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Inline bit-shifting
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@ -184,15 +184,6 @@ fn multiexp_serial<C: CurveAffine>(coeffs: &[C::Scalar], bases: &[C], acc: &mut
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/// Uses the double-and-add algorithm with doublings shared across points.
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pub fn small_multiexp<C: CurveAffine>(coeffs: &[C::Scalar], bases: &[C]) -> C::Projective {
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// Gets the bit at position `i`. Bits are numbered from 0 (least significant) to 7 (most significant).
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fn get_bit_at(byte: u8, i: usize) -> bool {
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if i < 8 {
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((byte >> i) & 1u8) != 0
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} else {
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false
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}
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}
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let coeffs: Vec<[u8; 32]> = coeffs.iter().map(|a| a.to_bytes()).collect();
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let mut acc = C::Projective::zero();
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@ -203,7 +194,8 @@ pub fn small_multiexp<C: CurveAffine>(coeffs: &[C::Scalar], bases: &[C]) -> C::P
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acc = acc.double();
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// for each coeff
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for coeff_idx in 0..coeffs.len() {
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if get_bit_at(coeffs[coeff_idx][byte_idx], bit_idx) {
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let byte = coeffs[coeff_idx][byte_idx];
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if (byte >> bit_idx & 1) != 0 {
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acc = acc + &bases[coeff_idx].to_projective();
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}
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}
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