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Perf epns #280

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merged 4 commits into from
Jan 1, 2025
Merged

Perf epns #280

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e751b36
perf: neg_3_base_le rangecheck optim
shramee Jan 1, 2025
0b5ab04
perf(scalar epns): divrem to p/n sums
shramee Jan 1, 2025
b31ba6f
chore: update ecip classhash
shramee Jan 1, 2025
013dfbd
chore: update risc0 verifier class hash
shramee Jan 1, 2025
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33 changes: 24 additions & 9 deletions src/src/utils/neg_3.cairo
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ pub fn neg_3_base_le(scalar: u128) -> Array<felt252> {

while scalar != 0 {
let (q, r) = core::traits::DivRem::div_rem(scalar, 3);
let r: felt252 = r.into();

if r == 2 {
if scalar_negative {
Expand All @@ -55,10 +56,10 @@ pub fn neg_3_base_le(scalar: u128) -> Array<felt252> {
} else {
if scalar_negative {
scalar = q;
digits.append(-r.into());
digits.append(-r);
} else {
scalar = q;
digits.append(r.into());
digits.append(r);
}
}
scalar_negative = !scalar_negative;
Expand Down Expand Up @@ -139,23 +140,37 @@ pub fn u128_array_to_epns(
// Where sum_p = sum(digits[i] * (-3)^i for i in [0, 81] if digits[i]==1)
// And sum_n = sum(digits[i] * (-3)^i for i in [0, 81] if digits[i]==-1)
// Returns (abs(sum_p), abs(sum_n), p_sign, n_sign)
pub fn scalar_to_epns(scalar: u128) -> (felt252, felt252, felt252, felt252) {
let mut digits: Array<felt252> = neg_3_base_le(scalar);

pub fn scalar_to_epns(mut scalar: u128) -> (felt252, felt252, felt252, felt252) {
let mut sum_p = 0;
let mut sum_n = 0;

let mut base_power = 1; // Init to (-3)^0

while let Option::Some(digit) = digits.pop_front() {
if digit != 0 {
if digit == 1 {
let mut scalar_negative: bool = false;

while scalar != 0 {
let (q, r) = core::traits::DivRem::div_rem(scalar, 3);
let r: felt252 = r.into();
if r == 0 {
scalar = q;
} else if r == 2 {
if scalar_negative {
scalar = q + 1;
sum_p += base_power;
} else {
scalar = q + 1;
sum_n += base_power;
}
} else {
if scalar_negative {
scalar = q;
sum_n += base_power;
} else {
scalar = q;
sum_p += base_power;
}
}

scalar_negative = !scalar_negative;
base_power = base_power * (-3);
};

Expand Down
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