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#pragma once
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* \defgroup i2ctcp i2ctcp
* \brief I2C over TCP
*
* This library includes protocol (de)serialization functions for sending and
* receiving I2C messages over TCP. These functions are used by the \ref main
* "main controller" and the \ref pbc "puzzle box client (pbc)". This library
* does not include any puzzle bus specific code.
*
* mpack is used for the actual (de)serialization, and the functions in this
* library act as helpers for parsing from chunked data streams.
*
* To use these functions, include the following statement in your
* CMakeLists.txt:
*
* ```cmake
* # include pbdrv
* add_subdirectory(lib/i2ctcp)
*
* # link with executable
* target_link_libraries(main i2ctcp)
* ```
*
* \{
*/
//! I2C over TCP message (v1)
typedef struct {
uint16_t addr; //!< I2C address
char * data; //!< message content
size_t length; //!< message size
size_t _rdata; //!< \private remaining bytes to read until message is complete
} i2ctcp_msg_t;
/**
* \brief Read chunk of input stream, and store resulting message in \p target
*
* This function is called for each chunk of data from an input stream, and
* will parse the next puzzle bus message into \p target. The input stream is
* assumed to only contain messages encoded by \c i2ctcp_write()
*
* \param target Pointer to struct that will contain the finished message data
* \param buf Pointer to input stream data chunk
* \param buf_sz Size of \p buf
*
* \returns Integer representing amount of bytes required to finish message, or
* -1 if the message header could not be read. If this function returns 0, the
* message in \p target is complete.
*
* \note \p target->data will automatically be allocated by this function, even
* if the message is not fully parsed. This variable must be free'd by the
* caller after each complete message to prevent memory leaks.
*/
int i2ctcp_read(i2ctcp_msg_t * target, const char * buf, size_t buf_sz);
/**
* \brief Reset the remaining message data counter
*
* Calling this function has the effect of forcing \c i2ctcp_read() to parse
* the next buffer chunk as the start of a new message. This function may be
* called before reading a TCP frame's data to mitigate any synchronization
* issues arising from earlier corrupt or otherwise malformed messages.
*/
void i2ctcp_read_reset(i2ctcp_msg_t * target);
/**
* \brief Allocate and write a msgpack-formatted message to \p buf
*
* This function allocates a buffer large enough to fit the message specified
* in \p target, and encodes the data in \p target in a format that can be
* decoded later using \c i2ctcp_read().
*
* \param target Pointer to struct that contains the message data
* \param buf Pointer to \c char* that will contain the formatted message
* \param buf_sz Pointer to \c size_t that will represent the final size of \p buf
*
* \returns Boolean \c true if a the message could be encoded successfully, \c
* false if there was some kind of error
*
* \note The pointer stored in \p buf must be free'd by the caller afterwards
*/
bool i2ctcp_write(const i2ctcp_msg_t * target, char ** buf, size_t * buf_sz);
/// \}
#ifdef __cplusplus
}
#endif
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