| #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; |
| } |