rain-math-float 0.1.1-alpha.1

Decimal floating-point arithmetic for Rainlang / DeFi smart contracts. Packs a 224-bit signed coefficient and 32-bit signed exponent into a single bytes32, with exact decimal semantics (no NaN, Infinity, or negative zero — operations error on nonsense). Rust bindings delegate to the Solidity reference via an in-memory EVM so on-chain and off-chain results match exactly.
Documentation 
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use alloy::primitives::{Address, Bytes};
use alloy::sol_types::SolInterface;
use revm::context::result::{ExecutionResult, Output, SuccessReason};
use revm::context::{BlockEnv, CfgEnv, Evm, TxEnv};
use revm::database::InMemoryDB;
use revm::handler::instructions::EthInstructions;
use revm::handler::EthPrecompiles;
use revm::interpreter::interpreter::EthInterpreter;
use revm::primitives::address;
use revm::{Context, MainBuilder, MainContext, SystemCallEvm};
use std::cell::RefCell;

use crate::{DecimalFloat, FloatError};

#[cfg(test)]
use crate::TestDecimalFloat;

/// Fixed address where the DecimalFloat contract is deployed in the in-memory EVM.
/// This arbitrary address is used consistently across all Calculator instances.
pub(crate) const FLOAT_ADDRESS: Address = address!("00000000000000000000000000000000000f10a2");

#[cfg(test)]
/// Fixed address where the TestDecimalFloat contract is deployed in the in-memory EVM.
pub(crate) const TEST_FLOAT_ADDRESS: Address = address!("00000000000000000000000000000000000f10a3");

type EvmContext = Context<BlockEnv, TxEnv, CfgEnv, InMemoryDB>;
type LocalEvm = Evm<EvmContext, (), EthInstructions<EthInterpreter, EvmContext>, EthPrecompiles>;

thread_local! {
    pub(crate) static LOCAL_EVM: RefCell<LocalEvm> = {
        let mut db = InMemoryDB::default();

        // Deploy DecimalFloat contract
        let bytecode = revm::state::Bytecode::new_legacy(DecimalFloat::DEPLOYED_BYTECODE.clone());
        let account_info = revm::state::AccountInfo::default().with_code(bytecode);
        db.insert_account_info(FLOAT_ADDRESS, account_info);

        #[cfg(test)]
        {
            // Deploy TestDecimalFloat contract for testing
            let test_bytecode = revm::state::Bytecode::new_legacy(TestDecimalFloat::DEPLOYED_BYTECODE.clone());
            let test_account_info = revm::state::AccountInfo::default().with_code(test_bytecode);
            db.insert_account_info(TEST_FLOAT_ADDRESS, test_account_info);
        }

        let evm = Context::mainnet().with_db(db).build_mainnet();
        RefCell::new(evm)
    };
}

pub(crate) fn execute_call<F, T>(calldata: Bytes, process_output: F) -> Result<T, FloatError>
where
    F: FnOnce(Bytes) -> Result<T, FloatError>,
{
    execute_call_at_address(FLOAT_ADDRESS, calldata, process_output)
}

#[cfg(test)]
pub(crate) fn execute_test_call<F, T>(calldata: Bytes, process_output: F) -> Result<T, FloatError>
where
    F: FnOnce(Bytes) -> Result<T, FloatError>,
{
    execute_call_at_address(TEST_FLOAT_ADDRESS, calldata, process_output)
}

fn execute_call_at_address<F, T>(
    address: Address,
    calldata: Bytes,
    process_output: F,
) -> Result<T, FloatError>
where
    F: FnOnce(Bytes) -> Result<T, FloatError>,
{
    let result = LOCAL_EVM.try_with(|evm| {
        let evm = &mut *evm.borrow_mut();
        let result_and_state = evm.transact_system_call_finalize(address, calldata)?;

        Ok::<_, FloatError>(result_and_state.result)
    })??;

    match result {
        ExecutionResult::Success {
            reason: SuccessReason::Return,
            output: Output::Call(output),
            ..
        } => process_output(output),
        ExecutionResult::Success { reason, output, .. } => {
            Err(FloatError::UnexpectedSuccess(reason, output))
        }
        ExecutionResult::Revert { output, .. } => {
            if let Ok(error) = DecimalFloat::DecimalFloatErrors::abi_decode(output.as_ref()) {
                return Err(FloatError::DecimalFloat(error));
            }

            Err(FloatError::Revert(output))
        }
        ExecutionResult::Halt { reason, .. } => Err(FloatError::Halt(reason)),
    }
}