Add most of the A32 instruction set to ARMeilleure (#897)

* Implement TEQ and MOV (Imm16)

* Initial work on A32 instructions + SVC. No tests yet, hangs in rtld.

* Implement CLZ, fix BFI and BFC

Now stops on SIMD initialization.

* Exclusive access instructions, fix to mul, system instructions.

Now gets to a break after SignalProcessWideKey64.

* Better impl of UBFX, add UDIV and SDIV

Now boots way further - now stuck on VMOV instruction.

* Many more instructions, start on SIMD and testing framework.

* Fix build issues

* svc: Rework 32 bit codepath

Fixing once and for all argument ordering issues.

* Fix 32 bits stacktrace

* hle debug: Add 32 bits dynamic section parsing

* Fix highCq mode, add many tests, fix some instruction bugs

Still suffers from critical malloc failure :weary:

* Fix incorrect opcode decoders and a few more instructions.

* Add a few instructions and fix others. re-disable highCq for now.

Disabled the svc memory clear since i'm not sure about it.

* Fix build

* Fix typo in ordered/exclusive stores.

* Implement some more instructions, fix others.

Uxtab16/Sxtab16 are untested.

* Begin impl of pairwise, some other instructions.

* Add a few more instructions, a quick hack to fix svcs for now.

* Add tests and fix issues with VTRN, VZIP, VUZP

* Add a few more instructions, fix Vmul_1 encoding.

* Fix way too many instruction bugs, add tests for some of the more important ones.

* Fix HighCq, enable FastFP paths for some floating point instructions

(not entirely sure why these were disabled, so important to note this
commit exists)

Branching has been removed in A32 shifts until I figure out if it's
worth it

* Cleanup Part 1

There should be no functional change between these next few commits.
Should is the key word. (except for removing break handler)

* Implement 32 bits syscalls

Co-authored-by: riperiperi <rhy3756547@hotmail.com>

Implement all 32 bits counterparts of the 64 bits syscalls we currently
have.

* Refactor part 2: Move index/subindex logic to Operand

May have inadvertently fixed one (1) bug

* Add FlushProcessDataCache32

* Address jd's comments

* Remove 16 bit encodings from OpCodeTable

Still need to catch some edge cases (operands that use the "F" flag) and
make Q encodings with non-even indexes undefined.

* Correct Fpscr handling for FP vector slow paths

WIP

* Add StandardFPSCRValue behaviour for all Arithmetic instructions

* Add StandardFPSCRValue behaviour to compare instructions.

* Force passing of fpcr to FPProcessException and FPUnpack.

Reduces potential for code error significantly

* OpCode cleanup

* Remove urgency from DMB comment in MRRC

DMB is currently a no-op via the instruction, so it should likely still
be a no-op here.

* Test Cleanup

* Fix FPDefaultNaN on Ryzen CPUs

* Improve some tests, fix some shift instructions, add slow path for Vadd

* Fix Typo

* More test cleanup

* Flip order of Fx and index, to indicate that the operand's is the "base"

* Remove Simd32 register type, use Int32 and Int64 for scalars like A64 does.

* Reintroduce alignment to DecoderHelper (removed by accident)

* One more realign as reading diffs is hard

* Use I32 registers in A32 (part 2)

Swap default integer register type based on current execution mode.

* FPSCR flags as Registers (part 1)

Still need to change NativeContext and ExecutionContext to allow
getting/setting with the flag values.

* Use I32 registers in A32 (part 1)

* FPSCR flags as registers (part 2)

Only CMP flags are on the registers right now. It could be useful to use
more of the space in non-fast-float when implementing A32 flags
accurately in the fast path.

* Address Feedback

* Correct FP->Int behaviour (should saturate)

* Make branches made by writing to PC eligible for Rejit

Greatly improves performance in most games.

* Remove unused branching for Vtbl

* RejitRequest as a class rather than a tuple

Makes a lot more sense than storing tuples on a dictionary.

* Add VMOVN, VSHR (imm), VSHRN (imm) and related tests

* Re-order InstEmitSystem32

Alphabetical sorting.

* Address Feedback

Feedback from Ac_K, remove and sort usings.

* Address Feedback 2

* Address Feedback from LDj3SNuD

Opcode table reordered to have alphabetical sorting within groups,
Vmaxnm and Vminnm have split names to be less ambiguous, SoftFloat nits,
Test nits and Test simplification with ValueSource.

* Add Debug Asserts to A32 helpers

Mainly to prevent the shift ones from being used on I64 operands, as
they expect I32 input for most operations (eg. carry flag setting), and
expect I32 input for shift and boolean amounts. Most other helper
functions don't take Operands, throw on out of range values, and take
specific types of OpCode, so didn't need any asserts.

* Use ConstF rather than creating an operand.

(useful for pooling in future)

* Move exclusive load to helper, reference call flag rather than literal 1.

* Address LDj feedback (minus table flatten)

one final look before it's all gone. the world is so beautiful.

