[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"article-deep-evm-12-advanced-huff-adaptive-execution":3},{"article":4,"author":59},{"id":5,"category_id":6,"title":7,"slug":8,"excerpt":9,"content_md":10,"content_html":11,"locale":12,"author_id":13,"published":14,"published_at":15,"meta_title":7,"meta_description":16,"focus_keyword":17,"og_image":18,"canonical_url":18,"robots_meta":19,"created_at":15,"updated_at":15,"tags":20,"category_name":38,"related_articles":39},"d0000000-0000-0000-0000-000000000112","a0000000-0000-0000-0000-000000000002","Deep EVM #12: Advanced Huff — Adaptive Execution and On-Chain Computation","deep-evm-12-advanced-huff-adaptive-execution","Production Huff patterns from real MEV contracts: adaptive execution with on-chain balance fallbacks, multi-operator auth via priority fee entropy, USDT safe approve, and memory layout tricks.","## Beyond Hello World\n\nThe previous articles covered Huff fundamentals — macros, stack management, jump tables. Now we move to production patterns extracted from real MEV bot contracts. These patterns solve problems that Solidity cannot express efficiently: adaptive execution based on calldata, multi-operator authorization without storage reads, and memory layouts that minimize bytecode size.\n\n## Pattern 1: Adaptive Execution — The `amount_in == 0` Fallback\n\nIn an MEV arbitrage contract, the bot pre-computes the optimal input amount off-chain and passes it via calldata. But sometimes the bot does not know the exact balance available — for example, when a previous swap in the same bundle deposits tokens into the contract, and the exact output amount depends on pool state at execution time.\n\nThe solution: if `amount_in == 0` in calldata, the contract reads its own balance on-chain and uses that instead.\n\n```huff\n#define macro GET_AMOUNT_IN() = takes(0) returns(1) {\n    \u002F\u002F Read amount from calldata[1..33]\n    0x01 calldataload           \u002F\u002F [amount_in]\n    dup1                        \u002F\u002F [amount_in, amount_in]\n    use_calldata_amount jumpi   \u002F\u002F [amount_in]\n\n    \u002F\u002F amount_in == 0 → read on-chain balance\n    pop                         \u002F\u002F []\n\n    \u002F\u002F Build balanceOf(address(this)) call\n    \u002F\u002F selector: 0x70a08231\n    0x70a08231                  \u002F\u002F [selector]\n    0xe0 shl                    \u002F\u002F [selector \u003C\u003C 224]\n    0x00 mstore                 \u002F\u002F [] — memory[0x00] = selector\n    address                     \u002F\u002F [this]\n    0x04 mstore                 \u002F\u002F [] — memory[0x04] = address(this)\n\n    \u002F\u002F staticcall to token\n    0x20                        \u002F\u002F [retSize]\n    0x00                        \u002F\u002F [retOffset]\n    0x24                        \u002F\u002F [argSize]\n    0x00                        \u002F\u002F [argOffset]\n    [TOKEN]                     \u002F\u002F [token, argOffset, argSize, retOffset, retSize]\n    gas                         \u002F\u002F [gas, token, ...]\n    staticcall                  \u002F\u002F [success]\n    pop                         \u002F\u002F []\n    0x00 mload                  \u002F\u002F [balance] — our actual token balance\n    \u002F\u002F falls through to use this as amount_in\n\n    use_calldata_amount:\n    \u002F\u002F Stack: [amount_in] (either from calldata or balanceOf)\n}\n```\n\nThis pattern adds ~200 gas when the fallback triggers (the staticcall) but zero gas when amount_in is provided in calldata (just a DUP + JUMPI). The bot uses the calldata path 90% of the time and falls back to on-chain reads only when executing multi-step bundles where intermediate amounts are unpredictable.