1 files changed, 70 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/jxl/entropy_coder.cc b/third_party/jpeg-xl/lib/jxl/entropy_coder.cc
new file mode 100644
index 0000000000..0043c2d31e
--- /dev/null
+++ b/third_party/jpeg-xl/lib/jxl/entropy_coder.cc
@@ -0,0 +1,70 @@
+// Copyright (c) the JPEG XL Project Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "lib/jxl/entropy_coder.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <algorithm>
+#include <utility>
+#include <vector>
+
+#include "lib/jxl/ac_context.h"
+#include "lib/jxl/ac_strategy.h"
+#include "lib/jxl/base/bits.h"
+#include "lib/jxl/base/compiler_specific.h"
+#include "lib/jxl/base/profiler.h"
+#include "lib/jxl/base/status.h"
+#include "lib/jxl/coeff_order.h"
+#include "lib/jxl/coeff_order_fwd.h"
+#include "lib/jxl/common.h"
+#include "lib/jxl/dec_ans.h"
+#include "lib/jxl/dec_bit_reader.h"
+#include "lib/jxl/dec_context_map.h"
+#include "lib/jxl/epf.h"
+#include "lib/jxl/image.h"
+#include "lib/jxl/image_ops.h"
+
+namespace jxl {
+
+Status DecodeBlockCtxMap(BitReader* br, BlockCtxMap* block_ctx_map) {
+  auto& dct = block_ctx_map->dc_thresholds;
+  auto& qft = block_ctx_map->qf_thresholds;
+  auto& ctx_map = block_ctx_map->ctx_map;
+  bool is_default = br->ReadFixedBits<1>();
+  if (is_default) {
+    *block_ctx_map = BlockCtxMap();
+    return true;
+  }
+  block_ctx_map->num_dc_ctxs = 1;
+  for (int j : {0, 1, 2}) {
+    dct[j].resize(br->ReadFixedBits<4>());
+    block_ctx_map->num_dc_ctxs *= dct[j].size() + 1;
+    for (int& i : dct[j]) {
+      i = UnpackSigned(U32Coder::Read(kDCThresholdDist, br));
+    }
+  }
+  qft.resize(br->ReadFixedBits<4>());
+  for (uint32_t& i : qft) {
+    i = U32Coder::Read(kQFThresholdDist, br) + 1;
+  }
+
+  if (block_ctx_map->num_dc_ctxs * (qft.size() + 1) > 64) {
+    return JXL_FAILURE("Invalid block context map: too big");
+  }
+
+  ctx_map.resize(3 * kNumOrders * block_ctx_map->num_dc_ctxs *
+                 (qft.size() + 1));
+  JXL_RETURN_IF_ERROR(DecodeContextMap(&ctx_map, &block_ctx_map->num_ctxs, br));
+  if (block_ctx_map->num_ctxs > 16) {
+    return JXL_FAILURE("Invalid block context map: too many distinct contexts");
+  }
+  return true;
+}
+
+constexpr uint8_t BlockCtxMap::kDefaultCtxMap[];  // from ac_context.h
+
+}  // namespace jxl