StrafesNET/fixed_wide_vectors
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deduplicate calculation

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Quaternions 2024-10-02 13:49:51 -07:00
parent fa547050e2
commit 2045d8047a
1 changed files with 4 additions and 4 deletions
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8
fixed_wide/src/fixed.rs
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@ -238,11 +238,10 @@ macro_rules! impl_from_float {
//extract exponent, add fractional offset
//usize is used to calculate digit_index. exp_cycle must be at least 8 bits so 32 bits is fine
let exp=((bits>>($mantissa_bits-1)) as usize&((1<<$exponent_bits)-1))+F;
//digit_index is where the hi digit should end up in a fixed point number
//if it's less than zero, that's a conversion underflow.
let digit_index=exp.checked_sub($exp_bias)?>>DIGIT_SHIFT;
let exp_bias=exp.checked_sub($exp_bias)?;
//cycle the exponent to keep the top bit of the mantissa within the hi digit
let exp_cycle=exp.overflowing_sub($exp_bias+64).0.rem_euclid(64).overflowing_add($exp_bias+64).0;
let exp_cycle=exp_bias.rem_euclid(64).overflowing_add($exp_bias+64).0;
let out_bits=
bits
//remove (mask) sign bit and exponent
@ -253,7 +252,8 @@ macro_rules! impl_from_float {
let _128=<$input>::from_bits(out_bits) as u128;
Some(FloatInfo{
sign:f.is_sign_negative(),
digit_index,
//digit_index is where the hi digit should end up in a fixed point number
digit_index:exp_bias>>DIGIT_SHIFT,
bits:[_128 as u64,(_128>>64) as u64],
})
}