\n\n## Pattern 2: Multi-Operator Auth via Priority Fee Entropy\n\nMEV bots often need multiple operators (hot wallets) that can call the contract. Storing authorized addresses in a mapping costs 2,100 gas per SLOAD (cold) or 100 gas (warm). For a contract called once per block, every call is cold.\n\nAn alternative: encode the operator's authorization in the transaction's `tx.gasprice` (or more precisely, the priority fee). The bot sets `maxPriorityFeePerGas` to a value that contains a secret nonce:\n\n```huff\n#define constant AUTH_MASK = 0xFFFF  \u002F\u002F last 16 bits of priority fee\n#define constant AUTH_SECRET = 0xBEEF\n\n#define macro CHECK_AUTH() = takes(0) returns(0) {\n    \u002F\u002F Extract priority fee: gasprice - basefee\n    gasprice            \u002F\u002F [gasprice]\n    basefee             \u002F\u002F [basefee, gasprice]\n    swap1 sub           \u002F\u002F [priority_fee]\n\n    \u002F\u002F Check last 16 bits match secret\n    [AUTH_MASK]         \u002F\u002F [mask, priority_fee]\n    and                 \u002F\u002F [fee & mask]\n    [AUTH_SECRET]       \u002F\u002F [secret, fee & mask]\n    eq                  \u002F\u002F [authorized?]\n    authorized jumpi\n    0x00 0x00 revert\n\n    authorized:\n}\n```\n\nThis costs only 14 gas (GASPRICE + BASEFEE + SUB + AND + EQ + JUMPI) compared to 2,100+ for a storage-based approach. The trade-off: the secret is visible in the mempool. But MEV bots use Flashbots or private mempools, so the transaction is never publicly visible before inclusion.\n\nYou can encode different secrets for different operators by partitioning the priority fee bits — e.g., bits 0-15 for the auth token, bits 16-31 for the operator ID.\n\n## Pattern 3: USDT Safe Approve (Reset to Zero)\n\nUSDT's `approve` function reverts if the current allowance is non-zero and you try to set a new non-zero value. This is a notorious quirk that has broken countless DeFi integrations. In Huff, we handle it by always resetting to zero first:\n\n```huff\n#define macro SAFE_APPROVE() = takes(2) returns(0) {\n    \u002F\u002F takes: [spender, amount]\n\n    \u002F\u002F First: approve(spender, 0)\n    0x095ea7b3 0xe0 shl     \u002F\u002F [approve_selector]\n    0x00 mstore             \u002F\u002F memory[0x00] = selector\n    dup2                    \u002F\u002F [spender, spender, amount]\n    0x04 mstore             \u002F\u002F memory[0x04] = spender  [spender, amount]\n    0x00 0x24 mstore        \u002F\u002F memory[0x24] = 0        [spender, amount]\n\n    0x00                    \u002F\u002F [retSize]\n    0x00                    \u002F\u002F [retOffset]\n    0x44                    \u002F\u002F [argSize]\n    0x00                    \u002F\u002F [argOffset]\n    0x00                    \u002F\u002F [value (no ETH)]\n    [USDT]                  \u002F\u002F [token]\n    gas call                \u002F\u002F [success]\n    pop                     \u002F\u002F [] — ignore result, some tokens return nothing\n\n    \u002F\u002F Second: approve(spender, amount)\n    \u002F\u002F selector is still in memory[0x00]\n    \u002F\u002F spender is still in memory[0x04]\n    swap1                   \u002F\u002F [amount, spender]\n    0x24 mstore             \u002F\u002F memory[0x24] = amount  [spender]\n    pop                     \u002F\u002F []\n\n    0x00 0x00 0x44 0x00 0x00\n    [USDT] gas call\n    pop\n}\n```\n\nThis pattern works for all ERC20 tokens, not just USDT — it is a safe universal approve. The extra call costs ~2,600 gas (warm CALL) but prevents silent failures.