//This test program shows how to use flash
//and uses the procedure 'write_flash' and
// the function 'write_flash' 
//The flash from 0 to FLASH_SIZE is filled and tested
//by numbers. By the end the blinkind of the LED
//connected to B7 indicates success and blinking
//of all LEDs connected to B0-B7 indicates failure

program flash;
var i, a, err: char;

const FLASH_SIZE = 64;

//the memory bank 0 should be selected
procedure write_flash( addr, data: char );
begin
    //Write flash
    EEADR := addr;
    EEDATA := data;

    set_bit( STATUS, 'RP0' );
    set_bit( EECON1, 'WREN' );
    EECON2 := 0x55;
    EECON2 := 0xAA;
    set_bit( EECON1, 'WR' );
    while EECON1&2 do nop;
    clear_bit( EECON1, 'WREN' );

    clear_bit( STATUS, 'RP0' );
end;

function read_flash( addr: char ): char;
begin
    //Read flash
    EEADR := addr;
    set_bit( STATUS, 'RP0' );
    set_bit( EECON1, 'RD' );
    clear_bit( STATUS, 'RP0' );
    asm movf EEDATA, W
end;


//a short delay
procedure delay;
var i, j: char;
begin
    i := 0;
    while i < 250 do
    begin
        i := i + 1;
        j := 0;
        while j < 200 do
            j := j + 1;
    end;
end;

begin
    err := 0;

    disable_interrupt( 'GIE' );
    set_bit( STATUS, 'RP0' );
    set_tris_b( 0 );
    clear_bit( STATUS, 'RP0' );
    output_port_b( 0 );

    for i := 0 to FLASH_SIZE-1 do
    begin
        write_flash( i, i*2 );
        a := read_flash( i );
        if a <> i*2 then
            err := 1;
    end;

    while 1  do
    begin
        if err then
        begin
            output_port_b( 0 );
            delay;
            output_port_b( 255 );
        end;
        else
        begin
            output_high_port_b( 7 );
            delay;
            output_low_port_b( 7 );
        end;
        delay;
    end;
end.