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# Algorand Specifications

| OPCODE | DESCRIPTION |
| --- | --- |
| `online_stake` | the total online stake in the agreement round |
| `log` | write A to log state of the current application |
| `block f` | field F of block A. Fail unless A falls between txn.LastValid-1002 and txn.FirstValid (exclusive) |

| OPCODE | DESCRIPTION |
| --- | --- |
| `balance` | balance for account A, in microalgos. The balance is observed after the effects of previous transactions in the group, and after the fee for the current transaction is deducted. Changes caused by inner transactions are observable immediately following `itxn_submit` |
| `min_balance` | minimum required balance for account A, in microalgos. Required balance is affected by ASA, App, and Box usage. When creating or opting into an app, the minimum balance grows before the app code runs, therefore the increase is visible there. When deleting or closing out, the minimum balance decreases after the app executes. Changes caused by inner transactions or box usage are observable immediately following the opcode effecting the change. |
| `acct_params_get f` | X is field F from account A. Y is 1 if A owns positive algos, else 0 |
| `voter_params_get f` | X is field F from online account A as of the balance round: 320 rounds before the current round. Y is 1 if A had positive algos online in the agreement round, else Y is 0 and X is a type specific zero-value |

| OPCODE | DESCRIPTION |
| --- | --- |
| `asset_holding_get f` | X is field F from account A’s holding of asset B. Y is 1 if A is opted into B, else 0 |
| `asset_params_get f` | X is field F from asset A. Y is 1 if A exists, else 0 |

| OPCODE | DESCRIPTION |
| --- | --- |
| `app_opted_in` | 1 if account A is opted in to application B, else 0 |
| `app_local_get` | local state of the key B in the current application in account A |
| `app_local_get_ex` | X is the local state of application B, key C in account A. Y is 1 if key existed, else 0 |
| `app_global_get` | global state of the key A in the current application |
| `app_global_get_ex` | X is the global state of application A, key B. Y is 1 if key existed, else 0 |
| `app_local_put` | write C to key B in account A’s local state of the current application |
| `app_global_put` | write B to key A in the global state of the current application |
| `app_local_del` | delete key B from account A’s local state of the current application |
| `app_global_del` | delete key A from the global state of the current application |
| `app_params_get f` | X is field F from app A. Y is 1 if A exists, else 0 |

Box opcodes that create, delete, or resize boxes affect the minimum balance requirement of the calling application’s account. The change is immediate, and can be observed after execution by using `min_balance`. If the account does not possess the new minimum balance, the opcode fails.

All box related opcodes fail immediately if used in a ClearStateProgram. This behavior is meant to discourage Smart Contract authors from depending upon the availability of boxes in a ClearState transaction, as accounts using ClearState are under no requirement to furnish appropriate Box References. Authors would do well to keep the same issue in mind with respect to the availability of Accounts, Assets, and Apps though State Access opcodes _are_ allowed in ClearState programs because the current application and sender account are sure to be _available_.

| OPCODE | DESCRIPTION |
| --- | --- |
| `box_create` | create a box named A, of length B. Fail if the name A is empty or B exceeds 32,768. Returns 0 if A already existed, else 1 |
| `box_extract` | read C bytes from box A, starting at offset B. Fail if A does not exist, or the byte range is outside A’s size. |
| `box_replace` | write byte-array C into box A, starting at offset B. Fail if A does not exist, or the byte range is outside A’s size. |
| `box_splice` | set box A to contain its previous bytes up to index B, followed by D, followed by the original bytes of A that began at index B+C. |
| `box_del` | delete box named A if it exists. Return 1 if A existed, 0 otherwise |
| `box_len` | X is the length of box A if A exists, else 0. Y is 1 if A exists, else 0. |
| `box_get` | X is the contents of box A if A exists, else ‘’. Y is 1 if A exists, else 0. |
| `box_put` | replaces the contents of box A with byte-array B. Fails if A exists and len(B) != len(box A). Creates A if it does not exist |
| `box_resize` | change the size of box named A to be of length B, adding zero bytes to end or removing bytes from the end, as needed. Fail if the name A is empty, A is not an existing box, or B exceeds 32,768.