How to store checksum at a permanent flash adress

Since no working example or correct answer..

Here comes my solution of how I solved it.

I added this to linker_ccs.cmd:

//(MEMORY)

CRCFLASH (RX) : origin = 0x00039600, length = 0x00000400 //1024 bytes one single erasable sector

//(SECTION)

.flashcrc :> CRCFLASH

I added this to my test_flash.c that is called from main.c, at bootup InitFlashCRC() and then -------CheckFlashCRC(SysCtlFlashSizeGet()

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/flash.h"
#include "driverlib/debug.h"
#include "test_flash.h"

//*****************************************************************************
//
//! The CRC-16 table for polynomial 0xA001 (standard CRC-16, aka IBM CRC-16).
//!
//! This table should be loaded into FLASH memory.
//
//*****************************************************************************
static const unsigned short g_usCRCTab16[256] =
{
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
    0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
    0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
    0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
    0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
    0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
    0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
    0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
    0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
    0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
    0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
    0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
    0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
    0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
    0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
    0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
    0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
    0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
    0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
    0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
    0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
    0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
    0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
    0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
    0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
    0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
    0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
    0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
    0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
    0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
    0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
    0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
};

//*****************************************************************************
//
// The macro executes one iteration of the 16-bit CRC
//
//*****************************************************************************
#define CRC_ITER(crc, data)     crc = ((crc >> 8) ^                         \
                                       g_usCRCTab16[(unsigned char)(crc ^   \
                                                                   (data))])
//*****************************************************************************
//
//! Storage for the FLASH CRC, initialized to all ones so that it can be
//! initialized either by a post-processing of the binary image, or at the
//! first time the CRC code is run on the board after programming.
//! We need 3 unsigned short values, but use 2 unsigned long values to ensure
//! word alignment of the data in FLASH memory so that the subsequent
//! programming of the actual CRC value will work properly.
//*****************************************************************************

#pragma DATA_SECTION (g_ulImageCRC, ".flashcrc")
const unsigned long g_ulImageCRC[2] = { 0xffffffff, 0xffffffff };
//*****************************************************************************
//
//! Macro to define the starting address of the CRC table.
//
//*****************************************************************************
#define CRC_TABLE_START     ((unsigned long)&g_ulImageCRC[0])
//*****************************************************************************
//
//! Macro to define the first address past the CRC table.
//
//*****************************************************************************
#define CRC_TABLE_END       (CRC_TABLE_START + sizeof(g_ulImageCRC))
//*****************************************************************************
//
//! Macro to define the size of the CRC table.
//
//*****************************************************************************
#define CRC_TABLE_SIZE      (sizeof(g_ulImageCRC))
#define CRC_SIGNATURE 0x01EC //Any valid 16 bits magic number
//*****************************************************************************
//
//! Compute and check CRC for FLASH memory region.
//!
//! \param ulBytes is the number of bytes to be calculated during this
//! iteration.
//!
//! This function will perform a check of the FLASH CRC for the specified
// number of bytes.  A base address for the calculation is maintained and
// updated each time the routine is called.  If the address being read is
// in the range of the stored CRC table, it will be skipped.  If the address
// reaches the end of the FLASH memory, the computed CRC value will be
// compared against the stored value.  If the comparison matches, or if
// the test loop has not yet reached the end of FLASH memory, the function
// will return true for success.  Only if the end of FLASH memory has been
// reached and the comparison fails will the function return a false for
// failure. 
//
//! \return Returns true if the test passes, false otherwise.
//
//*****************************************************************************
bool
CheckFlashCRC(unsigned long ulBytes)
{
    static unsigned short pusCrc3[4] = {0, 0, 0, 0};
    static unsigned long ulAddress = 0;
    unsigned long ulLoop, ulTemp;
    unsigned short *pusImageCRC;

    // Word-align the number of bytes, and calculate the ending
    // address for this transaction.
    ulBytes = ulBytes & ~3;

    // Check to see if we need to reset the CRC values.
    if(ulAddress == 0)
    {
        pusCrc3[0] = pusCrc3[1] = pusCrc3[2] = pusCrc3[3] = 0;
    }

    // Calculate CRC up to the CRC Table.
    for(ulLoop = 0; (ulLoop < (ulBytes/4)); ulLoop++)
    {
        // Check to see if we are inside the CRC Table.
        if((ulAddress >= CRC_TABLE_START) && (ulAddress < CRC_TABLE_END))
        {
            ulAddress += 4;
            continue;
        }