\n\n## Pattern 4: WETH Deposit and Withdraw\n\nWETH (Wrapped Ether) conversion is a frequent operation in MEV bots. The ABI is simple:\n\n```huff\n#define constant WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2\n\n#define macro WETH_DEPOSIT() = takes(1) returns(0) {\n    \u002F\u002F takes: [amount]\n    \u002F\u002F WETH.deposit{value: amount}()\n    0x00 0x00 0x00 0x00     \u002F\u002F [0, 0, 0, 0, amount] — retSize, retOff, argSize, argOff\n    swap4                   \u002F\u002F [amount, 0, 0, 0, 0]\n    [WETH]                  \u002F\u002F [weth, amount, 0, 0, 0, 0]\n    gas call                \u002F\u002F [success]\n    pop\n}\n\n#define macro WETH_WITHDRAW() = takes(1) returns(0) {\n    \u002F\u002F takes: [amount]\n    \u002F\u002F WETH.withdraw(amount)\n    0x2e1a7d4d 0xe0 shl     \u002F\u002F [selector, amount]\n    0x00 mstore             \u002F\u002F memory[0] = selector     [amount]\n    0x04 mstore             \u002F\u002F memory[4] = amount       []\n\n    0x00 0x00 0x24 0x00 0x00\n    [WETH] gas call\n    pop\n}\n```\n\nThe deposit function is particularly elegant — WETH's deposit has no arguments, so we send zero argSize with the ETH value. Total bytecode for deposit: ~20 bytes.\n\n## Memory Layout Tricks\n\nEVM memory is byte-addressable and free to expand (costs gas quadratically for expansion). MEV contracts use a fixed memory layout to avoid redundant MSTORE operations:\n\n```huff\n\u002F\u002F Fixed memory layout — never changes between calls\n\u002F\u002F 0x00 - 0x03:  Current function selector (4 bytes)\n\u002F\u002F 0x04 - 0x23:  Argument 1 (32 bytes)\n\u002F\u002F 0x24 - 0x43:  Argument 2 (32 bytes)\n\u002F\u002F 0x44 - 0x63:  Argument 3 (32 bytes)\n\u002F\u002F 0x64 - 0x83:  Return data scratch (32 bytes)\n\u002F\u002F 0x80 - 0x9f:  Stack spill area (32 bytes)\n\u002F\u002F 0xa0 - 0xbf:  Second spill slot (32 bytes)\n```\n\nThe key insight: if you are making multiple external calls with the same selector (e.g., multiple `transfer` calls), you only write the selector once. On subsequent calls, you only update the arguments that changed.\n\n```huff\n#define macro MULTI_TRANSFER() = takes(0) returns(0) {\n    \u002F\u002F Setup: write transfer selector once\n    0xa9059cbb 0xe0 shl\n    0x00 mstore                 \u002F\u002F memory[0] = transfer(address,uint256)\n\n    \u002F\u002F Transfer 1: to=Alice, amount=100\n    [ALICE] 0x04 mstore\n    0x64 0x24 mstore            \u002F\u002F 100\n    0x00 0x00 0x44 0x00 0x00 [TOKEN] gas call pop\n\n    \u002F\u002F Transfer 2: to=Bob, amount=200\n    \u002F\u002F Selector still in memory[0] — no need to rewrite!\n    [BOB] 0x04 mstore\n    0xc8 0x24 mstore            \u002F\u002F 200\n    0x00 0x00 0x44 0x00 0x00 [TOKEN] gas call pop\n\n    \u002F\u002F Transfer 3: to=Bob, amount=300\n    \u002F\u002F Address still in memory[4] — only update amount!\n    0x012c 0x24 mstore          \u002F\u002F 300\n    0x00 0x00 0x44 0x00 0x00 [TOKEN] gas call pop\n}\n```\n\nEach avoided MSTORE saves 3 gas + the PUSH for the value. Across a multi-hop arbitrage with 5-6 swap calls, this saves 50-100 gas.\n\n## The Free Memory Pointer Myth\n\nSolidity maintains a \"free memory pointer\" at `0x40` that tracks the next available memory offset. This is an abstraction for dynamic memory allocation (arrays, strings, abi.encode). In Huff, you do not need it.\n\nMEV contracts have a fixed, known set of external calls. You can statically assign memory regions at compile time. No free memory pointer means:\n\n- No 3-gas MLOAD to read the pointer before every memory write.\n- No 3-gas MSTORE to update the pointer after every allocation.\n- No risk of memory collision from reentrancy (your layout is deterministic).\n\nDelete the free memory pointer. Own your memory map.\n\n## Combining Patterns: A Production Swap Macro\n\nHere is a production-grade Uniswap V2 swap macro that combines several patterns:\n\n```huff\n#define macro SWAP_V2() = takes(3) returns(0) {\n    \u002F\u002F takes: [amountOut, zeroForOne, pair]\n\n    \u002F\u002F Build swap(uint256,uint256,address,bytes) call\n    0x022c0d9f 0xe0 shl\n    0x00 mstore                     \u002F\u002F selector\n\n    \u002F\u002F amount0Out = zeroForOne ? 