/*
    Fixed point implementation of 3 dimensional vectors.
    SSE2 extension availability is assumed, making it more viable.
    For mul and div we don't use com_fixed functions to make fewer bitshifts.
*/

#ifndef COM_VEC_H
#define COM_VEC_H

#include "def.h"
#include "fixed.h"
#include <stdint.h>

typedef union {
  com_fixed_t com_def_alignedas(16) a[3];
  com_def_alignedas(16) struct {
    com_fixed_t x;
    com_fixed_t y;
    com_fixed_t z;
  } s;
} com_vec_t;

static inline com_vec_t com_vec_identity(void) {
  return (com_vec_t){.s = {.x = COM_FIXED_FRACUNIT,
                           .y = COM_FIXED_FRACUNIT,
                           .z = COM_FIXED_FRACUNIT}};
}

static inline com_vec_t com_vec_add(com_vec_t a, com_vec_t b) {
  return (com_vec_t){.s = {.x = com_fixed_add(a.s.x, b.s.x),
                           .y = com_fixed_add(a.s.y, b.s.y),
                           .z = com_fixed_add(a.s.z, b.s.z)}};
}

static inline com_vec_t com_vec_sub(com_vec_t a, com_vec_t b) {
  return (com_vec_t){.s = {.x = com_fixed_sub(a.s.x, b.s.x),
                           .y = com_fixed_sub(a.s.y, b.s.y),
                           .z = com_fixed_sub(a.s.z, b.s.z)}};
}

static inline com_vec_t com_vec_mul(com_vec_t a, com_vec_t b) {
  return (com_vec_t){.s = {.x = com_fixed_mul(a.s.x, b.s.x),
                           .y = com_fixed_mul(a.s.y, b.s.y),
                           .z = com_fixed_mul(a.s.z, b.s.z)}};
}

/* Note: this does not clamp for over/underflow cases */
static inline com_vec_t com_vec_div(com_vec_t a, com_vec_t b) {
  return (com_vec_t){.s = {.x = com_fixed_div(a.s.x, b.s.x),
                           .y = com_fixed_div(a.s.y, b.s.y),
                           .z = com_fixed_div(a.s.z, b.s.z)}};
}

/* Scale vector by a fixed point number */
static inline com_vec_t com_vec_scl(com_vec_t a, com_fixed_t b) {
  return (com_vec_t){.s = {.x = com_fixed_mul(a.s.x, b),
                           .y = com_fixed_mul(a.s.y, b),
                           .z = com_fixed_mul(a.s.z, b)}};
}

/* Shows how much given vectors are correlated in direction to each other */
/* Resulted range depends on input, it's in -1 to 1 for normalized
 * input and otherwise is -ab to +ab */
static inline com_fixed_t com_vec_dot(com_vec_t a, com_vec_t b) {
  return (((int64_t)a.s.x * b.s.x) + ((int64_t)a.s.y * b.s.y) +
          ((int64_t)a.s.z * b.s.z)) >>
         COM_FIXED_FRACBITS;
}

/* Cross product produces a perpendicular for normalized vectors, or 0 for
 * parallel vectors */
static inline com_vec_t com_vec_crs(com_vec_t a, com_vec_t b) {
  int64_t const cx = ((int64_t)a.s.y * b.s.z) - ((int64_t)a.s.z - b.s.y);
  int64_t const cy = ((int64_t)a.s.z * b.s.x) - ((int64_t)a.s.x - b.s.z);
  int64_t const cz = ((int64_t)a.s.x * b.s.y) - ((int64_t)a.s.y - b.s.x);
  return (com_vec_t){.s = {.x = (com_fixed_t)(cx >> COM_FIXED_FRACBITS),
                           .y = (com_fixed_t)(cy >> COM_FIXED_FRACBITS),
                           .z = (com_fixed_t)(cz >> COM_FIXED_FRACBITS)}};
}

static inline com_vec_t com_vec_nrm(com_vec_t a) {
  com_fixed_t const n = com_fixed_sqrt(com_vec_dot(a, a));
  return com_vec_scl(a, com_fixed_div(COM_FIXED_FRACUNIT, n));
}

#endif