flashloan-rs 0.2.0

Minimal Multicall3 Flashloan Module
Documentation 
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/// @title Shuffling
/// @notice SPDX-License-Identifier: MIT
/// @author Philogy <https://github.com/Philogy>
/// @author asnared <https://github.com/abigger87>
/// @notice Refactored algorithms for shuffling and other bitwise algorithms.
/// @notice Adapted from Ethereum Consensus Specs (https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/beacon-chain.md#compute_shuffled_index)

#include "./Address.huff"
#include "./Ternary.huff"

#include "../math/Math.huff"

// Constants
#define constant POS_MASK = 0xffffffff00

/// @notice Shuffling Algorithm
#define macro MECHS__ONE_WAY_SHUFFLE(mem1, mem2) = takes (4) returns (1) {
    // Input Stack:                    [seed, index, index_count, iters]
    // Output Stack:                   [index']

    __Mechs__shuffleContinue:       // [seed, index, index_count, iters]
        <mem1> mstore               // [index, index_count, iters]
        0x20 <mem1> sha3            // [seed', index, index_count, iters]
        dup3 dup1                   // [index_count, index_count, seed' index, index_count, iters]
        dup3 mod                    // [pivot, index_count, seed', index, index_count, iters]
        dup4 dup3                   // [index_count, index, pivot, index_count, seed', index, index_count, iters]
        sub add mod                 // [flip, seed', index, index_count, iters]
        dup3 dup2 MAX()             // [position, flip, seed', index, index_count, iters]
        dup1 [POS_MASK] and         // [masked_position, position, flip, seed', index, index_count, iters]
        <mem2> mstore               // [position, flip, seed', index, index_count, iters]
        0x40 <mem1> sha3            // [rand2, position, flip, seed', index, index_count, iters]
        swap1 0xff and shr          // [rand_bit_unmasked, flip, seed', index, index_count, iters]
        0x1 and                     // [rand_bit, flip, seed', index, index_count, iters]
        swap2 swap3 swap2           // [rand_bit, flip, index, seed', index_count, iters]
        NOT_TERNARY()               // [index', seed', index_count, iters]
        swap1 swap3                 // [iters, index', index_count, seed']
        UNSAFE_SUB() swap3          // [seed', index', index_count, iters']

    // Continue if iters > 0
    dup4 __Mechs__shuffleContinue jumpi

    // Return the index
    pop swap2 pop pop               // [index']
}