badge/util/fixed_point.h

   1 #ifndef INCLUDED_FIXED_POINT_H
   2 #define INCLUDED_FIXED_POINT_H
   3
   4 #include <stdint.h>
   5 #include <stdbool.h>
   6
   7 /* Unterstes Byte als Nachkomma. 16 Bit Nutzlast! Sonst geht Multiplikation flöten. */
   8 typedef struct { int32_t data; } fixed_point;
   9
  10 static inline fixed_point fixed_point_add(fixed_point x, fixed_point y) { fixed_point r = { x.data + y.data         }; return r; }
  11 static inline fixed_point fixed_point_sub(fixed_point x, fixed_point y) { fixed_point r = { x.data - y.data         }; return r; }
  12 static inline fixed_point fixed_point_mul(fixed_point x, fixed_point y) { fixed_point r = { x.data * y.data / 256   }; return r; }
  13 static inline fixed_point fixed_point_div(fixed_point x, fixed_point y) { fixed_point r = { (x.data * 256) / y.data }; return r; }
  14
  15 static inline fixed_point fixed_point_neg(fixed_point x) { fixed_point r = { -x.data                       }; return r; }
  16 static inline fixed_point fixed_point_abs(fixed_point x) { fixed_point r = { x.data < 0 ? -x.data : x.data }; return r; }
  17
  18 static inline bool fixed_point_lt(fixed_point x, fixed_point y) { return x.data <  y.data; }
  19 static inline bool fixed_point_gt(fixed_point x, fixed_point y) { return x.data >  y.data; }
  20 static inline bool fixed_point_le(fixed_point x, fixed_point y) { return x.data <= y.data; }
  21 static inline bool fixed_point_ge(fixed_point x, fixed_point y) { return x.data >= y.data; }
  22 static inline bool fixed_point_eq(fixed_point x, fixed_point y) { return x.data == y.data; }
  23 static inline bool fixed_point_ne(fixed_point x, fixed_point y) { return x.data != y.data; }
  24
  25 #define FIXED_POINT_I(x, y) { ((x) * 256) + ((y) * 256 / 1000) }
  26 #define FIXED_INT_I(x) FIXED_POINT_I(x, 0)
  27
  28 static inline fixed_point FIXED_POINT(int32_t x, int32_t y) {
  29   fixed_point r = FIXED_POINT_I(x, y);
  30   return r;
  31 }
  32
  33 static inline fixed_point FIXED_INT(int32_t x) { return FIXED_POINT(x, 0); }
  34
  35 // sign bit is shifted in if x.data < 0, so this is x.data / 256 - (x.data < 0).
  36 // This means 0.123 is cast to 1, which is what we want when we cast a model coordinate
  37 // to a screen coordinate.
  38 static inline int fixed_point_cast_int(fixed_point x) { return x.data >> 8; }
  39
  40 static inline fixed_point fixed_point_min(fixed_point x, fixed_point y) { return fixed_point_lt(x, y) ? x : y; }
  41 static inline fixed_point fixed_point_max(fixed_point x, fixed_point y) { return fixed_point_gt(x, y) ? x : y; }
  42
  43 #endif