        // Check to see if we are past the end of FLASH.
        if(ulAddress >= SysCtlFlashSizeGet())
        {
            break;
        }

        // Preserve the current word in flash locally.
        ulTemp = *(unsigned long *)ulAddress;

        // Calculate the "full" CRC
        CRC_ITER(pusCrc3[0], ulTemp);
        CRC_ITER(pusCrc3[0], ulTemp>>8);
        CRC_ITER(pusCrc3[0], ulTemp>>16);
        CRC_ITER(pusCrc3[0], ulTemp>>24);

        // Calculate the "even" CRC
        CRC_ITER(pusCrc3[1], ulTemp);
        CRC_ITER(pusCrc3[1], ulTemp>>16);

        // Calculate the "odd" CRC
        CRC_ITER(pusCrc3[2], ulTemp>>8);
        CRC_ITER(pusCrc3[2], ulTemp>>24);

        ulAddress = ulAddress+4; //
    }

    // Check to see if we need to do a CRC comparison.
    if(ulAddress >= SysCtlFlashSizeGet())
    {
        // Reset the Address pointer for next time around.
        ulAddress = 0;

        // Setup the Image CRC pointer.
        pusImageCRC = (void *)&g_ulImageCRC[0];
 
        // Check the "full" CRC.
        if(pusCrc3[0] != pusImageCRC[0])
        {
            return(false);
        }
        
        // Check the "even" CRC.
        if(pusCrc3[1] != pusImageCRC[1])
        {
            return(false);
        }

        // Check the "odd" CRC.
         if(pusCrc3[2] != pusImageCRC[2])
        {
            return(false);
        }
        //Check signature
        if(CRC_SIGNATURE != pusImageCRC[3])
        {
           return(false);
        }
    }
     // CRC has passed if we get here, or we are still in the middle of a calculation.
     return(true);
}

//*****************************************************************************
//
//! Initialize FLASH CRC region table.
//!
//! This function will initialize the FLASH CRC data (if not already
//! initialized) so that subsequent calls to CheckFlashCRC() will work
//! properly.
//!
//! \note  In general, it would be preferable for a post-processing utility
//! to fill in this information in the binary image.  This function is
//! provided as an example of how to fill in this information.
//
//! \return None.
//
//*****************************************************************************
void
InitFlashCRC(void)
{
    unsigned long ulAddress;
    unsigned long ulTemp;
    unsigned short usCrc3[4];

    // Check if we have a checksum, if not found create a new one
    if((g_ulImageCRC[0] != 0xffffffff) || (g_ulImageCRC[1] != 0xffffffff))
    {
        // Assume non-ff value(s) mean CRC has been programmed.
        return;
    }

    // Initialize the CRC array to 0 for the initial calculation.
    usCrc3[0] = usCrc3[1] = usCrc3[2] = usCrc3[3] = 0;

    // Calculate CRC up to the CRC Table.
    for(ulAddress = 0; ulAddress < SysCtlFlashSizeGet(); ulAddress += 4)
    {
        // Check to see if we are inside the CRC Table.
        if((ulAddress >= CRC_TABLE_START) && (ulAddress < CRC_TABLE_END))
        {
            ulAddress += 4;
            continue;
        }
        // Preserve the current word in flash locally.
        ulTemp = *(unsigned long *)ulAddress;

        // Calculate the "full" CRC
        CRC_ITER(usCrc3[0], ulTemp);
        CRC_ITER(usCrc3[0], ulTemp>>8);
        CRC_ITER(usCrc3[0], ulTemp>>16);
        CRC_ITER(usCrc3[0], ulTemp>>24);

        // Calculate the "even" CRC
        CRC_ITER(usCrc3[1], ulTemp);
        CRC_ITER(usCrc3[1], ulTemp>>16);

        // Calculate the "odd" CRC
        CRC_ITER(usCrc3[2], ulTemp>>8);
        CRC_ITER(usCrc3[2], ulTemp>>24);
    }

    // Write the calculated CRC values to FLASH memory, with a "magic"
    // number in the unused 16 bits.
    usCrc3[3] = CRC_SIGNATURE;
    FlashErase(CRC_TABLE_START);
    FlashProgram((uint32_t *)(&usCrc3[0]), CRC_TABLE_START, CRC_TABLE_SIZE);
}

THE END