/* display.c
 * Author: Dan Burke
 * CSC 494 Project - An Interactive Internet LCD Display
 * compile with gcc -o display display.c
 * Give the compiled program "display" execute permissions and place it 
 * in the root directory of the user that will be running jakarta.
 * The program reads it's input from a text file called
 * "displayinput" that contains exactly 32 ascii characters to write to
 * the display.
 */
#include <stdio.h>
#include <asm/types.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <linux/module.h>
#include <linux/param.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <unistd.h>

#define LP_BASE 0x378
#define DATA LP_BASE+0
#define CONTROL LP_BASE+2


int main(int argc, char *argv[]){

	int y;
	
	/* The data to write to the display */
	FILE *inputfile = fopen("displayinput", "r");
	
	char ch;
	char space = ' ';
	
	/* Reserve space in i/o for the parallel port */
	if (ioperm(LP_BASE, 3, 1) < 0){
		fprintf(stderr, "Cannot reserve i/o space\n");
	}

	/* Change the display to instruction mode */
	outb(0x09, CONTROL);
	
	/* Write 15 to the display, the instruction to turn on the cursor */
	outb(0x0f, DATA);
	usleep(20);

	/* Now alternate to the read/write enable to write the instruction to
	 * the display
	 */
	outb(0x08, CONTROL);
	usleep(20);
	outb(0x09, CONTROL);
	
	/* Change the instruction to clear the display */
	outb(0x01, DATA);

	/* Ensure the display is in instruction mode */
	outb(0x09, CONTROL);
	usleep(20);

	/* Now alternate the read/write enable to write the instruction to 
	 * the display 
	 */
	outb(0x08, CONTROL);
	usleep(20);
	outb(0x09, CONTROL);

	/* Change the instruction to set the display to 2 line mode */
	outb(0x38, DATA);
	outb(0x09, CONTROL);
	usleep(20);

	/* Alternate the read/write enable to write the instruction */
	outb(0x08, CONTROL);
	usleep(20);
	outb(0x09, CONTROL);	
	
	/* Read the first 16 characters and write them to the display. */
	ch = getc(inputfile);
	for(y = 0; y < 16; y++){
		outb(ch, DATA);
		outb(0x00, CONTROL);
		usleep(2);
		outb(0x01, CONTROL);
		usleep(2);
		ch = getc(inputfile);
		if (ch == -1)
			break;
	}
	if (ch == -1){
		exit(0);
	}

	/* Since the display buffer for each line is 40 characters,
	 * write a space character to characters 17-40 to move to line
	 * 2.
	 */
	for(y = 16; y < 40; y++){
		outb(space, DATA);
		outb(0x00, CONTROL);
		usleep(2);
		outb(0x01, CONTROL);
		usleep(2);
	}

	/* Now read characters 17-32 from the file and write them to
	 * line 2 of the display.
	 */
	for (y = 0; y < 16; y++){
		outb(ch, DATA);
		outb(0x00, CONTROL);
		usleep(2);
		outb(0x01, CONTROL);
		usleep(2);
		ch = getc(inputfile);
		if (ch == -1)
			break;
	}	
	
	/* Release the i/o space for the parallel port. */
	if (ioperm(LP_BASE, 3, 0) < 0){
		printf("Error releasing\n");
	}


	return 0;
}