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multiply and check instead of doing bithacks

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This commit is contained in:
Quaternions 2023-12-12 15:27:12 -08:00
parent 1c4191cfc9
commit 14000c016e
1 changed files with 18 additions and 22 deletions
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40
src/integer.rs
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@ -459,26 +459,8 @@ pub enum Planar64TryFromFloatError{
Nan, Nan,
Infinite, Infinite,
Subnormal, Subnormal,
HighlyNegativeExponent(i16), HighlyNegativeExponent,
HighlyPositiveExponent(i16), HighlyPositiveExponent,
}
#[inline]
fn planar64_from_mes((m,e,s):(u64,i16,i8))->Result<Planar64,Planar64TryFromFloatError>{
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))
}
} }
impl TryFrom<f32> for Planar64{ impl TryFrom<f32> for Planar64{
type Error=Planar64TryFromFloatError; type Error=Planar64TryFromFloatError;
@ -489,7 +471,14 @@ impl TryFrom<f32> for Planar64{
std::num::FpCategory::Infinite=>Err(Self::Error::Infinite), std::num::FpCategory::Infinite=>Err(Self::Error::Infinite),
std::num::FpCategory::Zero=>Ok(Self::ZERO), std::num::FpCategory::Zero=>Ok(Self::ZERO),
std::num::FpCategory::Subnormal std::num::FpCategory::Subnormal
|std::num::FpCategory::Normal=>planar64_from_mes(integer_decode_f32(value)), |std::num::FpCategory::Normal=>{
let planar=value*PLANAR64_ONE_FLOAT32;
if planar<(i64::MIN as f32)||(i64::MAX as f32)<planar{
Err(Self::Error::HighlyPositiveExponent)
}else{
Ok(Planar64(unsafe{planar.to_int_unchecked()}))
}
}
} }
} }
} }
@ -502,7 +491,14 @@ impl TryFrom<f64> for Planar64{
std::num::FpCategory::Infinite=>Err(Self::Error::Infinite), std::num::FpCategory::Infinite=>Err(Self::Error::Infinite),
std::num::FpCategory::Zero=>Ok(Self::ZERO), std::num::FpCategory::Zero=>Ok(Self::ZERO),
std::num::FpCategory::Subnormal std::num::FpCategory::Subnormal
|std::num::FpCategory::Normal=>planar64_from_mes(integer_decode_f64(value)), |std::num::FpCategory::Normal=>{
let planar=value*PLANAR64_ONE_FLOAT64;
if planar<(i64::MIN as f64)||(i64::MAX as f64)<planar{
Err(Self::Error::HighlyPositiveExponent)
}else{
Ok(Planar64(unsafe{planar.to_int_unchecked()}))
}
}
} }
} }
} }