util.c

/* See LICENSE file for copyright and license details. */

#include "util.h"

// like calloc, but with error throwing
void* ecalloc(size_t nmemb, size_t size) {
  void* p;

  if (!(p = calloc(nmemb, size)))
    die("calloc:");
  return p;
}

// throw an error and die
void die(const char* fmt, ...) {
  va_list ap;

  va_start(ap, fmt);
  vfprintf(stderr, fmt, ap);
  va_end(ap);

  if (fmt[0] && fmt[strlen(fmt) - 1] == ':') {
    fputc(' ', stderr);
    perror(NULL);
  } else {
    fputc('\n', stderr);
  }

  exit(1);
}

// throw a message and die w/ success 🗿
void die_happy(const char* fmt, ...) {
  va_list ap;

  va_start(ap, fmt);
  vfprintf(stdout, fmt, ap);
  va_end(ap);

  fputc('\n', stdout);

  exit(0);
}

// count number of ones in binary representation
unsigned int n_ones(unsigned int n) {
  unsigned int c = 0;
  while (n) {
    c += n & 1;
    n >>= 1;
  }
  return c;
}

int cmpint(const void* p1, const void* p2) {
  /* The actual arguments to this function are "pointers to
     pointers to char", but strcmp(3) arguments are "pointers
     to char", hence the following cast plus dereference */
  return *((int*)p1) > *(int*)p2;
}

unsigned int intersect(int x1, int y1, unsigned w1, unsigned h1, int x2, int y2,
    unsigned w2, unsigned h2) {
  return MAX(0, MIN(x1 + w1, x2 + w2) - MAX(x1, x2))
       * MAX(0, MIN(y1 + h1, y2 + h2) - MAX(y1, y2));
}