runtime/src/sun/vm/fixed.h

   1 #ifndef SUN_VM_FIXED_H
   2 #define SUN_VM_FIXED_H
   3
   4 // Reference: https://en.wikipedia.org/wiki/Q_(number_format)
   5 //            http://www.superkits.net/whitepapers/Fixed%20Point%20Representation%20&%20Fractional%20Math.pdf
   6
   7 #include <assert.h>
   8 #include <stdint.h>
   9
  10 #ifdef __cplusplus
  11 extern "C" {
  12 #endif
  13
  14 #define FIXED_FRACTIONAL_BITS 8
  15 #define FIXED_INTEGRAL_BITS 8
  16
  17 #define FIXED_ONE (1 << FIXED_FRACTIONAL_BITS)
  18
  19 typedef int32_t Fixed;
  20 static_assert(sizeof(Fixed) == sizeof(int32_t), "Fixed incorrect size");
  21
  22 #define _fixed(v) ((Fixed)((v)))
  23
  24 #define FIXED(x) (_fixed((x) * FIXED_ONE))
  25 #define FIXED_TO_INT(x) ((int)((int32_t)(x) / FIXED_ONE))
  26
  27 #define FIXED_FROM_FLOAT(x) (_fixed((x) * (float)FIXED_ONE))
  28 #define FIXED_TO_FLOAT(x) ((float)((x) / (float)FIXED_ONE))
  29
  30 #define fixedLT(lhs, rhs) ((int32_t)(lhs) < (int32_t)(rhs))
  31 #define fixedGT(lhs, rhs) ((int32_t)(lhs) > (int32_t)(rhs))
  32
  33 #define fixedNegate(v) (_fixed(-(int32_t)(v)))
  34
  35 #define fixedAdd(lhs, rhs) (_fixed((int32_t)(lhs) + (int32_t)(rhs)))
  36 #define fixedSubtract(lhs, rhs) (_fixed((int32_t)(lhs) - (int32_t)(rhs)))
  37
  38 #define fixedMultiply(lhs, rhs) (_fixed((((int32_t)(lhs) * (int32_t)(rhs))) / FIXED_ONE))
  39 #define fixedDivide(lhs, rhs) (_fixed(((int32_t)(lhs * FIXED_ONE) / (int32_t)(rhs))))
  40 #define fixedMod(lhs, rhs) (_fixed((int32_t)(lhs) % (int32_t)(rhs)))
  41
  42 static inline Fixed fixedSgn(Fixed v) {
  43         return v == 0 ? 0 : (fixedGT(v, 0) ? FIXED(1) : FIXED(-1));
  44 }
  45
  46 static inline Fixed fixedMin(Fixed lhs, Fixed rhs) {
  47         return fixedLT(lhs, rhs) ? lhs : rhs;
  48 }
  49
  50 static inline Fixed fixedMax(Fixed lhs, Fixed rhs) {
  51         return fixedGT(lhs, rhs) ? lhs : rhs;
  52 }
  53
  54 static inline Fixed fixedMid(Fixed val1, Fixed val2, Fixed val3) {
  55         return fixedMin(fixedMin(fixedMax(val1, val2), fixedMax(val2, val3)), fixedMax(val1, val3));
  56 }
  57
  58 static inline Fixed fixedClamp(Fixed a, Fixed b, Fixed v) {
  59         return fixedMin(fixedMax(v, a), b);
  60 }
  61
  62 static inline Fixed fixedUnclampedLerp(Fixed a, Fixed b, Fixed t) {
  63         Fixed v = fixedSubtract(fixedMultiply(a, fixedSubtract(FIXED(1), t)), fixedMultiply(b, t));
  64         return v;
  65 }
  66
  67 static inline Fixed fixedUnclampedUnlerp(Fixed a, Fixed b, Fixed v) {
  68         Fixed t = fixedDivide(fixedSubtract(v, a), fixedSubtract(b, a));
  69         return t;
  70 }
  71
  72 static inline Fixed fixedLerp(Fixed a, Fixed b, Fixed t) {
  73         Fixed clampedT = fixedClamp(FIXED(0), FIXED(1), t);
  74         Fixed v = fixedUnclampedLerp(a, b, clampedT);
  75         return v;
  76 }
  77
  78 static inline Fixed fixedUnlerp(Fixed a, Fixed b, Fixed v) {
  79         Fixed t = fixedUnclampedUnlerp(a, b, v);
  80         Fixed clampedT = fixedClamp(FIXED(0), FIXED(1), t);
  81         return clampedT;
  82 }
  83
  84 extern Fixed fixedSqrt(Fixed value);
  85 extern Fixed fixedSin(Fixed value);
  86 extern Fixed fixedCos(Fixed value);
  87 extern Fixed fixedAtan2(Fixed x, Fixed y);
  88 extern Fixed fixedAbs(Fixed value);
  89 extern Fixed fixedCeil(Fixed value);
  90 extern Fixed fixedFloor(Fixed value);
  91
  92 #ifdef __cplusplus
  93 }
  94 #endif
  95
  96 #endif