* Flatten OpCodeTable

oh no

* Address more table ordering

* Call Flag as int on A32

Co-authored-by: Natalie C. <cyuubiapps@gmail.com>
Co-authored-by: Thog <thog@protonmail.com>

1 files changed, 649 insertions, 209 deletions

diff --git a/ARMeilleure/Instructions/SoftFloat.cs b/ARMeilleure/Instructions/SoftFloat.cs
index 256bc5b9..d3e15a2c 100644
--- a/ARMeilleure/Instructions/SoftFloat.cs
+++ b/ARMeilleure/Instructions/SoftFloat.cs
@@ -121,7 +121,7 @@ namespace ARMeilleure.Instructions
 
         private static float FPDefaultNaN()
         {
-            return -float.NaN;
+            return BitConverter.Int32BitsToSingle(0x7fc00000);
         }
 
         private static float FPInfinity(bool sign)
@@ -623,12 +623,18 @@ namespace ARMeilleure.Instructions
     {
         public static float FPAdd(float value1, float value2)
         {
+            return FPAddFpscr(value1, value2, false);
+        }
+
+        public static float FPAddFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -639,7 +645,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if ((inf1 && !sign1) || (inf2 && !sign2))
                 {
@@ -657,7 +663,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 + value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -672,9 +678,10 @@ namespace ARMeilleure.Instructions
         public static int FPCompare(float value1, float value2, bool signalNaNs)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out _, context, fpcr);
 
             int result;
 
@@ -684,7 +691,7 @@ namespace ARMeilleure.Instructions
 
                 if (type1 == FPType.SNaN || type2 == FPType.SNaN || signalNaNs)
                 {
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
             }
             else
@@ -708,10 +715,16 @@ namespace ARMeilleure.Instructions
 
         public static float FPCompareEQ(float value1, float value2)
         {
+            return FPCompareEQFpscr(value1, value2, false);
+        }
+
+        public static float FPCompareEQFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             float result;
 
@@ -721,7 +734,7 @@ namespace ARMeilleure.Instructions
 
                 if (type1 == FPType.SNaN || type2 == FPType.SNaN)
                 {
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
             }
             else
@@ -734,10 +747,16 @@ namespace ARMeilleure.Instructions
 
         public static float FPCompareGE(float value1, float value2)
         {
+            return FPCompareGEFpscr(value1, value2, false);
+        }
+
+        public static float FPCompareGEFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             float result;
 
@@ -745,7 +764,7 @@ namespace ARMeilleure.Instructions
             {
                 result = ZerosOrOnes(false);
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else
             {
@@ -757,10 +776,16 @@ namespace ARMeilleure.Instructions
 
         public static float FPCompareGT(float value1, float value2)
         {
+            return FPCompareGTFpscr(value1, value2, false);
+        }
+
+        public static float FPCompareGTFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             float result;
 
@@ -768,7 +793,7 @@ namespace ARMeilleure.Instructions
             {
                 result = ZerosOrOnes(false);
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else
             {
@@ -788,14 +813,25 @@ namespace ARMeilleure.Instructions
             return FPCompareGT(value2, value1);
         }
 
+        public static float FPCompareLEFpscr(float value1, float value2, bool standardFpscr)
+        {
+            return FPCompareGEFpscr(value2, value1, standardFpscr);
+        }
+
+        public static float FPCompareLTFpscr(float value1, float value2, bool standardFpscr)
+        {
+            return FPCompareGTFpscr(value2, value1, standardFpscr);
+        }
+
         public static float FPDiv(float value1, float value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -806,7 +842,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if (inf1 || zero2)
                 {
@@ -814,7 +850,7 @@ namespace ARMeilleure.Instructions
 
                     if (!inf1)
                     {
-                        FPProcessException(FPException.DivideByZero, context);
+                        FPProcessException(FPException.DivideByZero, context, fpcr);
                     }
                 }
                 else if (zero1 || inf2)
@@ -825,7 +861,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 / value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -839,12 +875,18 @@ namespace ARMeilleure.Instructions
 
         public static float FPMax(float value1, float value2)
         {
+            return FPMaxFpscr(value1, value2, false);
+        }
+
+        public static float FPMaxFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -877,7 +919,7 @@ namespace ARMeilleure.Instructions
                     {
                         result = value2;
 
-                        if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                        if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                         {
                             context.Fpsr |= FPSR.Ufc;
 
@@ -892,10 +934,16 @@ namespace ARMeilleure.Instructions
 
         public static float FPMaxNum(float value1, float value2)
         {
+            return FPMaxNumFpscr(value1, value2, false);
+        }
+
+        public static float FPMaxNumFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             if (type1 == FPType.QNaN && type2 != FPType.QNaN)
             {
@@ -906,17 +954,23 @@ namespace ARMeilleure.Instructions
                 value2 = FPInfinity(true);
             }
 
-            return FPMax(value1, value2);
+            return FPMaxFpscr(value1, value2, standardFpscr);
         }
 
         public static float FPMin(float value1, float value2)
         {
+            return FPMinFpscr(value1, value2, false);
+        }
+
+        public static float FPMinFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -949,7 +1003,7 @@ namespace ARMeilleure.Instructions
                     {
                         result = value2;
 
-                        if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                        if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                         {
                             context.Fpsr |= FPSR.Ufc;
 
@@ -964,10 +1018,16 @@ namespace ARMeilleure.Instructions
 
         public static float FPMinNum(float value1, float value2)
         {
+            return FPMinNumFpscr(value1, value2, false);
+        }
+
+        public static float FPMinNumFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             if (type1 == FPType.QNaN && type2 != FPType.QNaN)
             {
@@ -978,17 +1038,23 @@ namespace ARMeilleure.Instructions
                 value2 = FPInfinity(false);
             }
 
