Display driver for Sharp's range of SPI-driven memory LCD's, leveraging the power of asynchronous transfers. Currently supports LS013B7DH03, but easily extendable to other models as well.

Dependents:   memLCD-Demo memLCD-Demo memLCD-Demo MemLCD-Temperature-Humidity-Demo ... more

Information

All examples in this repo are considered EXPERIMENTAL QUALITY, meaning this code has been created as one-off proof-of-concept and is suitable as a demonstration for experimental purposes only. This code will not be regularly maintained by Silicon Labs and there is no guarantee that these projects will work across all environments, SDK versions and hardware.

Memory LCD extension board

Caution

This library builds upon the asynchronous SPI interface provided by mbed, but not all platforms currently support this. So, make sure your platform is capable of asynchronous SPI (all Silicon Labs platforms are), otherwise you will get compiler errors!

Usage

The library is purposefully quite simple to use. To set it up, you initialize an SPI object and the required I/O pins, and call the library constructor with those. Make sure the display is powered on, enabled, and the inversion mode is set to external (EXTMODE is high).

setup

#define SCK     PD2
#define MOSI 	PD0

DigitalOut CS(PD3);
DigitalOut EXTCOM(PC4);

SPI displaySPI(MOSI, NC, SCK);
silabs::LS013B7DH03 display(&displaySPI, &CS, &EXTCOM);

You should also swap out the pin names for the relevant names on your platform.

After setup, you usually want to clear any static information left on the screen. To do that, you would call clearImmediate, and optionally provide a callback. The callback will get called when the clearing operation is complete and the display has been cleared. In this example, refreshCallback sets a global boolean 'refreshed' to true when called.

clearing the display

refreshed = false;
int result = display.clearImmediate(refreshCallback);
if(result == LS013B7DH03_OK) {
    while(refreshed == false) sleep();
} else {
    printf("Display error: %d", result);
}

Of course, instead of sleeping while the display is clearing, you could also just continue with the program, and check back whether the callback happened or not.

Then comes the fun part, actually writing stuff on the display! Since the display only supports one-way communication (i.e. you cannot read from it), it uses an internal frame buffer in RAM. So, to actually display something on the LCD, two steps need to happen: writing to the pixel buffer, and at the very end writing the pixel buffer to the LCD.

Pixelbuffer operations

The MemoryLCD library builds upon Simon Ford's TextDisplay library, which means you can use all of that functionality. Even printf is supported!

most important display operations

// Set one pixel at x=10, y=40 to the color White
display.pixel(10,40,White); 

// print "I love mbed" at the character position x=4, y=5
// i.e. starting on row 5, 4 characters from the left border
display.locate(4,5);
display.printf("I love mbed!");

// show a bitmap at a given location
// Constraints: bitmap is 8-bit, MSB first, 1 bit per pixel. Width, height and starting coordinates must be divisible by 8.
// This example: show a bitmap which is 128 pixels wide and high, and start at location 0,0.
display.showBMP(&mbed_logo, 128, 128, 0, 0);

//Draw a line (really a 1px wide rectangle) from (4,10) until (4,15)
display.fill(4, 10, 1, 5, White);

Updating the LCD

Updating the LCD (i.e. moving the framebuffer to the display) happens much the same way as clearing it: asynchronously. To start the update, you call update() on the display, optionally providing a callback to be called after the whole update has happened. In the example below, refreshCallback sets a global boolean 'refreshed' to true when called. Signature: void refreshCallback(void);

updating the display

refreshed = false;
int result = display.update(refreshCallback);
if(result == LS013B7DH03_OK) {
    while(refreshed == false) sleep();
} else {
    printf("Display error: %d", result);
}

Full example

example program

#include "LS013B7DH03.h"
#include "mbed_logo.h"
/******************** Define I/O *****************************/
DigitalOut myled(LED1);

