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124 lines
4.4 KiB
Markdown
124 lines
4.4 KiB
Markdown
# Instructions
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Instructions are used to communicate with networks connected to Serai, and they
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come in two forms:
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- In Instructions are [Application Calls](../Serai.md#application-calls),
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paired with incoming funds. Encoded in transactions on connected networks,
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Serai will parse out instructions when it receives funds, executing the included
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calls.
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- Out Instructions detail how to transfer assets, either to a Serai address or
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an address native to the asset in question.
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A transaction containing an In Instruction and an Out Instruction (to a native
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address) will receive funds to Serai and send funds from Serai, without
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requiring directly performing any transactions on Serai itself.
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All instructions are encoded under [Shorthand](#shorthand). Shorthand provides
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frequent use cases to create minimal data representations on connected networks.
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Instructions are interpreted according to their non-Serai network. Addresses
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have no validation performed, beyond being a valid enum entry (when applicable)
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of the correct length, unless otherwise noted. If the processor is instructed to
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act on invalid data, or send to itself, it will drop the entire instruction.
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### Serialization
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- Numbers are exclusively unsigned and encoded as compact integers under
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SCALE.
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- Enums are prefixed by an ordinal byte of their type, followed by their
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actual values.
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- Vectors are prefixed by their length.
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- In Instruction fields are numbered and sequentially encoded, allowing
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omission, each prefixed by an ordinal byte. This is due to its fields being more
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frequently omitted than not, making their presence what's notable.
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- All other types have their fields sequentially encoded with no markers.
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Certain fields may be omitted depending on the network in question.
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### In Instructions
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- `origin` (Address): Address from the network of origin which sent funds in.
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- `target` (Address): The ink! contract to transfer the incoming funds to.
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- `data` (Vec\<u8>): The data to call `target` with.
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Networks may automatically provide `origin`. If they do, the instruction may
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still provide `origin`, overriding the automatically provided value. If no
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`origin` is provided, the instruction is dropped.
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Upon receiving funds, the respective Serai Asset contract is called, minting the
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appropriate amount of coins, and transferring them to `target`, calling it with
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the attached data.
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If the instruction fails, funds are scheduled to be returned to `origin`.
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### Out Instructions
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- `destination` (Enum { Native(Address), Serai(Address) }): Address to receive
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funds to.
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- `data` (Option\<Vec\<u8>>): The data to call
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the target with.
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Transfer the funds included with this instruction to the specified address with
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the specified data. Asset contracts perform no validation on native
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addresses/data.
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### Shorthand
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Shorthand is an enum which expands to an In Instruction.
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##### Raw
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Raw Shorthand encodes a raw In Instruction with no further processing. This is
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a verbose fallback option for infrequent use cases not covered by Shorthand.
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##### Swap
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- `origin` (Option\<Address>): In Instruction's `origin`.
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- `coin` (Coin): Coin to swap funds for.
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- `minimum` (Amount): Minimum amount of `coin` to receive.
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- `out` (Out Instruction): Final destination for funds.
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which expands to:
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```
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In Instruction {
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origin,
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target: Router,
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data: swap(Incoming Asset, out, minimum)
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}
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```
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where `swap` is a function which:
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1) Swaps the incoming funds for SRI.
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2) Swaps the SRI for `coin`.
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3) Checks the amount of `coin` received is greater than `minimum`.
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4) Executes `out` with the amount of `coin` received.
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##### Add Liquidity
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- `origin` (Option\<Address>): In Instruction's `origin`.
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- `minimum` (Amount): Minimum amount of SRI to receive.
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- `gas` (Amount): Amount of SRI to send to `address` to cover
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gas in the future.
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- `address` (Address): Account to send the created liquidity tokens.
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which expands to:
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```
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In Instruction {
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origin,
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target: Router,
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data: swap_and_add_liquidity(Incoming Asset, address, minimum, gas)
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}
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```
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where `swap_and_add_liquidity` is a function which:
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1) Swaps half of the incoming funds for SRI.
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2) Checks the amount of SRI received is greater than `minimum`.
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3) Calls `swap_and_add_liquidity` with the amount of SRI received - `gas`, and
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a matching amount of the incoming asset.
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4) Transfers any leftover funds to `address`.
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