1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * altera-comp.c
4 *
5 * altera FPGA driver
6 *
7 * Copyright (C) Altera Corporation 1998-2001
8 * Copyright (C) 2010 NetUP Inc.
9 * Copyright (C) 2010 Igor M. Liplianin <liplianin@netup.ru>
10 */
11
12#include <linux/kernel.h>
13#include "altera-exprt.h"
14
15#define	SHORT_BITS		16
16#define	CHAR_BITS		8
17#define	DATA_BLOB_LENGTH	3
18#define	MATCH_DATA_LENGTH	8192
19#define ALTERA_REQUEST_SIZE	1024
20#define ALTERA_BUFFER_SIZE	(MATCH_DATA_LENGTH + ALTERA_REQUEST_SIZE)
21
22static u32 altera_bits_req(u32 n)
23{
24	u32 result = SHORT_BITS;
25
26	if (n == 0)
27		result = 1;
28	else {
29		/* Look for the highest non-zero bit position */
30		while ((n & (1 << (SHORT_BITS - 1))) == 0) {
31			n <<= 1;
32			--result;
33		}
34	}
35
36	return result;
37}
38
39static u32 altera_read_packed(u8 *buffer, u32 bits, u32 *bits_avail,
40							u32 *in_index)
41{
42	u32 result = 0;
43	u32 shift = 0;
44	u32 databyte = 0;
45
46	while (bits > 0) {
47		databyte = buffer[*in_index];
48		result |= (((databyte >> (CHAR_BITS - *bits_avail))
49			& (0xff >> (CHAR_BITS - *bits_avail))) << shift);
50
51		if (bits <= *bits_avail) {
52			result &= (0xffff >> (SHORT_BITS - (bits + shift)));
53			*bits_avail -= bits;
54			bits = 0;
55		} else {
56			++(*in_index);
57			shift += *bits_avail;
58			bits -= *bits_avail;
59			*bits_avail = CHAR_BITS;
60		}
61	}
62
63	return result;
64}
65
66u32 altera_shrink(u8 *in, u32 in_length, u8 *out, u32 out_length, s32 version)
67{
68	u32 i, j, data_length = 0L;
69	u32 offset, length;
70	u32 match_data_length = MATCH_DATA_LENGTH;
71	u32 bits_avail = CHAR_BITS;
72	u32 in_index = 0L;
73
74	if (version > 0)
75		--match_data_length;
76
77	for (i = 0; i < out_length; ++i)
78		out[i] = 0;
79
80	/* Read number of bytes in data. */
81	for (i = 0; i < sizeof(in_length); ++i) {
82		data_length = data_length | (
83			altera_read_packed(in,
84					CHAR_BITS,
85					&bits_avail,
86					&in_index) << (i * CHAR_BITS));
87	}
88
89	if (data_length > out_length) {
90		data_length = 0L;
91		return data_length;
92	}
93
94	i = 0;
95	while (i < data_length) {
96		/* A 0 bit indicates literal data. */
97		if (altera_read_packed(in, 1, &bits_avail,
98						&in_index) == 0) {
99			for (j = 0; j < DATA_BLOB_LENGTH; ++j) {
100				if (i < data_length) {
101					out[i] = (u8)altera_read_packed(in,
102							CHAR_BITS,
103							&bits_avail,
104							&in_index);
105					i++;
106				}
107			}
108		} else {
109			/* A 1 bit indicates offset/length to follow. */
110			offset = altera_read_packed(in, altera_bits_req((s16)
111					(i > match_data_length ?
112						match_data_length : i)),
113					&bits_avail,
114					&in_index);
115			length = altera_read_packed(in, CHAR_BITS,
116					&bits_avail,
117					&in_index);
118			for (j = 0; j < length; ++j) {
119				if (i < data_length) {
120					out[i] = out[i - offset];
121					i++;
122				}
123			}
124		}
125	}
126
127	return data_length;
128}
129