#define SCK     PD2
#define MOSI 	PD0

DigitalOut CS(PD3);
DigitalOut EXTCOM(PC4);
DigitalOut EXTMODE(PD4);
DigitalOut DISP(PD5);

SPI displaySPI(MOSI, NC, SCK);
silabs::LS013B7DH03 display(&displaySPI, &CS, &EXTCOM);

/******************** Define Timers *****************************/

LowPowerTicker timeKeeping;

/***************** Define global variables **********************/
#define INIT_SECONDS		17600

volatile uint32_t prevSeconds = INIT_SECONDS, seconds = INIT_SECONDS;
volatile bool refreshed = false;

/***************** Define callback handlers *********************/
void secondsCallback(void);
void refreshCallback(void);

void secondsCallback(void) {
	seconds++;
}

/**
 * Callback for refresh completion
 */
void refreshCallback(void) {
	refreshed = true;
}

/*************************** MAIN *******************************/
int main() {
    // Enable the LCD
	EXTMODE = 1;
	DISP = 1;

	// Start generating the 1Hz call for keeping time
	timeKeeping.attach(&secondsCallback, 1.0f);

	// Reset the LCD to a blank state. (All white)
	refreshed = false;
	display.clearImmediate(refreshCallback);
	while(refreshed == false) sleep();

	printf("Initialization done! \n");

	// Apply mbed logo bitmap to the pixel buffer
	display.showBMP((uint8_t*)mbed_enabled_logo, 128, 128, 0, 0);
	display.printf("I like MBED!");

	// Push update to the display
	refreshed = false;
	display.update(refreshCallback);

	// Sleep while doing the transmit
	while(refreshed == false) sleep();

	// Go into clock mode
	while(1) {
		sleep();

		// In clock mode, only update once per second
		if(prevSeconds != seconds) {
			display.locate(4,15);
			display.printf("%02d:%02d:%02d", (seconds / 1200) % 24, (seconds / 60) % 60, seconds % 60);
			if(refreshed == true) {
				prevSeconds = seconds;
				refreshed = false;
				display.update(refreshCallback);
			}
		}
	}
}

Datasheet

Datasheet for the LCD (hosted by Mouser)

GraphicsDisplay.cpp

Committer:
stevew817
Date:
2015-08-12
Revision:
11:0f8ae10b308d
Parent:
5:26851f9655cf

File content as of revision 11:0f8ae10b308d:

/* mbed GraphicsDisplay Display Library Base Class
 * Copyright (c) 2007-2009 sford
 * Released under the MIT License: http://mbed.org/license/mit
 */
 
#include "GraphicsDisplay.h"

#define incx() x++, dxt += d2xt, t += dxt
#define incy() y--, dyt += d2yt, t += dyt

