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ARMeilleure: A32: Implement SHADD8 (#3086)

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merry 2022-02-06 15:25:45 +00:00 • committed by GitHub
parent 222b1ad7da
commit 88d3ffb97c
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4 changed files with 59 additions and 16 deletions
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52
ARMeilleure/Instructions/InstEmitAlu32.cs
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@ -387,6 +387,11 @@ namespace ARMeilleure.Instructions
EmitDiv(context, false);
}
public static void Shadd8(ArmEmitterContext context)
{
EmitHadd8(context, false);
}
public static void Ssat(ArmEmitterContext context)
{
OpCode32Sat op = (OpCode32Sat)context.CurrOp;
@ -474,20 +479,7 @@ namespace ARMeilleure.Instructions
public static void Uhadd8(ArmEmitterContext context)
{
OpCode32AluReg op = (OpCode32AluReg)context.CurrOp;
Operand m = GetIntA32(context, op.Rm);
Operand n = GetIntA32(context, op.Rn);
Operand xor, res;
res = context.BitwiseAnd(m, n);
xor = context.BitwiseExclusiveOr(m, n);
xor = context.ShiftRightUI(xor, Const(1));
xor = context.BitwiseAnd(xor, Const(0x7F7F7F7Fu));
res = context.Add(res, xor);
SetIntA32(context, op.Rd, res);
EmitHadd8(context, true);
}
public static void Usat(ArmEmitterContext context)
@ -659,6 +651,36 @@ namespace ARMeilleure.Instructions
context.MarkLabel(lblEnd);
}
private static void EmitHadd8(ArmEmitterContext context, bool unsigned)
{
OpCode32AluReg op = (OpCode32AluReg)context.CurrOp;
Operand m = GetIntA32(context, op.Rm);
Operand n = GetIntA32(context, op.Rn);
Operand xor, res, carry;
// This relies on the equality x+y == ((x&y) << 1) + (x^y).
// Note that x^y always contains the LSB of the result.
// Since we want to calculate (x+y)/2, we can instead calculate (x&y) + ((x^y)>>1).
// We mask by 0x7F to remove the LSB so that it doesn't leak into the field below.
res = context.BitwiseAnd(m, n);
carry = context.BitwiseExclusiveOr(m, n);
xor = context.ShiftRightUI(carry, Const(1));
xor = context.BitwiseAnd(xor, Const(0x7F7F7F7Fu));
res = context.Add(res, xor);
if (!unsigned)
{
// Propagates the sign bit from (x^y)>>1 upwards by one.
carry = context.BitwiseAnd(carry, Const(0x80808080u));
res = context.BitwiseExclusiveOr(res, carry);
}
SetIntA32(context, op.Rd, res);
}
private static void EmitSat(ArmEmitterContext context, int intMin, int intMax)
{
OpCode32Sat op = (OpCode32Sat)context.CurrOp;
@ -772,4 +794,4 @@ namespace ARMeilleure.Instructions
EmitGenericAluStoreA32(context, op.Rd, op.SetFlags, value);
}
}
}
}