0 : amountOut\n    \u002F\u002F amount1Out = zeroForOne ? amountOut : 0\n    swap1                           \u002F\u002F [zeroForOne, amountOut, pair]\n    skip_zero jumpi                 \u002F\u002F [amountOut, pair]\n\n    \u002F\u002F zeroForOne == 0: token1 → token0, amount0Out = amountOut\n    dup1 0x04 mstore                \u002F\u002F amount0Out = amountOut\n    0x00 0x24 mstore                \u002F\u002F amount1Out = 0\n    done_amounts jump\n\n    skip_zero:                      \u002F\u002F [amountOut, pair]\n    0x00 0x04 mstore                \u002F\u002F amount0Out = 0\n    dup1 0x24 mstore                \u002F\u002F amount1Out = amountOut\n\n    done_amounts:\n    pop                             \u002F\u002F [pair]\n    address 0x44 mstore             \u002F\u002F to = address(this)\n    0x80 0x64 mstore                \u002F\u002F bytes offset\n    0x00 0x84 mstore                \u002F\u002F bytes length = 0\n\n    \u002F\u002F call pair.swap\n    0x00 0x00 0xa4 0x00 0x00\n    swap5                           \u002F\u002F [pair, ...]\n    gas call\n\n    \u002F\u002F Check success\n    iszero revert_swap jumpi\n    stop\n\n    revert_swap:\n        returndatasize 0x00 0x00 returndatacopy\n        returndatasize 0x00 revert\n}\n```\n\nThis is 120 bytes of bytecode. The equivalent Solidity with SafeERC20, interface types, and ABI encoding generates 400+ bytes.\n\n## Summary\n\nAdvanced Huff is about production patterns, not academic exercises. The `amount_in == 0` fallback lets your bot adapt to unpredictable intermediate states. Priority fee auth eliminates cold SLOAD costs. USDT safe approve prevents silent reverts. Fixed memory layouts eliminate redundant writes. Every pattern saves 50-200 gas — and in MEV, those savings compound across thousands of daily executions into meaningful profit. In the next article, we shift focus from writing contracts to exploiting them: an introduction to MEV — extractable value, searchers, and block builders.","\u003Ch2 id=\"beyond-hello-world\">Beyond Hello World\u003C\u002Fh2>\n\u003Cp>The previous articles covered Huff fundamentals — macros, stack management, jump tables. Now we move to production patterns extracted from real MEV bot contracts. These patterns solve problems that Solidity cannot express efficiently: adaptive execution based on calldata, multi-operator authorization without storage reads, and memory layouts that minimize bytecode size.\u003C\u002Fp>\n\u003Ch2 id=\"pattern-1-adaptive-execution-the-amount-in-0-fallback\">Pattern 1: Adaptive Execution — The \u003Ccode>amount_in == 0\u003C\u002Fcode> Fallback\u003C\u002Fh2>\n\u003Cp>In an MEV arbitrage contract, the bot pre-computes the optimal input amount off-chain and passes it via calldata. But sometimes the bot does not know the exact balance available — for example, when a previous swap in the same bundle deposits tokens into the contract, and the exact output amount depends on pool state at execution time.\u003C\u002Fp>\n\u003Cp>The solution: if \u003Ccode>amount_in == 0\u003C\u002Fcode> in calldata, the contract reads its own balance on-chain and uses that instead.\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">#define macro GET_AMOUNT_IN() = takes(0) returns(1) {\n    \u002F\u002F Read amount from calldata[1..33]\n    0x01 calldataload           \u002F\u002F [amount_in]\n    dup1                        \u002F\u002F [amount_in, amount_in]\n    use_calldata_amount jumpi   \u002F\u002F [amount_in]\n\n    \u002F\u002F amount_in == 0 → read on-chain balance\n    pop                         \u002F\u002F []\n\n    \u002F\u002F Build balanceOf(address(this)) call\n    \u002F\u002F selector: 0x70a08231\n    0x70a08231                  \u002F\u002F [selector]\n    