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allow partial underflow

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Quaternions 2023-10-13 19:10:59 -07:00
parent 5f1d732b59
commit c88451c0f0
1 changed files with 13 additions and 5 deletions
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16
src/integer.rs
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@ -439,11 +439,19 @@ pub enum Planar64TryFromFloatError{
}
#[inline]
fn planar64_from_mes((m,e,s):(u64,i16,i8))->Result<Planar64,Planar64TryFromFloatError>{
if e< -32{
Err(Planar64TryFromFloatError::HighlyNegativeExponent(e))
}else if e<32-52{
Ok(Planar64((m as i64)*(s as i64)<<e))
let e32=e+32;
if e32<0&&(m>>-e32)==0{//shifting m will underflow to 0
Ok(Planar64::ZERO)
// println!("m{} e{} s{}",m,e,s);
// println!("f={}",(m as f64)*(2.0f64.powf(e as f64))*(s as f64));
// Err(Planar64TryFromFloatError::HighlyNegativeExponent(e))
}else if (64-m.leading_zeros() as i16)+e32<64{//shifting m will not overflow
if e32<0{
Ok(Planar64((m as i64)*(s as i64)>>-e32))
}else{
Ok(Planar64((m as i64)*(s as i64)<<e32))
}
}else{//if shifting m will overflow (prev check failed)
Err(Planar64TryFromFloatError::HighlyPositiveExponent(e))
}
}