/*
 * nvram.h
 *
 *  Created on: 4 Jun 2017
 *      Author: Mike
 */
#include "libPLX/plx.h"

#pragma once


#if defined __cplusplus
extern "C"
{
#endif
#pragma pack(push, 1)

    ///\brief State of currently displayed item
    /// this is expected to be packed into 32 bits 
    typedef union
    {
        struct
        {
            unsigned tag : 8; // dial tag 
            unsigned : 16;  // filler 
            int pos:  8;   // dial position code 
        } data;
        uint32_t u32;
    } nvram_info_t;
#pragma pack(pop)

// Allocation of NVRAM words : there are 4k bytes
#define NVRAM_WORDS (4096 / sizeof(nvram_info_t))

    /// @brief Erase every NVRAM entry
    extern void erase_nvram(); 
    
    /// @brief Save data, replacing any with a matching tag field.
    /// @param data data item to write 
    extern void write_nvram_data(nvram_info_t data);

    // 
    /// @brief Find data according to the tag field/
    /// @param tag tag code to find
    /// @return a pointer to the nvram data with matching tag or NULL if not found
    extern nvram_info_t *find_nvram_data(uint8_t tag);

#if defined __cplusplus
}
#endif