utility.c

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// mightymandel -- GPU-based Mandelbrot Set explorer
// Copyright (C) 2012,2013,2014,2015 Claude Heiland-Allen
// License GPL3+ http://www.gnu.org/licenses/gpl.html

#include <math.h>
#include <stdio.h>

#include "utility.h"

int min(int a, int b) { return a < b ? a : b; }

int max(int a, int b) { return a > b ? a : b; }

int ceil2n(int z) {
  int n = 1;
  while (0 < n && n < z) {
    n <<= 1;
  }
  return n;
}

int pxbits(const mpfr_t radius, double height) {
  mpfr_t r;
  mpfr_init2(r, 53);
  mpfr_log2(r, radius, MPFR_RNDN);
  int bits = 2 + ceil(log2(height)) - floor(mpfr_get_d(r, MPFR_RNDN));
  mpfr_clear(r);
  return bits;
}

void pixel_coordinate(mpfr_t x, mpfr_t y, int width, int height, const mpfr_t centerx, const mpfr_t centery, const mpfr_t radius, double i, double j) {
  mpfr_set_prec(x, mpfr_get_prec(centerx) + 8);
  mpfr_set_prec(y, mpfr_get_prec(centery) + 8);
  mpfr_mul_d(x, radius, 2.0 * (i  - width / 2.0) / height, MPFR_RNDN);
  mpfr_add(x, x, centerx, MPFR_RNDN);
  mpfr_mul_d(y, radius, 2.0 * (height / 2.0 - j) / height, MPFR_RNDN);
  mpfr_add(y, y, centery, MPFR_RNDN);
}