fixp.h

#ifndef PACHI_FIXP_H
#define PACHI_FIXP_H

/* Tools for counting fixed-point numbers. */

/* We implement a simple fixed-point number type, with fixed number of
 * fractional binary digits after the radix point. */

#include <stdint.h>

typedef uint_fast32_t fixp_t;

/* We should accomodate at least 0..131072 (17bits) in the whole number
 * portion; assuming at least 32bit integer, that leaves us with 15-bit
 * fractional part. Thankfully, we need only unsigned values. */
#define FIXP_BITS 15

#define FIXP_SCALE (1<<FIXP_BITS)

#define double_to_fixp(n) ((fixp_t) ((n) * (FIXP_SCALE)))
#define fixp_to_double(n) ((double) (n) / FIXP_SCALE)

#endif