-            return FPMin(value1, value2);
+            return FPMinFpscr(value1, value2, standardFpscr);
         }
 
         public static float FPMul(float value1, float value2)
         {
+            return FPMulFpscr(value1, value2, false);
+        }
+
+        public static float FPMulFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -999,7 +1065,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if (inf1 || inf2)
                 {
@@ -1013,7 +1079,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 * value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1027,22 +1093,28 @@ namespace ARMeilleure.Instructions
 
         public static float FPMulAdd(float valueA, float value1, float value2)
         {
+            return FPMulAddFpscr(valueA, value1, value2, false);
+        }
+
+        public static float FPMulAddFpscr(float valueA, float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            valueA = valueA.FPUnpack(out FPType typeA, out bool signA, out uint addend, context);
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1,    context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2,    context);
+            valueA = valueA.FPUnpack(out FPType typeA, out bool signA, out uint addend, context, fpcr);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1,    context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2,    context, fpcr);
 
             bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
             bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
 
-            float result = FPProcessNaNs3(typeA, type1, type2, addend, op1, op2, out bool done, context);
+            float result = FPProcessNaNs3(typeA, type1, type2, addend, op1, op2, out bool done, context, fpcr);
 
             if (typeA == FPType.QNaN && ((inf1 && zero2) || (zero1 && inf2)))
             {
                 result = FPDefaultNaN();
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
 
             if (!done)
@@ -1057,7 +1129,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if ((infA && !signA) || (infP && !signP))
                 {
@@ -1075,7 +1147,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = MathF.FusedMultiplyAdd(value1, value2, valueA);
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1094,14 +1166,22 @@ namespace ARMeilleure.Instructions
             return FPMulAdd(valueA, value1, value2);
         }
 
+        public static float FPMulSubFpscr(float valueA, float value1, float value2, bool standardFpscr)
+        {
+            value1 = value1.FPNeg();
+
+            return FPMulAddFpscr(valueA, value1, value2, standardFpscr);
+        }
+
         public static float FPMulX(float value1, float value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1124,7 +1204,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 * value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1153,15 +1233,21 @@ namespace ARMeilleure.Instructions
 
         public static float FPRecipEstimate(float value)
         {
+            return FPRecipEstimateFpscr(value, false);
+        }
+
+        public static float FPRecipEstimateFpscr(float value, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value.FPUnpack(out FPType type, out bool sign, out uint op, context);
+            value.FPUnpack(out FPType type, out bool sign, out uint op, context, fpcr);
 
             float result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else if (type == FPType.Infinity)
             {
@@ -1171,13 +1257,13 @@ namespace ARMeilleure.Instructions
             {
                 result = FPInfinity(sign);
 
-                FPProcessException(FPException.DivideByZero, context);
+                FPProcessException(FPException.DivideByZero, context, fpcr);
             }
             else if (MathF.Abs(value) < MathF.Pow(2f, -128))
             {
                 bool overflowToInf;
 
-                switch (context.Fpcr.GetRoundingMode())
+                switch (fpcr.GetRoundingMode())
                 {
                     default:
                     case FPRoundingMode.ToNearest:            overflowToInf = true;  break;
@@ -1188,10 +1274,10 @@ namespace ARMeilleure.Instructions
 
                 result = overflowToInf ? FPInfinity(sign) : FPMaxNormal(sign);
 
-                FPProcessException(FPException.Overflow, context);
-                FPProcessException(FPException.Inexact,  context);
+                FPProcessException(FPException.Overflow, context, fpcr);
+                FPProcessException(FPException.Inexact,  context, fpcr);
             }
-            else if ((context.Fpcr & FPCR.Fz) != 0 && (MathF.Abs(value) >= MathF.Pow(2f, 126)))
+            else if ((fpcr & FPCR.Fz) != 0 && (MathF.Abs(value) >= MathF.Pow(2f, 126)))
             {
                 result = FPZero(sign);
 
@@ -1240,16 +1326,49 @@ namespace ARMeilleure.Instructions
             return result;
         }
 
+        public static float FPRecipStep(float value1, float value2)
+        {
+            ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.StandardFpcrValue;
+
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
+
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
+
+            if (!done)
+            {
+                bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
+                bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
+
+                float product;
+
+                if ((inf1 && zero2) || (zero1 && inf2))
+                {
+                    product = FPZero(false);
+                }
+                else
+                {
+                    product = FPMulFpscr(value1, value2, true);
+                }
+
+                result = FPSubFpscr(FPTwo(false), product, true);
+            }
+
+            return result;
+        }
+
         public static float FPRecipStepFused(float value1, float value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
             value1 = value1.FPNeg();
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1268,7 +1387,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = MathF.FusedMultiplyAdd(value1, value2, 2f);
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1283,14 +1402,15 @@ namespace ARMeilleure.Instructions
         public static float FPRecpX(float value)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value.FPUnpack(out FPType type, out bool sign, out uint op, context);
+            value.FPUnpack(out FPType type, out bool sign, out uint op, context, fpcr);
 
             float result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else
             {
@@ -1306,27 +1426,33 @@ namespace ARMeilleure.Instructions
 
         public static float FPRSqrtEstimate(float value)
         {
+            return FPRSqrtEstimateFpscr(value, false);
+        }
+
+        public static float FPRSqrtEstimateFpscr(float value, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value.FPUnpack(out FPType type, out bool sign, out uint op, context);
+            value.FPUnpack(out FPType type, out bool sign, out uint op, context, fpcr);
 
             float result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else if (type == FPType.Zero)
             {
                 result = FPInfinity(sign);
 