const unsigned char FONT8x8[97][8] = {
{0x08,0x08,0x08,0x00,0x00,0x00,0x00,0x00}, // columns, rows, num_bytes_per_char
{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}, // space 0x20
{0x30,0x78,0x78,0x30,0x30,0x00,0x30,0x00}, // !
{0x6C,0x6C,0x6C,0x00,0x00,0x00,0x00,0x00}, // "
{0x6C,0x6C,0xFE,0x6C,0xFE,0x6C,0x6C,0x00}, // #
{0x18,0x3E,0x60,0x3C,0x06,0x7C,0x18,0x00}, // $
{0x00,0x63,0x66,0x0C,0x18,0x33,0x63,0x00}, // %
{0x1C,0x36,0x1C,0x3B,0x6E,0x66,0x3B,0x00}, // &
{0x30,0x30,0x60,0x00,0x00,0x00,0x00,0x00}, // '
{0x0C,0x18,0x30,0x30,0x30,0x18,0x0C,0x00}, // (
{0x30,0x18,0x0C,0x0C,0x0C,0x18,0x30,0x00}, // )
{0x00,0x66,0x3C,0xFF,0x3C,0x66,0x00,0x00}, // *
{0x00,0x30,0x30,0xFC,0x30,0x30,0x00,0x00}, // +
{0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x30}, // ,
{0x00,0x00,0x00,0x7E,0x00,0x00,0x00,0x00}, // -
{0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x00}, // .
{0x03,0x06,0x0C,0x18,0x30,0x60,0x40,0x00}, // / (forward slash)
{0x3E,0x63,0x63,0x6B,0x63,0x63,0x3E,0x00}, // 0 0x30
{0x18,0x38,0x58,0x18,0x18,0x18,0x7E,0x00}, // 1
{0x3C,0x66,0x06,0x1C,0x30,0x66,0x7E,0x00}, // 2
{0x3C,0x66,0x06,0x1C,0x06,0x66,0x3C,0x00}, // 3
{0x0E,0x1E,0x36,0x66,0x7F,0x06,0x0F,0x00}, // 4
{0x7E,0x60,0x7C,0x06,0x06,0x66,0x3C,0x00}, // 5
{0x1C,0x30,0x60,0x7C,0x66,0x66,0x3C,0x00}, // 6
{0x7E,0x66,0x06,0x0C,0x18,0x18,0x18,0x00}, // 7
{0x3C,0x66,0x66,0x3C,0x66,0x66,0x3C,0x00}, // 8
{0x3C,0x66,0x66,0x3E,0x06,0x0C,0x38,0x00}, // 9
{0x00,0x18,0x18,0x00,0x00,0x18,0x18,0x00}, // :
{0x00,0x18,0x18,0x00,0x00,0x18,0x18,0x30}, // ;
{0x0C,0x18,0x30,0x60,0x30,0x18,0x0C,0x00}, // <
{0x00,0x00,0x7E,0x00,0x00,0x7E,0x00,0x00}, // =
{0x30,0x18,0x0C,0x06,0x0C,0x18,0x30,0x00}, // >
{0x3C,0x66,0x06,0x0C,0x18,0x00,0x18,0x00}, // ?
{0x3E,0x63,0x6F,0x69,0x6F,0x60,0x3E,0x00}, // @ 0x40
{0x18,0x3C,0x66,0x66,0x7E,0x66,0x66,0x00}, // A
{0x7E,0x33,0x33,0x3E,0x33,0x33,0x7E,0x00}, // B
{0x1E,0x33,0x60,0x60,0x60,0x33,0x1E,0x00}, // C
{0x7C,0x36,0x33,0x33,0x33,0x36,0x7C,0x00}, // D
{0x7F,0x31,0x34,0x3C,0x34,0x31,0x7F,0x00}, // E
{0x7F,0x31,0x34,0x3C,0x34,0x30,0x78,0x00}, // F
{0x1E,0x33,0x60,0x60,0x67,0x33,0x1F,0x00}, // G
{0x66,0x66,0x66,0x7E,0x66,0x66,0x66,0x00}, // H
{0x3C,0x18,0x18,0x18,0x18,0x18,0x3C,0x00}, // I
{0x0F,0x06,0x06,0x06,0x66,0x66,0x3C,0x00}, // J
{0x73,0x33,0x36,0x3C,0x36,0x33,0x73,0x00}, // K
{0x78,0x30,0x30,0x30,0x31,0x33,0x7F,0x00}, // L
{0x63,0x77,0x7F,0x7F,0x6B,0x63,0x63,0x00}, // M
