diff --git a/quic/core/qpack/qpack_constants.cc b/quic/core/qpack/qpack_constants.cc
new file mode 100644
index 0000000..b9144e0
--- /dev/null
+++ b/quic/core/qpack/qpack_constants.cc
@@ -0,0 +1,200 @@
+// Copyright 2018 The Chromium 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 "net/third_party/quiche/src/quic/core/qpack/qpack_constants.h"
+
+#include <limits>
+
+#include "base/logging.h"
+
+namespace quic {
+
+namespace {
+
+// Validate that
+//  * in each instruction, the bits of |value| that are zero in |mask| are zero;
+//  * every byte matches exactly one opcode.
+void ValidateLangague(const QpackLanguage* language) {
+#ifndef NDEBUG
+  for (const auto* instruction : *language) {
+    DCHECK_EQ(0, instruction->opcode.value & ~instruction->opcode.mask);
+  }
+
+  for (uint8_t byte = 0; byte < std::numeric_limits<uint8_t>::max(); ++byte) {
+    size_t match_count = 0;
+    for (const auto* instruction : *language) {
+      if ((byte & instruction->opcode.mask) == instruction->opcode.value) {
+        ++match_count;
+      }
+    }
+    DCHECK_EQ(1u, match_count) << static_cast<int>(byte);
+  }
+#endif
+}
+
+}  // namespace
+
+bool operator==(const QpackInstructionOpcode& a,
+                const QpackInstructionOpcode& b) {
+  return std::tie(a.value, a.mask) == std::tie(b.value, b.mask);
+}
+
+const QpackInstruction* InsertWithNameReferenceInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b10000000, 0b10000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kSbit, 0b01000000},
+                            {QpackInstructionFieldType::kVarint, 6},
+                            {QpackInstructionFieldType::kValue, 7}}};
+  return instruction;
+}
+
+const QpackInstruction* InsertWithoutNameReferenceInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b01000000, 0b11000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kName, 5},
+                            {QpackInstructionFieldType::kValue, 7}}};
+  return instruction;
+}
+
+const QpackInstruction* DuplicateInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00000000, 0b11100000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode, {{QpackInstructionFieldType::kVarint, 5}}};
+  return instruction;
+}
+
+const QpackInstruction* SetDynamicTableCapacityInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00100000, 0b11100000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode, {{QpackInstructionFieldType::kVarint, 5}}};
+  return instruction;
+}
+
+const QpackLanguage* QpackEncoderStreamLanguage() {
+  static const QpackLanguage* const language = new QpackLanguage{
+      InsertWithNameReferenceInstruction(),
+      InsertWithoutNameReferenceInstruction(), DuplicateInstruction(),
+      SetDynamicTableCapacityInstruction()};
+  ValidateLangague(language);
+  return language;
+}
+
+const QpackInstruction* InsertCountIncrementInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00000000, 0b11000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode, {{QpackInstructionFieldType::kVarint, 6}}};
+  return instruction;
+}
+
+const QpackInstruction* HeaderAcknowledgementInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b10000000, 0b10000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode, {{QpackInstructionFieldType::kVarint, 7}}};
+  return instruction;
+}
+
+const QpackInstruction* StreamCancellationInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b01000000, 0b11000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode, {{QpackInstructionFieldType::kVarint, 6}}};
+  return instruction;
+}
+
+const QpackLanguage* QpackDecoderStreamLanguage() {
+  static const QpackLanguage* const language = new QpackLanguage{
+      InsertCountIncrementInstruction(), HeaderAcknowledgementInstruction(),
+      StreamCancellationInstruction()};
+  ValidateLangague(language);
+  return language;
+}
+
+const QpackInstruction* QpackPrefixInstruction() {
+  // This opcode matches every input.
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00000000, 0b00000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kVarint, 8},
+                            {QpackInstructionFieldType::kSbit, 0b10000000},
+                            {QpackInstructionFieldType::kVarint2, 7}}};
+  return instruction;
+}
+
+const QpackLanguage* QpackPrefixLanguage() {
+  static const QpackLanguage* const language =
+      new QpackLanguage{QpackPrefixInstruction()};
+  ValidateLangague(language);
+  return language;
+}
+
+const QpackInstruction* QpackIndexedHeaderFieldInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b10000000, 0b10000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kSbit, 0b01000000},
+                            {QpackInstructionFieldType::kVarint, 6}}};
+  return instruction;
+}
+
+const QpackInstruction* QpackIndexedHeaderFieldPostBaseInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00010000, 0b11110000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode, {{QpackInstructionFieldType::kVarint, 4}}};
+  return instruction;
+}
+
+const QpackInstruction* QpackLiteralHeaderFieldNameReferenceInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b01000000, 0b11000000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kSbit, 0b00010000},
+                            {QpackInstructionFieldType::kVarint, 4},
+                            {QpackInstructionFieldType::kValue, 7}}};
+  return instruction;
+}
+
+const QpackInstruction* QpackLiteralHeaderFieldPostBaseInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00000000, 0b11110000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kVarint, 3},
+                            {QpackInstructionFieldType::kValue, 7}}};
+  return instruction;
+}
+
+const QpackInstruction* QpackLiteralHeaderFieldInstruction() {
+  static const QpackInstructionOpcode* const opcode =
+      new QpackInstructionOpcode{0b00100000, 0b11100000};
+  static const QpackInstruction* const instruction =
+      new QpackInstruction{*opcode,
+                           {{QpackInstructionFieldType::kName, 3},
+                            {QpackInstructionFieldType::kValue, 7}}};
+  return instruction;
+}
+
+const QpackLanguage* QpackRequestStreamLanguage() {
+  static const QpackLanguage* const language =
+      new QpackLanguage{QpackIndexedHeaderFieldInstruction(),
+                        QpackIndexedHeaderFieldPostBaseInstruction(),
+                        QpackLiteralHeaderFieldNameReferenceInstruction(),
+                        QpackLiteralHeaderFieldPostBaseInstruction(),
+                        QpackLiteralHeaderFieldInstruction()};
+  ValidateLangague(language);
+  return language;
+}
+
+}  // namespace quic