From 6aa02db3fb1ebbc0f2f97ed3be1006912a489e6e Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Tue, 7 Jun 2022 20:52:27 +0000
Subject: [PATCH 01/13] Add ERC2309 mint function and tests

---
 contracts/ERC721A.sol                      | 53 ++++++++++++++++++++++
 contracts/IERC721A.sol                     |  9 ++++
 contracts/mocks/ERC721AWithERC2309Mock.sol | 23 ++++++++++
 test/ERC721A.test.js                       | 24 ++++++++++
 test/GasUsage.test.js                      | 14 ++++++
 5 files changed, 123 insertions(+)
 create mode 100644 contracts/mocks/ERC721AWithERC2309Mock.sol

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index ef2ec2235..b2dc780ad 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -504,6 +504,59 @@ contract ERC721A is IERC721A {
         _afterTokenTransfers(address(0), to, startTokenId, quantity);
     }
 
+    /**
+     * @dev Mints `quantity` tokens and transfers them to `to`.
+     *
+     * This function is intended for efficient minting during contract creation.
+     *
+     * It emits only one {ConsecutiveTransfer} as defined in 
+     * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
+     * instead of one or more {Transfer} events.
+     *
+     * Calling this function outside of contract creation WILL break the ERC721 standard.
+     *
+     * Requirements:
+     *
+     * - `to` cannot be the zero address.
+     * - `quantity` must be greater than 0.
+     *
+     * Emits a {ConsecutiveTransfer} event.
+     */
+    function _mintERC2309(address to, uint256 quantity) internal {
+        uint256 startTokenId = _currentIndex;
+        if (_addressToUint256(to) == 0) revert MintToZeroAddress();
+        if (quantity == 0) revert MintZeroQuantity();
+
+        _beforeTokenTransfers(address(0), to, startTokenId, quantity);
+
+        // Overflows are incredibly unrealistic.
+        // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
+        // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
+        unchecked {
+            // Updates:
+            // - `balance += quantity`.
+            // - `numberMinted += quantity`.
+            //
+            // We can directly add to the balance and number minted.
+            _packedAddressData[to] += quantity * ((1 << BITPOS_NUMBER_MINTED) | 1);
+
+            // Updates:
+            // - `address` to the owner.
+            // - `startTimestamp` to the timestamp of minting.
+            // - `burned` to `false`.
+            // - `nextInitialized` to `quantity == 1`.
+            _packedOwnerships[startTokenId] =
+                _addressToUint256(to) |
+                (block.timestamp << BITPOS_START_TIMESTAMP) |
+                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED);
+
+            emit ConsecutiveTransfer(startTokenId, startTokenId + quantity - 1, address(0), to);
+
+            _currentIndex = startTokenId + quantity;
+        }
+        _afterTokenTransfers(address(0), to, startTokenId, quantity);
+    }
+
     /**
      * @dev Transfers `tokenId` from `from` to `to`.
      *
diff --git a/contracts/IERC721A.sol b/contracts/IERC721A.sol
index 6d0be7231..f60800709 100644
--- a/contracts/IERC721A.sol
+++ b/contracts/IERC721A.sol
@@ -252,4 +252,13 @@ interface IERC721A {
      * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
      */
     function tokenURI(uint256 tokenId) external view returns (string memory);
+
+    // ==============================
+    //            IERC2309
+    // ==============================
+
+    /**
+     * @dev Emitted when tokens in `fromTokenId` to `toTokenId` (inclusive) is transferred from `from` to `to.
+     */
+    event ConsecutiveTransfer(uint256 indexed fromTokenId, uint256 toTokenId, address indexed from, address indexed to);
 }
diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
new file mode 100644
index 000000000..fde2df221
--- /dev/null
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: MIT
+// ERC721A Contracts v4.0.0
+// Creators: Chiru Labs
+
+pragma solidity ^0.8.4;
+
+import '../ERC721A.sol';
+
+/**
+ * @dev Mock for testing and benchmarking purposes. 
+ * Calling `_mintERC2309` outside of contract creation breaks the ERC721 standard.
+ */
+contract ERC721AWithERC2309Mock is ERC721A {
+    constructor(string memory name_, string memory symbol_) ERC721A(name_, symbol_) {}
+
+    function mintOneERC2309(address to) public {
+        _mintERC2309(to, 1);
+    }
+
+    function mintTenERC2309(address to) public {
+        _mintERC2309(to, 10);
+    }
+}
\ No newline at end of file
diff --git a/test/ERC721A.test.js b/test/ERC721A.test.js
index 10a261792..aa9e82de7 100644
--- a/test/ERC721A.test.js
+++ b/test/ERC721A.test.js
@@ -680,3 +680,27 @@ describe(
   'ERC721A override _startTokenId()',
   createTestSuite({ contract: 'ERC721AStartTokenIdMock', constructorArgs: ['Azuki', 'AZUKI', 1] })
 );
+
+describe('ERC721A with ERC2309', async function () {
+  beforeEach(async function () {
+    this.erc721a = await deployContract('ERC721AWithERC2309Mock', ['Azuki', 'AZUKI']);
+    const [owner, addr1] = await ethers.getSigners();
+    this.owner = owner;
+    this.addr1 = addr1;
+    this.testEmit = async (methodName, fromTokenId, toTokenId) => {
+      await expect(await this.erc721a[methodName](this.addr1.address))
+        .to.emit(this.erc721a, 'ConsecutiveTransfer')
+        .withArgs(fromTokenId, toTokenId, ZERO_ADDRESS, this.addr1.address);
+    };
+  });
+
+  it('emits a ConsecutiveTransfer event for single mint', async function () {
+    await this.testEmit('mintOneERC2309', 0, 0);
+    await this.testEmit('mintOneERC2309', 1, 1);
+  });
+
+  it('emits a ConsecutiveTransfer event for batch mint', async function () {
+    await this.testEmit('mintTenERC2309', 0, 9);
+    await this.testEmit('mintTenERC2309', 10, 19);
+  });
+});
diff --git a/test/GasUsage.test.js b/test/GasUsage.test.js
index 50eeda415..295a158d2 100644
--- a/test/GasUsage.test.js
+++ b/test/GasUsage.test.js
@@ -40,6 +40,20 @@ describe('ERC721A Gas Usage', function () {
     });
   });
 
