1 files changed, 59 insertions, 0 deletions
diff --git a/extern/draco/draco/src/draco/compression/bit_coders/adaptive_rans_bit_encoder.cc b/extern/draco/draco/src/draco/compression/bit_coders/adaptive_rans_bit_encoder.cc
new file mode 100644
index 00000000000..5ce9dc388b8
--- /dev/null
+++ b/extern/draco/draco/src/draco/compression/bit_coders/adaptive_rans_bit_encoder.cc
@@ -0,0 +1,59 @@
+// Copyright 2016 The Draco Authors.
+//
+// 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.
+//
+#include "draco/compression/bit_coders/adaptive_rans_bit_encoder.h"
+
+#include "draco/compression/bit_coders/adaptive_rans_bit_coding_shared.h"
+
+namespace draco {
+
+AdaptiveRAnsBitEncoder::AdaptiveRAnsBitEncoder() {}
+
+AdaptiveRAnsBitEncoder::~AdaptiveRAnsBitEncoder() { Clear(); }
+
+void AdaptiveRAnsBitEncoder::StartEncoding() { Clear(); }
+
+void AdaptiveRAnsBitEncoder::EndEncoding(EncoderBuffer *target_buffer) {
+  // Buffer for ans to write.
+  std::vector<uint8_t> buffer(bits_.size() + 16);
+  AnsCoder ans_coder;
+  ans_write_init(&ans_coder, buffer.data());
+
+  // Unfortunately we have to encode the bits in reversed order, while the
+  // probabilities that should be given are those of the forward sequence.
+  double p0_f = 0.5;
+  std::vector<uint8_t> p0s;
+  p0s.reserve(bits_.size());
+  for (bool b : bits_) {
+    p0s.push_back(clamp_probability(p0_f));
+    p0_f = update_probability(p0_f, b);
+  }
+  auto bit = bits_.rbegin();
+  auto pit = p0s.rbegin();
+  while (bit != bits_.rend()) {
+    rabs_write(&ans_coder, *bit, *pit);
+    ++bit;
+    ++pit;
+  }
+
+  const uint32_t size_in_bytes = ans_write_end(&ans_coder);
+  target_buffer->Encode(size_in_bytes);
+  target_buffer->Encode(buffer.data(), size_in_bytes);
+
+  Clear();
+}
+
+void AdaptiveRAnsBitEncoder::Clear() { bits_.clear(); }
+
+}  // namespace draco