flashloan-rs 0.2.3

Minimal Multicall3 Flashloan Module
Documentation 
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/// @title BitPackLib
/// @notice SPDX-License-Identifier: MIT
/// @author kadenzipfel <https://github.com/kadenzipfel>
/// @notice Efficient bit packing library

#define constant MAX = 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff

/// @notice Packs value of given length at index of given word
/// @dev Assumes index < 256 - length
#define macro PACK_VALUE() = takes (4) returns (1) {
    // Input stack:             // [length, index, value, word]
    0x100 sub sub               // [shift, value, word]
    shl swap1 or                // [new_word]
}

/// @notice Unpacks value of given length from right of word
/// @dev word & (~0 >> (256 - length))
#define macro UNPACK_FROM_RIGHT() = takes (2) returns (1) {
    // Input stack:             // [length, word]
    [MAX]                       // [not(0), length, word]
    swap1 0x100 sub             // [offset, not(0), word]
    shr and                     // [value]
}

/// @notice Unpacks value of given length from left of word
/// @dev word >> (256 - length)
#define macro UNPACK_FROM_LEFT() = takes (2) returns (1) {
    // Input stack:             // [length, word]
    0x100 sub                   // [shift, word]
    shr                         // [value]
}

/// @notice Unpcks value of given length from index of word
/// @dev Assume index < 256 - length
///      (word & ((~0 >> 256 - length) << (256 - length - index))) >> (256 - length - index)
#define macro UNPACK_FROM_CENTER() = takes (3) returns (1) {
    // Input stack:             // [length, index, word]
    0x100 sub                   // [offset, index, word]
    swap1 dup2 sub              // [shift, offset, word]
    [MAX] swap1 swap2 shr       // [offset_shift, shift, word]
    dup2 shl swap1 swap2 and    // [left_shifted_word, shift]
    swap1 shr                   // [value]
}