-                FPProcessException(FPException.DivideByZero, context);
+                FPProcessException(FPException.DivideByZero, context, fpcr);
             }
             else if (sign)
             {
                 result = FPDefaultNaN();
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else if (type == FPType.Infinity)
             {
@@ -1369,16 +1495,95 @@ namespace ARMeilleure.Instructions
             return result;
         }
 
+        public static float FPHalvedSub(float value1, float value2, ExecutionContext context, FPCR fpcr)
+        {
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
+
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
+
+            if (!done)
+            {
+                bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
+                bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
+
+                if (inf1 && inf2 && sign1 == sign2)
+                {
+                    result = FPDefaultNaN();
+
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
+                }
+                else if ((inf1 && !sign1) || (inf2 && sign2))
+                {
+                    result = FPInfinity(false);
+                }
+                else if ((inf1 && sign1) || (inf2 && !sign2))
+                {
+                    result = FPInfinity(true);
+                }
+                else if (zero1 && zero2 && sign1 == !sign2)
+                {
+                    result = FPZero(sign1);
+                }
+                else
+                {
+                    result = (value1 - value2) / 2.0f;
+
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    {
+                        context.Fpsr |= FPSR.Ufc;
+
+                        result = FPZero(result < 0f);
+                    }
+                }
+            }
+
+            return result;
+        }
+
+        public static float FPRSqrtStep(float value1, float value2)
+        {
+            ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.StandardFpcrValue;
+
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
+
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
+
+            if (!done)
+            {
+                bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
+                bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
+
+                float product;
+
+                if ((inf1 && zero2) || (zero1 && inf2))
+                {
+                    product = FPZero(false);
+                }
+                else
+                {
+                    product = FPMulFpscr(value1, value2, true);
+                }
+                
+                result = FPHalvedSub(FPThree(false), product, context, fpcr);
+            }
+
+            return result;
+        }
+
         public static float FPRSqrtStepFused(float value1, float value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
             value1 = value1.FPNeg();
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1397,7 +1602,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = MathF.FusedMultiplyAdd(value1, value2, 3f) / 2f;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1412,14 +1617,15 @@ namespace ARMeilleure.Instructions
         public static float FPSqrt(float value)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value = value.FPUnpack(out FPType type, out bool sign, out uint op, context);
+            value = value.FPUnpack(out FPType type, out bool sign, out uint op, context, fpcr);
 
             float result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else if (type == FPType.Zero)
             {
@@ -1433,13 +1639,13 @@ namespace ARMeilleure.Instructions
             {
                 result = FPDefaultNaN();
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else
             {
                 result = MathF.Sqrt(value);
 
-                if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                 {
                     context.Fpsr |= FPSR.Ufc;
 
@@ -1452,12 +1658,18 @@ namespace ARMeilleure.Instructions
 
         public static float FPSub(float value1, float value2)
         {
+            return FPSubFpscr(value1, value2, false);
+        }
+
+        public static float FPSubFpscr(float value1, float value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out uint op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out uint op2, context, fpcr);
 
-            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            float result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1468,7 +1680,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if ((inf1 && !sign1) || (inf2 && sign2))
                 {
@@ -1486,7 +1698,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 - value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && float.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1500,7 +1712,7 @@ namespace ARMeilleure.Instructions
 
         private static float FPDefaultNaN()
         {
-            return -float.NaN;
+            return BitConverter.Int32BitsToSingle(0x7fc00000);
         }
 
         private static float FPInfinity(bool sign)
@@ -1523,6 +1735,11 @@ namespace ARMeilleure.Instructions
             return sign ? -2f : +2f;
         }
 
+        private static float FPThree(bool sign)
+        {
+            return sign ? -3f : +3f;
+        }
+
         private static float FPOnePointFive(bool sign)
         {
             return sign ? -1.5f : +1.5f;
@@ -1543,7 +1760,8 @@ namespace ARMeilleure.Instructions
             out FPType type,
             out bool sign,
             out uint valueBits,
-            ExecutionContext context)
+            ExecutionContext context,
+            FPCR fpcr)
         {
             valueBits = (uint)BitConverter.SingleToInt32Bits(value);
 
@@ -1551,14 +1769,14 @@ namespace ARMeilleure.Instructions
 
             if ((valueBits & 0x7F800000u) == 0u)
             {
-                if ((valueBits & 0x007FFFFFu) == 0u || (context.Fpcr & FPCR.Fz) != 0)
+                if ((valueBits & 0x007FFFFFu) == 0u || (fpcr & FPCR.Fz) != 0)
                 {
                     type  = FPType.Zero;
                     value = FPZero(sign);
 
                     if ((valueBits & 0x007FFFFFu) != 0u)
                     {
-                        FPProcessException(FPException.InputDenorm, context);
+                        FPProcessException(FPException.InputDenorm, context, fpcr);
                     }
                 }
                 else
@@ -1592,25 +1810,26 @@ namespace ARMeilleure.Instructions
             uint op1,
             uint op2,
             out bool done,
-            ExecutionContext context)
+            ExecutionContext context,
+            FPCR fpcr)
         {
             done = true;
 
             if (type1 == FPType.SNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.SNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
             else if (type1 == FPType.QNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.QNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
 
             done = false;
@@ -1626,33 +1845,34 @@ namespace ARMeilleure.Instructions
             uint op2,
             uint op3,
             out bool done,
-            ExecutionContext context)
+            ExecutionContext context,
+            FPCR fpcr)
         {
             done = true;
 
             if (type1 == FPType.SNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.SNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
             else if (type3 == FPType.SNaN)
             {
-                return FPProcessNaN(type3, op3, context);
+                return FPProcessNaN(type3, op3, context, fpcr);
             }
             else if (type1 == FPType.QNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.QNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
             else if (type3 == FPType.QNaN)
             {
-                return FPProcessNaN(type3, op3, context);
+                return FPProcessNaN(type3, op3, context, fpcr);
             }
 
             done = false;
@@ -1660,16 +1880,16 @@ namespace ARMeilleure.Instructions
             return FPZero(false);
         }
 
