Minichain supports deploying and executing smart contracts written in the custom assembly language. The deploy and call commands handle contract operations.
Deploy Contract Deploy a smart contract from assembly source code.
minichain deploy --from < NAM E > --source < FIL E > --gas-limit < LIMI T > [OPTIONS]
Basic Usage Create a simple counter contract (counter.asm):
.entry main main: LOADI R0, 0 ; storage slot 0 = counter SLOAD R1, R0 ; load current value LOADI R2, 1 ADD R1, R1, R2 ; increment SSTORE R0, R1 ; save back HALT
Deploy it:
cargo run --release -- deploy \ --from alice \ --source counter.asm \ --gas-limit 80000
Output: Deploying contract... Compiling: counter.asm ✓ Compiled to 28 bytes Deployer: 0x3f8c2a6e9b5d1f4a7c9e2b8d5f3a1c6e Nonce: 0 Balance: 50000 ✓ Transaction created Hash: 0x7d9f2a5c8e4b1f3a6c9e2d5f8a1c4e7b... ✓ Contract deployment submitted Contract Address: 0xa7b3c9e5d1f4a8c2b6e9d2f5a8c1e4b7 Transaction will be included in the next block. Use minichain block produce to produce a block.
Options From Account Keypair name of the deployer (without .json extension).
Example: Source File Path to the assembly source file.
Example: --source counter.asm --source contracts/token.asm --source ../examples/storage.asm
The file must contain valid Minichain assembly. See the Assembly Language documentation.
Gas Limit Maximum gas the deployer is willing to spend. This is a safety cap—the actual gas used is calculated automatically.
Gas calculation: gas_required = 21000 + (bytecode.len() * 200)
Example: If the gas limit is too low:
Error: Gas limit too low: required 26600, got 20000
The actual gas consumed is 21000 + (bytecode_bytes * 200). Set your limit higher than this to ensure deployment succeeds.
Gas Price Gas price per unit. Defaults to 1.
Example: Total cost: gas_required * gas_price
Contract Address Calculation The contract address is deterministically computed from:
contract_address = blake3 ( deployer_address || deployer_nonce )
This ensures:
Each deployment gets a unique address
The address is predictable before deployment
No address collisions
The CLI displays the contract address before the transaction is included in a block. You can use this address immediately in subsequent call commands (though they won’t execute until the deployment is finalized).
Compilation The deploy command automatically compiles assembly to bytecode:
Lexer - Tokenize assembly sourceParser - Build abstract syntax treeAssembler - Generate VM bytecodeValidation - Verify bytecode is valid
Example compilation: .entry main main: LOADI R0, 42 HALT
↓
Bytecode: [0x01, 0x00, 0x00, 0x2A, 0x00, ...] Size: 28 bytes
See the Assembler documentation for the full assembly language specification.
Call Contract Execute a deployed contract’s code.
minichain call --from < NAM E > --to < ADDRES S > [OPTIONS]
Basic Usage cargo run --release -- call \ --from alice \ --to 0xa7b3c9e5d1f4a8c2b6e9d2f5a8c1e4b7
Output: Calling contract... Caller: 0x3f8c2a6e9b5d1f4a7c9e2b8d5f3a1c6e Contract: 0xa7b3c9e5d1f4a8c2b6e9d2f5a8c1e4b7 Amount: 0 Data: 0 bytes Nonce: 1 Balance: 28900 ✓ Transaction created Hash: 0x5c1e9f3a6d8b2f4a7c9e2d5f8a1c4e7b... ✓ Contract call submitted Transaction will be included in the next block. Use minichain block produce to produce a block.
Options From Account Keypair name of the caller.
To Address Contract address in hexadecimal format.
Example: --to 0xa7b3c9e5d1f4a8c2b6e9d2f5a8c1e4b7
The CLI verifies this is a contract address (has code) before submitting.
Call Data Hexadecimal calldata passed to the contract. Defaults to empty.
Example: --data 01020304 --data "a7b3c9e5"
The contract can read this data using LOAD64 and STORE64 memory operations.
Currently, Minichain doesn’t have a standardized ABI. Calldata interpretation depends on your contract’s logic.
Amount Tokens to send with the call. Defaults to 0.
