Initial version of astc-codec for open source release

Contains an implementation of an ASTC decoder that is able to pass the
dEQP ASTC LDR tests.

astc-codec has no external dependencies for the main library, only for
test code, and is licensed under the Apache license.

Components:

include/ - Public API that can decode ASTC LDR data into a RGBA UNORM8
buffer.

src/base/ - Base library with common functionality not directly related
to ASTC decoding.  Contains a uint128 implementation, BitStream for
reading/writing bits with a primitive (or uint128 type), Optional
implementation (to not take a dependency on C++17), and more.

src/decoder/ - Internal implementation of the ASTC decoder.

src/base/test/, src/decoder/test/ - Unit tests (and a fuzzing test) for
the astc decoder.

src/decoder/testdata/ - Sample ASTC images and golden image results for
testing.

src/decoder/tools/ - A tool to inspect contents of an ASTC file.

third_party/ - Third party libraries, only used for tests.

Change-Id: Ia98e5a7dc847daa3d3a48c5e62d94b8fb1cb98bd

1 files changed, 97 insertions, 0 deletions

diff --git a/src/decoder/astc_file.h b/src/decoder/astc_file.h
new file mode 100644
index 0000000..c31c2ba
--- /dev/null
+++ b/src/decoder/astc_file.h
@@ -0,0 +1,97 @@
+// 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.
+
+#ifndef ASTC_CODEC_DECODER_ASTC_FILE_H_
+#define ASTC_CODEC_DECODER_ASTC_FILE_H_
+
+#include "src/base/optional.h"
+#include "src/decoder/footprint.h"
+#include "src/decoder/physical_astc_block.h"
+
+#include <memory>
+#include <string>
+
+namespace astc_codec {
+
+// A thin wrapper around a .astc file on disk. This class simply reads the ASTC
+// header, and stores the block data in memory.
+class ASTCFile {
+ private:
+  struct Header {
+    Header(size_t width, size_t height, size_t depth, size_t block_width,
+           size_t block_height, size_t block_depth)
+        : width_(width),
+          height_(height),
+          depth_(depth),
+          block_width_(block_width),
+          block_height_(block_height),
+          block_depth_(block_depth) {}
+
+    size_t width_;
+    size_t height_;
+    size_t depth_;
+
+    size_t block_width_;
+    size_t block_height_;
+    size_t block_depth_;
+  };
+
+  ASTCFile(ASTCFile::Header&& header, std::string&& blocks);
+
+ public:
+  // Load an ASTC file from memory.
+  // If loading failed, nullptr is returned and an error string is populated
+  // in the error parameter.
+  static std::unique_ptr<ASTCFile> LoadFromMemory(const char* data,
+                                                  size_t length,
+                                                  std::string* error);
+
+  // Load an ASTC file from file.
+  // If loading failed, nullptr is returned and an error string is populated
+  // in the error parameter.
+  static std::unique_ptr<ASTCFile> LoadFile(const std::string& path,
+                                            std::string* error);
+
+  // Returns the footprint for the file, if it is considered to be a valid
+  // footprint.
+  base::Optional<Footprint> GetFootprint() const;
+
+  // Returns the string of the form "NxM" where N and M are the width and height
+  // of the block footprint, respectively.
+  std::string GetFootprintString() const;
+
+  // Get the raw block data for the astc file.
+  const std::string& GetRawBlockData() const;
+
+  // Returns the physical block at the associated block index.
+  PhysicalASTCBlock GetBlock(size_t block_idx) const;
+
+  size_t GetWidth() const { return header_.width_; }
+  size_t GetHeight() const { return header_.height_; }
+  size_t GetDepth() const { return header_.depth_; }
+
+  size_t NumBlocks() const {
+    return blocks_.size() / PhysicalASTCBlock::kSizeInBytes;
+  }
+
+ private:
+  static base::Optional<ASTCFile::Header> ParseHeader(const char* header);
+
+  const Header header_;
+  const std::string blocks_;
+};
+
+}  // namespace astc_codec
+
+#endif  // ASTC_CODEC_DECODER_ASTC_FILE_H_