-        private static float FPProcessNaN(FPType type, uint op, ExecutionContext context)
+        private static float FPProcessNaN(FPType type, uint op, ExecutionContext context, FPCR fpcr)
         {
             if (type == FPType.SNaN)
             {
                 op |= 1u << 22;
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
 
-            if ((context.Fpcr & FPCR.Dn) != 0)
+            if ((fpcr & FPCR.Dn) != 0)
             {
                 return FPDefaultNaN();
             }
@@ -1677,11 +1897,11 @@ namespace ARMeilleure.Instructions
             return BitConverter.Int32BitsToSingle((int)op);
         }
 
-        private static void FPProcessException(FPException exc, ExecutionContext context)
+        private static void FPProcessException(FPException exc, ExecutionContext context, FPCR fpcr)
         {
             int enable = (int)exc + 8;
 
-            if ((context.Fpcr & (FPCR)(1 << enable)) != 0)
+            if ((fpcr & (FPCR)(1 << enable)) != 0)
             {
                 throw new NotImplementedException("Floating-point trap handling.");
             }
@@ -1696,12 +1916,18 @@ namespace ARMeilleure.Instructions
     {
         public static double FPAdd(double value1, double value2)
         {
+            return FPAddFpscr(value1, value2, false);
+        }
+
+        public static double FPAddFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1712,7 +1938,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if ((inf1 && !sign1) || (inf2 && !sign2))
                 {
@@ -1730,7 +1956,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 + value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1745,9 +1971,10 @@ namespace ARMeilleure.Instructions
         public static int FPCompare(double value1, double value2, bool signalNaNs)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out _, context, fpcr);
 
             int result;
 
@@ -1757,7 +1984,7 @@ namespace ARMeilleure.Instructions
 
                 if (type1 == FPType.SNaN || type2 == FPType.SNaN || signalNaNs)
                 {
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
             }
             else
@@ -1781,10 +2008,16 @@ namespace ARMeilleure.Instructions
 
         public static double FPCompareEQ(double value1, double value2)
         {
+            return FPCompareEQFpscr(value1, value2, false);
+        }
+
+        public static double FPCompareEQFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             double result;
 
@@ -1794,7 +2027,7 @@ namespace ARMeilleure.Instructions
 
                 if (type1 == FPType.SNaN || type2 == FPType.SNaN)
                 {
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
             }
             else
@@ -1807,10 +2040,16 @@ namespace ARMeilleure.Instructions
 
         public static double FPCompareGE(double value1, double value2)
         {
+            return FPCompareGEFpscr(value1, value2, false);
+        }
+
+        public static double FPCompareGEFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             double result;
 
@@ -1818,7 +2057,7 @@ namespace ARMeilleure.Instructions
             {
                 result = ZerosOrOnes(false);
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else
             {
@@ -1830,10 +2069,16 @@ namespace ARMeilleure.Instructions
 
         public static double FPCompareGT(double value1, double value2)
         {
+            return FPCompareGTFpscr(value1, value2, false);
+        }
+
+        public static double FPCompareGTFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2 = value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1 = value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             double result;
 
@@ -1841,7 +2086,7 @@ namespace ARMeilleure.Instructions
             {
                 result = ZerosOrOnes(false);
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else
             {
@@ -1861,14 +2106,25 @@ namespace ARMeilleure.Instructions
             return FPCompareGT(value2, value1);
         }
 
+        public static double FPCompareLEFpscr(double value1, double value2, bool standardFpscr)
+        {
+            return FPCompareGEFpscr(value2, value1, standardFpscr);
+        }
+
+        public static double FPCompareLTFpscr(double value1, double value2, bool standardFpscr)
+        {
+            return FPCompareGTFpscr(value2, value1, standardFpscr);
+        }
+
         public static double FPDiv(double value1, double value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1879,7 +2135,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if (inf1 || zero2)
                 {
@@ -1887,7 +2143,7 @@ namespace ARMeilleure.Instructions
 
                     if (!inf1)
                     {
-                        FPProcessException(FPException.DivideByZero, context);
+                        FPProcessException(FPException.DivideByZero, context, fpcr);
                     }
                 }
                 else if (zero1 || inf2)
@@ -1898,7 +2154,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 / value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -1912,12 +2168,18 @@ namespace ARMeilleure.Instructions
 
         public static double FPMax(double value1, double value2)
         {
+            return FPMaxFpscr(value1, value2, false);
+        }
+
+        public static double FPMaxFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -1950,7 +2212,7 @@ namespace ARMeilleure.Instructions
                     {
                         result = value2;
 
-                        if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                        if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                         {
                             context.Fpsr |= FPSR.Ufc;
 
