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diff --git a/third_party/jpeg-xl/lib/jxl/coeff_order_fwd.h b/third_party/jpeg-xl/lib/jxl/coeff_order_fwd.h
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+// 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.
+
+#ifndef LIB_JXL_COEFF_ORDER_FWD_H_
+#define LIB_JXL_COEFF_ORDER_FWD_H_
+
+// Breaks circular dependency between ac_strategy and coeff_order.
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "lib/jxl/base/compiler_specific.h"
+
+namespace jxl {
+
+// Needs at least 16 bits. A 32-bit type speeds up DecodeAC by 2% at the cost of
+// more memory.
+using coeff_order_t = uint32_t;
+
+// Maximum number of orders to be used. Note that this needs to be multiplied by
+// the number of channels. One per "size class" (plus one extra for DCT8),
+// shared between transforms of size XxY and of size YxX.
+constexpr uint8_t kNumOrders = 13;
+
+// DCT coefficients are laid out in such a way that the number of rows of
+// coefficients is always the smaller coordinate.
+JXL_INLINE constexpr size_t CoefficientRows(size_t rows, size_t columns) {
+  return rows < columns ? rows : columns;
+}
+
+JXL_INLINE constexpr size_t CoefficientColumns(size_t rows, size_t columns) {
+  return rows < columns ? columns : rows;
+}
+
+JXL_INLINE void CoefficientLayout(size_t* JXL_RESTRICT rows,
+                                  size_t* JXL_RESTRICT columns) {
+  size_t r = *rows;
+  size_t c = *columns;
+  *rows = CoefficientRows(r, c);
+  *columns = CoefficientColumns(r, c);
+}
+
+}  // namespace jxl
+
+#endif  // LIB_JXL_COEFF_ORDER_FWD_H_