/*
 Operation TB6600 Stepper Controller with PC Parallel Port
 https://www.bristolwatch.com/pport2/tb6600.htm
 by Lewis Loflin lewis@bvu.net
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/io.h>

// #include <string.h>
// #include <math.h>
// #include "myfile.h"

#define DATA 0x378  /* parallel port base address */
// D0-D7 pins 2-9

#define STATUS DATA + 1 // inputs only
// base address 0x379 - five bit 3-7
// bit 3 pin 15
// bit 4 pin 13
// bit 5 pin 12
// bit 6 pin 10
// bit 7 pin 11 inverted - HIGH reads LOW

#define CONTROL DATA + 2 // outputs
// base address 0x37A - four bits 0-3
// bit 0 pin 1 inverted
// bit 1 pin 14 inverted
// bit 2 pin 16 not inverted
// bit 3 pin 17 inverted

#define D0 1
#define D1 2
#define D2 4
#define D3 8
#define D4 16
#define D5 32
#define D6 64
#define D7 128

#define HIGH 1
#define LOW 0
#define CW 0
#define CCW 1
#define PUL 1 // 0x378 D0
#define DIR 2 // 0x378 D1
#define ENA 4 // 0x378 D2

#define SW1 8
#define SW2 16
#define SW3 32
#define SW4 64
#define SW5 128

// declare subroutines
void digitalWrite(int, int); // pin, state
void stepperOn(int, int); // steps, step_delay
int readSwitch(int bit);


// uses bits 3-7 with 7 inverted
// all have internal PU to HIGH
// Bitwise AND port data with bit value
int readSwitch(int SW_Number)   {
  int x;
  x = inb(Status) & SW_Number;
  if (x) return 1; // non-zero result
  else return 0;
}


// set pin state on DB25 pins 2-9 (D0-D7) at 0x378
void digitalWrite(int pinNumber, int state)   {
  unsigned char x, y, z;
  x = inb(DATA); // read data latches
  y = x & pinNumber; // determine pin state HIGH or LOW
  // pinNumber is a numeric value based on powers of 2
  if (state == 0  && y != 0)   {
    z = x & (0xFF - pinNumber); // bitwise AND clear bit
    outb(z, DATA);
  }
  if (state == 1)   {
    z = x | pinNumber; // bitwise OR set bit
    outb(z, DATA);
  }
}


// D0 is clk, D1 is direction, D2 is enable
// enable LOW to turn on
// 1 is CW, 0 is CCW
void stepperOn(int count, int delayMs)   {
  int x;
  digitalWrite(ENA, LOW); // motor enable
  for (x = 0; x <= count; x++)   {
    printf("Count = %d\n", x);
    //    if (readSwitch(D3) == 0) break;
    digitalWrite(PUL, HIGH);
    usleep(10);
    digitalWrite(PUL, LOW);
    usleep(delayMs * 1000);
  }
  digitalWrite(ENA, HIGH); // motor off
}


int main(void)   {

  // must include to access port
  if (ioperm(DATA, 3, 1))
    fprintf(stderr, "Access denied to %x\n", DATA), exit(1);
  printf("Hello world.");
  digitalWrite(PUL, LOW);
  digitalWrite(ENA, HIGH); // off

  while (1) {

    // HIGH is CW, LOW is CCW
    digitalWrite(DIR, CW);
    stepperOn(100, 10);
    sleep(1); // wait 2 sec.
    digitalWrite(DIR, CCW);
    stepperOn(200, 10);
  }
  return 0;
}