sha1.hh

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#ifndef SHA1_HH
#define SHA1_HH

#include <ostream>
#include <string>
#include <string_view>
#include <cstdint>

namespace openmsx {

class Sha1Sum
{
public:
        struct UninitializedTag {};
        Sha1Sum(UninitializedTag) {}

        // note: default copy and assign are ok
        Sha1Sum();
        explicit Sha1Sum(std::string_view hex);

        void parse40(const char* str);
        [[nodiscard]] std::string toString() const;

        // Test or set 'null' value.
        [[nodiscard]] bool empty() const;
        void clear();

        [[nodiscard]] bool operator==(const Sha1Sum& other) const {
                for (int i = 0; i < 5; ++i) {
                        if (a[i] != other.a[i]) return false;
                }
                return true;
        }
        [[nodiscard]] bool operator!=(const Sha1Sum& other) const { return !(*this == other); }
        [[nodiscard]] bool operator< (const Sha1Sum& other) const {
                for (int i = 0; i < 5-1; ++i) {
                        if (a[i] != other.a[i]) return a[i] < other.a[i];
                }
                return a[5-1] < other.a[5-1];
        }

        [[nodiscard]] bool operator<=(const Sha1Sum& other) const { return !(other <  *this); }
        [[nodiscard]] bool operator> (const Sha1Sum& other) const { return  (other <  *this); }
        [[nodiscard]] bool operator>=(const Sha1Sum& other) const { return !(*this <  other); }

        friend std::ostream& operator<<(std::ostream& os, const Sha1Sum& sum) {
                os << sum.toString();
                return os;
        }

private:
        uint32_t a[5];
        friend class SHA1;
};


class SHA1
{
public:
        SHA1();

        void update(const uint8_t* data, size_t len);

        [[nodiscard]] Sha1Sum digest();

        [[nodiscard]] static Sha1Sum calc(const uint8_t* data, size_t len);

private:
        void transform(const uint8_t buffer[64]);
        void finalize();

        uint64_t m_count;
        Sha1Sum m_state;
        uint8_t m_buffer[64];
        bool m_finalized;
};

} // namespace openmsx

#endif