Precompiles

Precompiles refers to code segment that can be used directly in a contract. As a result, the actual code is not necessary to be included in the contract so that gas cost can be reduced. Moreover, precompiles help in compilcated calculations which are not feasible in Wasmer enviornment (e.g. encryption, hashing).

In ParallelChain Mainnet SDK, precompiles are set of functions that can be called directly. Please be noted that some functions are selected based on popularity of blockchain ecosystem, but not necessary adopted in the implementation of ParallelChain Mainnet node.

Function	Description	Gas Consumption
random	psuedo random number	25
sha256	SHA256 hash function	55 x length of the input
keccak256	Keccak-256 hash function	16 x length of the input
keccak512	Keccak-512 hash function	16 x length of the input
ripemd160	RIPEMD-160 hash function	53 x length of the input
blake2b	Blake2 Hash Function (BLAKE2b)	37 x length of the input
verify_signature	Verification on ed25519 signature	14 x length of the input

The gas consumption is estimated by the compute costs for precompile functions used by developers to deploy smart contracts on ParallelChain Mainnet.

To use the precompile functions, include the module precompile and then call the associate methods. For example,

use pchain_sdk::precompile;
...
precompile::sha256(input);
...