@@ -1965,10 +2227,16 @@ namespace ARMeilleure.Instructions
 
         public static double FPMaxNum(double value1, double value2)
         {
+            return FPMaxNumFpscr(value1, value2, false);
+        }
+
+        public static double FPMaxNumFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             if (type1 == FPType.QNaN && type2 != FPType.QNaN)
             {
@@ -1979,17 +2247,23 @@ namespace ARMeilleure.Instructions
                 value2 = FPInfinity(true);
             }
 
-            return FPMax(value1, value2);
+            return FPMaxFpscr(value1, value2, standardFpscr);
         }
 
         public static double FPMin(double value1, double value2)
         {
+            return FPMinFpscr(value1, value2, false);
+        }
+
+        public static double FPMinFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -2022,7 +2296,7 @@ namespace ARMeilleure.Instructions
                     {
                         result = value2;
 
-                        if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                        if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                         {
                             context.Fpsr |= FPSR.Ufc;
 
@@ -2037,10 +2311,16 @@ namespace ARMeilleure.Instructions
 
         public static double FPMinNum(double value1, double value2)
         {
+            return FPMinNumFpscr(value1, value2, false);
+        }
+
+        public static double FPMinNumFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1.FPUnpack(out FPType type1, out _, out _, context);
-            value2.FPUnpack(out FPType type2, out _, out _, context);
+            value1.FPUnpack(out FPType type1, out _, out _, context, fpcr);
+            value2.FPUnpack(out FPType type2, out _, out _, context, fpcr);
 
             if (type1 == FPType.QNaN && type2 != FPType.QNaN)
             {
@@ -2051,17 +2331,23 @@ namespace ARMeilleure.Instructions
                 value2 = FPInfinity(false);
             }
 
-            return FPMin(value1, value2);
+            return FPMinFpscr(value1, value2, standardFpscr);
         }
 
         public static double FPMul(double value1, double value2)
         {
+            return FPMulFpscr(value1, value2, false);
+        }
+
+        public static double FPMulFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -2072,7 +2358,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if (inf1 || inf2)
                 {
@@ -2086,7 +2372,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 * value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -2100,22 +2386,28 @@ namespace ARMeilleure.Instructions
 
         public static double FPMulAdd(double valueA, double value1, double value2)
         {
+            return FPMulAddFpscr(valueA, value1, value2, false);
+        }
+
+        public static double FPMulAddFpscr(double valueA, double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            valueA = valueA.FPUnpack(out FPType typeA, out bool signA, out ulong addend, context);
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1,    context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2,    context);
+            valueA = valueA.FPUnpack(out FPType typeA, out bool signA, out ulong addend, context, fpcr);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1,    context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2,    context, fpcr);
 
             bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
             bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
 
-            double result = FPProcessNaNs3(typeA, type1, type2, addend, op1, op2, out bool done, context);
+            double result = FPProcessNaNs3(typeA, type1, type2, addend, op1, op2, out bool done, context, fpcr);
 
             if (typeA == FPType.QNaN && ((inf1 && zero2) || (zero1 && inf2)))
             {
                 result = FPDefaultNaN();
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
 
             if (!done)
@@ -2130,7 +2422,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if ((infA && !signA) || (infP && !signP))
                 {
@@ -2148,7 +2440,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = Math.FusedMultiplyAdd(value1, value2, valueA);
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -2167,14 +2459,22 @@ namespace ARMeilleure.Instructions
             return FPMulAdd(valueA, value1, value2);
         }
 
+        public static double FPMulSubFpscr(double valueA, double value1, double value2, bool standardFpscr)
+        {
+            value1 = value1.FPNeg();
+
+            return FPMulAddFpscr(valueA, value1, value2, standardFpscr);
+        }
+
         public static double FPMulX(double value1, double value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -2197,7 +2497,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 * value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -2226,15 +2526,21 @@ namespace ARMeilleure.Instructions
 
         public static double FPRecipEstimate(double value)
         {
+            return FPRecipEstimateFpscr(value, false);
+        }
+
+        public static double FPRecipEstimateFpscr(double value, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value.FPUnpack(out FPType type, out bool sign, out ulong op, context);
+            value.FPUnpack(out FPType type, out bool sign, out ulong op, context, fpcr);
 
             double result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else if (type == FPType.Infinity)
             {
@@ -2244,13 +2550,13 @@ namespace ARMeilleure.Instructions
             {
                 result = FPInfinity(sign);
 
-                FPProcessException(FPException.DivideByZero, context);
+                FPProcessException(FPException.DivideByZero, context, fpcr);
             }
             else if (Math.Abs(value) < Math.Pow(2d, -1024))
             {
                 bool overflowToInf;
 
-                switch (context.Fpcr.GetRoundingMode())
+                switch (fpcr.GetRoundingMode())
                 {
                     default:
                     case FPRoundingMode.ToNearest:            overflowToInf = true;  break;
@@ -2261,10 +2567,10 @@ namespace ARMeilleure.Instructions
 
                 result = overflowToInf ? FPInfinity(sign) : FPMaxNormal(sign);
 
-                FPProcessException(FPException.Overflow, context);
-                FPProcessException(FPException.Inexact,  context);
+                FPProcessException(FPException.Overflow, context, fpcr);
+                FPProcessException(FPException.Inexact,  context, fpcr);
             }
-            else if ((context.Fpcr & FPCR.Fz) != 0 && (Math.Abs(value) >= Math.Pow(2d, 1022)))
+            else if ((fpcr & FPCR.Fz) != 0 && (Math.Abs(value) >= Math.Pow(2d, 1022)))
             {
                 result = FPZero(sign);
 
