#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <dos.h>
#include <bios.h>

#define CLOCK_LOW		0xfb
#define CLOCK_HIGH	0x04
#define DIN_LOW		0xef
#define DIN_HIGH		0x10
#define CS_LOW		0xf7
#define CS_HIGH		0x08
#define POWER_ON		0x01
#define POWER_OFF		0xfe

typedef unsigned int WORD;

int 	out_port, in_port, out, power_boost_status=0;
char	msg[80];

float read_data(int measure)	/* read data from MAX132 	*/
{
 int i, j, test_bit, data[3], command[4];
 float data_dis;
 data[0]=0;
 data[1]=0;
 data[2]=0;
 if (measure==0)
   command[0]=0x92;		/* set to read zero offset 	*/
 else
   command[0]=0x82;		/* set to read input voltage 	*/
 command[1]=0x04;
 command[2]=0x00;
 command[3]=0x00;
 out|=CS_HIGH;
 outportb(out_port, out);
 for (j=0; j<4; j++)
   {
     out&=CS_LOW;           		/* CS low		*/
     outportb(out_port, out);
     delay(1);
     test_bit=0x80;
     for (i=0; i<8; i++)		/* start convert 	*/
	{
	 if ((command[j]&test_bit)==0)
	    out&=DIN_LOW;
	 else
	    out|=DIN_HIGH;
	 outportb(out_port, out);
	 delay(1);
	 out|=CLOCK_HIGH;          	/* clock high 	*/
	 outportb(out_port, out);
	 delay(1);
	 if (j!=0)
	    data[j-1]=data[j-1]*2+(inportb(in_port)&0x10)/16;
	 out&=CLOCK_LOW;
	 outportb(out_port, out); 	/* clock low	*/
	 delay(1);
	 test_bit/=2;
	}
     out|=CS_HIGH;                 	/* CS high		*/
     outportb(out_port, out);
     delay(1);
     if (j==0)
       delay(100);		     	/* wait 100ms 	*/
    }
 data_dis=((float)data[2])/64+((float)data[1])*4+((float)(data[0]&0x07))/512;
 if ((data[0]&0x08)==0)
   return (data_dis);
 else
   return (data_dis-1024+1/512);
}

void display_data(float data_dis)
{
 int current_x;
 current_x=(int)(data_dis/2);
 setviewport(10, 200, 630, 220, 1);
 clearviewport();
 setfillstyle(1, YELLOW);
 bar(310, 0, (current_x+310), 10);	/* show a bar on screen 	*/
 setviewport(280, 240, 630, 300, 1);
 clearviewport();
 if (data_dis>512 || data_dis<-512)
   sprintf(msg, "Overrange!");
 else
   sprintf(msg, "%.2f mV", data_dis);
 outtext(msg);				/* show data on screen 		*/
}

void init_screen(void)			/* initialize display screen 	*/
{
 setbkcolor (BLUE);
 setcolor(WHITE);
 line(2,2,637,2);
 line(5,4,634,4);
 line(2,2,2,477);
 line(5,4,5,475);
 line(5,475,634,475);
 line(2,477,637,477);
 line(634,5,634,475);
 line(637,2,637,477);
 line(3,350,634,350);
 setviewport(450,440,630,460,1);
 sprintf(msg, "press any key to quit");
 outtext(msg);
 setviewport(0,0,639,479,1);
}

int init_graph(void)			/* initialize graphic mode 	*/
{
   int gdriver = DETECT, gmode, errorcode;
   initgraph(&gdriver, &gmode, "");
   errorcode = graphresult();
   if (errorcode != grOk)  		/* an error occurred 		*/
   {
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);             		/* return with error code 	*/
   }
}

void find_port(void)			/* find printer port address 	*/
{
 out=0;
 out_port=*(WORD far *)MK_FP(0x0040, 8);
 in_port=out_port+1;
 out|=POWER_ON;
 outportb(out_port, out);
 delay(100);
}

void clean_up(void)			/* close graphic mode 		*/
{
 closegraph();
 out&=POWER_OFF;
 outportb(out_port, out);		/* turn off power supply 	*/
}

void main(void)
{
 int channel, measure=0, k;
 float tp, measured_data=0, zero_offset;
 find_port();
 init_graph();
 init_screen();
 delay(1000);
 read_data(measure);
 read_data(measure);
 read_data(measure);
 for (k=0; k<8; k++)
   measured_data+=read_data(measure);
 zero_offset=measured_data/8;
 measure=1;
 do{
   measured_data=0;
   for (k=0; k<8; k++)
    {
     tp=read_data(measure);
     measured_data+=(tp-zero_offset);
    }
   display_data(measured_data/8);
  } while(!kbhit());			/* quit if hit any key 		*/
 clean_up();
}