mirror of
https://github.com/wpilibsuite/allwpilib
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134 lines
3.6 KiB
C++
134 lines
3.6 KiB
C++
/*----------------------------------------------------------------------------*/
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/* Copyright (c) FIRST 2015. All Rights Reserved. */
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/* Open Source Software - may be modified and shared by FRC teams. The code */
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/* must be accompanied by the FIRST BSD license file in the root directory of */
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/* the project. */
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/*----------------------------------------------------------------------------*/
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#ifndef NT_WIREDECODER_H_
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#define NT_WIREDECODER_H_
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#include <cstddef>
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#include "nt_Value.h"
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#include "leb128.h"
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#include "raw_istream.h"
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namespace nt {
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/* Decodes network data into native representation.
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* This class is designed to read from a raw_istream, which provides a blocking
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* read interface. There are no provisions in this class for resuming a read
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* that was interrupted partway. Read functions return false if
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* raw_istream.read() returned false (indicating the end of the input data
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* stream).
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*/
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class WireDecoder {
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public:
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explicit WireDecoder(raw_istream& is, unsigned int proto_rev);
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~WireDecoder();
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void set_proto_rev(unsigned int proto_rev) { m_proto_rev = proto_rev; }
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/* Get the active protocol revision. */
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unsigned int proto_rev() const { return m_proto_rev; }
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/* Clears error indicator. */
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void Reset() { m_error = nullptr; }
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/* Returns error indicator (a string describing the error). Returns nullptr
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* if no error has occurred.
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*/
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const char* error() const { return m_error; }
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void set_error(const char* error) { m_error = error; }
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/* Reads the specified number of bytes.
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* @param buf pointer to read data (output parameter)
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* @param len number of bytes to read
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* Caution: the buffer is only temporarily valid.
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*/
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bool Read(const char** buf, std::size_t len) {
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if (len > m_allocated) Realloc(len);
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*buf = m_buf;
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return m_is.read(m_buf, len);
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}
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/* Reads a single byte. */
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bool Read8(unsigned int* val) {
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const char* buf;
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if (!Read(&buf, 1)) return false;
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*val = (*((unsigned char*)buf)) & 0xff;
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return true;
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}
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/* Reads a 16-bit word. */
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bool Read16(unsigned int* val) {
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const char* buf;
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if (!Read(&buf, 2)) return false;
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unsigned int v = (*((unsigned char*)buf)) & 0xff;
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++buf;
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v <<= 8;
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v |= (*((unsigned char*)buf)) & 0xff;
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*val = v;
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return true;
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}
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/* Reads a 32-bit word. */
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bool Read32(unsigned long* val) {
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const char* buf;
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if (!Read(&buf, 4)) return false;
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unsigned int v = (*((unsigned char*)buf)) & 0xff;
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++buf;
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v <<= 8;
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v |= (*((unsigned char*)buf)) & 0xff;
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++buf;
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v <<= 8;
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v |= (*((unsigned char*)buf)) & 0xff;
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++buf;
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v <<= 8;
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v |= (*((unsigned char*)buf)) & 0xff;
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*val = v;
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return true;
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}
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/* Reads a double. */
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bool ReadDouble(double* val);
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/* Reads an ULEB128-encoded unsigned integer. */
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bool ReadUleb128(unsigned long* val) {
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return nt::ReadUleb128(m_is, val);
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}
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bool ReadType(NT_Type* type);
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bool ReadString(std::string* str);
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std::shared_ptr<Value> ReadValue(NT_Type type);
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WireDecoder(const WireDecoder&) = delete;
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WireDecoder& operator=(const WireDecoder&) = delete;
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protected:
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/* The protocol revision. E.g. 0x0200 for version 2.0. */
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unsigned int m_proto_rev;
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/* Error indicator. */
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const char* m_error;
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private:
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/* Reallocate temporary buffer to specified length. */
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void Realloc(std::size_t len);
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/* input stream */
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raw_istream& m_is;
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/* temporary buffer */
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char* m_buf;
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/* allocated size of temporary buffer */
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std::size_t m_allocated;
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};
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} // namespace nt
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#endif // NT_WIREDECODER_H_
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