+  it('mintOneERC2309', async function () {
+    let contract = await deployContract('ERC721AWithERC2309Mock', ['Azuki', 'AZUKI']);
+    await contract.mintOneERC2309(this.owner.address);
+    await contract.mintOneERC2309(this.owner.address);
+    await contract.mintOneERC2309(this.addr1.address); 
+  });
+
+  it('mintTenERC2309', async function () {
+    let contract = await deployContract('ERC721AWithERC2309Mock', ['Azuki', 'AZUKI']);
+    await contract.mintTenERC2309(this.owner.address);
+    await contract.mintTenERC2309(this.owner.address);
+    await contract.mintTenERC2309(this.addr1.address);  
+  });
+
   context('transferFrom', function () {
     beforeEach(async function () {
       await this.erc721a.mintTen(this.owner.address);

From 1b0f7491f01c24497174edd0eb89072facfb7971 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Tue, 7 Jun 2022 22:02:00 +0000
Subject: [PATCH 02/13] Add tests for full coverage

---
 contracts/mocks/ERC721AWithERC2309Mock.sol | 4 ++++
 test/ERC721A.test.js                       | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index fde2df221..d130a8ea2 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -20,4 +20,8 @@ contract ERC721AWithERC2309Mock is ERC721A {
     function mintTenERC2309(address to) public {
         _mintERC2309(to, 10);
     }
+
+    function mintERC2309(address to, uint256 quantity) public {
+        _mintERC2309(to, quantity);
+    }
 }
\ No newline at end of file
diff --git a/test/ERC721A.test.js b/test/ERC721A.test.js
index aa9e82de7..928a7b0bf 100644
--- a/test/ERC721A.test.js
+++ b/test/ERC721A.test.js
@@ -703,4 +703,12 @@ describe('ERC721A with ERC2309', async function () {
     await this.testEmit('mintTenERC2309', 0, 9);
     await this.testEmit('mintTenERC2309', 10, 19);
   });
+
+  it('rejects mints to the zero address', async function () {
+    await expect(this.erc721a.mintERC2309(ZERO_ADDRESS, 1)).to.be.revertedWith('MintToZeroAddress');
+  });
+
+  it('requires quantity to be greater than 0', async function () {
+    await expect(this.erc721a.mintERC2309(this.owner.address, 0)).to.be.revertedWith('MintZeroQuantity');
+  });
 });

From 0d98abb1fb0796d5ffb0dc65e09f797636a29dc9 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Wed, 8 Jun 2022 00:36:21 +0000
Subject: [PATCH 03/13] Lint