0xe0 shl                    \u002F\u002F [selector << 224]\n    0x00 mstore                 \u002F\u002F [] — memory[0x00] = selector\n    address                     \u002F\u002F [this]\n    0x04 mstore                 \u002F\u002F [] — memory[0x04] = address(this)\n\n    \u002F\u002F staticcall to token\n    0x20                        \u002F\u002F [retSize]\n    0x00                        \u002F\u002F [retOffset]\n    0x24                        \u002F\u002F [argSize]\n    0x00                        \u002F\u002F [argOffset]\n    [TOKEN]                     \u002F\u002F [token, argOffset, argSize, retOffset, retSize]\n    gas                         \u002F\u002F [gas, token, ...]\n    staticcall                  \u002F\u002F [success]\n    pop                         \u002F\u002F []\n    0x00 mload                  \u002F\u002F [balance] — our actual token balance\n    \u002F\u002F falls through to use this as amount_in\n\n    use_calldata_amount:\n    \u002F\u002F Stack: [amount_in] (either from calldata or balanceOf)\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>This pattern adds ~200 gas when the fallback triggers (the staticcall) but zero gas when amount_in is provided in calldata (just a DUP + JUMPI). The bot uses the calldata path 90% of the time and falls back to on-chain reads only when executing multi-step bundles where intermediate amounts are unpredictable.\u003C\u002Fp>\n\u003Ch2 id=\"pattern-2-multi-operator-auth-via-priority-fee-entropy\">Pattern 2: Multi-Operator Auth via Priority Fee Entropy\u003C\u002Fh2>\n\u003Cp>MEV bots often need multiple operators (hot wallets) that can call the contract. Storing authorized addresses in a mapping costs 2,100 gas per SLOAD (cold) or 100 gas (warm). For a contract called once per block, every call is cold.\u003C\u002Fp>\n\u003Cp>An alternative: encode the operator’s authorization in the transaction’s \u003Ccode>tx.gasprice\u003C\u002Fcode> (or more precisely, the priority fee). The bot sets \u003Ccode>maxPriorityFeePerGas\u003C\u002Fcode> to a value that contains a secret nonce:\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">#define constant AUTH_MASK = 0xFFFF  \u002F\u002F last 16 bits of priority fee\n#define constant AUTH_SECRET = 0xBEEF\n\n#define macro CHECK_AUTH() = takes(0) returns(0) {\n    \u002F\u002F Extract priority fee: gasprice - basefee\n    gasprice            \u002F\u002F [gasprice]\n    basefee             \u002F\u002F [basefee, gasprice]\n    swap1 sub           \u002F\u002F [priority_fee]\n\n    \u002F\u002F Check last 16 bits match secret\n    [AUTH_MASK]         \u002F\u002F [mask, priority_fee]\n    and                 \u002F\u002F [fee & mask]\n    [AUTH_SECRET]       \u002F\u002F [secret, fee & mask]\n    eq                  \u002F\u002F [authorized?]\n    authorized jumpi\n    0x00 0x00 revert\n\n    authorized:\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>This costs only 14 gas (GASPRICE + BASEFEE + SUB + AND + EQ + JUMPI) compared to 2,100+ for a storage-based approach. The trade-off: the secret is visible in the mempool. But MEV bots use Flashbots or private mempools, so the transaction is never publicly visible before inclusion.\u003C\u002Fp>\n\u003Cp>You can encode different secrets for different operators by partitioning the priority fee bits — e.g., bits 0-15 for the auth token, bits 16-31 for the operator ID.