vector bytes_to_coeffs()

in pir.cpp [121:151]

• 27 lines of code
• 5 McCabe index (conditional complexity)

vector<uint64_t> bytes_to_coeffs(uint32_t limit, const uint8_t *bytes, uint64_t size) {

    uint64_t size_out = coefficients_per_element(limit, size);
    vector<uint64_t> output(size_out);

    uint32_t room = limit;
    uint64_t *target = &output[0];

    for (uint32_t i = 0; i < size; i++) {
        uint8_t src = bytes[i];
        uint32_t rest = 8;
        while (rest) {
            if (room == 0) {
                target++;
                room = limit;
            }
            uint32_t shift = rest;
            if (room < rest) {
                shift = room;
            }
            *target = *target << shift;
            *target = *target | (src >> (8 - shift));
            src = src << shift;
            room -= shift;
            rest -= shift;
        }
    }

    *target = *target << room;
    return output;
}