问如何使用PIC18编写和读取内存？

EN

#define PRGM_BUFFER_SIZE 8
#define TABLE_WRITE_SIZE 64

#define LOAD_TBL_PTR(x) { TBLPTRU = ((((x)>>8)>>8)&0xff);\
                      TBLPTRH = (((x) >> 8) & 0xff);\
                      TBLPTRL = ((x) & 0xff);\
                    }

/******************************************************
 * Function     : write_block
 * Input        : uint16_t position in destination flash
 * Global       : uint8_t buffer[64] - Location of source data
 * Output       : None
 * Description  : Writes the contents of the 64 byte
 * data buffer to program flash space.  Only 64 bytes
 * can be written at once.   The process of writing
 * to flash is: Erase->Write.
 ******************************************************/
static void write_block(uint16_t addr)
{
    int r, c;

    // Erase flash block first.  Erases a 64 byte block at a time.

    LOAD_TBL_PTR(addr);

    EECON1bits.EEPGD = 1;   // Point to flash program memory
    EECON1bits.CFGS = 0;    // Access flash memory
    EECON1bits.WREN = 1;    // Enable write to memory
    EECON1bits.FREE = 1;    // Enable Erase operation

    EECON2 = 0x55;
    EECON2 = 0xAA;

    EECON1bits.WR = 1;      // Clear the flash

    asm("NOP");             // Stall

    // Write buffer to internal buffer.  This process writes 8 bytes at a time
    // so we need to loop 8 times (8*8 = 64).)

    for (r = 0; r < 8; r++)
    {
        LOAD_TBL_PTR((addr + (r * 8)));

        for (c = 0; c < PRGM_BUFFER_SIZE; c++)
        {
            TABLAT = buffer[(r * 8) + c];

            asm("TBLWT*+");      // Push byte and then inc to next internal buffer cell
        }

        // Write the block to flash

        asm("TBLRD*-");         // Point back to original row

        // Write internal buffer to flash

        EECON1bits.EEPGD = 1;   // Point to flash program memory
        EECON1bits.CFGS = 0;    // Access flash program memory
        EECON1bits.WREN = 1;    // Enable write to memory
        INTCONbits.GIE = 0;     // Disable interrupts

        EECON2 = 0x55;
        EECON2 = 0xAA;

        EECON1bits.WR = 1;      // Start programming flash
        INTCONbits.GIE = 1;     // Re-enable interrupts
        EECON1bits.WREN = 0;    // Disable write to memory
    }
}

/******************************************************
 * Function     : compare_block
 * Input        : uint16_t position in destination flash
 * Global       : uint8_t buffer[64] - Location of previous written data
 * Output       : bool true=successful, false=did not match
 * Description  : Reads a 64 byte block of flash memory and
 * compares it to the data found in the global buffer.
 ******************************************************/
static bool compare_block(uint16_t addr)
{
    bool retVal = true; // succeeds
    uint8_t i = 0;

    INTCONbits.GIE = 0;     // Disable interrupts

    LOAD_TBL_PTR(addr);

    for (i = 0; i < TABLE_WRITE_SIZE && retVal == true; i++)
    {
        asm("TBLRD*+");

        if (buffer[i] != TABLAT)
            retVal = false;
    }

    INTCONbits.GIE = 1;     // Enable interrupts

    return retVal;
}

void my_assembler_function(void)
{
    // Inline assembler code, actioned via C.
    asm("MOV x y");
    asm("MOV y z");
}