/* programme that outputs to a scope using the "LabMaster" set of libraries;
   MUST be linked with the Labmaster! eg
   gcc -Wall -O3 -ansi -pedantic -lm -llabmaster -o drawing drawing.c */

#include <stdio.h>     /* (f)printf stderr */
#include <stdlib.h>    /* sscanf */
#include <math.h>      /* sqrt */
#include <string.h>    /* strncmp */
#include <labmaster.h> /* out_dac etc */
#include "dac.h"

/* prototypes */
int main(int argc, char **argv);
int VtoDAC(double v);
void fillSinwave(int *buffer, double amp, int length);
void fillTriangle(int *buffer, double amp, int length);
void fillSquarewave(int *buffer, double amp, int length);
void fillSawtooth(int *buffer, double amp, int length);
void fillCalibration(int *buffer, double amp, int length);

/* constants */
const static int timerDAC = 0;  /* the timer DAC */
const static int outDAC = 1;    /* the output DAC */
const static double pi = 3.141592653589793238462643383279502884197169399375105\
820974944592307816406286208998; /* etc; since ansi apperantly does'n't define
				   M_PI */

/* main (duh?) */
int main(int argc, char **argv) {
  void (*fn)(int *, double, int);
  int i;
  int length; /* length of the buffer @= the wavelength */
  int *buffer;
  double amp, fre;

  /* initialize arguments */
  if((argc > 1) && (!strncmp(argv[1], "-h", 2) || !strncmp(argv[1], "--h", 3))) {
    fprintf(stderr, "Usage: drawing [sinewave|triangle|squarewave|sawtooth] ");
    fprintf(stderr, "[amplitude] [frequency]\n");
    return 1;
  }

  /* fill with def val */
  fn = fillSinwave;
  amp = 1;
  length = 1024;

  /* user input */
  if(argc > 1) {
    if     (strncmp(argv[1], "sawtooth",    2) == 0) fn = fillSawtooth;
    else if(strncmp(argv[1], "squarewave",  2) == 0) fn = fillSquarewave;
    else if(strncmp(argv[1], "triangle",    2) == 0) fn = fillTriangle;
    else if(strncmp(argv[1], "sinewave",    2) == 0) fn = fillSinwave;
    else if(strncmp(argv[1], "calibration", 2) == 0) fn = fillCalibration;
    else {
      fprintf(stderr, "%s?\n", argv[1]);
      return 1;
    }
  }
  if(argc > 2) {
    if(sscanf(argv[2], "%lg", &amp) != 1) {
      fprintf(stderr, "Ca'n't parse number; use --h for help.\n");
      return 1;
    }
    fprintf(stderr, "Using amp = %g.\n", amp);
  }
  if(argc > 3) {
    if(sscanf(argv[3], "%lg", &fre) != 1) {
      fprintf(stderr, "Ca'n't parse number; use --h for help.\n");
      return 1;
    }
    if(fre <= 10) {
      fprintf(stderr, "Frequency must be 10.\n");
      return 1;
    }
    length = 115000 / (double)fre;
    fprintf(stderr, "Using fre = %g, len = %d.\n", fre, length);
  }

  buffer = malloc(length * sizeof(int));
  if(!buffer) {
    fprintf(stderr, "Wavelength too big for memory allocation: %d.", length);
    return 0; /* mucho scecthy! */
  }

  /* call *fn to fill the buffer */
  (*fn)(buffer, amp, length);

  /* "This step is critical," OK */
  labmaster_initialize();

  /* display instuctions */
  printf("Connect DAC-%d to the timer trigger, ext.\n", timerDAC);
  printf("Connect DAC-%d to Y.\n", outDAC);
  /* system dependent */
  printf("Ctrl-C to exit?\n");

  /* display infinitaly (FIXME: timer?) */
  for( ; ; ) {
    /* for every buffer[i] */
    for(i = 0; i < length; i++) {
      /* -'ve pulse to trigger scope */
      out_dac(timerDAC, (i == 0) ? (-2048) : (2047));
      /* this is the output */
      out_dac(outDAC, buffer[i]);
    }
  }

  /* I assume this step is critical too */
  /* FIXME: but it does'n't get executed ever since Ctrl-C is the 
     only way to end */
  labmaster_terminate();

  /* the fn that's never called */
  free(buffer);

  return 0;
}

/* volts to DAC; in dac.h */
int VtoDAC (double v) { return (v - a[outDAC]) / b[outDAC]; }

/* sinwave */
void fillSinwave(int *buffer, double amp, int length) {
  int i;
  double x;

  for(i = 0; i < length; i++) {
    x = i * 2 * pi / length;
    buffer[i] = VtoDAC(sin(x) * amp);
  }
}

/* triangle */
void fillTriangle(int *buffer, double amp, int length) {
  int i;
  double x;

  for(i = 0; i < length; i++) {
    x = i / (double)length;
    if(x < .5) buffer[i] = VtoDAC((-1 + 4 * x) * amp);
    else       buffer[i] = VtoDAC(( 3 - 4 * x) * amp);
  }
}

/* squarewave */
void fillSquarewave(int *buffer, double amp, int length) {
  int i;
  double x;

  for(i = 0; i < length; i++) {
    x = i / (double)length;
    if(x < .5) buffer[i] = VtoDAC( amp);
    else       buffer[i] = VtoDAC(-amp);
  }
}

/* sawtooth */
void fillSawtooth(int *buffer, double amp, int length) {
  int i;
  double x;

  for(i = 0; i < length; i++) {
    x = i / (double)length;
    buffer[i] = VtoDAC((-1 + 2 * x) * amp);
  }
}

/* calibration; FIXME: calibration is not implemented, the only thing to do 
   is change the code, which is Bad, but suits our needs */
void fillCalibration(int *buffer, double amp, int length) {
  int i;

  fprintf(stderr,
	  "Calibration . . . sampling frequency = 2 measured frequency.\n");
  for(i = 0; i < length; i++) {
    buffer[i] = (i & 1) ? (2047) : (-2048);
  }
}