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Merged
thedavidmeister merged 2 commits into from
Aug 15, 2025
Merged

update div precision #104

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update div precision
thedavidmeister Aug 15, 2025
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thedavidmeister Aug 15, 2025
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159 changes: 75 additions & 84 deletions .gas-snapshot
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10 changes: 5 additions & 5 deletions src/lib/implementation/LibDecimalFloatImplementation.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -189,11 +189,11 @@ library LibDecimalFloatImplementation {
returns (int256, int256)
{
unchecked {
(signedCoefficientA, exponentA) = normalize(signedCoefficientA, exponentA);
(signedCoefficientA, exponentA) = maximize(signedCoefficientA, exponentA);
(signedCoefficientB, exponentB) = normalize(signedCoefficientB, exponentB);

int256 signedCoefficient = (signedCoefficientA * 1e38) / signedCoefficientB;
int256 exponent = exponentA - exponentB - 38;
int256 signedCoefficient = signedCoefficientA / signedCoefficientB;
int256 exponent = exponentA - exponentB;
return (signedCoefficient, exponent);
}
}
Expand Down Expand Up @@ -371,8 +371,8 @@ library LibDecimalFloatImplementation {
function inv(int256 signedCoefficient, int256 exponent) internal pure returns (int256, int256) {
(signedCoefficient, exponent) = normalize(signedCoefficient, exponent);

signedCoefficient = 1e75 / signedCoefficient;
exponent = -exponent - 75;
signedCoefficient = 1e76 / signedCoefficient;
exponent = -exponent - 76;

return (signedCoefficient, exponent);
}
Expand Down
4 changes: 2 additions & 2 deletions test/lib/LibCommonResults.sol
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
// SPDX-License-Identifier: CAL
pragma solidity ^0.8.25;

int256 constant ONES = 11111111111111111111111111111111111111;
int256 constant THREES = 33333333333333333333333333333333333333;
int256 constant ONES = 111111111111111111111111111111111111111;
int256 constant THREES = 333333333333333333333333333333333333333;
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6 changes: 3 additions & 3 deletions test/src/lib/LibDecimalFloat.mixed.t.sol
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Expand Up @@ -16,12 +16,12 @@ contract LibDecimalFloatMixedTest is Test {
Float c = a.div(b);
(int256 signedCoefficientDiv, int256 exponentDiv) = LibDecimalFloat.unpack(c);
assertEq(signedCoefficientDiv, THREES, "coefficient");
assertEq(exponentDiv, -38, "exponent");
assertEq(exponentDiv, -39, "exponent");

Float d = c.mul(LibDecimalFloat.packLossless(555, 18));
(int256 signedCoefficientMul, int256 exponentMul) = LibDecimalFloat.unpack(d);

assertEq(signedCoefficientMul, 18499999999999999999999999999999999999815);
assertEq(exponentMul, -20);
assertEq(signedCoefficientMul, 184999999999999999999999999999999999999815);
assertEq(exponentMul, -21);
}
}
4 changes: 2 additions & 2 deletions test/src/lib/LibDecimalFloat.pow.t.sol
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Expand Up @@ -38,8 +38,8 @@ contract LibDecimalFloatPowTest is LogTest {
}

function testPows() external {
checkPow(5e37, -38, 3e37, -36, 9.3283582089552238805970149253731343283e37, -47);
checkPow(5e37, -38, 6e37, -36, 8.7108013937282229965156794425087108013e37, -56);
checkPow(5e37, -38, 3e37, -36, 9.32835820895522388059701492537313432835e38, -48);
checkPow(5e37, -38, 6e37, -36, 8.71080139372822299651567944250871080139e38, -57);
// // Issues found in fuzzing from here.
checkPow(99999, 0, 12182, 0, 1000, 60907);
checkPow(1785215562, 0, 18, 0, 3388, 163);
Expand Down
22 changes: 11 additions & 11 deletions test/src/lib/implementation/LibDecimalFloatImplementation.div.t.sol
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Expand Up @@ -40,12 +40,12 @@ contract LibDecimalFloatImplementationDivTest is Test {

