try to reverse engineer THIS:
public static byte[] DecompressOverlay(byte[] sourcedata)
{
uint DataVar1, DataVar2;
//uint last 8-5 bytes
DataVar1 = (uint)(sourcedata[sourcedata.Length - 8] | (sourcedata[sourcedata.Length - 7] << 8) | (sourcedata[sourcedata.Length - 6] << 16) | (sourcedata[sourcedata.Length - 5] << 24))
//uint last 4 bytes
DataVar2 = (uint)(sourcedata[sourcedata.Length - 4] | (sourcedata[sourcedata.Length - 3] << 8) | (sourcedata[sourcedata.Length - 2] << 16) | (sourcedata[sourcedata.Length - 1] << 24))
byte[] memory = new byte[sourcedata.Length + DataVar2];
sourcedata.CopyTo(memory, 0)
uint r0, r1, r2, r3, r5, r6, r7, r12;
bool N, V;
r0 = (uint)sourcedata.Length;
if (r0 == 0) {
return null;
}
r1 = DataVar1;
r2 = DataVar2;
r2 = r0 + r2; //length + datavar2 -> decompressed length
r3 = r0 - (r1 >> 0x18) //delete the latest 3 bits??
r1 &= 0xFFFFFF; //save the latest 3 bits
r1 = r0 - r1;
a958:
if (r3 <= r1) { //if r1 is 0 they will be equal
goto a9B8; //return the memory buffer
}
r3 -= 1;
r5 = memory[r3];
r6 = 8;
a968:
SubS(out r6, r6, 1, out N, out V)
if (N != V) {
goto a958;
}
if ((r5 & 0x80) != 0) {
goto a984;
}
r3 -= 1;
r0 = memory[r3];
r2 -= 1;
memory[r2] = (byte)r0;
goto a9AC;
a984:
r3 -= 1;
r12 = memory[r3];
r3 -= 1;
r7 = memory[r3];
r7 |= (r12 << 8)
r7 &= 0xFFF;
r7 += 2;
r12 += 0x20;
a99C:
r0 = memory[r2 + r7];
r2 -= 1;
memory[r2] = (byte)r0;
SubS(out r12, r12, 0x10, out N, out V)
if (N == V) {
goto a99C;
}
a9AC:
r5 <<= 1;
if (r3 > r1) {
goto a968;
}
a9B8:
return memory;
}
private static void SubS(out uint dest, uint v1, uint v2, out bool N, out bool V) {
dest = v1 - v2;
N = (dest & 2147483648) != 0;
V = ((((v1 & 2147483648) != 0) && ((v2 & 2147483648) == 0) && ((dest & 2147483648) == 0)) || ((v1 & 2147483648) == 0) && ((v2 & 2147483648) != 0) && ((dest & 2147483648) != 0))
}
It has been translated from the ASM code of the game directly, we have NO IDEA of what it does |
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