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namespace ARMeilleure.Decoders
{
public static class OpCodeSimdHelper
{
public static (long Immediate, int Size) GetSimdImmediateAndSize(int cMode, int op, long imm)
{
int modeLow = cMode & 1;
int modeHigh = cMode >> 1;
int size = 0;
if (modeHigh == 0b111)
{
switch (op | (modeLow << 1))
{
case 0:
// 64-bits Immediate.
// Transform abcd efgh into abcd efgh abcd efgh ...
size = 3;
imm = (long)((ulong)imm * 0x0101010101010101);
break;
case 1:
// 64-bits Immediate.
// Transform abcd efgh into aaaa aaaa bbbb bbbb ...
size = 3;
imm = (imm & 0xf0) >> 4 | (imm & 0x0f) << 4;
imm = (imm & 0xcc) >> 2 | (imm & 0x33) << 2;
imm = (imm & 0xaa) >> 1 | (imm & 0x55) << 1;
imm = (long)((ulong)imm * 0x8040201008040201);
imm = (long)((ulong)imm & 0x8080808080808080);
imm |= imm >> 4;
imm |= imm >> 2;
imm |= imm >> 1;
break;
case 2:
// 2 x 32-bits floating point Immediate.
size = 3;
imm = (long)DecoderHelper.Imm8ToFP32Table[(int)imm];
imm |= imm << 32;
break;
case 3:
// 64-bits floating point Immediate.
size = 3;
imm = (long)DecoderHelper.Imm8ToFP64Table[(int)imm];
break;
}
}
else if ((modeHigh & 0b110) == 0b100)
{
// 16-bits shifted Immediate.
size = 1; imm <<= (modeHigh & 1) << 3;
}
else if ((modeHigh & 0b100) == 0b000)
{
// 32-bits shifted Immediate.
size = 2; imm <<= modeHigh << 3;
}
else if ((modeHigh & 0b111) == 0b110)
{
// 32-bits shifted Immediate (fill with ones).
size = 2; imm = ShlOnes(imm, 8 << modeLow);
}
else
{
// 8-bits without shift.
size = 0;
}
return (imm, size);
}
private static long ShlOnes(long value, int shift)
{
if (shift != 0)
{
return value << shift | (long)(ulong.MaxValue >> (64 - shift));
}
else
{
return value;
}
}
}
}
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