use super::{exp2, exp2f, modff};

const LN10_F32: f32 = 3.32192809488736234787031942948939;

const LN10_F64: f64 = 3.32192809488736234787031942948939;

const P10: &[f32] = &[

    1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1, 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7,

];

/// Calculates 10 raised to the power of `x` (f32).

#[cfg_attr(assert_no_panic, no_panic::no_panic)]

pub fn exp10f(x: f32) -> f32 {

    select_implementation! {

        name: x87_exp10f,

        use_arch_required: x86_no_sse,

        args: x,

    }

    let (mut y, n) = modff(x);

    let u = n.to_bits();

    /* fabsf(n) < 8 without raising invalid on nan */

    if ((u >> 23) & 0xff) < 0x7f + 3 {

        if y == 0.0 {

            return i!(P10, ((n as isize) + 7) as usize);

        }

        y = exp2f(LN10_F32 * y);

        return y * i!(P10, ((n as isize) + 7) as usize);

    }

    return exp2(LN10_F64 * (x as f64)) as f32;

}