mirrors/Ryujinx
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Faster soft implementation of smulh and umulh

Browse source
This commit is contained in:
riperiperi 2018-06-06 22:56:27 +01:00
parent df33dcc489
commit 658e3fe24a
1 changed files with 20 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
ChocolArm64/Instruction/ASoftFallback.cs
View file

@ -153,12 +153,30 @@ namespace ChocolArm64.Instruction
public static long SMulHi128(long LHS, long RHS)
{
return (long)(BigInteger.Multiply(LHS, RHS) >> 64);
bool LSign = (LHS < 0);
bool RSign = (RHS < 0);
long Result = (long)UMulHi128((ulong)(LSign ? -LHS : LHS), (ulong)(RSign ? -RHS : RHS));
if (LSign != RSign)
return (-Result) - 1; //for negative results, hi 64-bits start at 0xFFF... and count back
return Result;
}
public static ulong UMulHi128(ulong LHS, ulong RHS)
{
return (ulong)(BigInteger.Multiply(LHS, RHS) >> 64);
//long multiplication
//multiply 32 bits at a time in 64 bit, the result is what's carried over 64 bits.
ulong LHigh = LHS >> 32;
ulong LLow = LHS & 0xFFFFFFFF;
ulong RHigh = RHS >> 32;
ulong RLow = RHS & 0xFFFFFFFF;
ulong Z2 = LLow * RLow;
ulong T = LHigh * RLow + (Z2 >> 32);
ulong Z1 = T & 0xFFFFFFFF;
ulong Z0 = T >> 32;
Z1 += LLow * RHigh;
return LHigh * RHigh + Z0 + (Z1 >> 32);
}
}
}