hush3/src/zcash/circuit/utils.tcc

#include "uint252.h"

template<typename FieldT>
pb_variable_array<FieldT> from_bits(std::vector<bool> bits, pb_variable<FieldT>& ZERO) {
    pb_variable_array<FieldT> acc;

    BOOST_FOREACH(bool bit, bits) {
        acc.emplace_back(bit ? ONE : ZERO);
    }

    return acc;
}

std::vector<bool> trailing252(std::vector<bool> input) {
    if (input.size() != 256) {
        throw std::length_error("trailing252 input invalid length");
    }

    return std::vector<bool>(input.begin() + 4, input.end());
}

template<typename T>
std::vector<bool> to_bool_vector(T input) {
    std::vector<unsigned char> input_v(input.begin(), input.end());

    return convertBytesVectorToVector(input_v);
}

std::vector<bool> uint256_to_bool_vector(uint256 input) {
    return to_bool_vector(input);
}

std::vector<bool> uint252_to_bool_vector(uint252 input) {
    return trailing252(to_bool_vector(input));
}

std::vector<bool> uint64_to_bool_vector(uint64_t input) {
    auto num_bv = convertIntToVectorLE(input);
    
    return convertBytesVectorToVector(num_bv);
}

void insert_uint256(std::vector<bool>& into, uint256 from) {
    std::vector<bool> blob = uint256_to_bool_vector(from);
    into.insert(into.end(), blob.begin(), blob.end());
}

void insert_uint64(std::vector<bool>& into, uint64_t from) {
    std::vector<bool> num = uint64_to_bool_vector(from);
    into.insert(into.end(), num.begin(), num.end());
}

template<typename T>
T swap_endianness_u64(T v) {
    if (v.size() != 64) {
        throw std::length_error("invalid bit length for 64-bit unsigned integer");
    }

    for (size_t i = 0; i < 4; i++) {
        for (size_t j = 0; j < 8; j++) {
            std::swap(v[i*8 + j], v[((7-i)*8)+j]);
        }
    }

    return v;
}

template<typename FieldT>
linear_combination<FieldT> packed_addition(pb_variable_array<FieldT> input) {
    auto input_swapped = swap_endianness_u64(input);

    return pb_packing_sum<FieldT>(pb_variable_array<FieldT>(
        input_swapped.rbegin(), input_swapped.rend()
    ));
}