mirror of
https://github.com/kwsch/PKHeX
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552676ed3a
Never will happen, but not worth arguing over because this is essentially what the ROM does. Entry to this method requires both OK.
91c040b081/src/save.c (L587-L605)
Closes #3805
43 lines
1.4 KiB
C#
43 lines
1.4 KiB
C#
using System;
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using System.Buffers.Binary;
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namespace PKHeX.Core;
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/// <summary>
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/// Finds the index of the most recent save block for <see cref="SAV3"/> blocks.
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/// </summary>
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public static class SAV3BlockDetection
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{
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private const int First = 0;
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private const int Second = 1;
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private const int Same = 2;
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/// <summary>
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/// Compares the footers of the two blocks to determine which is newest.
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/// </summary>
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/// <returns>0=Primary, 1=Secondary.</returns>
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public static int CompareFooters(ReadOnlySpan<byte> data, int offset1, int offset2)
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{
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var counter1 = BinaryPrimitives.ReadUInt32LittleEndian(data[(offset1 + 0x0FFC)..]);
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var counter2 = BinaryPrimitives.ReadUInt32LittleEndian(data[(offset2 + 0x0FFC)..]);
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var result = CompareCounters(counter1, counter2);
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return result == Second ? Second : First; // Same -> First, shouldn't happen for valid saves.
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}
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private static int CompareCounters(uint counter1, uint counter2)
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{
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// Uninitialized -- only continue if a rollover case (humanly impossible)
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if (counter1 == uint.MaxValue && counter2 != uint.MaxValue - 1)
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return Second;
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if (counter2 == uint.MaxValue && counter1 != uint.MaxValue - 1)
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return First;
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// Different
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if (counter1 > counter2)
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return First;
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if (counter1 < counter2)
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return Second;
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return Same;
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}
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}
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