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implement Ratio::try_from(f32)

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This commit is contained in:
Quaternions 2023-10-13 14:41:25 -07:00
parent d939fbff94
commit 2f33a28c95
1 changed files with 44 additions and 18 deletions
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62
src/integer.rs
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@ -102,6 +102,20 @@ impl Ratio64{
}
//from num_traits crate
#[inline]
fn integer_decode_f32(f: f32) -> (u64, i16, i8) {
let bits: u32 = f.to_bits();
let sign: i8 = if bits >> 31 == 0 { 1 } else { -1 };
let mut exponent: i16 = ((bits >> 23) & 0xff) as i16;
let mantissa = if exponent == 0 {
(bits & 0x7fffff) << 1
} else {
(bits & 0x7fffff) | 0x800000
};
// Exponent bias + mantissa shift
exponent -= 127 + 23;
(mantissa as u64, exponent, sign)
}
#[inline]
fn integer_decode_f64(f: f64) -> (u64, i16, i8) {
let bits: u64 = f.to_bits();
let sign: i8 = if bits >> 63 == 0 { 1 } else { -1 };
@ -116,37 +130,49 @@ fn integer_decode_f64(f: f64) -> (u64, i16, i8) {
(mantissa, exponent, sign)
}
#[derive(Debug)]
enum Ratio64TryFromFloat64Error{
enum Ratio64TryFromFloatError{
Nan,
Infinite,
Subnormal,
HighlyNegativeExponent(i16),
HighlyPositiveExponent(i16),
}
fn ratio64_from_mes((m,e,s):(u64,i16,i8))->Result<Ratio64,Ratio64TryFromFloatError>{
if e< -127{
//bye bye
Err(Ratio64TryFromFloatError::HighlyNegativeExponent(e))
}else if e< -63{
//TODO
Err(Ratio64TryFromFloatError::HighlyNegativeExponent(e))
}else if e<0{
Ok(Ratio64::new((m as i64)*(s as i64),1<<-e).unwrap())
}else if e<62-52{
Ok(Ratio64::new((m as i64)*(s as i64)*(1<<e),1).unwrap())
}else{
Err(Ratio64TryFromFloatError::HighlyPositiveExponent(e))
}
}
impl TryFrom<f32> for Ratio64{
type Error=Ratio64TryFromFloatError;
fn try_from(value:f32)->Result<Self,Self::Error>{
match value.classify(){
std::num::FpCategory::Nan=>Err(Self::Error::Nan),
std::num::FpCategory::Infinite=>Err(Self::Error::Infinite),
std::num::FpCategory::Zero=>Ok(Self::ZERO),
std::num::FpCategory::Subnormal=>Err(Self::Error::Subnormal),
std::num::FpCategory::Normal=>ratio64_from_mes(integer_decode_f32(value)),
}
}
}
impl TryFrom<f64> for Ratio64{
type Error=Ratio64TryFromFloat64Error;
type Error=Ratio64TryFromFloatError;
fn try_from(value:f64)->Result<Self,Self::Error>{
match value.classify(){
std::num::FpCategory::Nan=>Err(Self::Error::Nan),
std::num::FpCategory::Infinite=>Err(Self::Error::Infinite),
std::num::FpCategory::Zero=>Ok(Self::ZERO),
std::num::FpCategory::Subnormal=>Err(Self::Error::Subnormal),
std::num::FpCategory::Normal=>{
let (m,e,s)=integer_decode_f64(value);
if e< -127{
//bye bye
Err(Self::Error::HighlyNegativeExponent(e))
}else if e< -63{
//TODO
Err(Self::Error::HighlyNegativeExponent(e))
}else if e<0{
Ok(Ratio64::new((m as i64)*(s as i64),1<<-e).unwrap())
}else if e<62-52{
Ok(Ratio64::new((m as i64)*(s as i64)*(1<<e),1).unwrap())
}else{
Err(Self::Error::HighlyPositiveExponent(e))
}
},
std::num::FpCategory::Normal=>ratio64_from_mes(integer_decode_f64(value)),
}
}
}