source: git/src-cryptopp/fltrimpl.h

#ifndef CRYPTOPP_FLTRIMPL_H
#define CRYPTOPP_FLTRIMPL_H

#if CRYPTOPP_MSC_VERSION
# pragma warning(push)
# pragma warning(disable: 4100)
#endif

#if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wunused-value"
#endif

#define FILTER_BEGIN    \
        switch (m_continueAt)   \
        {       \
        case 0: \
                m_inputPosition = 0;

#define FILTER_END_NO_MESSAGE_END_NO_RETURN     \
                break;  \
        default:        \
                CRYPTOPP_ASSERT(false); \
        }

#define FILTER_END_NO_MESSAGE_END       \
        FILTER_END_NO_MESSAGE_END_NO_RETURN     \
        return 0;

/*
#define FILTER_END      \
        case -1:        \
                if (messageEnd && Output(-1, NULL, 0, messageEnd, blocking))    \
                        return 1;       \
        FILTER_END_NO_MESSAGE_END
*/

#define FILTER_OUTPUT3(site, statement, output, length, messageEnd, channel)    \
        {\
        case site:      \
        statement;      \
        if (Output(site, output, length, messageEnd, blocking, channel))        \
                return STDMAX(size_t(1), length-m_inputPosition);\
        }

#define FILTER_OUTPUT2(site, statement, output, length, messageEnd)     \
        FILTER_OUTPUT3(site, statement, output, length, messageEnd, DEFAULT_CHANNEL)

#define FILTER_OUTPUT(site, output, length, messageEnd) \
        FILTER_OUTPUT2(site, 0, output, length, messageEnd)

#define FILTER_OUTPUT_BYTE(site, output)        \
        FILTER_OUTPUT(site, &(const byte &)(byte)output, 1, 0)

#define FILTER_OUTPUT2_MODIFIABLE(site, statement, output, length, messageEnd)  \
        {\
        case site:      \
        statement;      \
        if (OutputModifiable(site, output, length, messageEnd, blocking))       \
                return STDMAX(size_t(1), length-m_inputPosition);\
        }

#define FILTER_OUTPUT_MODIFIABLE(site, output, length, messageEnd)      \
        FILTER_OUTPUT2_MODIFIABLE(site, 0, output, length, messageEnd)

#define FILTER_OUTPUT2_MAYBE_MODIFIABLE(site, statement, output, length, messageEnd, modifiable)        \
        {\
        case site:      \
        statement;      \
        if (modifiable ? OutputModifiable(site, output, length, messageEnd, blocking) : Output(site, output, length, messageEnd, blocking))     \
                return STDMAX(size_t(1), length-m_inputPosition);\
        }

#define FILTER_OUTPUT_MAYBE_MODIFIABLE(site, output, length, messageEnd, modifiable)    \
        FILTER_OUTPUT2_MAYBE_MODIFIABLE(site, 0, output, length, messageEnd, modifiable)

#if CRYPTOPP_MSC_VERSION
# pragma warning(pop)
#endif

#if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic pop
#endif

#endif