strafe-project/lib/fixed_wide/src/tests.rs

use crate::types::I32F32;
use crate::types::I256F256;

#[test]
fn you_can_add_numbers(){
	let a=I256F256::from((3i128*2).pow(4));
	assert_eq!(a+a,I256F256::from((3i128*2).pow(4)*2));
}

#[test]
fn to_f32(){
	let a=I256F256::from(1)>>2;
	let f:f32=a.into();
	assert_eq!(f,0.25f32);
	let f:f32=(-a).into();
	assert_eq!(f,-0.25f32);
	let a=I256F256::from(0);
	let f:f32=(-a).into();
	assert_eq!(f,0f32);
	let a=I256F256::from(237946589723468975i64)<<16;
	let f:f32=a.into();
	assert_eq!(f,237946589723468975f32*2.0f32.powi(16));
}

#[test]
fn to_f64(){
	let a=I256F256::from(1)>>2;
	let f:f64=a.into();
	assert_eq!(f,0.25f64);
	let f:f64=(-a).into();
	assert_eq!(f,-0.25f64);
	let a=I256F256::from(0);
	let f:f64=(-a).into();
	assert_eq!(f,0f64);
	let a=I256F256::from(237946589723468975i64)<<16;
	let f:f64=a.into();
	assert_eq!(f,237946589723468975f64*2.0f64.powi(16));
}

#[test]
fn from_f32(){
	let a=I256F256::from(1)>>2;
	let b:Result<I256F256,_>=0.25f32.try_into();
	assert_eq!(b,Ok(a));
	let a=I256F256::from(-1)>>2;
	let b:Result<I256F256,_>=(-0.25f32).try_into();
	assert_eq!(b,Ok(a));
	let a=I256F256::from(0);
	let b:Result<I256F256,_>=0.try_into();
	assert_eq!(b,Ok(a));
	let a=I256F256::from(0b101011110101001010101010000000000000000000000000000i64)<<16;
	let b:Result<I256F256,_>=(0b101011110101001010101010000000000000000000000000000u64 as f32*2.0f32.powi(16)).try_into();
	assert_eq!(b,Ok(a));
	//I32F32::MAX into f32 is truncated into this value
	let a=I32F32::raw(0b111111111111111111111111000000000000000000000000000000000000000i64);
	let b:Result<I32F32,_>=Into::<f32>::into(I32F32::MAX).try_into();
	assert_eq!(b,Ok(a));
	//I32F32::MIN hits a special case since it's not representable as a positive signed integer
	//TODO: don't return an overflow because this is technically possible
	let a=I32F32::MIN;
	let b:Result<I32F32,_>=Into::<f32>::into(I32F32::MIN).try_into();
	assert_eq!(b,Err(crate::fixed::FixedFromFloatError::Overflow));
	//16 is within the 24 bits of float precision
	let b:Result<I32F32,_>=Into::<f32>::into(-I32F32::MIN.fix_2()).try_into();
	assert_eq!(b,Err(crate::fixed::FixedFromFloatError::Overflow));
	let b:Result<I32F32,_>=f32::MIN_POSITIVE.try_into();
	assert_eq!(b,Err(crate::fixed::FixedFromFloatError::Underflow));
	//test many cases
	for i in 0..64{
		let a=crate::fixed::Fixed::<2,64>::raw_digit(0b111111111111111111111111000000000000000000000000000000000000000i64)<<i;
		let f:f32=a.into();
		let b:Result<crate::fixed::Fixed<2,64>,_>=f.try_into();
		assert_eq!(b,Ok(a));
	}
}

#[test]
fn from_f64(){
	let a=I256F256::from(1)>>2;
	let b:Result<I256F256,_>=0.25f64.try_into();
	assert_eq!(b,Ok(a));
	let a=I256F256::from(-1)>>2;
	let b:Result<I256F256,_>=(-0.25f64).try_into();
	assert_eq!(b,Ok(a));
	let a=I256F256::from(0);
	let b:Result<I256F256,_>=0.try_into();
	assert_eq!(b,Ok(a));
	let a=I256F256::from(0b101011110101001010101010000000000000000000000000000i64)<<16;
	let b:Result<I256F256,_>=(0b101011110101001010101010000000000000000000000000000u64 as f64*2.0f64.powi(16)).try_into();
	assert_eq!(b,Ok(a));
}

#[test]
fn you_can_shr_numbers(){
	let a=I32F32::from(4);
	assert_eq!(a>>1,I32F32::from(2));
}

#[test]
fn test_wide_mul(){
	let a=I32F32::ONE;
	let aa=a.wide_mul_1_1(a);
	assert_eq!(aa,crate::types::I64F64::ONE);
}

