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use core::convert::{From, Into};
use core::intrinsics as int;
pub fn powf32(base: f32, exponent: f32) -> f32 {
unsafe { int::powf32(base, exponent) }
}
pub fn powif32(base: f32, exponent: i32) -> f32 {
unsafe { int::powif32(base, exponent) }
}
pub fn sqrtf32(num: f32) -> f32 {
unsafe { int::sqrtf32(num) }
}
extern "C" {
fn __errno() -> &'static mut i32;
}
pub fn get_errno() -> i32 {
unsafe {
let errnoaddr = __errno();
let ret = *errnoaddr;
*errnoaddr = 0;
ret
}
}
pub fn closest_power_of_two(mut num: u32) -> u32 {
num -= 1;
num |= num >> 1;
num |= num >> 2;
num |= num >> 4;
num |= num >> 8;
num |= num >> 16;
num += 1;
num
}
#[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq, Ord)]
pub struct PowerOfTwo(u32);
impl PowerOfTwo {
pub fn exp<R>(self) -> R
where
R: From<u32>,
{
From::from(self.0)
}
pub fn floor<F: Into<u32>>(f: F) -> PowerOfTwo {
PowerOfTwo(log_base_two(f.into()))
}
pub fn ceiling<F: Into<u32>>(f: F) -> PowerOfTwo {
PowerOfTwo(log_base_two(closest_power_of_two(f.into())))
}
pub fn zero() -> PowerOfTwo {
PowerOfTwo(0)
}
pub fn as_num<F: From<u32>>(self) -> F {
(1 << self.0).into()
}
}
pub fn log_base_two(num: u32) -> u32 {
if num == 0 {
0
} else {
31 - num.leading_zeros()
}
}