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use core::f64;
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn trunc(x: f64) -> f64 {
// On wasm32 we know that LLVM's intrinsic will compile to an optimized
// `f64.trunc` native instruction, so we can leverage this for both code size
// and speed.
llvm_intrinsically_optimized! {
#[cfg(target_arch = "wasm32")] {
return unsafe { ::core::intrinsics::truncf64(x) }
}
}
let x1p120 = f64::from_bits(0x4770000000000000); // 0x1p120f === 2 ^ 120
let mut i: u64 = x.to_bits();
let mut e: i64 = (i >> 52 & 0x7ff) as i64 - 0x3ff + 12;
let m: u64;
if e >= 52 + 12 {
return x;
}
if e < 12 {
e = 1;
}
m = -1i64 as u64 >> e;
if (i & m) == 0 {
return x;
}
force_eval!(x + x1p120);
i &= !m;
f64::from_bits(i)
}
#[cfg(test)]
mod tests {
#[test]
fn sanity_check() {
assert_eq!(super::trunc(1.1), 1.0);
}
}