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Have split_low_high use range_check (#311)

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Daniel Lubarov 2021-10-20 23:43:35 -07:00 committed by GitHub
parent cd13a3be65
commit 0b75b24c09
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1 changed files with 6 additions and 4 deletions
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10
src/gadgets/range_check.rs
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@ -24,10 +24,9 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
/// Returns `(a,b)` such that `x = a + 2^n_log * b` with `a < 2^n_log`.
/// `x` is assumed to be range-checked for having `num_bits` bits.
pub fn split_low_high(&mut self, x: Target, n_log: usize, num_bits: usize) -> (Target, Target) {
let low_gate = self.add_gate(BaseSumGate::<2>::new(n_log), vec![]);
let high_gate = self.add_gate(BaseSumGate::<2>::new(num_bits - n_log), vec![]);
let low = Target::wire(low_gate, BaseSumGate::<2>::WIRE_SUM);
let high = Target::wire(high_gate, BaseSumGate::<2>::WIRE_SUM);
let low = self.add_virtual_target();
let high = self.add_virtual_target();
self.add_simple_generator(LowHighGenerator {
integer: x,
n_log,
@ -35,6 +34,9 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
high,
});
self.range_check(low, n_log);
self.range_check(high, num_bits - n_log);
let pow2 = self.constant(F::from_canonical_u64(1 << n_log));
let comp_x = self.mul_add(high, pow2, low);
self.connect(x, comp_x);