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(buffer: in,
84 CHAR_BITS,
85 bits_avail: &bits_avail,
86 in_index: &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(buffer: in, bits: 1, bits_avail: &bits_avail,
98 in_index: &in_index) == 0) {
99 for (j = 0; j < DATA_BLOB_LENGTH; ++j) {
100 if (i < data_length) {
101 out[i] = (u8)altera_read_packed(buffer: in,
102 CHAR_BITS,
103 bits_avail: &bits_avail,
104 in_index: &in_index);
105 i++;
106 }
107 }
108 } else {
109 /* A 1 bit indicates offset/length to follow. */
110 offset = altera_read_packed(buffer: in, bits: altera_bits_req(n: (s16)
111 (i > match_data_length ?
112 match_data_length : i)),
113 bits_avail: &bits_avail,
114 in_index: &in_index);
115 length = altera_read_packed(buffer: in, CHAR_BITS,
116 bits_avail: &bits_avail,
117 in_index: &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

source code of linux/drivers/misc/altera-stapl/altera-comp.c