---
 contracts/ERC721A.sol                      | 2 +-
 contracts/mocks/ERC721AWithERC2309Mock.sol | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index b2dc780ad..565bf1fcc 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -509,7 +509,7 @@ contract ERC721A is IERC721A {
      *
      * This function is intended for efficient minting during contract creation.
      *
-     * It emits only one {ConsecutiveTransfer} as defined in 
+     * It emits only one {ConsecutiveTransfer} as defined in
      * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
      * instead of one or more {Transfer} events.
      *
diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index d130a8ea2..3e3f8572a 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -7,7 +7,7 @@ pragma solidity ^0.8.4;
 import '../ERC721A.sol';
 
 /**
- * @dev Mock for testing and benchmarking purposes. 
+ * @dev Mock for testing and benchmarking purposes.
  * Calling `_mintERC2309` outside of contract creation breaks the ERC721 standard.
  */
 contract ERC721AWithERC2309Mock is ERC721A {
@@ -24,4 +24,4 @@ contract ERC721AWithERC2309Mock is ERC721A {
     function mintERC2309(address to, uint256 quantity) public {
         _mintERC2309(to, quantity);
     }
-}
\ No newline at end of file
+}

From d3434d47f0356a46207797923f8ff64c41f24f3e Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Wed, 8 Jun 2022 01:07:00 +0000
Subject: [PATCH 04/13] Edit comments

---
 contracts/ERC721A.sol                      | 4 +++-
 contracts/mocks/ERC721AWithERC2309Mock.sol | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index 565bf1fcc..fb70494bb 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -511,9 +511,11 @@ contract ERC721A is IERC721A {
      *
      * It emits only one {ConsecutiveTransfer} as defined in
      * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
-     * instead of one or more {Transfer} events.
+     * instead of a sequence of {Transfer} events.
      *
      * Calling this function outside of contract creation WILL break the ERC721 standard.
+     * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
+     * {ConsecutiveTransfer} event is only permissible during contract creation.
      *
      * Requirements:
      *
diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index 3e3f8572a..5646ddfa8 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -9,6 +9,8 @@ import '../ERC721A.sol';
 /**
  * @dev Mock for testing and benchmarking purposes.
  * Calling `_mintERC2309` outside of contract creation breaks the ERC721 standard.
+ * The mock exposes the function for simplicity of testing and gas comparisons with
+ * the other mint functions.
  */
 contract ERC721AWithERC2309Mock is ERC721A {
     constructor(string memory name_, string memory symbol_) ERC721A(name_, symbol_) {}

From b9e6d078d87d93a593df60d2d2716d7690e8e652 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Wed, 8 Jun 2022 01:10:36 +0000
Subject: [PATCH 05/13] Edit comments

---
 contracts/ERC721A.sol  | 2 +-
 contracts/IERC721A.sol | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index fb70494bb..ad13f1b1c 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -511,7 +511,7 @@ contract ERC721A is IERC721A {
      *
      * It emits only one {ConsecutiveTransfer} as defined in
      * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
-     * instead of a sequence of {Transfer} events.
+     * instead of a sequence of {Transfer} event(s).
      *
      * Calling this function outside of contract creation WILL break the ERC721 standard.
      * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
diff --git a/contracts/IERC721A.sol b/contracts/IERC721A.sol
index f60800709..d779b03fa 100644
--- a/contracts/IERC721A.sol
+++ b/contracts/IERC721A.sol
@@ -258,7 +258,8 @@ interface IERC721A {
     // ==============================
 
     /**
-     * @dev Emitted when tokens in `fromTokenId` to `toTokenId` (inclusive) is transferred from `from` to `to.
+     * @dev Emitted when tokens in `fromTokenId` to `toTokenId` (inclusive) is transferred from `from` to `to`,
+     * as defined in the ERC2309 standard. See `_mintERC2309` for more details.
      */
     event ConsecutiveTransfer(uint256 indexed fromTokenId, uint256 toTokenId, address indexed from, address indexed to);
 }

From f1bf9070450c10ee812e87dd77a5c53b1b39f3a8 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Thu, 9 Jun 2022 23:21:09 +0000
Subject: [PATCH 06/13] Add more comments