{0x63,0x73,0x7B,0x6F,0x67,0x63,0x63,0x00}, // N
{0x3E,0x63,0x63,0x63,0x63,0x63,0x3E,0x00}, // O
{0x7E,0x33,0x33,0x3E,0x30,0x30,0x78,0x00}, // P 0x50
{0x3C,0x66,0x66,0x66,0x6E,0x3C,0x0E,0x00}, // Q
{0x7E,0x33,0x33,0x3E,0x36,0x33,0x73,0x00}, // R
{0x3C,0x66,0x30,0x18,0x0C,0x66,0x3C,0x00}, // S
{0x7E,0x5A,0x18,0x18,0x18,0x18,0x3C,0x00}, // T
{0x66,0x66,0x66,0x66,0x66,0x66,0x7E,0x00}, // U
{0x66,0x66,0x66,0x66,0x66,0x3C,0x18,0x00}, // V
{0x63,0x63,0x63,0x6B,0x7F,0x77,0x63,0x00}, // W
{0x63,0x63,0x36,0x1C,0x1C,0x36,0x63,0x00}, // X
{0x66,0x66,0x66,0x3C,0x18,0x18,0x3C,0x00}, // Y
{0x7F,0x63,0x46,0x0C,0x19,0x33,0x7F,0x00}, // Z
{0x3C,0x30,0x30,0x30,0x30,0x30,0x3C,0x00}, // [
{0x60,0x30,0x18,0x0C,0x06,0x03,0x01,0x00}, // \ (back slash)
{0x3C,0x0C,0x0C,0x0C,0x0C,0x0C,0x3C,0x00}, // ]
{0x08,0x1C,0x36,0x63,0x00,0x00,0x00,0x00}, // ^
{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF}, // _
{0x18,0x18,0x0C,0x00,0x00,0x00,0x00,0x00}, // ` 0x60
{0x00,0x00,0x3C,0x06,0x3E,0x66,0x3B,0x00}, // a
{0x70,0x30,0x3E,0x33,0x33,0x33,0x6E,0x00}, // b
{0x00,0x00,0x3C,0x66,0x60,0x66,0x3C,0x00}, // c
{0x0E,0x06,0x3E,0x66,0x66,0x66,0x3B,0x00}, // d
{0x00,0x00,0x3C,0x66,0x7E,0x60,0x3C,0x00}, // e
{0x1C,0x36,0x30,0x78,0x30,0x30,0x78,0x00}, // f
{0x00,0x00,0x3B,0x66,0x66,0x3E,0x06,0x7C}, // g
{0x70,0x30,0x36,0x3B,0x33,0x33,0x73,0x00}, // h
{0x18,0x00,0x38,0x18,0x18,0x18,0x3C,0x00}, // i
{0x06,0x00,0x06,0x06,0x06,0x66,0x66,0x3C}, // j
{0x70,0x30,0x33,0x36,0x3C,0x36,0x73,0x00}, // k
{0x38,0x18,0x18,0x18,0x18,0x18,0x3C,0x00}, // l
{0x00,0x00,0x66,0x7F,0x7F,0x6B,0x63,0x00}, // m
{0x00,0x00,0x7C,0x66,0x66,0x66,0x66,0x00}, // n
{0x00,0x00,0x3C,0x66,0x66,0x66,0x3C,0x00}, // o
{0x00,0x00,0x6E,0x33,0x33,0x3E,0x30,0x78}, // p
{0x00,0x00,0x3B,0x66,0x66,0x3E,0x06,0x0F}, // q
{0x00,0x00,0x6E,0x3B,0x33,0x30,0x78,0x00}, // r
{0x00,0x00,0x3E,0x60,0x3C,0x06,0x7C,0x00}, // s
{0x08,0x18,0x3E,0x18,0x18,0x1A,0x0C,0x00}, // t
{0x00,0x00,0x66,0x66,0x66,0x66,0x3B,0x00}, // u
{0x00,0x00,0x66,0x66,0x66,0x3C,0x18,0x00}, // v
{0x00,0x00,0x63,0x6B,0x7F,0x7F,0x36,0x00}, // w
{0x00,0x00,0x63,0x36,0x1C,0x36,0x63,0x00}, // x
{0x00,0x00,0x66,0x66,0x66,0x3E,0x06,0x7C}, // y
{0x00,0x00,0x7E,0x4C,0x18,0x32,0x7E,0x00}, // z
{0x0E,0x18,0x18,0x70,0x18,0x18,0x0E,0x00}, // {
{0x0C,0x0C,0x0C,0x00,0x0C,0x0C,0x0C,0x00}, // |
{0x70,0x18,0x18,0x0E,0x18,0x18,0x70,0x00}, // }
{0x3B,0x6E,0x00,0x00,0x00,0x00,0x00,0x00}, // ~
{0x1C,0x36,0x36,0x1C,0x00,0x00,0x00,0x00}}; // DEL
    
