Syscall Implementation
Syscalls are the bridge between NeoVM bytecode and the Neo N3 platform services. They are invoked via the SYSCALL opcode followed by a 4-byte interop ID.
Syscall ID Computation
Syscall IDs are the first 4 bytes of the SHA-256 hash of the syscall name string:
ID = SHA256("System.Storage.Get")[0..4]This is computed at compile time and embedded in the bytecode.
Storage Syscalls
| Syscall | Description |
|---|---|
System.Storage.GetContext | Get the current contract's read-write storage context |
System.Storage.GetReadOnlyContext | Get a read-only storage context |
System.Storage.AsReadOnly | Convert a context to read-only |
System.Storage.Get | Read a value by key from storage |
System.Storage.Put | Write a key-value pair to storage |
System.Storage.Delete | Delete a key from storage |
System.Storage.Find | Find entries by key prefix, returns iterator |
System.Storage.Local.Get | Read from local storage |
System.Storage.Local.Put | Write to local storage |
System.Storage.Local.Delete | Delete from local storage |
System.Storage.Local.Find | Find in local storage by prefix |
Iterator Syscalls
| Syscall | Description |
|---|---|
System.Iterator.Next | Advance iterator to next entry; returns boolean |
System.Iterator.Value | Get current iterator entry value |
Iterator handles are created by Storage.Find and are validated by ISTYPE (type code 0x80) while alive.
INFO
The embedded runtime currently registers Iterator.Next and Iterator.Value. It does not expose an Iterator.Dispose syscall.
Runtime Syscalls
| Syscall | Description |
|---|---|
System.Runtime.GetTrigger | Get execution trigger type |
System.Runtime.Platform | Get platform identifier string |
System.Runtime.GetNetwork | Get network magic number |
System.Runtime.GetAddressVersion | Get address version byte |
System.Runtime.GetTime | Get current block timestamp |
System.Runtime.GetScriptContainer | Get the transaction that triggered execution |
System.Runtime.GetExecutingScriptHash | Get hash of currently executing contract |
System.Runtime.GetCallingScriptHash | Get hash of the calling contract |
System.Runtime.GetEntryScriptHash | Get hash of the entry-point contract |
System.Runtime.LoadScript | Registered for Neo N3 parity, but intentionally unsupported in the embedded runtime; use System.Contract.Call for inter-contract calls |
System.Runtime.CheckWitness | Verify that the specified account has witnessed the transaction |
System.Runtime.GetInvocationCounter | Get number of times current contract was called |
System.Runtime.GetRandom | Get a pseudo-random number |
System.Runtime.Log | Emit a log message |
System.Runtime.Notify | Emit a notification event (name + state array) |
System.Runtime.GetNotifications | Embedded runtime returns []; notification lookup state is not exposed |
System.Runtime.GasLeft | Get remaining gas |
System.Runtime.BurnGas | Burn specified amount of gas |
System.Runtime.CurrentSigners | Embedded runtime returns []; transaction signer set is not modeled |
System.Runtime.GetMsgValue | Read the runtime-side msg.value override; returns 0 when no host override is set |
Neo-side ABI serialization fallbacks use the StdLib native contract (serialize / deserialize) rather than System.Runtime.Serialize or System.Runtime.Deserialize.
Crypto Syscalls
| Syscall | Description |
|---|---|
System.Crypto.CheckSig | Verify a single signature (secp256k1) |
System.Crypto.CheckMultisig | Verify multiple signatures |
Additional crypto operations are available through the CryptoLib native contract: SHA256, RIPEMD160, Keccak256, Murmur32, Hash160, Hash256.
Contract Syscalls
| Syscall | Description |
|---|---|
System.Contract.Call | Call another contract by hash |
System.Contract.GetCallFlags | Get current call flags |
System.Contract.CreateStandardAccount | Create standard account script hash from public key |
System.Contract.CreateMultisigAccount | Create multisig account script hash |