Lab 4 for Computer and Graphics Architecture

gistfile1.c

//================
//    HEADERS
//================
#include <stdint.h>
#include "gba.h"
#include <stdlib.h>
#include <time.h>

//================
//   CONSTANTS
//================

#define BG2_ENABLE		0x400	 
#define MODE3			0x3
#define FRONTBUFFER		(u16*)0x6000000

#define RGB(r,g,b) ((b<<10)+(g<<5)+r) //u16 --> unsigned short, this is macro for RGB() 15bit color format
#define ScreenWidth 240
#define ScreenHeight 160

//================
//    GLOBALS
//================
u16* g_uspVideoBuffer	= FRONTBUFFER; //This is were we are currently drawing 

//================
//   FUNCTIONS
//================

//================
//   Function: PlotPixel16(int, int, unsigned short int)
//      Notes: Plots a pixel in the specified colour
//		 Date: 14/2/2002
//================
void PlotPixel16(int in_iX,int in_iY, unsigned short int in_usColour) 
{
	g_uspVideoBuffer[(in_iY) * ScreenWidth + (in_iX)] = (in_usColour);
}


//================
//   Function: main()
//      Notes: Main entry point into rom
//		 Date: 14/2/2002
//================
int main()
{

	//REG_DISPCNT (defined in gba.h) is the main display register that controls
	//the mode of operation which backgrounds are enabled and which buffer is
	//currently being drawn by the GPU.
	//this sets the screen mode to mode three and enables background 2
	//background 2 is required for all bitmap modes(3-5)
	REG_DISPCNT = MODE3 | BG2_ENABLE;
	
	srand(time(NULL));
	
	unsigned short red  = RGB(31,0,0);
	unsigned short green= RGB(0,31,0);
	unsigned short blue = RGB(0,0,31);
	unsigned short white= RGB(31,31,31);
	unsigned short black= RGB(0,0,0);
	
	// Assign new variables to make colors move around
	int old_xred, old_xgreen, old_xblue, old_xwhite, old_yred, old_ygreen, old_yblue, old_ywhite;
	int xred=110, xgreen=130, xblue=110, xwhite=130, yred=70, ygreen=70, yblue=90, ywhite=90;
	
	//Draw Original and New Pixels.
	PlotPixel16(xred,yred,red);
	PlotPixel16(xgreen,ygreen,green);
	PlotPixel16(xblue,yblue,blue);
	PlotPixel16(xwhite,ywhite,white);
	
	while(1){

	//Save old coordinates
	old_xred=xred;
	old_xgreen=xgreen;
	old_xblue=xblue;
	old_xwhite=xwhite;
	old_yred=yred;
	old_ygreen=ygreen;
	old_yblue=yblue;
	old_ywhite=ywhite;
	
	//Erase old pixels
	PlotPixel16(old_xred,old_yred,black);
	PlotPixel16(old_xgreen,old_ygreen,black);
	PlotPixel16(old_xblue,old_yblue,black);
	PlotPixel16(old_xwhite,old_ywhite,black);
	
	//Come up with new coordinates for the new pixels
	xred=rand()%ScreenWidth;
	xgreen=rand()%ScreenWidth;
	xblue=rand()%ScreenWidth;
	xwhite=rand()%ScreenWidth;
	yred=rand()%ScreenHeight;
	ygreen=rand()%ScreenHeight;
	yblue=rand()%ScreenHeight;
	ywhite=rand()%ScreenHeight;
	
	//Draw new pixels
	for (int i=0; i<=350; i=i+1) {
	PlotPixel16(xred,yred,red);
	PlotPixel16(xgreen,ygreen,green);
	PlotPixel16(xblue,yblue,blue);
	PlotPixel16(xwhite,ywhite,white);
	}
	
	//No WaitVSync in this lab's gba.h apparently so delay is a bit more crude for now.
	
	}

	return 0;

}