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
|
/*
Minetest-c55
Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
(c) 2010 Perttu Ahola <celeron55@gmail.com>
*/
#include "serialization.h"
#include "utility.h"
void compress(SharedBuffer<u8> data, std::ostream &os, u8 version)
{
if(data.getSize() == 0)
return;
// Write length (u32)
u8 tmp[4];
writeU32(tmp, data.getSize());
os.write((char*)tmp, 4);
// We will be writing 8-bit pairs of more_count and byte
u8 more_count = 0;
u8 current_byte = data[0];
for(u32 i=1; i<data.getSize(); i++)
{
if(
data[i] != current_byte
|| more_count == 255
)
{
// write count and byte
os.write((char*)&more_count, 1);
os.write((char*)¤t_byte, 1);
more_count = 0;
current_byte = data[i];
}
else
{
more_count++;
}
}
// write count and byte
os.write((char*)&more_count, 1);
os.write((char*)¤t_byte, 1);
}
void decompress(std::istream &is, std::ostream &os, u8 version)
{
// Read length (u32)
u8 tmp[4];
is.read((char*)tmp, 4);
u32 len = readU32(tmp);
// We will be reading 8-bit pairs of more_count and byte
u32 count = 0;
for(;;)
{
u8 more_count=0;
u8 byte=0;
is.read((char*)&more_count, 1);
is.read((char*)&byte, 1);
if(is.eof())
throw SerializationError("decompress: stream ended halfway");
for(s32 i=0; i<(u16)more_count+1; i++)
os.write((char*)&byte, 1);
count += (u16)more_count+1;
if(count == len)
break;
}
}
|
