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fix a typo #201

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Merged
niconiconi merged 1 commit into from
Feb 9, 2026
Merged

fix a typo #201

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2 changes: 1 addition & 1 deletion circuit-std-rs/src/logup.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -426,7 +426,7 @@ impl LogUpRangeProofTable {
let rem = n % self.rangeproof_bits;
let shift = self.rangeproof_bits - rem;
let constant = (1 << shift) - 1;
let mut mul_factor = 0;
let mut mul_factor = 1;
mul_factor <<= n;
let a_shift = builder.mul(constant, mul_factor);
Comment on lines +429 to 431
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@gemini-code-assist gemini-code-assist bot Feb 7, 2026

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medium

While initializing mul_factor to 1 is the correct fix, the code can be made more robust. The type of mul_factor is inferred by the compiler and could overflow if n is large (e.g., > 31). To prevent potential overflows and align with the implementation in the rangeproof function, it's better to explicitly type mul_factor as u128 and convert it to a circuit variable before the multiplication.

A similar issue exists for constant on line 428, which would also benefit from an explicit type like u128 to prevent potential overflows.

Suggested change
let mut mul_factor = 1;
mul_factor <<= n;
let a_shift = builder.mul(constant, mul_factor);
let mul_factor: u128 = 1 << n;
let mul_factor_u256 = U256::new(mul_factor);
let mul_factor_var = builder.constant(CircuitField::<C>::from_u256(mul_factor_u256));
let a_shift = builder.mul(constant, mul_factor_var);

new_a = builder.add(a, a_shift);
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