---
 contracts/ERC721A.sol | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index ad13f1b1c..9a3d73136 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -432,6 +432,8 @@ contract ERC721A is IERC721A {
      *   {IERC721Receiver-onERC721Received}, which is called for each safe transfer.
      * - `quantity` must be greater than 0.
      *
+     * See {_mint}.
+     *
      * Emits a {Transfer} event for each mint.
      */
     function _safeMint(
@@ -464,6 +466,10 @@ contract ERC721A is IERC721A {
      * - `to` cannot be the zero address.
      * - `quantity` must be greater than 0.
      *
+     * Note: some marketplaces may have difficulties fully registering a very large `quantity`.
+     * We have verified full support on OpenSea's and LooksRare's Rinkeby testnet marketplaces
+     * for `quantity = 5000` on 5th May 2022. Support may vary, and may change over time.
+     *
      * Emits a {Transfer} event for each mint.
      */
     function _mint(address to, uint256 quantity) internal {
@@ -517,6 +523,10 @@ contract ERC721A is IERC721A {
      * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
      * {ConsecutiveTransfer} event is only permissible during contract creation.
      *
+     * Note: some marketplaces may have difficulties fully registering a very large `quantity`.
+     * We have verified full support on OpenSea's and LooksRare's Rinkeby testnet marketplaces
+     * for `quantity = 5000` on 5th May 2022. Support may vary, and may change over time.
+     *
      * Requirements:
      *
      * - `to` cannot be the zero address.

From acb7cbcd5490810bb9bfaf3c57434b4ff83f3531 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Thu, 9 Jun 2022 23:43:31 +0000
Subject: [PATCH 07/13] Edit comments

---
 contracts/ERC721A.sol | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index 9a3d73136..9ff83261d 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -468,7 +468,7 @@ contract ERC721A is IERC721A {
      *
      * Note: some marketplaces may have difficulties fully registering a very large `quantity`.
      * We have verified full support on OpenSea's and LooksRare's Rinkeby testnet marketplaces
-     * for `quantity = 5000` on 5th May 2022. Support may vary, and may change over time.
+     * for `quantity = 5000` on 5th June 2022. Support may vary, and may change over time.
      *
      * Emits a {Transfer} event for each mint.
      */
@@ -525,7 +525,7 @@ contract ERC721A is IERC721A {
      *
      * Note: some marketplaces may have difficulties fully registering a very large `quantity`.
      * We have verified full support on OpenSea's and LooksRare's Rinkeby testnet marketplaces
-     * for `quantity = 5000` on 5th May 2022. Support may vary, and may change over time.
+     * for `quantity = 5000` on 5th June 2022. Support may vary, and may change over time.
      *
      * Requirements:
      *

From cb1cc884e8639d896c26704a12b64f931ba73507 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 13 Jun 2022 02:09:00 +0000
Subject: [PATCH 08/13] Add requested changes

---
 contracts/ERC721A.sol                      | 24 ++++++-------
 contracts/IERC721A.sol                     |  5 +++
 contracts/mocks/ERC721AWithERC2309Mock.sol | 16 ++++++---
 test/ERC721A.test.js                       | 41 ++++++++++++++--------
 test/GasUsage.test.js                      |  6 ++--
 5 files changed, 59 insertions(+), 33 deletions(-)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index 9ff83261d..0abee10ff 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -56,6 +56,12 @@ contract ERC721A is IERC721A {
     // The bit mask of the `nextInitialized` bit in packed ownership.
     uint256 private constant BITMASK_NEXT_INITIALIZED = 1 << 225;
 
+    // The maximum `quantity` that can be minted with `_mintERC2309`.
+    // This limit is to prevent overflows on the address data entries.
+    // For a limit of 5000, a total of 3.689e15 calls to `_mintERC2309`
+    // is required to cause an overflow, which is unrealistic.
+    uint256 private constant MAX_MINT_ERC2309_QUANTITY_LIMIT = 5000;
+
     // The tokenId of the next token to be minted.
     uint256 private _currentIndex;
 
