Merge pull request #6 from FuelLabs/adlerjohn-initial_tx_format

Add initial transaction format

Author: adlerjohn

tx_format.md

@@ -0,0 +1,92 @@
+# Transaction Format
+
+- [Transaction](#transaction)
+- [Input](#input)
+    - [InputCoin](#inputcoin)
+    - [InputContract](#inputcontract)
+- [Output](#output)
+    - [OutputCoin](#outputcoin)
+    - [OutputContract](#outputcontract)
+- [Witness](#witness)
+
+## Transaction
+
+| name             | type                    | description                |
+| ---------------- | ----------------------- | -------------------------- |
+| `scriptLength`   | `uint16`                | Script length, in words.   |
+| `script`         | `byte[]`                | Script to execute.         |
+| `gasPrice`       | `uint64`                | Gas price for transaction. |
+| `gasLimit`       | `uint64`                | Gas limit for transaction. |
+| `inputsCount`    | `uint8`                 | Number of inputs.          |
+| `inputs`         | [Input](#input)`[]`     | List of inputs.            |
+| `outputsCount`   | `uint8`                 | Number of outputs.         |
+| `outputs`        | [Output](#output)`[]`   | List of outputs.           |
+| `witnessesCount` | `uint8`                 | Number of witnesses.       |
+| `witnesses`      | [Witness](#witness)`[]` | List of witnesses.         |
+
+## Input
+
+```
+enum  InputType : uint8 {
+    Coin = 0,
+    Contract = 1,
+}
+```
+
+| name   | type                                                              | description    |
+| ------ | ----------------------------------------------------------------- | -------------- |
+| `type` | `InputType`                                                       | Type of input. |
+| `data` | One of [InputCoin](#inputcoin) or [InputContract](#inputcontract) | Input data.    |
+
+
+### InputCoin
+
+| name           | type       | description                                         |
+| -------------- | ---------- | --------------------------------------------------- |
+| `utxoID`       | `byte[32]` | UTXO ID.                                            |
+| `dataLength`   | `uint16`   | Length of data, in bytes.                           |
+| `data`         | `byte[]`   | Data to input into script.                          |
+| `witnessIndex` | `uint8`    | Index of witness that authorizes spending the coin. |
+
+### InputContract
+
+| name         | type       | description  |
+| ------------ | ---------- | ------------ |
+| `utxoID`     | `byte[32]` | UTXO ID.     |
+| `contractID` | `byte[32]` | Contract ID. |
+
+## Output
+
+```
+enum  OutputType : uint8 {
+    Coin = 0,
+    Contract = 1,
+}
+```
+
+| name   | type                                                                  | description     |
+| ------ | --------------------------------------------------------------------- | --------------- |
+| `type` | `OutputType`                                                          | Type of output. |
+| `data` | One of [OutputCoin](#outputcoin) or [OutputContract](#outputcontract) | Output data.    |
+
+### OutputCoin
+
+| name     | type       | description                       |
+| -------- | ---------- | --------------------------------- |
+| `to`     | `byte[32]` | Receiving address or script hash. |
+| `amount` | `uint64`   | Amount of coins to send.          |
+
+### OutputContract
+
+| name                 | type    | description                                             |
+| -------------------- | ------- | ------------------------------------------------------- |
+| `inputIndex`         | `uint8` | Index of input contract.                                |
+| `amountWitnessIndex` | `uint8` | Index of witness for amount of coins owned by contract. |
+| `stateWitnessIndex`  | `uint8` | Index of witness for state root of contract.            |
+
+## Witness
+
+| name         | type     | description                       |
+| ------------ | -------- | --------------------------------- |
+| `dataLength` | `uint16` | Length of witness data, in bytes. |
+| `data`       | `byte[]` | Witness data.                     |