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
|
// Copyright 2018 Google LLC
//
// 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
//
// https://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.
#include "src/decoder/astc_file.h"
#include <cstring>
#include <fstream>
#include <memory>
#include <sstream>
namespace astc_codec {
namespace {
static constexpr size_t kASTCHeaderSize = 16;
// Reads a value of size T from the buffer at the current offset, then
// increments the offset.
template<typename T>
inline T ReadVal(const char* file_data, size_t& offset) {
T x;
memcpy(&x, &file_data[offset], sizeof(T));
offset += sizeof(T);
return x;
}
} // namespace
ASTCFile::ASTCFile(Header&& header, std::string&& blocks)
: header_(std::move(header)), blocks_(std::move(blocks)) {}
std::unique_ptr<ASTCFile> ASTCFile::LoadFromMemory(const char* data,
size_t length,
std::string* error) {
if (length < kASTCHeaderSize) {
*error = "Incomplete header.";
return nullptr;
}
base::Optional<Header> header_opt = ParseHeader(data);
if (!header_opt) {
*error = "Invalid ASTC header.";
return nullptr;
}
Header header = header_opt.value();
if (header.block_width_ == 0 || header.block_height_ == 0) {
*error = "Invalid block size.";
return nullptr;
}
std::string blocks(data + kASTCHeaderSize, data + length);
// Check that this file has the expected number of blocks.
const size_t expected_block_count =
((header.width_ + header.block_width_ - 1) / header.block_width_) *
((header.height_ + header.block_height_ - 1) / header.block_height_);
if (blocks.size() % PhysicalASTCBlock::kSizeInBytes != 0 ||
blocks.size() / PhysicalASTCBlock::kSizeInBytes != expected_block_count) {
std::stringstream ss;
ss << "Unexpected file length " << blocks.size() << " expected "
<< kASTCHeaderSize +
expected_block_count * PhysicalASTCBlock::kSizeInBytes
<< " bytes.";
*error = ss.str();
return nullptr;
}
return std::unique_ptr<ASTCFile>(
new ASTCFile(std::move(header), std::move(blocks)));
}
std::unique_ptr<ASTCFile> ASTCFile::LoadFile(const std::string& path,
std::string* error) {
std::ifstream is(path, std::ios::binary);
if (!is) {
*error = "File not found: " + path;
return nullptr;
}
char header_data[kASTCHeaderSize] = {};
if (!is.read(header_data, kASTCHeaderSize)) {
*error = "Failed to load ASTC header.";
return nullptr;
}
base::Optional<Header> header_opt = ParseHeader(header_data);
if (!header_opt) {
*error = "Invalid ASTC header.";
return nullptr;
}
Header header = header_opt.value();
std::string blocks;
{
std::ostringstream ss;
ss << is.rdbuf();
blocks = ss.str();
}
// Check that this file has the expected number of blocks.
const size_t expected_block_count =
((header.width_ + header.block_width_ - 1) / header.block_width_) *
((header.height_ + header.block_height_ - 1) / header.block_height_);
if (blocks.size() % PhysicalASTCBlock::kSizeInBytes != 0 ||
blocks.size() / PhysicalASTCBlock::kSizeInBytes != expected_block_count) {
std::stringstream ss;
ss << "Unexpected file length " << blocks.size() << " expected "
<< kASTCHeaderSize +
expected_block_count * PhysicalASTCBlock::kSizeInBytes
<< " bytes.";
*error = ss.str();
return nullptr;
}
return std::unique_ptr<ASTCFile>(
new ASTCFile(std::move(header), std::move(blocks)));
}
base::Optional<Footprint> ASTCFile::GetFootprint() const {
return Footprint::FromDimensions(header_.block_width_, header_.block_height_);
}
std::string ASTCFile::GetFootprintString() const {
std::stringstream footprint;
footprint << header_.block_width_ << "x" << header_.block_height_;
return footprint.str();
}
const std::string& ASTCFile::GetRawBlockData() const {
return blocks_;
}
PhysicalASTCBlock ASTCFile::GetBlock(size_t block_idx) const {
const size_t sz = PhysicalASTCBlock::kSizeInBytes;
const size_t offset = PhysicalASTCBlock::kSizeInBytes * block_idx;
assert(offset <= blocks_.size() - sz);
return PhysicalASTCBlock(blocks_.substr(offset, sz));
}
base::Optional<ASTCFile::Header> ASTCFile::ParseHeader(const char* header) {
size_t offset = 0;
// TODO(google): Handle endianness.
const uint32_t magic = ReadVal<uint32_t>(header, offset);
if (magic != 0x5CA1AB13) {
return {};
}
const uint32_t block_width = ReadVal<uint8_t>(header, offset);
const uint32_t block_height = ReadVal<uint8_t>(header, offset);
const uint32_t block_depth = ReadVal<uint8_t>(header, offset);
uint32_t width = 0;
width |= ReadVal<uint8_t>(header, offset);
width |= ReadVal<uint8_t>(header, offset) << 8;
width |= ReadVal<uint8_t>(header, offset) << 16;
uint32_t height = 0;
height |= ReadVal<uint8_t>(header, offset);
height |= ReadVal<uint8_t>(header, offset) << 8;
height |= ReadVal<uint8_t>(header, offset) << 16;
uint32_t depth = 0;
depth |= ReadVal<uint8_t>(header, offset);
depth |= ReadVal<uint8_t>(header, offset) << 8;
depth |= ReadVal<uint8_t>(header, offset) << 16;
assert(offset == kASTCHeaderSize);
return Header(width, height, depth, block_width, block_height, block_depth);
}
} // namespace astc_codec
|
