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, 75 insertions, 0 deletions

diff --git a/include/astc-codec/astc-codec.h b/include/astc-codec/astc-codec.h
new file mode 100644
index 0000000..1d41218
--- /dev/null
+++ b/include/astc-codec/astc-codec.h
@@ -0,0 +1,75 @@
+// 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_ASTC_CODEC_H_
+#define ASTC_CODEC_ASTC_CODEC_H_
+
+#include <cstddef>
+#include <cstdint>
+
+namespace astc_codec {
+
+// These are the valid ASTC footprints according to the specification in
+// Section C.2.7.
+enum class FootprintType {
+  k4x4,
+  k5x4,
+  k5x5,
+  k6x5,
+  k6x6,
+  k8x5,
+  k8x6,
+  k10x5,
+  k10x6,
+  k8x8,
+  k10x8,
+  k10x10,
+  k12x10,
+  k12x12,
+
+  kCount
+};
+
+// Decompresses ASTC LDR image data to a RGBA32 buffer.
+//
+// Supports formats defined in the KHR_texture_compression_astc_ldr spec and
+// returns UNORM8 values.  sRGB is not supported, and should be implemented
+// by the caller.
+//
+// |astc_data| - Compressed ASTC image buffer, must be at least |astc_data_size|
+//               bytes long.
+// |astc_data_size| - The size of |astc_data|, in bytes.
+// |width| - Image width, in pixels.
+// |height| - Image height, in pixels.
+// |footprint| - The ASTC footprint (block size) of the compressed image buffer.
+// |out_buffer| - Pointer to a buffer where the decompressed image will be
+//                stored, must be at least |out_buffer_size| bytes long.
+// |out_buffer_size| - The size of |out_buffer|, in bytes, at least
+//                     height*out_buffer_stride. If this is too small, this
+//                     function will return false and no data will be
+//                     decompressed.
+// |out_buffer_stride| - The stride that should be used to store rows of the
+//                       decoded image, must be at least 4*width bytes.
+//
+// Returns true if the decompression succeeded, or false if decompression
+// failed, or if the astc_data_size was too small for the given width, height,
+// and footprint, or if out_buffer_size is too small.
+bool ASTCDecompressToRGBA(const uint8_t* astc_data, size_t astc_data_size,
+                          size_t width, size_t height, FootprintType footprint,
+                          uint8_t* out_buffer, size_t out_buffer_size,
+                          size_t out_buffer_stride);
+
+}  // namespace astc_codec
+
+#endif  // ASTC_CODEC_ASTC_CODEC_H_