@@ -2313,16 +2619,49 @@ namespace ARMeilleure.Instructions
             return result;
         }
 
+        public static double FPRecipStep(double value1, double value2)
+        {
+            ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.StandardFpcrValue;
+
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
+
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
+
+            if (!done)
+            {
+                bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
+                bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
+
+                double product;
+
+                if ((inf1 && zero2) || (zero1 && inf2))
+                {
+                    product = FPZero(false);
+                }
+                else
+                {
+                    product = FPMulFpscr(value1, value2, true);
+                }
+
+                result = FPSubFpscr(FPTwo(false), product, true);
+            }
+
+            return result;
+        }
+
         public static double FPRecipStepFused(double value1, double value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
             value1 = value1.FPNeg();
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -2341,7 +2680,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = Math.FusedMultiplyAdd(value1, value2, 2d);
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -2356,14 +2695,15 @@ namespace ARMeilleure.Instructions
         public static double FPRecpX(double value)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value.FPUnpack(out FPType type, out bool sign, out ulong op, context);
+            value.FPUnpack(out FPType type, out bool sign, out ulong op, context, fpcr);
 
             double result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else
             {
@@ -2379,27 +2719,33 @@ namespace ARMeilleure.Instructions
 
         public static double FPRSqrtEstimate(double value)
         {
+            return FPRSqrtEstimateFpscr(value, false);
+        }
+
+        public static double FPRSqrtEstimateFpscr(double value, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value.FPUnpack(out FPType type, out bool sign, out ulong op, context);
+            value.FPUnpack(out FPType type, out bool sign, out ulong op, context, fpcr);
 
             double result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else if (type == FPType.Zero)
             {
                 result = FPInfinity(sign);
 
-                FPProcessException(FPException.DivideByZero, context);
+                FPProcessException(FPException.DivideByZero, context, fpcr);
             }
             else if (sign)
             {
                 result = FPDefaultNaN();
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else if (type == FPType.Infinity)
             {
@@ -2442,16 +2788,95 @@ namespace ARMeilleure.Instructions
             return result;
         }
 
+        public static double FPHalvedSub(double value1, double value2, ExecutionContext context, FPCR fpcr)
+        {
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
+
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
+
+            if (!done)
+            {
+                bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
+                bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
+
+                if (inf1 && inf2 && sign1 == sign2)
+                {
+                    result = FPDefaultNaN();
+
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
+                }
+                else if ((inf1 && !sign1) || (inf2 && sign2))
+                {
+                    result = FPInfinity(false);
+                }
+                else if ((inf1 && sign1) || (inf2 && !sign2))
+                {
+                    result = FPInfinity(true);
+                }
+                else if (zero1 && zero2 && sign1 == !sign2)
+                {
+                    result = FPZero(sign1);
+                }
+                else
+                {
+                    result = (value1 - value2) / 2.0;
+
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    {
+                        context.Fpsr |= FPSR.Ufc;
+
+                        result = FPZero(result < 0d);
+                    }
+                }
+            }
+
+            return result;
+        }
+
+        public static double FPRSqrtStep(double value1, double value2)
+        {
+            ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.StandardFpcrValue;
+
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
+
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
+
+            if (!done)
+            {
+                bool inf1 = type1 == FPType.Infinity; bool zero1 = type1 == FPType.Zero;
+                bool inf2 = type2 == FPType.Infinity; bool zero2 = type2 == FPType.Zero;
+
+                double product;
+
+                if ((inf1 && zero2) || (zero1 && inf2))
+                {
+                    product = FPZero(false);
+                }
+                else
+                {
+                    product = FPMulFpscr(value1, value2, true);
+                }
+
+                result = FPHalvedSub(FPThree(false), product, context, fpcr);
+            }
+
+            return result;
+        }
+
         public static double FPRSqrtStepFused(double value1, double value2)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
             value1 = value1.FPNeg();
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -2470,7 +2895,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = Math.FusedMultiplyAdd(value1, value2, 3d) / 2d;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -2485,14 +2910,15 @@ namespace ARMeilleure.Instructions
         public static double FPSqrt(double value)
         {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = context.Fpcr;
 
-            value = value.FPUnpack(out FPType type, out bool sign, out ulong op, context);
+            value = value.FPUnpack(out FPType type, out bool sign, out ulong op, context, fpcr);
 
             double result;
 
             if (type == FPType.SNaN || type == FPType.QNaN)
             {
-                result = FPProcessNaN(type, op, context);
+                result = FPProcessNaN(type, op, context, fpcr);
             }
             else if (type == FPType.Zero)
             {
@@ -2506,13 +2932,13 @@ namespace ARMeilleure.Instructions
             {
                 result = FPDefaultNaN();
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
             else
             {
                 result = Math.Sqrt(value);
 
-                if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                 {
                     context.Fpsr |= FPSR.Ufc;
 
@@ -2525,12 +2951,18 @@ namespace ARMeilleure.Instructions
 
         public static double FPSub(double value1, double value2)
         {
+            return FPSubFpscr(value1, value2, false);
+        }
+
+        public static double FPSubFpscr(double value1, double value2, bool standardFpscr)
+        {
             ExecutionContext context = NativeInterface.GetContext();
+            FPCR fpcr = standardFpscr ? context.StandardFpcrValue : context.Fpcr;
 