@@ -466,10 +472,6 @@ contract ERC721A is IERC721A {
      * - `to` cannot be the zero address.
      * - `quantity` must be greater than 0.
      *
-     * Note: some marketplaces may have difficulties fully registering a very large `quantity`.
-     * We have verified full support on OpenSea's and LooksRare's Rinkeby testnet marketplaces
-     * for `quantity = 5000` on 5th June 2022. Support may vary, and may change over time.
-     *
      * Emits a {Transfer} event for each mint.
      */
     function _mint(address to, uint256 quantity) internal {
@@ -513,20 +515,17 @@ contract ERC721A is IERC721A {
     /**
      * @dev Mints `quantity` tokens and transfers them to `to`.
      *
-     * This function is intended for efficient minting during contract creation.
+     * This function is intended for efficient minting only during contract creation.
      *
      * It emits only one {ConsecutiveTransfer} as defined in
      * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
      * instead of a sequence of {Transfer} event(s).
      *
-     * Calling this function outside of contract creation WILL break the ERC721 standard.
+     * Calling this function outside of contract creation WILL make your contract
+     * non-compliant with the ERC721 standard.
      * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
      * {ConsecutiveTransfer} event is only permissible during contract creation.
      *
-     * Note: some marketplaces may have difficulties fully registering a very large `quantity`.
-     * We have verified full support on OpenSea's and LooksRare's Rinkeby testnet marketplaces
-     * for `quantity = 5000` on 5th June 2022. Support may vary, and may change over time.
-     *
      * Requirements:
      *
      * - `to` cannot be the zero address.
@@ -538,12 +537,11 @@ contract ERC721A is IERC721A {
         uint256 startTokenId = _currentIndex;
         if (_addressToUint256(to) == 0) revert MintToZeroAddress();
         if (quantity == 0) revert MintZeroQuantity();
+        if (quantity > MAX_MINT_ERC2309_QUANTITY_LIMIT) revert MintERC2309QuantityExceedsLimit();
 
         _beforeTokenTransfers(address(0), to, startTokenId, quantity);
 
-        // Overflows are incredibly unrealistic.
-        // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1
-        // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1
+        // Overflows are unrealistic due to the above check for `quantity` to be below the limit.
         unchecked {
             // Updates:
             // - `balance += quantity`.
diff --git a/contracts/IERC721A.sol b/contracts/IERC721A.sol
index d779b03fa..143132dcf 100644
--- a/contracts/IERC721A.sol
+++ b/contracts/IERC721A.sol
@@ -68,6 +68,11 @@ interface IERC721A {
      */
     error URIQueryForNonexistentToken();
 
+    /**
+     * The `quantity` minted with ERC2309 exceeds the safety limit.
+     */
+    error MintERC2309QuantityExceedsLimit();
+
     struct TokenOwnership {
         // The address of the owner.
         address addr;
diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index 5646ddfa8..9e5d65aa9 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -8,12 +8,20 @@ import '../ERC721A.sol';
 
 /**
  * @dev Mock for testing and benchmarking purposes.
- * Calling `_mintERC2309` outside of contract creation breaks the ERC721 standard.
- * The mock exposes the function for simplicity of testing and gas comparisons with
- * the other mint functions.
+ * The mock exposes the function for gas benchmarks with other mint functions.
  */
 contract ERC721AWithERC2309Mock is ERC721A {
-    constructor(string memory name_, string memory symbol_) ERC721A(name_, symbol_) {}
+    constructor(
+        string memory name_,
+        string memory symbol_,
+        address to,
+        uint256 quantity,
+        bool mintInConstructor
+    ) ERC721A(name_, symbol_) {
+        if (mintInConstructor) {
+            _mintERC2309(to, quantity);
+        }
+    }
 
     function mintOneERC2309(address to) public {
         _mintERC2309(to, 1);
diff --git a/test/ERC721A.test.js b/test/ERC721A.test.js
index 928a7b0bf..29c5ddd99 100644
--- a/test/ERC721A.test.js
+++ b/test/ERC721A.test.js
@@ -683,32 +683,45 @@ describe(
 
 describe('ERC721A with ERC2309', async function () {
   beforeEach(async function () {
-    this.erc721a = await deployContract('ERC721AWithERC2309Mock', ['Azuki', 'AZUKI']);
     const [owner, addr1] = await ethers.getSigners();
     this.owner = owner;
     this.addr1 = addr1;
-    this.testEmit = async (methodName, fromTokenId, toTokenId) => {
-      await expect(await this.erc721a[methodName](this.addr1.address))
-        .to.emit(this.erc721a, 'ConsecutiveTransfer')
-        .withArgs(fromTokenId, toTokenId, ZERO_ADDRESS, this.addr1.address);
-    };
+
+    let args;
+    args = ['Azuki', 'AZUKI', this.owner.address, 1, true];
+    this.erc721aMint1 = await deployContract('ERC721AWithERC2309Mock', args);
+    args = ['Azuki', 'AZUKI', this.owner.address, 10, true];
+    this.erc721aMint10 = await deployContract('ERC721AWithERC2309Mock', args);
   });
 
-  it('emits a ConsecutiveTransfer event for single mint', async function () {
-    await this.testEmit('mintOneERC2309', 0, 0);
-    await this.testEmit('mintOneERC2309', 1, 1);
+  it('emits a ConsecutiveTransfer event for single mint', async function () {    
+    expect(this.erc721aMint1.deployTransaction)
+      .to.emit(this.erc721aMint1, 'ConsecutiveTransfer')
+      .withArgs(0, 0, ZERO_ADDRESS, this.owner.address);
   });
 
