T-FF シミュレータ：タイムチャート描画

t-ff.c

#include <stdio.h>
#include <stdlib.h>

typedef struct {
  int time;
  int length;
} pulse;

typedef struct {
  unsigned char negative_edge : 1;
  unsigned char t : 1;
  unsigned char q : 1;
  unsigned char not_q : 1;
} t_ff;

void
t_ff_init(t_ff *ff, int negative_edge)
{
  ff->negative_edge = negative_edge ? 1 : 0;
  ff->t = 0;
  ff->q = 0;
  ff->not_q = 1;
}

void
t_ff_update(t_ff *ff, t_ff *prev)
{
#define INVERT(x) ((x) ? 0 : 1);

  ff->q = prev->q;

  if (ff->negative_edge) {
    if (prev->t && !ff->t) {
      ff->q = INVERT(ff->q);
    }
  } else {
    if (!prev->t && ff->t) {
      ff->q = INVERT(ff->q);
    }
  }

  ff->not_q = INVERT(ff->q);
}

void
print_high_or_low(int x)
{
  putchar(x ? '^' : '_');
}

void
print_time_chart(t_ff ff[], int length)
{
  int i;

  printf(" T ");
  for (i = 0; i < length; i++) {
    print_high_or_low(ff[i].t);
  }
  putchar('\n');

  printf("\n Q ");
  for (i = 0; i < length; i++) {
    print_high_or_low(ff[i].q);
  }
  putchar('\n');

  printf("\n!Q ");
  for (i = 0; i < length; i++) {
    print_high_or_low(ff[i].not_q);
  }
  putchar('\n');
}

void
simulate_t_ff(
  unsigned int pulse_width,
  unsigned int interval,
  unsigned int length,
  int negative_edge
)
{
  t_ff *ff;
  unsigned int cycle = pulse_width + interval;
  unsigned int i;

  ff = (t_ff*)malloc(length * sizeof(t_ff));
  if (!ff) {
    perror("malloc");
    exit(1);
  }

  for (i = 0; i < length; i++) {
    unsigned int j = (i - 1) % cycle;

    t_ff_init(&ff[i], negative_edge);

    if (i > 0) {
      if (j < pulse_width) {
        ff[i].t = 1;
      }

      t_ff_update(&ff[i], &ff[i - 1]);
    }
  }

  print_time_chart(ff, length);

  free(ff);
}

int
main(void)
{
  unsigned int pulse_width, interval, length;

  printf("パルス幅: ");
  scanf("%u", &pulse_width);

  printf("間隔: ");
  scanf("%u", &interval);

  printf("時間: ");
  scanf("%u", &length);

  puts("\n[ポジティブエッジ]");
  simulate_t_ff(pulse_width, interval, length, 0);

  puts("\n[ネガティブエッジ]");
  simulate_t_ff(pulse_width, interval, length, 1);

  return 0;
}