#include "libm.h"

float tanhf(float x) {
  union {
    float f;
    uint32_t i;
  } u = {.f = x};
  uint32_t w;
  int sign;
  float t;

  /* x = |x| */
  sign = u.i >> 31;
  u.i &= 0x7fffffff;
  x = u.f;
  w = u.i;

  if (w > 0x3f0c9f54) {
    /* |x| > log(3)/2 ~= 0.5493 or nan */
    if (w > 0x41200000) {
      /* |x| > 10 */
      t = 1 + 0 / x;
    } else {
      t = expm1f(2 * x);
      t = 1 - 2 / (t + 2);
    }
  } else if (w > 0x3e82c578) {
    /* |x| > log(5/3)/2 ~= 0.2554 */
    t = expm1f(2 * x);
    t = t / (t + 2);
  } else if (w >= 0x00800000) {
    /* |x| >= 0x1p-126 */
    t = expm1f(-2 * x);
    t = -t / (t + 2);
  } else {
    /* |x| is subnormal */
    FORCE_EVAL(x * x);
    t = x;
  }
  return sign ? -t : t;
}