#[test]
fn test_wide_div(){
	let a=I32F32::ONE*4;
	let b=I32F32::ONE*2;
	let wide_a=a.wide_mul_1_1(I32F32::ONE);
	let wide_b=b.wide_mul_1_1(I32F32::ONE);
	let ab=a.wide_div_1_1(b);
	assert_eq!(ab,crate::types::I64F64::ONE*2);
	let wab=wide_a.wide_div_2_1(b);
	assert_eq!(wab,crate::fixed::Fixed::<3,96>::ONE*2);
	let awb=a.wide_div_1_2(wide_b);
	assert_eq!(awb,crate::fixed::Fixed::<3,96>::ONE*2);
}

#[test]
fn test_wide_mul_repeated() {
	let a=I32F32::from(2);
	let b=I32F32::from(3);

	let w1=a.wide_mul_1_1(b);
	let w2=w1.wide_mul_2_2(w1);
	let w3=w2.wide_mul_4_4(w2);

	assert_eq!(w3,I256F256::from((3i128*2).pow(4)));
}

#[test]
fn test_bint(){
	let a=I32F32::ONE;
	assert_eq!(a*2,I32F32::from(2));
}

#[test]
fn test_fix(){
	assert_eq!(I32F32::ONE.fix_8(),I256F256::ONE);
	assert_eq!(I32F32::ONE,I256F256::ONE.fix_1());
	assert_eq!(I32F32::NEG_ONE.fix_8(),I256F256::NEG_ONE);
	assert_eq!(I32F32::NEG_ONE,I256F256::NEG_ONE.fix_1());
}
#[test]
fn test_sqrt(){
	let a=I32F32::ONE*4;
	assert_eq!(a.sqrt(),I32F32::from(2));
}
#[test]
fn test_sqrt_zero(){
	let a=I32F32::ZERO;
	assert_eq!(a.sqrt(),I32F32::ZERO);
}
#[test]
fn test_sqrt_low(){
	let a=I32F32::HALF;
	let b=a.fixed_mul(a);
	assert_eq!(b.sqrt(),a);
}
fn find_equiv_sqrt_via_f64(n:I32F32)->I32F32{
	//GIMME THEM BITS BOY
	let &[bits]=n.to_bits().to_bits().digits();
	let ibits=bits as i64;
	let f=(ibits as f64)/((1u64<<32) as f64);
	let f_ans=f.sqrt();
	let i=(f_ans*((1u64<<32) as f64)) as i64;
	let r=I32F32::from_bits(bnum::BInt::<1>::from(i));
	//mimic the behaviour of the algorithm,
	//return the result if it truncates to the exact answer
	if (r+I32F32::EPSILON).wide_mul_1_1(r+I32F32::EPSILON)==n.wide_mul_1_1(I32F32::ONE){
		return r+I32F32::EPSILON;
	}
	if (r-I32F32::EPSILON).wide_mul_1_1(r-I32F32::EPSILON)==n.wide_mul_1_1(I32F32::ONE){
		return r-I32F32::EPSILON;
	}
	return r;
}
fn test_exact(n:I32F32){
	assert_eq!(n.sqrt(),find_equiv_sqrt_via_f64(n));
}
#[test]
fn test_sqrt_exact(){
	//43
	for i in 0..((i64::MAX as f32).ln() as u32){
		let n=I32F32::from_bits(bnum::BInt::<1>::from((i as f32).exp() as i64));
		test_exact(n);
	}
}
#[test]
fn test_sqrt_max(){
	let a=I32F32::MAX;
	test_exact(a);
}
#[test]
#[cfg(all(feature="zeroes",not(feature="deferred-division")))]
fn test_zeroes_normal(){
	// (x-1)*(x+1)
	// x^2-1
	let zeroes=I32F32::zeroes2(I32F32::NEG_ONE,I32F32::ZERO,I32F32::ONE);
	assert_eq!(zeroes,arrayvec::ArrayVec::from_iter([I32F32::NEG_ONE,I32F32::ONE]));
	let zeroes=I32F32::zeroes2(I32F32::NEG_ONE*3,I32F32::ONE*2,I32F32::ONE);
	assert_eq!(zeroes,arrayvec::ArrayVec::from_iter([I32F32::NEG_ONE*3,I32F32::ONE]));
}
#[test]
#[cfg(all(feature="zeroes",feature="deferred-division"))]
fn test_zeroes_deferred_division(){
	// (x-1)*(x+1)
	// x^2-1
	let zeroes=I32F32::zeroes2(I32F32::NEG_ONE,I32F32::ZERO,I32F32::ONE);
	assert_eq!(
		zeroes,
		arrayvec::ArrayVec::from_iter([
			ratio_ops::ratio::Ratio::new(I32F32::ONE*2,I32F32::NEG_ONE*2),
			ratio_ops::ratio::Ratio::new(I32F32::ONE*2,I32F32::ONE*2),
		])
	);
}