Example: The tokens are transferred from caller to contract before execution. The contract can query its balance using the state.
Gas Price Gas price per unit. Defaults to 1.
Gas Estimation Call gas is estimated as:
gas_limit = 21000 + (calldata.len() * 68) + 2100
21,000: Base transaction cost68 per byte: Calldata cost2,100: CALL opcode overhead
Actual execution may use more or less depending on the contract code:
Arithmetic ops: 2-4 gas eachMemory ops: 3 gas eachStorage reads: 100 gas eachStorage writes: 5,000-20,000 gas each
See the Gas Metering documentation for complete details.
Complete Example Deploy and call a counter contract:
# 1. Create counter contract cat > counter.asm << 'EOF' .entry main main: LOADI R0, 0 ; storage slot 0 SLOAD R1, R0 ; load counter LOADI R2, 1 ADD R1, R1, R2 ; increment SSTORE R0, R1 ; save HALT EOF # 2. Deploy contract minichain deploy \ --from alice \ --source counter.asm \ --gas-limit 80000 # Output: # ✓ Contract deployment submitted # Contract Address: 0xa7b3c9e5d1f4a8c2... # 3. Produce block to finalize deployment minichain block produce --authority authority_0 # 4. Verify contract exists minichain account info 0xa7b3c9e5d1f4a8c2... # Output: # Is Contract: Yes # Code Hash: 0x8f2a5c9e1d4b7f3a... # 5. Call contract (increments counter to 1) minichain call --from alice --to 0xa7b3c9e5d1f4a8c2... minichain block produce --authority authority_0 # 6. Call again (increments to 2) minichain call --from alice --to 0xa7b3c9e5d1f4a8c2... minichain block produce --authority authority_0 # 7. Call a third time (increments to 3) minichain call --from bob --to 0xa7b3c9e5d1f4a8c2... minichain block produce --authority authority_0 # The contract's storage slot 0 now holds value 3
Contract Execution When a call transaction is included in a block:
Load contract bytecode from stateInitialize VM with gas limitLoad calldata into memoryExecute bytecode instruction by instructionUpdate storage for SSTORE operationsReturn result (VM halts successfully or runs out of gas)Update state - Save storage changes, increment nonce, deduct gas
If a contract runs out of gas, all state changes are reverted, but gas is still consumed. Set sufficient gas limits.
Contract Storage Contracts have isolated storage:
Key-value store: u64 -> u64 mappingsPersistent: Storage survives across callsPer-contract: Each contract has its own storage namespace
Example: ; Store value 42 at slot 0 LOADI R0, 0 LOADI R1, 42 SSTORE R0, R1 ; Load value from slot 0 LOADI R0, 0 SLOAD R2, R0 ; R2 now contains 42
See the Virtual Machine documentation for complete instruction details.
Example Contracts Simple Storage .entry main main: ; Write 123 to slot 0 LOADI R0, 0 LOADI R1, 123 SSTORE R0, R1 HALT
Accumulator .entry main main: ; Load current value from slot 0 LOADI R0, 0 SLOAD R1, R0 ; Add 5 LOADI R2, 5 ADD R1, R1, R2 ; Store result SSTORE R0, R1 HALT
Conditional Logic .entry main main: LOADI R0, 0 SLOAD R1, R0 ; load counter LOADI R2, 10 BLT R1, R2, increment ; Counter >= 10, reset to 0 LOADI R1, 0 JMP store increment: LOADI R2, 1 ADD R1, R1, R2 store: SSTORE R0, R1 HALT
Common Errors Contract Not Found Error: Address 0xABC... is not a contract
Solution: Verify the address is correct and the deployment was finalized in a block.Compilation Failed Error: Failed to compile assembly code Parse error at line 5: unexpected token
Solution: Fix syntax errors in your assembly file.Insufficient Balance Error: Insufficient balance: have 10000, need 26600 (estimated)
Solution: Mint more tokens to the deployer account.Gas Limit Too Low Error: Gas limit too low: required 26600, got 20000
Solution: Increase --gas-limit to at least the required amount.Next Steps
Assembly Language Learn the full assembly syntax
Virtual Machine Understand VM execution model
Example Contracts Explore sample contracts
Gas Optimization Optimize gas usage