CHAR_BITS;
	u32 in_index = 0L;

	if (version > 0)
		--match_data_length;

	for (i = 0; i < out_length; ++i)
		out[i] = 0;

	/* Read number of bytes in data. */
	for (i = 0; i < sizeof(in_length); ++i) {
		data_length = data_length | (
			altera_read_packed(in,
					CHAR_BITS,
					&bits_avail,
					&in_index) << (i * CHAR_BITS));
	}

	if (data_length > out_length) {
		data_length = 0L;
		return data_length;
	}

	i = 0;
	while (i < data_length) {
		/* A 0 bit indicates literal data. */
		if (altera_read_packed(in, 1, &bits_avail,
						&in_index) == 0) {
			for (j = 0; j < DATA_BLOB_LENGTH; ++j) {
				if (i < data_length) {
					out[i] = (u8)altera_read_packed(in,
							CHAR_BITS,
							&bits_avail,
							&in_index);
					i++;
				}
			}
		} else {
			/* A 1 bit indicates offset/length to follow. */
			offset = altera_read_packed(in, altera_bits_req((s16)
					(i > match_data_length ?
						match_data_length : i)),
					&bits_avail,
					&in_index);
			length = altera_read_packed(in, CHAR_BITS,
					&bits_avail,
					&in_index);
			for (j = 0; j < length; ++j) {
				if (i < data_length) {
					out[i] = out[i - offset];
					i++;
				}
			}
		}
	}

	return data_length;
}