-  it('emits a ConsecutiveTransfer event for batch mint', async function () {
-    await this.testEmit('mintTenERC2309', 0, 9);
-    await this.testEmit('mintTenERC2309', 10, 19);
+  it('emits a ConsecutiveTransfer event for a batch mint', async function () {    
+    expect(this.erc721aMint10.deployTransaction)
+      .to.emit(this.erc721aMint10, 'ConsecutiveTransfer')
+      .withArgs(0, 9, ZERO_ADDRESS, this.owner.address);
   });
 
+  it('requires quantity to be below mint limit', async function () {
+    let args;
+    const mintLimit = 5000;
+    args = ['Azuki', 'AZUKI', this.owner.address, mintLimit, true];
+    await deployContract('ERC721AWithERC2309Mock', args);
+    args = ['Azuki', 'AZUKI', this.owner.address, mintLimit + 1, true];
+    await expect(deployContract('ERC721AWithERC2309Mock', args)).to.be.revertedWith('MintERC2309QuantityExceedsLimit');
+  })
+
   it('rejects mints to the zero address', async function () {
-    await expect(this.erc721a.mintERC2309(ZERO_ADDRESS, 1)).to.be.revertedWith('MintToZeroAddress');
+    let args = ['Azuki', 'AZUKI', ZERO_ADDRESS, 1, true];
+    await expect(deployContract('ERC721AWithERC2309Mock', args)).to.be.revertedWith('MintToZeroAddress');
   });
 
   it('requires quantity to be greater than 0', async function () {
-    await expect(this.erc721a.mintERC2309(this.owner.address, 0)).to.be.revertedWith('MintZeroQuantity');
+    let args = ['Azuki', 'AZUKI', this.owner.address, 0, true];
+    await expect(deployContract('ERC721AWithERC2309Mock', args)).to.be.revertedWith('MintZeroQuantity');
   });
 });
diff --git a/test/GasUsage.test.js b/test/GasUsage.test.js
index 295a158d2..7790ffb29 100644
--- a/test/GasUsage.test.js
+++ b/test/GasUsage.test.js
@@ -41,14 +41,16 @@ describe('ERC721A Gas Usage', function () {
   });
 
   it('mintOneERC2309', async function () {
-    let contract = await deployContract('ERC721AWithERC2309Mock', ['Azuki', 'AZUKI']);
+    let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
+    let contract = await deployContract('ERC721AWithERC2309Mock', args);
     await contract.mintOneERC2309(this.owner.address);
     await contract.mintOneERC2309(this.owner.address);
     await contract.mintOneERC2309(this.addr1.address); 
   });
 
   it('mintTenERC2309', async function () {
-    let contract = await deployContract('ERC721AWithERC2309Mock', ['Azuki', 'AZUKI']);
+    let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
+    let contract = await deployContract('ERC721AWithERC2309Mock', args);
     await contract.mintTenERC2309(this.owner.address);
     await contract.mintTenERC2309(this.owner.address);
     await contract.mintTenERC2309(this.addr1.address);  

From e3a7cbd068b0c0c17d56bc023674324c98cb0fa7 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 13 Jun 2022 02:23:31 +0000
Subject: [PATCH 09/13] Remove unused mock function

---
 contracts/mocks/ERC721AWithERC2309Mock.sol | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index 9e5d65aa9..46d523843 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -30,8 +30,4 @@ contract ERC721AWithERC2309Mock is ERC721A {
     function mintTenERC2309(address to) public {
         _mintERC2309(to, 10);
     }
-
-    function mintERC2309(address to, uint256 quantity) public {
-        _mintERC2309(to, quantity);
-    }
 }

From 285b7d3281419efb3dcfc79ba5278d6c22a107fa Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 13 Jun 2022 05:50:58 +0000
Subject: [PATCH 10/13] Add comments on non-compliant benchmarks

---
 contracts/mocks/ERC721AWithERC2309Mock.sol | 12 +++++---
 test/GasUsage.test.js                      | 36 ++++++++++++----------
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index 46d523843..980118242 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -6,10 +6,6 @@ pragma solidity ^0.8.4;
 
 import '../ERC721A.sol';
 
