SD-dat.h

#ifndef __SD_DAT_H
    #define __SD_DAT_H
    //needed for ERR_ADDR_END
    #include <Error.h>

    //sizes for data areas
    #define SD_LEDL_DAT_SIZE      (1000000ul)
    #define SD_IMG_DAT_SIZE       (20000ul)
    #define SD_ACDS_DAT_SIZE      (20000ul)

    //Identifier for the data table
    #define DATA_TABLE_MAGIC      (0xAFCA)

    //storage location definitions for SD card
    //NOTE: use #define because enum is short
    #define SD_DAT_TABLE          (ERR_ADDR_END+1)
    #define SD_LEDL_DAT_START     (SD_DAT_TABLE+1)
    #define SD_LEDL_DAT_END       (SD_LEDL_DAT_START+SD_LEDL_DAT_SIZE)
    #define SD_IMG_DAT_START      (SD_LEDL_DAT_END+1)
    #define SD_IMG_DAT_END        (SD_IMG_DAT_START+SD_IMG_DAT_SIZE)
    #define SD_ACDS_DAT_START     (SD_IMG_DAT_END+1)
    #define SD_ACDS_DAT_END       (SD_ACDS_DAT_START+SD_ACDS_DAT_SIZE)

    //return values for data_setup
    enum{SD_DAT_INIT=1,SD_DAT_INIT_WRITE_ERR=2,SD_DAT_INIT_ERR=-1,SD_DAT_BAD_SUBSYSTEM=-2,SD_DAT_BLOCK_WRITE_ERROR=-3,SD_DAT_TABLE_WRITE_ERROR=-4,SD_DAT_BLOCK_READ_ERROR=-5};

    typedef struct{
        //saved data values
        unsigned long next_LEDL;
        unsigned short next_IMG;
        unsigned short next_ACDS;
    }DATA_TABLE;

    //structure for keeping track of data in memory
    typedef struct{
        //ID for data
        unsigned short magic;
        //use a union to add padding
        union{
            DATA_TABLE table;
            //ensure a 512 byte structure
            unsigned char fill[508];
        }dat;
        //CRC from crc16
        unsigned short CRC;
    }SD_DATA_TABLE;
    
    
    
    extern DATA_TABLE sd_data_table;
    
    //initialize data writing
    int data_setup(void);
    //write data to SD card in the proper area
    int writeSD_Data(unsigned char subsystem,unsigned char type,const unsigned char *dat);
    //read data block from SD card
    int readSD_Data(unsigned char subsystem,unsigned long index,unsigned char *dat);

#endif