Inputs

The entrypoint reads instruction data via the SIMD-0321 r2 pointer, which provides the instruction data address directly in a register. It dispatches on the instruction discriminant to the appropriate handler.

Entrypoint

Input buffer

The Solana runtime serializes accounts and instruction data into a contiguous input buffer pointed to by r1. Dropset enables direct pointer addressing by requiring the user (signer) account first with no data, followed by the market account.

Through this design, all user and market account metadata can be accessed at compile-time-known offsets from r1, and more importantly, market account data offsets are persisted across transactions. The header also overlays a MarketHeader directly after the RuntimeAccount so that market data fields (pointers, bump seeds) are addressable at static offsets. A trailing market_data_bytes field marks the first allocatable byte after the header, giving MarketHeader.next its initialization target. The InputBufferHeader layout captures this design:

Account data regions in the Solana input buffer are variable-length and would normally prevent static offset computation. FullRuntimeAccount solves this by extending RuntimeAccount with a compile-time-sized data buffer and trailing rent epoch:

The type alias EmptyAccount specializes FullRuntimeAccount with zero-length data, which is the common case for accounts whose data is not statically known. Because the user data length is zero, EmptyAccount has a fixed size and the market account begins at a deterministic offset. This makes every account metadata field in the header addressable as an immediate offset from r1.