-/**
- * @dev Mock for testing and benchmarking purposes.
- * The mock exposes the function for gas benchmarks with other mint functions.
- */
 contract ERC721AWithERC2309Mock is ERC721A {
     constructor(
         string memory name_,
@@ -23,10 +19,18 @@ contract ERC721AWithERC2309Mock is ERC721A {
         }
     }
 
+    /**
+     * @dev This function is only for gas benchmarking purposes.
+     * Calling `_mintERC3201` outside of contract creation is non-compliant with ERC721.
+     */
     function mintOneERC2309(address to) public {
         _mintERC2309(to, 1);
     }
 
+    /**
+     * @dev This function is only for gas benchmarking purposes.
+     * Calling `_mintERC3201` outside of contract creation is non-compliant with ERC721.
+     */
     function mintTenERC2309(address to) public {
         _mintERC2309(to, 10);
     }
diff --git a/test/GasUsage.test.js b/test/GasUsage.test.js
index 7790ffb29..71da3f62e 100644
--- a/test/GasUsage.test.js
+++ b/test/GasUsage.test.js
@@ -40,22 +40,6 @@ describe('ERC721A Gas Usage', function () {
     });
   });
 
-  it('mintOneERC2309', async function () {
-    let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
-    let contract = await deployContract('ERC721AWithERC2309Mock', args);
-    await contract.mintOneERC2309(this.owner.address);
-    await contract.mintOneERC2309(this.owner.address);
-    await contract.mintOneERC2309(this.addr1.address); 
-  });
-
-  it('mintTenERC2309', async function () {
-    let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
-    let contract = await deployContract('ERC721AWithERC2309Mock', args);
-    await contract.mintTenERC2309(this.owner.address);
-    await contract.mintTenERC2309(this.owner.address);
-    await contract.mintTenERC2309(this.addr1.address);  
-  });
-
   context('transferFrom', function () {
     beforeEach(async function () {
       await this.erc721a.mintTen(this.owner.address);
@@ -84,4 +68,24 @@ describe('ERC721A Gas Usage', function () {
       await this.erc721a.connect(this.owner).transferTenAvg(this.addr1.address);
     });
   });
+
+  it('mintOneERC2309', async function () {
+    // The following call `_mintERC3201` internally outside of contract creation.
+    // This is non-compliant with ERC721, and is only meant for gas benchmark purposes.
+    let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
+    let contract = await deployContract('ERC721AWithERC2309Mock', args);
+    await contract.mintOneERC2309(this.owner.address);
+    await contract.mintOneERC2309(this.owner.address);
+    await contract.mintOneERC2309(this.addr1.address); 
+  });
+
+  it('mintTenERC2309', async function () {
+    // The following call `_mintERC3201` internally outside of contract creation.
+    // This is non-compliant with ERC721, and is only meant for gas benchmark purposes.
+    let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
+    let contract = await deployContract('ERC721AWithERC2309Mock', args);
+    await contract.mintTenERC2309(this.owner.address);
+    await contract.mintTenERC2309(this.owner.address);
+    await contract.mintTenERC2309(this.addr1.address);  
+  });
 });

From 897079968cdc93f98b87cb5ebd8d394f33fb97ab Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 13 Jun 2022 05:52:37 +0000
Subject: [PATCH 11/13] Edit comments

---
 test/GasUsage.test.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/GasUsage.test.js b/test/GasUsage.test.js
index 71da3f62e..a6637fc47 100644
--- a/test/GasUsage.test.js
+++ b/test/GasUsage.test.js
@@ -71,7 +71,7 @@ describe('ERC721A Gas Usage', function () {
 
   it('mintOneERC2309', async function () {
     // The following call `_mintERC3201` internally outside of contract creation.
-    // This is non-compliant with ERC721, and is only meant for gas benchmark purposes.
+    // This is non-compliant with ERC721, and is only meant for gas comparisons.
     let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
     let contract = await deployContract('ERC721AWithERC2309Mock', args);
     await contract.mintOneERC2309(this.owner.address);
@@ -81,7 +81,7 @@ describe('ERC721A Gas Usage', function () {
 
   it('mintTenERC2309', async function () {
     // The following call `_mintERC3201` internally outside of contract creation.
-    // This is non-compliant with ERC721, and is only meant for gas benchmark purposes.
+    // This is non-compliant with ERC721, and is only meant for gas comparisons.
     let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
     let contract = await deployContract('ERC721AWithERC2309Mock', args);
     await contract.mintTenERC2309(this.owner.address);

From 801a482ca65c676242a550f2875bef11121c7ff7 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Mon, 13 Jun 2022 05:59:28 +0000
Subject: [PATCH 12/13] Edit comments