\u003C\u002Fp>\n\u003Ch2 id=\"pattern-3-usdt-safe-approve-reset-to-zero\">Pattern 3: USDT Safe Approve (Reset to Zero)\u003C\u002Fh2>\n\u003Cp>USDT’s \u003Ccode>approve\u003C\u002Fcode> function reverts if the current allowance is non-zero and you try to set a new non-zero value. This is a notorious quirk that has broken countless DeFi integrations. In Huff, we handle it by always resetting to zero first:\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">#define macro SAFE_APPROVE() = takes(2) returns(0) {\n    \u002F\u002F takes: [spender, amount]\n\n    \u002F\u002F First: approve(spender, 0)\n    0x095ea7b3 0xe0 shl     \u002F\u002F [approve_selector]\n    0x00 mstore             \u002F\u002F memory[0x00] = selector\n    dup2                    \u002F\u002F [spender, spender, amount]\n    0x04 mstore             \u002F\u002F memory[0x04] = spender  [spender, amount]\n    0x00 0x24 mstore        \u002F\u002F memory[0x24] = 0        [spender, amount]\n\n    0x00                    \u002F\u002F [retSize]\n    0x00                    \u002F\u002F [retOffset]\n    0x44                    \u002F\u002F [argSize]\n    0x00                    \u002F\u002F [argOffset]\n    0x00                    \u002F\u002F [value (no ETH)]\n    [USDT]                  \u002F\u002F [token]\n    gas call                \u002F\u002F [success]\n    pop                     \u002F\u002F [] — ignore result, some tokens return nothing\n\n    \u002F\u002F Second: approve(spender, amount)\n    \u002F\u002F selector is still in memory[0x00]\n    \u002F\u002F spender is still in memory[0x04]\n    swap1                   \u002F\u002F [amount, spender]\n    0x24 mstore             \u002F\u002F memory[0x24] = amount  [spender]\n    pop                     \u002F\u002F []\n\n    0x00 0x00 0x44 0x00 0x00\n    [USDT] gas call\n    pop\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>This pattern works for all ERC20 tokens, not just USDT — it is a safe universal approve. The extra call costs ~2,600 gas (warm CALL) but prevents silent failures.\u003C\u002Fp>\n\u003Ch2 id=\"pattern-4-weth-deposit-and-withdraw\">Pattern 4: WETH Deposit and Withdraw\u003C\u002Fh2>\n\u003Cp>WETH (Wrapped Ether) conversion is a frequent operation in MEV bots. The ABI is simple:\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">#define constant WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2\n\n#define macro WETH_DEPOSIT() = takes(1) returns(0) {\n    \u002F\u002F takes: [amount]\n    \u002F\u002F WETH.deposit{value: amount}()\n    0x00 0x00 0x00 0x00     \u002F\u002F [0, 0, 0, 0, amount] — retSize, retOff, argSize, argOff\n    swap4                   \u002F\u002F [amount, 0, 0, 0, 0]\n    [WETH]                  \u002F\u002F [weth, amount, 0, 0, 0, 0]\n    gas call                \u002F\u002F [success]\n    pop\n}\n\n#define macro WETH_WITHDRAW() = takes(1) returns(0) {\n    \u002F\u002F takes: [amount]\n    \u002F\u002F WETH.withdraw(amount)\n    0x2e1a7d4d 0xe0 shl     \u002F\u002F [selector, amount]\n    0x00 mstore             \u002F\u002F memory[0] = selector     [amount]\n    0x04 mstore             \u002F\u002F memory[4] = amount       []\n\n    0x00 0x00 0x24 0x00 0x00\n    [WETH] gas call\n    pop\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>The deposit function is particularly elegant — WETH’s deposit has no arguments, so we send zero argSize with the ETH value. Total bytecode for deposit: ~20 bytes.\u003C\u002Fp>\n\u003Ch2 id=\"memory-layout-tricks\">Memory Layout Tricks\u003C\u002Fh2>\n\u003Cp>EVM memory is byte-addressable and free to expand (costs gas quadratically for expansion). MEV contracts use a fixed memory layout to avoid redundant MSTORE operations:\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">\u002F\u002F Fixed memory layout — never changes between calls\n\u002F\u002F 0x00 - 0x03:  Current function selector (4 bytes)\n\u002F\u002F 0x04 - 0x23:  Argument 1 (32 bytes)\n\u002F\u002F 0x24 - 0x43:  Argument 2 (32 bytes)\n\u002F\u002F 0x44 - 0x63:  Argument 3 (32 bytes)\n\u002F\u002F 0x64 - 0x83:  Return data scratch (32 bytes)\n\u002F\u002F 0x80 - 0x9f:  Stack spill area (32 bytes)\n\u002F\u002F 0xa0 - 0xbf:  Second spill slot (32 bytes)\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>The key insight: if you are making multiple external calls with the same selector (e.g., multiple \u003Ccode>transfer\u003C\u002Fcode> calls), you only write the selector once. On subsequent calls, you only update the arguments that changed.