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Merge pull request #123 from mlemanczyk/codex/adjust-bydivisor-path-for-divisor-cycles

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Align CPU by-divisor scan with divisor cycle cache filters
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Marek Lemańczyk authored and GitHub committed 2025-10-08 20:16:05 +02:00
2 parents 632957e4f4 c45b3951c3
commit 4afe0e356e
1 file changed
+9 -1
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PerfectNumbers.Core/Cpu/MersenneNumberDivisorByDivisorCpuTester.cs
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@@ -196,12 +196,18 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
byte step8 = (byte)(step % 8UL); byte step8 = (byte)(step % 8UL);
byte step5 = (byte)(step % 5UL); byte step5 = (byte)(step % 5UL);
byte step3 = (byte)(step % 3UL); byte step3 = (byte)(step % 3UL);
byte step7 = (byte)(step % 7UL);
byte step11 = (byte)(step % 11UL);
byte remainder10 = (byte)(divisor % 10UL); byte remainder10 = (byte)(divisor % 10UL);
byte remainder8 = (byte)(divisor % 8UL); byte remainder8 = (byte)(divisor % 8UL);
byte remainder5 = (byte)(divisor % 5UL); byte remainder5 = (byte)(divisor % 5UL);
byte remainder3 = (byte)(divisor % 3UL); byte remainder3 = (byte)(divisor % 3UL);
byte remainder7 = (byte)(divisor % 7UL);
byte remainder11 = (byte)(divisor % 11UL);
// Keep the divisibility filters aligned with the divisor-cycle generator so the
// CPU path never requests cycles that were skipped during cache creation.
bool lastIsSeven = (prime & 3UL) == 3UL; bool lastIsSeven = (prime & 3UL) == 3UL;
while (divisor <= limit) while (divisor <= limit)
@@ -214,7 +220,7 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
? (remainder10 == 3 || remainder10 == 7 || remainder10 == 9) ? (remainder10 == 3 || remainder10 == 7 || remainder10 == 9)
: (remainder10 == 1 || remainder10 == 3 || remainder10 == 9); : (remainder10 == 1 || remainder10 == 3 || remainder10 == 9);
if (admissible && (remainder8 == 1 || remainder8 == 7) && remainder3 != 0 && remainder5 != 0) if (admissible && (remainder8 == 1 || remainder8 == 7) && remainder3 != 0 && remainder5 != 0 && remainder7 != 0 && remainder11 != 0)
{ {
MontgomeryDivisorData divisorData = MontgomeryDivisorDataCache.Get(candidate); MontgomeryDivisorData divisorData = MontgomeryDivisorDataCache.Get(candidate);
ulong divisorCycle; ulong divisorCycle;
@@ -244,6 +250,8 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
remainder8 = AddMod(remainder8, step8, (byte)8); remainder8 = AddMod(remainder8, step8, (byte)8);
remainder5 = AddMod(remainder5, step5, (byte)5); remainder5 = AddMod(remainder5, step5, (byte)5);
remainder3 = AddMod(remainder3, step3, (byte)3); remainder3 = AddMod(remainder3, step3, (byte)3);
remainder7 = AddMod(remainder7, step7, (byte)7);
remainder11 = AddMod(remainder11, step11, (byte)11);
} }
processedAll = divisor > limit; processedAll = divisor > limit;