allwpilib/src/nt_wiredecoder.h

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2015. All Rights Reserved.                             */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

#ifndef NT_WIREDECODER_H_
#define NT_WIREDECODER_H_

#include <cstddef>

#include "ntcore.h"
#include "nt_leb128.h"
#include "nt_raw_istream.h"
#include "nt_encoding.h"

namespace NtImpl {

class WireDecoder
{
public:
    explicit WireDecoder(raw_istream& is, unsigned int proto_rev);
    ~WireDecoder();

    void SetProtocolRev(unsigned int proto_rev)
    {
        m_proto_rev = proto_rev;
    }

    void Reset()
    {
        m_error = 0;
    }

    const char *GetError() const
    {
        return m_error;
    }

    bool Read(char **buf, std::size_t len)
    {
        if (len > m_allocated)
            Realloc(len);
        *buf = m_buf;
        return m_is.read(m_buf, len);
    }

    bool Read8(unsigned int *val)
    {
        char *buf;
        if (!Read(&buf, 1)) return false;
        *val = NtImpl::Read8(buf);
        return true;
    }

    bool Read16(unsigned int *val)
    {
        char *buf;
        if (!Read(&buf, 2)) return false;
        *val = NtImpl::Read16(buf);
        return true;
    }

    bool Read32(unsigned long *val)
    {
        char *buf;
        if (!Read(&buf, 4)) return false;
        *val = NtImpl::Read32(buf);
        return true;
    }

    bool ReadDouble(double *val)
    {
        char *buf;
        if (!Read(&buf, 8)) return false;
        *val = NtImpl::ReadDouble(buf);
        return true;
    }

    bool ReadULEB128(unsigned long *val)
    {
        return read_uleb128(m_is, val);
    }

    bool ReadType(NT_Type *type);
    bool ReadValue(NT_Type type, NT_Value *value);
    bool ReadString(NT_String *str);

protected:
    unsigned int m_proto_rev;
    const char *m_error;

private:
    WireDecoder(const WireDecoder&);
    WireDecoder& operator= (const WireDecoder&);

    void Realloc(std::size_t len);

    raw_istream &m_is;

    char *m_buf;
    std::size_t m_allocated;
};

} // namespace NtImpl

#endif /* NT_WIREDECODER_H_ */