\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">#define macro MULTI_TRANSFER() = takes(0) returns(0) {\n    \u002F\u002F Setup: write transfer selector once\n    0xa9059cbb 0xe0 shl\n    0x00 mstore                 \u002F\u002F memory[0] = transfer(address,uint256)\n\n    \u002F\u002F Transfer 1: to=Alice, amount=100\n    [ALICE] 0x04 mstore\n    0x64 0x24 mstore            \u002F\u002F 100\n    0x00 0x00 0x44 0x00 0x00 [TOKEN] gas call pop\n\n    \u002F\u002F Transfer 2: to=Bob, amount=200\n    \u002F\u002F Selector still in memory[0] — no need to rewrite!\n    [BOB] 0x04 mstore\n    0xc8 0x24 mstore            \u002F\u002F 200\n    0x00 0x00 0x44 0x00 0x00 [TOKEN] gas call pop\n\n    \u002F\u002F Transfer 3: to=Bob, amount=300\n    \u002F\u002F Address still in memory[4] — only update amount!\n    0x012c 0x24 mstore          \u002F\u002F 300\n    0x00 0x00 0x44 0x00 0x00 [TOKEN] gas call pop\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>Each avoided MSTORE saves 3 gas + the PUSH for the value. Across a multi-hop arbitrage with 5-6 swap calls, this saves 50-100 gas.\u003C\u002Fp>\n\u003Ch2 id=\"the-free-memory-pointer-myth\">The Free Memory Pointer Myth\u003C\u002Fh2>\n\u003Cp>Solidity maintains a “free memory pointer” at \u003Ccode>0x40\u003C\u002Fcode> that tracks the next available memory offset. This is an abstraction for dynamic memory allocation (arrays, strings, abi.encode). In Huff, you do not need it.\u003C\u002Fp>\n\u003Cp>MEV contracts have a fixed, known set of external calls. You can statically assign memory regions at compile time. No free memory pointer means:\u003C\u002Fp>\n\u003Cul>\n\u003Cli>No 3-gas MLOAD to read the pointer before every memory write.\u003C\u002Fli>\n\u003Cli>No 3-gas MSTORE to update the pointer after every allocation.\u003C\u002Fli>\n\u003Cli>No risk of memory collision from reentrancy (your layout is deterministic).\u003C\u002Fli>\n\u003C\u002Ful>\n\u003Cp>Delete the free memory pointer. Own your memory map.\u003C\u002Fp>\n\u003Ch2 id=\"combining-patterns-a-production-swap-macro\">Combining Patterns: A Production Swap Macro\u003C\u002Fh2>\n\u003Cp>Here is a production-grade Uniswap V2 swap macro that combines several patterns:\u003C\u002Fp>\n\u003Cpre>\u003Ccode class=\"language-huff\">#define macro SWAP_V2() = takes(3) returns(0) {\n    \u002F\u002F takes: [amountOut, zeroForOne, pair]\n\n    \u002F\u002F Build swap(uint256,uint256,address,bytes) call\n    0x022c0d9f 0xe0 shl\n    0x00 mstore                     \u002F\u002F selector\n\n    \u002F\u002F amount0Out = zeroForOne ? 0 : amountOut\n    \u002F\u002F amount1Out = zeroForOne ? amountOut : 0\n    swap1                           \u002F\u002F [zeroForOne, amountOut, pair]\n    skip_zero jumpi                 \u002F\u002F [amountOut, pair]\n\n    \u002F\u002F zeroForOne == 0: token1 → token0, amount0Out = amountOut\n    dup1 0x04 mstore                \u002F\u002F amount0Out = amountOut\n    0x00 0x24 mstore                \u002F\u002F amount1Out = 0\n    done_amounts jump\n\n    skip_zero:                      \u002F\u002F [amountOut, pair]\n    0x00 0x04 mstore                \u002F\u002F amount0Out = 0\n    dup1 0x24 mstore                \u002F\u002F amount1Out = amountOut\n\n    done_amounts:\n    pop                             \u002F\u002F [pair]\n    address 0x44 mstore             \u002F\u002F to = address(this)\n    0x80 0x64 mstore                \u002F\u002F bytes offset\n    0x00 0x84 mstore                \u002F\u002F bytes length = 0\n\n    \u002F\u002F call pair.swap\n    0x00 0x00 0xa4 0x00 0x00\n    swap5                           \u002F\u002F [pair, ...]