/// 1 / 3
function testDiv1Over3() external pure {
checkDiv(1, 0, 3, 0, THREES, -38);
checkDiv(1, 0, 3, 0, THREES, -39);
}
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/// - 1 / 3
function testDivNegative1Over3() external pure {
checkDiv(-1, 0, 3, 0, -THREES, -38);
checkDiv(-1, 0, 3, 0, -THREES, -39);
}
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/// 1 / 3 gas
Expand All @@ -56,41 +56,41 @@ contract LibDecimalFloatImplementationDivTest is Test {

/// 1e18 / 3
function testDiv1e18Over3() external pure {
checkDiv(1e18, 0, 3, 0, THREES, -20);
checkDiv(1e18, 0, 3, 0, THREES, -21);
}
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/// 10,0 / 1e38,-37 == 1
function testDivTenOverOOMs() external pure {
checkDiv(10, 0, 1e38, -37, 1e38, -38);
checkDiv(10, 0, 1e38, -37, 1e39, -39);
}
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/// 1e38,-37 / 2,0 == 5
function testDivOOMsOverTen() external pure {
checkDiv(1e38, -37, 2, 0, 5e37, -37);
checkDiv(1e38, -37, 2, 0, 5e38, -38);
}
Comment on lines +69 to 70
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@coderabbitai coderabbitai Bot Aug 15, 2025

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🧹 Nitpick (assertive)

Express -38 as 1 - SCALE to tie it to global precision.

This better communicates the relation to the base scale.

-        checkDiv(1e38, -37, 2, 0, 5e38, -38);
+        checkDiv(1e38, -37, 2, 0, 5e38, 1 - SCALE);
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
checkDiv(1e38, -37, 2, 0, 5e38, -38);
}
checkDiv(1e38, -37, 2, 0, 5e38, 1 - SCALE);
}
🤖 Prompt for AI Agents 
In test/src/lib/implementation/LibDecimalFloatImplementation.div.t.sol around
lines 69-70, the exponent literal "-38" should be expressed relative to the
global SCALE constant; replace the hardcoded -38 with "1 - SCALE" so the test
ties the exponent to the library's precision (i.e., change the call
checkDiv(1e38, -37, 2, 0, 5e38, -38) to use 1 - SCALE instead of -38).


/// 5e37,-37 / 2e37,-37 == 2.5
function testDivOOMs5and2() external pure {
checkDiv(5e37, -37, 2e37, -37, 25e37, -38);
checkDiv(5e37, -37, 2e37, -37, 25e38, -39);
}
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/// (1 / 9) / (1 / 3) == 0.333..
function testDiv1Over9Over1Over3() external pure {
// 1 / 9
(int256 signedCoefficientA, int256 exponentA) = LibDecimalFloatImplementation.div(1, 0, 9, 0);
assertEq(signedCoefficientA, ONES);
assertEq(exponentA, -38);
assertEq(exponentA, -39);

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// 1 / 3
(int256 signedCoefficientB, int256 exponentB) = LibDecimalFloatImplementation.div(1, 0, 3, 0);
assertEq(signedCoefficientB, THREES);
assertEq(exponentB, -38);
assertEq(exponentB, -39);

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// (1 / 9) / (1 / 3)
(int256 signedCoefficient, int256 exponent) =
LibDecimalFloatImplementation.div(signedCoefficientA, exponentA, signedCoefficientB, exponentB);
assertEq(signedCoefficient, THREES);
assertEq(exponent, -38);
assertEq(signedCoefficient, 333333333333333333333333333333333333336);
assertEq(exponent, -39);
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}

/// forge-config: default.fuzz.runs = 100
Expand All @@ -102,7 +102,7 @@ contract LibDecimalFloatImplementationDivTest is Test {
int256 di = 0;
while (true) {
int256 i = 1;
int256 j = -38 - di;
int256 j = -39 - di;
while (true) {
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// want to see full precision on the THREES regardless of the
// scale of the numerator and denominator.
Expand Down
2 changes: 1 addition & 1 deletion test/src/lib/implementation/LibDecimalFloatImplementation.pow10.t.sol
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Expand Up @@ -56,7 +56,7 @@ contract LibDecimalFloatImplementationPow10Test is LogTest {
checkPow10(0.5e37, -37, 3162, -3);

checkPow10(0.3e37, -37, 1995, -3);
checkPow10(-0.3e37, -37, 5.012531328320802005012531328320802005e37, -38);
checkPow10(-0.3e37, -37, 0.501253132832080200501253132832080200501e39, -39);
}

function testInterpolatedLookupsPower() external {
Expand Down
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