plonky2_por 1.4.4

OtterSec plonky2 proof of reserves
Documentation 
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use plonky2::plonk::circuit_builder::CircuitBuilder;    
use plonky2::iop::target::{BoolTarget, Target};
use plonky2::field::types::Field;
use crate::config::*;   

#[inline]
pub fn is_negative(builder: &mut CircuitBuilder<F, D>, x: Target) -> BoolTarget {
    let min_neg = F::from_canonical_u64(9223372034707292161u64); // 2**64 - 2**32 + 1 (GoldilocksField max negative integer)

    let min_neg_target = builder.constant(min_neg);
    let divided = builder.div(x, min_neg_target);
    let one = builder.one();

    // return if negative
    builder.is_equal(divided, one)
}

#[inline]
pub fn is_positive(builder: &mut CircuitBuilder<F, D>, x: Target) -> BoolTarget {
    let is_negative = is_negative(builder, x);
    builder.not(is_negative)
}