/** @file   display.c
    @author M. P. Hayes, UCECE
    @date   23 August 2010
    @brief  Bit-mapped display driver.
*/
#include "system.h"
#include "ledmat.h"
#include "display.h"

/** The state of the display (frame buffer).  */
static uint8_t display[DISPLAY_WIDTH];


/** Set state of a display pixel.
    @param col pixel column
    @param row pixel row
    @param val pixel state.  */
void display_pixel_set (uint8_t col, uint8_t row, bool val)
{
    uint8_t bitmask;
    uint8_t pattern;

    if (col >= DISPLAY_WIDTH || row >= DISPLAY_HEIGHT)
        return;

    bitmask = BIT (row);
    pattern = display[col] & ~bitmask;

    if (val)
        pattern |= bitmask;

    display[col] = pattern;
}


/** Get state of a display pixel.
    @param col pixel column
    @param row pixel row
    @return pixel state or zero if outside display.  */
bool display_pixel_get (uint8_t col, uint8_t row)
{
    uint8_t bitmask;

    if (col >= DISPLAY_WIDTH || row >= DISPLAY_HEIGHT)
        return 0;

    bitmask = BIT (row);

    return (display[col] & bitmask) != 0;
}


/** Update display (perform refreshing).  */
void display_update (void)
{
    static uint8_t col = 0;

    ledmat_display_column (display[col], col);
    
    col++;
    if (col >= DISPLAY_WIDTH)
        col = 0;
}


/** Clear display.   */
void display_clear (void)
{
    int col;

    for (col = 0; col < DISPLAY_WIDTH; col++)
        display[col] = 0;
}


/** Initialise display.   */
void display_init (void)
{
    ledmat_init ();
    display_clear ();
}