Initialization

State of TVM before smart contract execution

Initialization of cc, cp, and gas limits

• The original cc, current continuation, is initialized using the cell slice created from the code section of the smart contract. If the account is frozen or uninitialized, the code must be provided in the init field of the incoming message.

• The cp, current TVM codepage, is set to the default value of 0.

• The gas limit values are initialized based on the results of the credit phase.

Registers initialization

• c0: Quit — extraordinary continuation which terminates TVM with exit code 0.

• c1: Quit — extraordinary continuation which terminates TVM with exit code 1. Both exit codes 0 and 1 are considered successful terminations of TVM.

• c2: ExcQuit — extraordinary continuation which terminates TVM with an exception. In this case, the exit code is an exception number.

• c3: root cell of code currently executing in TVM.

• c4: root cell of account data.

• c5: empty cell.

• c7: Tuple[Tuple[0x076ef1ea, 0, 0, ...]].

Stack

The contents of the stack depend on the event that triggered the transaction:

• Internal message
• External message
• Tick-tock
• Split prepare
• Merge install
• Get method (off-chain)

The top of the stack is always the function selector, an integer that identifies the event that caused the transaction.

The following function selectors are defined:

ID	Name	Description
0	onInternalMessage	Received an internal message
-1	onExternalMessage	Received an external message
-2	onRunTickTock	Received a tick-tock event
-3	onSplitPrepare	Received a split prepare event (unimplemented yet)
-4	onSplitInstall	Received a split install event (unimplemented yet)

Get methods can have arbitrary IDs and should not overlap with the ones listed above.

External/internal message

Index	Name	Type	Description
s0	Function selector	Integer	-1 for external messages, 0 for internal messages.
s1	Message body	Slice	This is an arbitrary payload of a message, which can be used for text comments (when sending TONs from one wallet to another) or for smart contract commands.
s2	Message	Cell	Cell containing message metadata (sender, receiver, amount) as well as message body.
s3	Message value	Integer	Amount of received nanotons (0 for externals).
s4	Contract balance	Integer	Current account balance in nanotons.

Tick‑tock

Index	Name	Type	Description
s0	Function selector	Integer	-2 for tick-tock transactions.
s1	Tick or tock?	Integer	0 for tick transactions, -1 for tock transactions.
s2	Account address	Integer	256-bit raw account address (without workchain).
s3	Contract	Integer	Current account balance in nanotons.

Split/merge events

These events are not implemented yet. Possible stack layout for split/merge events is described in TON Blockchain whitepaper. However, it is subject to change.