Skip to main content

​
Overview

The account_transfer syscall transfers a specified amount of balance from one account to another. Both accounts must exist and meet writability requirements.

​
Syscall Code

Code: 0x03 (TN_SYSCALL_CODE_ACCOUNT_TRANSFER)

​
C SDK Function

ulong tsys_account_transfer(ulong from_account_idx, ulong to_account_idx, ulong amount);

​
Arguments

​
from_account_idx
ulong
required
Index of the source account to transfer balance from. Must be writable by the current program.
​
to_account_idx
ulong
required
Index of the destination account to transfer balance to. Must be writable in the transaction.
​
amount
ulong
required
Amount of balance to transfer from source to destination account.

​
Return Value

Returns a syscall result code:
​
Success
ulong
  • TN_VM_SYSCALL_SUCCESS (0) - Transfer completed successfully
​
Error Codes
ulong
  • TN_VM_ERR_SYSCALL_INVALID_ACCOUNT_INDEX (-7) - Invalid from or to account index
  • TN_VM_ERR_SYSCALL_ACCOUNT_NOT_WRITABLE (-26) - From account not writable by program or to account not writable in transaction
  • TN_VM_ERR_SYSCALL_ACCOUNT_DOES_NOT_EXIST (-8) - Source or destination account does not exist
  • TN_VM_ERR_SYSCALL_INSUFFICIENT_BALANCE (-37) - Source account has insufficient balance
  • TN_VM_ERR_SYSCALL_INVALID_ACCOUNT (-26) - Either account is ephemeral (not allowed for transfers)
  • TN_VM_ERR_SYSCALL_BALANCE_OVERFLOW (-10) - Destination balance would overflow

​
Resource Consumption

​
Compute Units

  • Base cost: TN_VM_SYSCALL_BASE_COST (512 units)
  • Additional cost: None
  • Total cost: Fixed at 512 units regardless of transfer amount

​
Memory Pages

  • Page usage: No direct page allocation or deallocation
  • Metadata impact: May trigger metadata page allocation for both accounts if not already writable

​
Side Effects

  • Balance modification: Decreases source account balance and increases destination balance
  • Account metadata: Makes account metadata writable if not already

​
Usage Notes

  • Both accounts must be non-ephemeral accounts
  • Source account must be writable by the current program
  • Destination account must be writable in the transaction (signer approval)
  • Transfer amount cannot exceed source account balance
  • Destination balance cannot overflow (exceed maximum value)
  • Account metadata is automatically made writable for both accounts

​
Example

#include "tn_sdk_syscall.h"

// Transfer 1000 units from account 0 to account 1
ulong from_account = 0;
ulong to_account = 1;
ulong amount = 1000;

ulong result = tsys_account_transfer(from_account, to_account, amount);

if (result == TN_VM_SYSCALL_SUCCESS) {
    // Transfer completed successfully
    // from_account balance decreased by 1000
    // to_account balance increased by 1000
}