---
 contracts/mocks/ERC721AWithERC2309Mock.sol | 10 ++++++----
 test/GasUsage.test.js                      | 10 ++++++----
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/contracts/mocks/ERC721AWithERC2309Mock.sol b/contracts/mocks/ERC721AWithERC2309Mock.sol
index 980118242..802fd9915 100644
--- a/contracts/mocks/ERC721AWithERC2309Mock.sol
+++ b/contracts/mocks/ERC721AWithERC2309Mock.sol
@@ -20,16 +20,18 @@ contract ERC721AWithERC2309Mock is ERC721A {
     }
 
     /**
-     * @dev This function is only for gas benchmarking purposes.
-     * Calling `_mintERC3201` outside of contract creation is non-compliant with ERC721.
+     * @dev This function is only for gas comparison purposes.
+     * Calling `_mintERC3201` outside of contract creation is non-compliant
+     * with the ERC721 standard.
      */
     function mintOneERC2309(address to) public {
         _mintERC2309(to, 1);
     }
 
     /**
-     * @dev This function is only for gas benchmarking purposes.
-     * Calling `_mintERC3201` outside of contract creation is non-compliant with ERC721.
+     * @dev This function is only for gas comparison purposes.
+     * Calling `_mintERC3201` outside of contract creation is non-compliant
+     * with the ERC721 standard.
      */
     function mintTenERC2309(address to) public {
         _mintERC2309(to, 10);
diff --git a/test/GasUsage.test.js b/test/GasUsage.test.js
index a6637fc47..380ff9583 100644
--- a/test/GasUsage.test.js
+++ b/test/GasUsage.test.js
@@ -70,8 +70,9 @@ describe('ERC721A Gas Usage', function () {
   });
 
   it('mintOneERC2309', async function () {
-    // The following call `_mintERC3201` internally outside of contract creation.
-    // This is non-compliant with ERC721, and is only meant for gas comparisons.
+    // The following call `_mintERC3201` outside of contract creation.
+    // This is non-compliant with the ERC721 standard, 
+    // and is only meant for gas comparisons.
     let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
     let contract = await deployContract('ERC721AWithERC2309Mock', args);
     await contract.mintOneERC2309(this.owner.address);
@@ -80,8 +81,9 @@ describe('ERC721A Gas Usage', function () {
   });
 
   it('mintTenERC2309', async function () {
-    // The following call `_mintERC3201` internally outside of contract creation.
-    // This is non-compliant with ERC721, and is only meant for gas comparisons.
+    // The following call `_mintERC3201` outside of contract creation.
+    // This is non-compliant with the ERC721 standard, 
+    // and is only meant for gas comparisons.
     let args = ['Azuki', 'AZUKI', this.owner.address, 0, false];
     let contract = await deployContract('ERC721AWithERC2309Mock', args);
     await contract.mintTenERC2309(this.owner.address);

From 39d9a82bea135f039f03fdc1a7294e4973b4e90b Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Tue, 14 Jun 2022 09:43:20 +0800
Subject: [PATCH 13/13] Update ERC721A.sol

---
 contracts/ERC721A.sol | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/contracts/ERC721A.sol b/contracts/ERC721A.sol
index 1f8183a79..1a2cd4556 100644
--- a/contracts/ERC721A.sol
+++ b/contracts/ERC721A.sol
@@ -547,7 +547,7 @@ contract ERC721A is IERC721A {
      */
     function _mintERC2309(address to, uint256 quantity) internal {
         uint256 startTokenId = _currentIndex;
-        if (_addressToUint256(to) == 0) revert MintToZeroAddress();
+        if (to == address(0)) revert MintToZeroAddress();
         if (quantity == 0) revert MintZeroQuantity();
         if (quantity > MAX_MINT_ERC2309_QUANTITY_LIMIT) revert MintERC2309QuantityExceedsLimit();
 
@@ -567,10 +567,10 @@ contract ERC721A is IERC721A {
             // - `startTimestamp` to the timestamp of minting.
             // - `burned` to `false`.
             // - `nextInitialized` to `quantity == 1`.
-            _packedOwnerships[startTokenId] =
-                _addressToUint256(to) |
-                (block.timestamp << BITPOS_START_TIMESTAMP) |
-                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED);
+            _packedOwnerships[startTokenId] = _packOwnershipData(
+                to,
+                (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED) | _nextExtraData(address(0), to, 0)
+            );
 
             emit ConsecutiveTransfer(startTokenId, startTokenId + quantity - 1, address(0), to);