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
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
// Copyright (c) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Contains utils for reading, writing and debug printing bit streams.
#include <map>
#include <sstream>
#include <string>
#include <unordered_map>
#include "util/huffman_codec.h"
#include "util/bit_stream.h"
#include "gmock/gmock.h"
namespace {
using spvutils::HuffmanCodec;
using spvutils::BitsToStream;
const std::map<std::string, uint32_t>& GetTestSet() {
static const std::map<std::string, uint32_t> hist = {
{"a", 4},
{"e", 7},
{"f", 3},
{"h", 2},
{"i", 3},
{"m", 2},
{"n", 2},
{"s", 2},
{"t", 2},
{"l", 1},
{"o", 2},
{"p", 1},
{"r", 1},
{"u", 1},
{"x", 1},
};
return hist;
}
class TestBitReader {
public:
TestBitReader(const std::string& bits) : bits_(bits) {}
bool ReadBit(bool* bit) {
if (pos_ < bits_.length()) {
*bit = bits_[pos_++] == '0' ? false : true;
return true;
}
return false;
}
private:
std::string bits_;
size_t pos_ = 0;
};
TEST(Huffman, PrintTree) {
HuffmanCodec<std::string> huffman(GetTestSet());
std::stringstream ss;
huffman.PrintTree(ss);
const std::string expected = std::string(R"(
15-----7------e
8------4------a
4------2------m
2------n
19-----8------4------2------o
2------s
4------2------t
2------1------l
1------p
11-----5------2------1------r
1------u
3------f
6------3------i
3------1------x
2------h
)").substr(1);
EXPECT_EQ(expected, ss.str());
}
TEST(Huffman, PrintTable) {
HuffmanCodec<std::string> huffman(GetTestSet());
std::stringstream ss;
huffman.PrintTable(ss);
const std::string expected = std::string(R"(
e 7 11
a 4 101
i 3 0001
f 3 0010
t 2 0101
s 2 0110
o 2 0111
n 2 1000
m 2 1001
h 2 00000
x 1 00001
u 1 00110
r 1 00111
p 1 01000
l 1 01001
)").substr(1);
EXPECT_EQ(expected, ss.str());
}
TEST(Huffman, TestValidity) {
HuffmanCodec<std::string> huffman(GetTestSet());
const auto& encoding_table = huffman.GetEncodingTable();
std::vector<std::string> codes;
for (const auto& entry : encoding_table) {
codes.push_back(BitsToStream(entry.second.first, entry.second.second));
}
std::sort(codes.begin(), codes.end());
ASSERT_LT(codes.size(), 20u) << "Inefficient test ahead";
for (size_t i = 0; i < codes.size(); ++i) {
for (size_t j = i + 1; j < codes.size(); ++j) {
ASSERT_FALSE(codes[i] == codes[j].substr(0, codes[i].length()))
<< codes[i] << " is prefix of " << codes[j];
}
}
}
TEST(Huffman, TestEncode) {
HuffmanCodec<std::string> huffman(GetTestSet());
uint64_t bits = 0;
size_t num_bits = 0;
EXPECT_TRUE(huffman.Encode("e", &bits, &num_bits));
EXPECT_EQ(2u, num_bits);
EXPECT_EQ("11", BitsToStream(bits, num_bits));
EXPECT_TRUE(huffman.Encode("a", &bits, &num_bits));
EXPECT_EQ(3u, num_bits);
EXPECT_EQ("101", BitsToStream(bits, num_bits));
EXPECT_TRUE(huffman.Encode("x", &bits, &num_bits));
EXPECT_EQ(5u, num_bits);
EXPECT_EQ("00001", BitsToStream(bits, num_bits));
EXPECT_FALSE(huffman.Encode("y", &bits, &num_bits));
}
TEST(Huffman, TestDecode) {
HuffmanCodec<std::string> huffman(GetTestSet());
TestBitReader bit_reader("01001""0001""1000""00110""00001""00");
auto read_bit = [&bit_reader](bool* bit) {
return bit_reader.ReadBit(bit);
};
std::string decoded;
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ("l", decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ("i", decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ("n", decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ("u", decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ("x", decoded);
ASSERT_FALSE(huffman.DecodeFromStream(read_bit, &decoded));
}
TEST(Huffman, TestDecodeNumbers) {
const std::map<uint32_t, uint32_t> hist = { {1, 10}, {2, 5}, {3, 15} };
HuffmanCodec<uint32_t> huffman(hist);
TestBitReader bit_reader("1""1""01""00""01""1");
auto read_bit = [&bit_reader](bool* bit) {
return bit_reader.ReadBit(bit);
};
uint32_t decoded;
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ(3u, decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ(3u, decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ(2u, decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ(1u, decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ(2u, decoded);
ASSERT_TRUE(huffman.DecodeFromStream(read_bit, &decoded));
EXPECT_EQ(3u, decoded);
}
} // anonymous namespace
|
