Implementation of stack based scripting language for validation of transactions(clearing)
| Word | Opcode | Hex | Input | Output | Description |
|---|---|---|---|---|---|
| OP_0, OP_FALSE | 0 | 0x00 | Nothing. | (empty value) | An empty array of bytes is pushed onto the stack. (This is not a no-op: an item is added to the stack.) |
| N/A | 1-75 | 0x01-0x4b | (special) | data | The next opcode bytes is data to be pushed onto the stack |
| OP_PUSHDATA1 | 76 | 0x4c | (special) | data | The next byte contains the number of bytes to be pushed onto the stack. |
| OP_PUSHDATA2 | 77 | 0x4d | (special) | data | The next two bytes contain the number of bytes to be pushed onto the stack in little endian order. |
| OP_PUSHDATA4 | 78 | 0x4e | (special) | data | The next four bytes contain the number of bytes to be pushed onto the stack in little endian order. |
| OP_1NEGATE | 79 | 0x4f | Nothing. | -1 | The number -1 is pushed onto the stack. |
| OP_1, OP_TRUE 81 | 0x51 | Nothing. | 1 | The number 1 is pushed onto the stack. | |
| OP_2-OP_16 | 82-96 | 0x52-0x60 | Nothing. | 2-16 | The number in the word name (2-16) is pushed onto the stack. |
| Word | Opcode | Hex | Input | Output | Description |
|---|---|---|---|---|---|
| OP_NOP | 97 | 0x61 | Nothing | Nothing | Does nothing. |
| OP_IF | 99 | 0x63 | if [statements] [else [statements]]* endif | if [statements] [else [statements]]* endif | If the top stack value is not False, the statements are executed. The top stack value is removed. |
| OP_NOTIF | 100 | 0x64 | notif [statements] [else [statements]]* endif | notif [statements] [else [statements]]* endif | If the top stack value is False, the statements are executed. The top stack value is removed. |
| OP_ELSE | 103 | 0x67 | if [statements] [else [statements]]* endif | if [statements] [else [statements]]* endif | If the preceding OP_IF or OP_NOTIF or OP_ELSE was not executed then these statements are and if the preceding OP_IF or OP_NOTIF or OP_ELSE was executed then these statements are not. |
| OP_ENDIF | 104 | 0x68 | if [statements] [else [statements]]* endif | if [statements] [else [statements]]* endif | Ends an if/else block. All blocks must end, or the transaction is invalid. An OP_ENDIF without OP_IF earlier is also invalid. |
| OP_VERIFY | 105 | 0x69 | True / false | Nothing / fail | Marks transaction as invalid if top stack value is not true. The top stack value is removed. |
| OP_RETURN | 106 | 0x6a | Nothing | fail | Marks transaction as invalid. Since bitcoin 0.9, a standard way of attaching extra data to transactions is to add a zero-value output with a scriptPubKey consisting of OP_RETURN followed by data. Such outputs are provably unspendable and specially discarded from storage in the UTXO set, reducing their cost to the network. Since 0.12, standard relay rules allow a single output with OP_RETURN, that contains any sequence of push statements (or OP_RESERVED[1]) after the OP_RETURN provided the total scriptPubKey length is at most 83 bytes. |
| Word | Opcode | Hex | Input | Output | Description |
|---|---|---|---|---|---|
| OP_TOALTSTACK | 107 | 0x6b | x1 | (alt)x1 | Puts the input onto the top of the alt stack. Removes it from the main stack. |
| OP_FROMALTSTACK | 108 | 0x6c | (alt)x1 | x1 | Puts the input onto the top of the main stack. Removes it from the alt stack. |
| OP_IFDUP | 115 | 0x73 | x | x / x x | If the top stack value is not 0, duplicate it. |
| OP_DEPTH | 116 | 0x74 | Nothing | Puts the number of stack items onto the stack. | |
| OP_DROP | 117 | 0x75 | x | Nothing | Removes the top stack item. |
| OP_DUP | 118 | 0x76 | x | x x | Duplicates the top stack item. |
| OP_NIP | 119 | 0x77 | x1 x2 | x2 | Removes the second-to-top stack item. |
| OP_OVER | 120 | 0x78 | x1 x2 | x1 x2 x1 | Copies the second-to-top stack item to the top. |
| OP_PICK | 121 | 0x79 | xn ... x2 x1 x0 | xn ... x2 x1 x0 xn | The item n back in the stack is copied to the top. |
| OP_ROLL | 122 | 0x7a | xn ... x2 x1 x0 | ... x2 x1 x0 xn | The item n back in the stack is moved to the top. |
| OP_ROT | 123 | 0x7b | x1 x2 x3 | x2 x3 x1 | The top three items on the stack are rotated to the left. |
| OP_SWAP | 124 | 0x7c | x1 x2 | x2 x1 | The top two items on the stack are swapped. |
| OP_TUCK | 125 | 0x7d | x1 x2 | x2 x1 x2 | The item at the top of the stack is copied and inserted before the second-to-top item. |
| OP_2DROP | 109 | 0x6d | x1 x2 | Nothing | Removes the top two stack items. |
| OP_2DUP | 110 | 0x6e | x1 x2 | x1 x2 x1 x2 | Duplicates the top two stack items. |
| OP_3DUP | 111 | 0x6f | x1 x2 x3 | x1 x2 x3 x1 x2 x3 | Duplicates the top three stack items. |
| OP_2OVER | 112 | 0x70 | x1 x2 x3 x4 | x1 x2 x3 x4 x1 x2 | Copies the pair of items two spaces back in the stack to the front. |
| OP_2ROT | 113 | 0x71 | x1 x2 x3 x4 x5 x6 | x3 x4 x5 x6 x1 x2 | The fifth and sixth items back are moved to the top of the stack. |
| OP_2SWAP | 114 | 0x72 | x1 x2 x3 x4 | x3 x4 x1 x2 | Swaps the top two pairs of items. |