GraphicsDisplay::GraphicsDisplay(const char *name):TextDisplay(name) {
    foreground((uint16_t)Black);
    background((uint16_t)White);
    // current pixel location
	_x = 0;
	_y = 0;
	// window settings
	_x1 = 0;
	_x2 = 0;
	_y1 = 0;
	_y2 = 0;
}
    
void GraphicsDisplay::character(int column, int row, int value) { 
    if(externalfont){ // send external font
        unsigned int hor,vert,offset,bpl,j,i,b;
        const unsigned char* sign;
        unsigned char z,w;
        if ((value < 31) || (value > 127)) return;   // test char range
        // read font parameter from start of array
        offset = font[0];                    // bytes / char
        hor = font[1];                       // get hor size of font
        vert = font[2];                      // get vert size of font
        bpl = font[3];                       // bytes per line
        if (char_x + hor > width()) {
            char_x = 0;
            char_y = char_y + vert;
            if (char_y >= height() - font[2]) {
                char_y = 0;
            }
        }     
        window(char_x, char_y,hor,vert); // char box
        sign = &font[((value -32) * offset) + 4]; // start of char bitmap
        w = sign[0];                          // width of actual char
        for (j=0; j<vert; j++) {  //  vert line
            for (i=0; i<hor; i++) {   //  horz line
                z =  sign[bpl * i + ((j & 0xF8) >> 3)+1];
                b = 1 << (j & 0x07);
                if (( z & b ) == 0x00) {               
                    putp(_foreground);              
                } 
                else {                     
                    putp(_background);                                
                }
            }
        }
        if ((w + 2) < hor) {                   // x offset to next char
            char_x += w + 2;
            }
            else char_x += hor;
    }   
    // send default font            
    else {
        blitbit(column * 8, row * 8, 8, 8, (char*)&(FONT8x8[value - 0x1F][0]));
    }
}

void GraphicsDisplay::window(int x, int y, int w, int h) {
    // current pixel location
    _x = x;
    _y = y;
    // window settings
    _x1 = x;
    _x2 = x + w - 1;
    _y1 = y;
    _y2 = y + h - 1;
}
    
void GraphicsDisplay::putp(int colour) {
    // put pixel at current pixel location
    pixel(_x, _y, colour);
    // update pixel location based on window settings
    _x++;
    if(_x > _x2) {
        _x = _x1;
        _y++;
        if(_y > _y2) {
            _y = _y1;
        }
    }
}

void GraphicsDisplay::rect(int x0, int y0, int x1, int y1, int color) {
    if (x1 > x0) hline(x0,x1,y0,color);
    else  hline(x1,x0,y0,color);
    if (y1 > y0) vline(x0,y0,y1,color);
    else vline(x0,y1,y0,color);
    if (x1 > x0) hline(x0,x1,y1,color);
    else  hline(x1,x0,y1,color);
    if (y1 > y0) vline(x1,y0,y1,color);
    else vline(x1,y1,y0,color);
    return;
}
 
void GraphicsDisplay::fillrect(int x0, int y0, int w, int h, int colour) {
    unsigned long int index=0;
    if (w < 0) {
        x0 = x0 + w;
        w = -w;
    }
    if (h < 0) {
        y0 = y0 + h;
        h = -h;
    }
    window(x0,y0,w,h);
    int num = h*w;
    for( index = 0; index<num; index++ ) {
       putp(colour); 
    }
    return;
}

