Program Listing for File openfhebase64.h

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//==================================================================================
// BSD 2-Clause License
//
// Copyright (c) 2014-2022, NJIT, Duality Technologies Inc. and other contributors
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// Author TPOC: contact@openfhe.org
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/*
  OpenFHE native base 64 utlities
 */

#ifndef SRC_CORE_LIB_UTILS_OPENFHEBASE64_H_
#define SRC_CORE_LIB_UTILS_OPENFHEBASE64_H_

#include <utils/exception.h>

#include <cctype>
#include <cstdint>

namespace lbcrypto {

extern const char to_base64_char[];

inline unsigned char value_to_base64(int c) {
    return to_base64_char[c];
}

inline unsigned char base64_to_value(unsigned char b64) {
    if (isupper(b64))
        return b64 - 'A';
    if (islower(b64))
        return b64 - 'a' + 26;
    if (isdigit(b64))
        return b64 - '0' + 52;
    if (b64 == '+')
        return 62;
    return 63;
}

inline unsigned char get_6bits_atoffset(uint64_t m_value, uint32_t index) {
    static unsigned char smallmask[] = {0, 0x1, 0x3, 0x7, 0xf, 0x1f, 0x3f};
    if (index == 0)
        OPENFHE_THROW("Zero index in GetBitAtIndex");
    if (index <= 6)
        return m_value & smallmask[index];
    return (m_value >> (index - 6)) & 0x3f;
}

} /* namespace lbcrypto */

#endif /* SRC_CORE_LIB_UTILS_OPENFHEBASE64_H_ */