fvm 3.0.0-alpha.21

// Copyright 2021-2023 Protocol Labs
// SPDX-License-Identifier: Apache-2.0, MIT
use fvm_shared::randomness::RANDOMNESS_LENGTH;

use super::Context;
use crate::kernel::Result;
use crate::Kernel;

/// Gets 32 bytes of randomness from the ticket chain.
/// The supplied output buffer must have at least 32 bytes of capacity.
/// If this syscall succeeds, exactly 32 bytes will be written starting at the
/// supplied offset.
pub fn get_chain_randomness(
    context: Context<'_, impl Kernel>,
    pers: i64,  // DomainSeparationTag
    round: i64, // ChainEpoch
    entropy_off: u32,
    entropy_len: u32,
) -> Result<[u8; RANDOMNESS_LENGTH]> {
    let entropy = context.memory.try_slice(entropy_off, entropy_len)?;
    context
        .kernel
        .get_randomness_from_tickets(pers, round, entropy)
}

/// Gets 32 bytes of randomness from the beacon system (currently Drand).
/// The supplied output buffer must have at least 32 bytes of capacity.
/// If this syscall succeeds, exactly 32 bytes will be written starting at the
/// supplied offset.
pub fn get_beacon_randomness(
    context: Context<'_, impl Kernel>,
    pers: i64,  // DomainSeparationTag
    round: i64, // ChainEpoch
    entropy_off: u32,
    entropy_len: u32,
) -> Result<[u8; RANDOMNESS_LENGTH]> {
    let entropy = context.memory.try_slice(entropy_off, entropy_len)?;
    context
        .kernel
        .get_randomness_from_beacon(pers, round, entropy)
}