void GraphicsDisplay::fill(int x, int y, int w, int h, int colour) { 
    fillrect(x, y, w, h, colour);
}

void GraphicsDisplay::circle(int x, int y, int r,int colour){
	int ce = -r;
	int cx = r;
	int cy = 0;
	while(cx >= cy){
		pixel(x+cx,y+cy,colour);
		pixel(x-cx,y-cy,colour);
		pixel(x-cx,y+cy,colour);
		pixel(x+cx,y-cy,colour);
		pixel(x+cy,y+cx,colour);
		pixel(x-cy,y+cx,colour);
		pixel(x-cy,y-cx,colour);
		pixel(x+cy,y-cx,colour);
		ce += 2*cy++ + 1;
		if(ce >= 0){
			ce -= 2*cx---1;	
		}
		
	}

}

// To draw circle set a and b to the same values
void GraphicsDisplay::ellipse(int xc, int yc, int a, int b, unsigned int colour)
{
    /* e(x,y) = b^2*x^2 + a^2*y^2 - a^2*b^2 */
    int x = 0, y = b;
    long a2 = (long)a*a, b2 = (long)b*b;
    long crit1 = -(a2/4 + a%2 + b2);
    long crit2 = -(b2/4 + b%2 + a2);
    long crit3 = -(b2/4 + b%2);
    long t = -a2*y;                         // e(x+1/2,y-1/2) - (a^2+b^2)/4
    long dxt = 2*b2*x, dyt = -2*a2*y;
    long d2xt = 2*b2, d2yt = 2*a2;
 
    while (y>=0 && x<=a) {
        pixel(xc+x, yc+y, colour);
        if (x!=0 || y!=0)
            pixel(xc-x, yc-y, colour);
        if (x!=0 && y!=0) {
            pixel(xc+x, yc-y, colour);
            pixel(xc-x, yc+y, colour);
        }
        if (t + b2*x <= crit1 ||            // e(x+1,y-1/2) <= 0
                t + a2*y <= crit3)          // e(x+1/2,y) <= 0
            incx();
        else if (t - a2*y > crit2)          // e(x+1/2,y-1) > 0
            incy();
        else {
            incx();
            incy();
        }
    }
}
// To draw circle set a and b to the same values
void GraphicsDisplay::fillellipse(int xc, int yc, int a, int b, unsigned int colour)
{
    /* e(x,y) = b^2*x^2 + a^2*y^2 - a^2*b^2 */
    int x = 0, y = b;
    int rx = x, ry = y;
    unsigned int width = 1;
    unsigned int height = 1;
    long a2 = (long)a*a, b2 = (long)b*b;
    long crit1 = -(a2/4 + a%2 + b2);
    long crit2 = -(b2/4 + b%2 + a2);
    long crit3 = -(b2/4 + b%2);
    long t = -a2*y;                         // e(x+1/2,y-1/2) - (a^2+b^2)/4
    long dxt = 2*b2*x, dyt = -2*a2*y;
    long d2xt = 2*b2, d2yt = 2*a2;
    if (b == 0) {
        fillrect(xc-a, yc, 2*a+1, 1, colour);
        return;
    }
    while (y>=0 && x<=a) {
        if (t + b2*x <= crit1 ||            // e(x+1,y-1/2) <= 0
                t + a2*y <= crit3) {        // e(x+1/2,y) <= 0
            if (height == 1)
                ;                           // draw nothing
            else if (ry*2+1 > (height-1)*2) {
                fillrect(xc-rx, yc-ry, width, height-1, colour);
                fillrect(xc-rx, yc+ry+1, width, 1-height, colour);
                ry -= height-1;
                height = 1;
            } else {
                fillrect(xc-rx, yc-ry, width, ry*2+1, colour);
                ry -= ry;
                height = 1;
            }
            incx();
            rx++;
            width += 2;
        } else if (t - a2*y > crit2) {      // e(x+1/2,y-1) > 0
            incy();
            height++;
        } else {
            if (ry*2+1 > height*2) {
                fillrect(xc-rx, yc-ry, width, height, colour);
                fillrect(xc-rx, yc+ry+1, width, -height, colour);
            } else {
                fillrect(xc-rx, yc-ry, width, ry*2+1, colour);
            }
            incx();
            incy();
            rx++;
            width += 2;
            ry -= height;
            height = 1;
        }
    }
    if (ry > height) {
        fillrect(xc-rx, yc-ry, width, height, colour);
        fillrect(xc-rx, yc+ry+1, width, -height, colour);
    } else {
        fillrect(xc-rx, yc-ry, width, ry*2+1, colour);
    }
}
 
