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Save gas for pow by using uncheck #93

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merged 1 commit into from
Jun 19, 2024
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Save gas for pow by using uncheck #93

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13 changes: 8 additions & 5 deletions contracts/BinaryRelated.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -5,12 +5,15 @@ library BinaryRelated {
function pow(uint256 fp, uint256 n) internal pure returns (uint256) {
// 1.0 in Q128.128
uint256 v = 1 << 128;
while (n != 0) {
if ((n & 1) == 1) {
v = (v * fp) >> 128;
// we can use unchecked here because we know that fp is in the range [0, 2^128), and it can save gas if n is large
unchecked {
while (n != 0) {
if ((n & 1) == 1) {
v = (v * fp) >> 128;
}
fp = (fp * fp) >> 128;
n = n / 2;
}
fp = (fp * fp) >> 128;
n = n / 2;
}
return v;
}
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