Implement Frsqrte_S (#72)

* Implement Frsqrte_S

* Implement Frsqrte_V

* Add Frsqrte_S test
This commit is contained in:
Merry 2018-04-06 00:36:19 +01:00 committed by gdkchan
parent ee98d50e17
commit c4c247deb4
4 changed files with 141 additions and 0 deletions

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@ -225,6 +225,8 @@ namespace ChocolArm64
Set("0>0011101<100001100010xxxxxxxxxx", AInstEmit.Frintp_V, typeof(AOpCodeSimd));
Set("000111100x100111010000xxxxxxxxxx", AInstEmit.Frintx_S, typeof(AOpCodeSimd));
Set("0>1011100<100001100110xxxxxxxxxx", AInstEmit.Frintx_V, typeof(AOpCodeSimd));
Set("011111101x100001110110xxxxxxxxxx", AInstEmit.Frsqrte_S, typeof(AOpCodeSimd));
Set("0>1011101<100001110110xxxxxxxxxx", AInstEmit.Frsqrte_V, typeof(AOpCodeSimd));
Set("000111100x100001110000xxxxxxxxxx", AInstEmit.Fsqrt_S, typeof(AOpCodeSimd));
Set("000111100x1xxxxx001110xxxxxxxxxx", AInstEmit.Fsub_S, typeof(AOpCodeSimdReg));
Set("0>0011101<1xxxxx110101xxxxxxxxxx", AInstEmit.Fsub_V, typeof(AOpCodeSimdReg));

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@ -476,6 +476,22 @@ namespace ChocolArm64.Instruction
});
}
public static void Frsqrte_S(AILEmitterCtx Context)
{
EmitScalarUnaryOpF(Context, () =>
{
EmitUnarySoftFloatCall(Context, nameof(ASoftFloat.InvSqrtEstimate));
});
}
public static void Frsqrte_V(AILEmitterCtx Context)
{
EmitVectorUnaryOpF(Context, () =>
{
EmitUnarySoftFloatCall(Context, nameof(ASoftFloat.InvSqrtEstimate));
});
}
public static void Fsqrt_S(AILEmitterCtx Context)
{
EmitScalarUnaryOpF(Context, () =>

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@ -100,6 +100,26 @@ namespace ChocolArm64.Instruction
Context.EmitCall(MthdInfo);
}
public static void EmitUnarySoftFloatCall(AILEmitterCtx Context, string Name)
{
IAOpCodeSimd Op = (IAOpCodeSimd)Context.CurrOp;
int SizeF = Op.Size & 1;
MethodInfo MthdInfo;
if (SizeF == 0)
{
MthdInfo = typeof(ASoftFloat).GetMethod(Name, new Type[] { typeof(float) });
}
else /* if (SizeF == 1) */
{
MthdInfo = typeof(ASoftFloat).GetMethod(Name, new Type[] { typeof(double) });
}
Context.EmitCall(MthdInfo);
}
public static void EmitScalarUnaryOpSx(AILEmitterCtx Context, Action Emit)
{
EmitScalarOp(Context, Emit, OperFlags.Rn, true);

103
Instruction/ASoftFloat.cs Normal file
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@ -0,0 +1,103 @@
using System;
namespace ChocolArm64.Instruction
{
static class ASoftFloat
{
static ASoftFloat()
{
InvSqrtEstimateTable = BuildInvSqrtEstimateTable();
}
private static readonly byte[] InvSqrtEstimateTable;
private static byte[] BuildInvSqrtEstimateTable()
{
byte[] Table = new byte[512];
for (ulong index = 128; index < 512; index++)
{
ulong a = index;
if (a < 256)
{
a = (a << 1) + 1;
}
else
{
a = (a | 1) << 1;
}
ulong b = 256;
while (a * (b + 1) * (b + 1) < (1ul << 28))
{
b++;
}
b = (b + 1) >> 1;
Table[index] = (byte)(b & 0xFF);
}
return Table;
}
public static float InvSqrtEstimate(float x)
{
return (float)InvSqrtEstimate((double)x);
}
public static double InvSqrtEstimate(double x)
{
ulong x_bits = (ulong)BitConverter.DoubleToInt64Bits(x);
ulong x_sign = x_bits & 0x8000000000000000;
long x_exp = (long)((x_bits >> 52) & 0x7FF);
ulong scaled = x_bits & ((1ul << 52) - 1);
if (x_exp == 0x7ff)
{
if (scaled == 0)
{
// Infinity -> Zero
return BitConverter.Int64BitsToDouble((long)x_sign);
}
// NaN
return BitConverter.Int64BitsToDouble((long)(x_bits | 0x0008000000000000));
}
if (x_exp == 0)
{
if (scaled == 0)
{
// Zero -> Infinity
return BitConverter.Int64BitsToDouble((long)(x_sign | 0x7ff0000000000000));
}
// Denormal
while ((scaled & (1 << 51)) == 0)
{
scaled <<= 1;
x_exp--;
}
scaled <<= 1;
}
if (((ulong)x_exp & 1) == 1)
{
scaled >>= 45;
scaled &= 0xFF;
scaled |= 0x80;
}
else
{
scaled >>= 44;
scaled &= 0xFF;
scaled |= 0x100;
}
ulong result_exp = ((ulong)(3068 - x_exp) / 2) & 0x7FF;
ulong estimate = (ulong)InvSqrtEstimateTable[scaled];
ulong fraction = estimate << 44;
ulong result = x_sign | (result_exp << 52) | fraction;
return BitConverter.Int64BitsToDouble((long)result);
}
}
}