 
void GraphicsDisplay::line(int x0, int y0, int x1, int y1, int colour) {
    //window(x0, y, w, h);
    int   dx = 0, dy = 0;
    int   dx_sym = 0, dy_sym = 0;
    int   dx_x2 = 0, dy_x2 = 0;
    int   di = 0;
    dx = x1-x0;
    dy = y1-y0;
 
    if (dx == 0) {        /* vertical line */
        if (y1 > y0) vline(x0,y0,y1,colour);
        else vline(x0,y1,y0,colour);
        return;
    }
    if (dx > 0) {
        dx_sym = 1;
    } else {
        dx_sym = -1;
    }
    if (dy == 0) {        /* horizontal line */
        if (x1 > x0) hline(x0,x1,y0,colour);
        else  hline(x1,x0,y0,colour);
        return;
    }
    if (dy > 0) {
        dy_sym = 1;
    } else {
        dy_sym = -1;
    }
    dx = dx_sym*dx;
    dy = dy_sym*dy;
    dx_x2 = dx*2;
    dy_x2 = dy*2;
    if (dx >= dy) {
        di = dy_x2 - dx;
        while (x0 != x1) {
 
            pixel(x0, y0, colour);
            x0 += dx_sym;
            if (di<0) {
                di += dy_x2;
            } else {
                di += dy_x2 - dx_x2;
                y0 += dy_sym;
            }
        }
        pixel(x0, y0, colour);
    } else {
        di = dx_x2 - dy;
        while (y0 != y1) {
            pixel(x0, y0, colour);
            y0 += dy_sym;
            if (di < 0) {
                di += dx_x2;
            } else {
                di += dx_x2 - dy_x2;
                x0 += dx_sym;
            }
        }
        pixel(x0, y0, colour);
    }
    return;
}
 
void GraphicsDisplay::hline(int x0, int x1, int y, int colour) {
    int w;
    w = x1 - x0 + 1;
    window(x0,y,w,1);
    for (int x=0; x<w; x++) {
        putp(colour);
    }
    return;
}
 
void GraphicsDisplay::vline(int x, int y0, int y1, int colour) {
    int h;
    h = y1 - y0 + 1;
    window(x,y0,1,h);
    for (int y=0; y<h; y++) {
        putp(colour);
    }
    return;
}

void GraphicsDisplay::cls() {
    fill(0, 0, width(), height(), _background);
}
    
void GraphicsDisplay::blit(int x, int y, int w, int h, const int *colour) { 
    window(x, y, w, h);
    for(int i=0; i<w*h; i++) {
        putp(colour[i]);
    }
}
    
void GraphicsDisplay::blitbit(int x, int y, int w, int h, const char* colour) {
    window(x, y, w, h);
    for(int i = 0; i < w*h; i++) {
        char byte = colour[i >> 3];
        int offset = i & 0x7;
        int c = ((byte << (offset)) & 0x80) ? _foreground : _background;
        putp(c);
    }
}
    
int GraphicsDisplay::columns() { 
    return width() / 8; 
}

int GraphicsDisplay::rows() { 
    return height() / 8; 
}