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
|
#include <qpdf/Pl_RunLength.hh>
#include <qpdf/QUtil.hh>
#include <qpdf/QTC.hh>
Pl_RunLength::Pl_RunLength(char const* identifier, Pipeline* next,
action_e action) :
Pipeline(identifier, next),
action(action),
state(st_top),
length(0)
{
}
Pl_RunLength::~Pl_RunLength()
{
}
void
Pl_RunLength::write(unsigned char* data, size_t len)
{
if (this->action == a_encode)
{
encode(data, len);
}
else
{
decode(data, len);
}
}
void
Pl_RunLength::encode(unsigned char* data, size_t len)
{
for (size_t i = 0; i < len; ++i)
{
if ((this->state == st_top) != (this->length <= 1))
{
throw std::logic_error(
"Pl_RunLength::encode: state/length inconsistency");
}
unsigned char ch = data[i];
if ((this->length > 0) &&
((this->state == st_copying) || (this->length < 128)) &&
(ch == this->buf[this->length-1]))
{
QTC::TC("libtests", "Pl_RunLength: switch to run",
(this->length == 128) ? 0 : 1);
if (this->state == st_copying)
{
--this->length;
flush_encode();
this->buf[0] = ch;
this->length = 1;
}
this->state = st_run;
this->buf[this->length] = ch;
++this->length;
}
else
{
if ((this->length == 128) || (this->state == st_run))
{
flush_encode();
}
else if (this->length > 0)
{
this->state = st_copying;
}
this->buf[this->length] = ch;
++this->length;
}
}
}
void
Pl_RunLength::decode(unsigned char* data, size_t len)
{
for (size_t i = 0; i < len; ++i)
{
unsigned char ch = data[i];
switch (this->state)
{
case st_top:
if (ch < 128)
{
// length represents remaining number of bytes to copy
this->length = 1 + ch;
this->state = st_copying;
}
else if (ch > 128)
{
// length represents number of copies of next byte
this->length = 257 - ch;
this->state = st_run;
}
else // ch == 128
{
// EOD; stay in this state
}
break;
case st_copying:
this->getNext()->write(&ch, 1);
if (--this->length == 0)
{
this->state = st_top;
}
break;
case st_run:
for (unsigned int j = 0; j < this->length; ++j)
{
this->getNext()->write(&ch, 1);
}
this->state = st_top;
break;
}
}
}
void
Pl_RunLength::flush_encode()
{
if (this->length == 128)
{
QTC::TC("libtests", "Pl_RunLength flush full buffer",
(this->state == st_copying ? 0 :
this->state == st_run ? 1 :
-1));
}
if (this->length == 0)
{
QTC::TC("libtests", "Pl_RunLength flush empty buffer");
}
if (this->state == st_run)
{
if ((this->length < 2) || (this->length > 128))
{
throw std::logic_error(
"Pl_RunLength: invalid length in flush_encode for run");
}
unsigned char ch = static_cast<unsigned char>(257 - this->length);
this->getNext()->write(&ch, 1);
this->getNext()->write(&this->buf[0], 1);
}
else if (this->length > 0)
{
unsigned char ch = static_cast<unsigned char>(this->length - 1);
this->getNext()->write(&ch, 1);
this->getNext()->write(this->buf, this->length);
}
this->state = st_top;
this->length = 0;
}
void
Pl_RunLength::finish()
{
// When decoding, we might have read a length byte not followed by
// data, which means the stream was terminated early, but we will
// just ignore this case since this is the only sensible thing to
// do.
if (this->action == a_encode)
{
flush_encode();
unsigned char ch = 128;
this->getNext()->write(&ch, 1);
}
this->getNext()->finish();
}
|
