57 lines
1.3 KiB
Rust
57 lines
1.3 KiB
Rust
use fixed_wide_traits::wide::WideMul;
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use crate::types::I32F32;
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#[test]
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fn test_wide_mul(){
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let a=I32F32::ONE;
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let aa=a.wide_mul(a);
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assert_eq!(aa,crate::types::I64F64::ONE);
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}
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#[test]
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fn test_bint(){
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let a=I32F32::ONE;
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assert_eq!(a*2,I32F32::from(2));
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}
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#[test]
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fn test_sqrt(){
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let a=I32F32::ONE*4;
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assert_eq!(a.sqrt(),I32F32::from(2));
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}
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#[test]
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fn test_sqrt_low(){
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let a=I32F32::HALF;
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let b=a*a;
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assert_eq!(b.sqrt(),a);
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}
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fn find_equiv_sqrt_via_f64(n:I32F32)->I32F32{
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//GIMME THEM BITS BOY
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let &[bits]=n.to_bits().to_bits().digits();
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let ibits=bits as i64;
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let f=(ibits as f64)/((1u64<<32) as f64);
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let f_ans=f.sqrt();
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let i=(f_ans*((1u64<<32) as f64)) as i64;
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let r=I32F32::from_bits(bnum::BInt::<1>::from(i));
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//mimic the behaviour of the algorithm,
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//return the result if it truncates to the exact answer
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if (r+I32F32::EPSILON).wide_mul(r+I32F32::EPSILON)==n.wide_mul(I32F32::ONE){
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return r+I32F32::EPSILON;
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}
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if (r-I32F32::EPSILON).wide_mul(r-I32F32::EPSILON)==n.wide_mul(I32F32::ONE){
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return r-I32F32::EPSILON;
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}
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return r;
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}
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fn test_exact(n:I32F32){
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assert_eq!(n.sqrt(),find_equiv_sqrt_via_f64(n));
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}
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#[test]
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fn test_sqrt_exact(){
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//43
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for i in 0..((i64::MAX as f32).ln() as u32){
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let n=I32F32::from_bits(bnum::BInt::<1>::from((i as f32).exp() as i64));
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test_exact(n);
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}
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}
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