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| @@ -0,0 +1,4 @@ | ||
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| mod snark; | ||
| pub mod scaling_helpers; | ||
| pub use snark::*; |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,101 @@ | ||
| use std::convert::{TryFrom, TryInto}; | ||
| use std::{fmt::Debug, ops::Div}; | ||
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| use ark_ff::{BigInteger256, PrimeField}; | ||
| use ark_relations::r1cs::SynthesisError; | ||
| use num_bigint::{BigInt, BigUint, ToBigInt}; | ||
| use super::CircuitField; | ||
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||
| #[derive(Debug, Clone, Copy)] | ||
| /// Defines a scaling of a float by: x => round(s * x) + z | ||
| pub struct ScaleT { | ||
| pub s : u128, | ||
| pub z : u128 | ||
| } | ||
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||
| /// Convert a float to a scaled integer. | ||
| /// | ||
| /// See [Note: floats as ints] | ||
| pub fn scaled_float(x: f32, scale: &ScaleT) -> BigInt { | ||
| // // TODO: handle errors upstream | ||
| let s = scale.s; | ||
| let z = scale.z; | ||
| let x : f64 = x.into(); | ||
| // assert!( (- (z as f64) / (s as f64) <= x) && (x <= (z as f64) / (s as f64)) , "Float within allowed range"); | ||
| let scaled: BigInt = ((x * (s as f64)).round()).to_bigint().expect("scaled_float: Conversion to bigint failed"); | ||
| scaled + z | ||
| // todo: handle the unwrap upstream | ||
| // assert!(y.is_positive(), "Scaled float outside of the range!"); | ||
| // assert!( ((((y - z) / s) as f64) - x).abs() <= x * 0.0001 , "Float is recoverable"); | ||
| } | ||
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| // TODO: factor out a module with conversion helpers | ||
| pub fn unscaled_f(x : CircuitField, scale: &ScaleT) -> Option<f32> { | ||
| unscaled_bigint(i256_to_bigint(x.into_repr()), scale) | ||
| } | ||
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| pub fn unscaled_bigint(x: BigInt, scale: &ScaleT) -> Option<f32> { | ||
| // // TODO: handle errors upstream | ||
| let s = scale.s; | ||
| let z = scale.z; | ||
| let div: i128 = ((x.clone() - z) / s).try_into().ok()?; | ||
| let rem: u64 = ((x - z) % s).try_into().ok()?; | ||
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| Some(((div as f64) + ((rem as f64) / (s as f64))) as f32) | ||
| // todo: handle the unwrap upstream | ||
| // assert!(y.is_positive(), "Scaled float outside of the range!"); | ||
| // assert!( ((((y - z) / s) as f64) - x).abs() <= x * 0.0001 , "Float is recoverable"); | ||
| } | ||
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| pub fn positive_bigint(b: BigInt) -> BigUint { | ||
| b.try_into().expect("Expects positive bigint, otherwise its negative float overflow") | ||
| } | ||
| pub fn f_from_bigint(b: BigInt) -> Result<CircuitField, SynthesisError> { | ||
| CircuitField::try_from(positive_bigint(b)).map_err(|_| SynthesisError::AssignmentMissing) | ||
| } | ||
| pub fn f_from_bigint_unsafe(b: BigInt) -> CircuitField { | ||
| f_from_bigint(b).expect("Expects bigint to fit in the prime field range, otherwise its positive float overflow") | ||
| } | ||
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| pub fn i256_to_bigint(a: BigInteger256) -> BigInt { | ||
| let x : BigUint = a.into(); | ||
| x.into() | ||
| // // let x: u128 = a.try_into(); | ||
| // (BigInt::from(q) << (64 * 3)) + (BigInt::from(w) << (64 * 2)) + (BigInt::from(e) << 64) + BigInt::from(r) | ||
| } | ||
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| pub fn field_elems_close(a : CircuitField , b : CircuitField, scale: ScaleT) -> bool { | ||
| let a = i256_to_bigint(a.into_repr()); | ||
| let b = i256_to_bigint(b.into_repr()); | ||
| let diff = if a < b {b.clone() - a.clone()} else {a.clone() - b.clone()}; | ||
| diff.le( | ||
| & ( (a.max(b)).div(scale.s * 100) ) | ||
| ) | ||
| } | ||
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| pub fn floats_close(a : f32, b: f32) -> bool { | ||
| (a - b).abs().le( & (0.001 * (a.abs() + b.abs()).max(1.0) ) ) | ||
| } | ||
| pub fn bigints_close_as_floats(a : BigInt, b: BigInt, scale: &ScaleT) -> bool { | ||
| let ab = || { | ||
| let aa = unscaled_bigint(a, scale)?; | ||
| let bb = unscaled_bigint(b, scale)?; | ||
| Some((aa, bb)) | ||
| }; | ||
| match ab() { | ||
| None => false, | ||
| Some((a, b)) => floats_close(a, b) | ||
| } | ||
| } | ||
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| pub fn field_close_as_floats(a : CircuitField, b: CircuitField, scale: &ScaleT) -> bool { | ||
| let ab = || { | ||
| let aa = unscaled_f(a, scale)?; | ||
| let bb = unscaled_f(b, scale)?; | ||
| Some((aa, bb)) | ||
| }; | ||
| match ab() { | ||
| None => false, | ||
| Some((a, b)) => floats_close(a, b) | ||
| } | ||
| } |
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