\n    gas call\n\n    \u002F\u002F Check success\n    iszero revert_swap jumpi\n    stop\n\n    revert_swap:\n        returndatasize 0x00 0x00 returndatacopy\n        returndatasize 0x00 revert\n}\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>This is 120 bytes of bytecode. The equivalent Solidity with SafeERC20, interface types, and ABI encoding generates 400+ bytes.\u003C\u002Fp>\n\u003Ch2 id=\"summary\">Summary\u003C\u002Fh2>\n\u003Cp>Advanced Huff is about production patterns, not academic exercises. The \u003Ccode>amount_in == 0\u003C\u002Fcode> fallback lets your bot adapt to unpredictable intermediate states. Priority fee auth eliminates cold SLOAD costs. USDT safe approve prevents silent reverts. Fixed memory layouts eliminate redundant writes. Every pattern saves 50-200 gas — and in MEV, those savings compound across thousands of daily executions into meaningful profit. In the next article, we shift focus from writing contracts to exploiting them: an introduction to MEV — extractable value, searchers, and block builders.\u003C\u002Fp>\n","en","b0000000-0000-0000-0000-000000000001",true,"2026-03-28T10:44:22.901180Z","Production Huff patterns for MEV contracts: on-chain balance fallbacks, priority fee auth, USDT safe approve, WETH handling, and memory layout tricks.","advanced huff mev patterns",null,"index, follow",[21,26,30,34],{"id":22,"name":23,"slug":24,"created_at":25},"c0000000-0000-0000-0000-000000000016","EVM","evm","2026-03-28T10:44:21.513630Z",{"id":27,"name":28,"slug":29,"created_at":25},"c0000000-0000-0000-0000-000000000017","Huff","huff",{"id":31,"name":32,"slug":33,"created_at":25},"c0000000-0000-0000-0000-000000000019","MEV","mev",{"id":35,"name":36,"slug":37,"created_at":25},"c0000000-0000-0000-0000-000000000013","Security","security","Blockchain",[40,47,53],{"id":41,"title":42,"slug":43,"excerpt":44,"locale":12,"category_name":45,"published_at":46},"d0200000-0000-0000-0000-000000000003","Why Bali Is Becoming Southeast Asia's Impact-Tech Hub in 2026","why-bali-becoming-southeast-asia-impact-tech-hub-2026","Bali ranks #16 among Southeast Asian startup ecosystems. With a growing concentration of Web3 builders, AI sustainability startups, and eco-travel tech companies, the island is carving a niche as the region's impact-tech capital.","Engineering","2026-03-28T10:44:37.748283Z",{"id":48,"title":49,"slug":50,"excerpt":51,"locale":12,"category_name":45,"published_at":52},"d0200000-0000-0000-0000-000000000002","ASEAN Data Protection Patchwork: A Developer's Compliance Checklist","asean-data-protection-patchwork-developer-compliance-checklist","Seven ASEAN countries now have comprehensive data protection laws, each with different consent models, localization requirements, and penalty structures. Here is a practical compliance checklist for developers building multi-country applications.","2026-03-28T10:44:37.374741Z",{"id":54,"title":55,"slug":56,"excerpt":57,"locale":12,"category_name":45,"published_at":58},"d0200000-0000-0000-0000-000000000001","Indonesia's $29 Billion Digital Transformation: Opportunities for Software Companies","indonesia-29-billion-digital-transformation-opportunities-software-companies","Indonesia's IT services market is projected to reach $29.03 billion in 2026, up from $24.37 billion in 2025. Cloud infrastructure, AI, e-commerce, and data centers are driving the fastest growth in Southeast Asia.","2026-03-28T10:44:37.349311Z",{"id":13,"name":60,"slug":61,"bio":62,"photo_url":18,"linkedin":18,"role":63,"created_at":64,"updated_at":64},"Open Soft Team","open-soft-team","The engineering team at Open Soft, building premium software solutions from Bali, Indonesia.","Engineering Team","2026-03-28T08:31:22.226811Z"]