-            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context);
-            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context);
+            value1 = value1.FPUnpack(out FPType type1, out bool sign1, out ulong op1, context, fpcr);
+            value2 = value2.FPUnpack(out FPType type2, out bool sign2, out ulong op2, context, fpcr);
 
-            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context);
+            double result = FPProcessNaNs(type1, type2, op1, op2, out bool done, context, fpcr);
 
             if (!done)
             {
@@ -2541,7 +2973,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = FPDefaultNaN();
 
-                    FPProcessException(FPException.InvalidOp, context);
+                    FPProcessException(FPException.InvalidOp, context, fpcr);
                 }
                 else if ((inf1 && !sign1) || (inf2 && sign2))
                 {
@@ -2559,7 +2991,7 @@ namespace ARMeilleure.Instructions
                 {
                     result = value1 - value2;
 
-                    if ((context.Fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
+                    if ((fpcr & FPCR.Fz) != 0 && double.IsSubnormal(result))
                     {
                         context.Fpsr |= FPSR.Ufc;
 
@@ -2573,7 +3005,7 @@ namespace ARMeilleure.Instructions
 
         private static double FPDefaultNaN()
         {
-            return -double.NaN;
+            return BitConverter.Int64BitsToDouble(0x7ff8000000000000);
         }
 
         private static double FPInfinity(bool sign)
@@ -2596,6 +3028,11 @@ namespace ARMeilleure.Instructions
             return sign ? -2d : +2d;
         }
 
+        private static double FPThree(bool sign)
+        {
+            return sign ? -3d : +3d;
+        }
+
         private static double FPOnePointFive(bool sign)
         {
             return sign ? -1.5d : +1.5d;
@@ -2616,7 +3053,8 @@ namespace ARMeilleure.Instructions
             out FPType type,
             out bool sign,
             out ulong valueBits,
-            ExecutionContext context)
+            ExecutionContext context,
+            FPCR fpcr)
         {
             valueBits = (ulong)BitConverter.DoubleToInt64Bits(value);
 
@@ -2624,14 +3062,14 @@ namespace ARMeilleure.Instructions
 
             if ((valueBits & 0x7FF0000000000000ul) == 0ul)
             {
-                if ((valueBits & 0x000FFFFFFFFFFFFFul) == 0ul || (context.Fpcr & FPCR.Fz) != 0)
+                if ((valueBits & 0x000FFFFFFFFFFFFFul) == 0ul || (fpcr & FPCR.Fz) != 0)
                 {
                     type  = FPType.Zero;
                     value = FPZero(sign);
 
                     if ((valueBits & 0x000FFFFFFFFFFFFFul) != 0ul)
                     {
-                        FPProcessException(FPException.InputDenorm, context);
+                        FPProcessException(FPException.InputDenorm, context, fpcr);
                     }
                 }
                 else
@@ -2665,25 +3103,26 @@ namespace ARMeilleure.Instructions
             ulong op1,
             ulong op2,
             out bool done,
-            ExecutionContext context)
+            ExecutionContext context,
+            FPCR fpcr)
         {
             done = true;
 
             if (type1 == FPType.SNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.SNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
             else if (type1 == FPType.QNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.QNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
 
             done = false;
@@ -2699,33 +3138,34 @@ namespace ARMeilleure.Instructions
             ulong op2,
             ulong op3,
             out bool done,
-            ExecutionContext context)
+            ExecutionContext context,
+            FPCR fpcr)
         {
             done = true;
 
             if (type1 == FPType.SNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.SNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
             else if (type3 == FPType.SNaN)
             {
-                return FPProcessNaN(type3, op3, context);
+                return FPProcessNaN(type3, op3, context, fpcr);
             }
             else if (type1 == FPType.QNaN)
             {
-                return FPProcessNaN(type1, op1, context);
+                return FPProcessNaN(type1, op1, context, fpcr);
             }
             else if (type2 == FPType.QNaN)
             {
-                return FPProcessNaN(type2, op2, context);
+                return FPProcessNaN(type2, op2, context, fpcr);
             }
             else if (type3 == FPType.QNaN)
             {
-                return FPProcessNaN(type3, op3, context);
+                return FPProcessNaN(type3, op3, context, fpcr);
             }
 
             done = false;
@@ -2733,16 +3173,16 @@ namespace ARMeilleure.Instructions
             return FPZero(false);
         }
 
-        private static double FPProcessNaN(FPType type, ulong op, ExecutionContext context)
+        private static double FPProcessNaN(FPType type, ulong op, ExecutionContext context, FPCR fpcr)
         {
             if (type == FPType.SNaN)
             {
                 op |= 1ul << 51;
 
-                FPProcessException(FPException.InvalidOp, context);
+                FPProcessException(FPException.InvalidOp, context, fpcr);
             }
 
-            if ((context.Fpcr & FPCR.Dn) != 0)
+            if ((fpcr & FPCR.Dn) != 0)
             {
                 return FPDefaultNaN();
             }
@@ -2750,11 +3190,11 @@ namespace ARMeilleure.Instructions
             return BitConverter.Int64BitsToDouble((long)op);
         }
 
-        private static void FPProcessException(FPException exc, ExecutionContext context)
+        private static void FPProcessException(FPException exc, ExecutionContext context, FPCR fpcr)
         {
             int enable = (int)exc + 8;
 
-            if ((context.Fpcr & (FPCR)(1 << enable)) != 0)
+            if ((fpcr & (FPCR)(1 << enable)) != 0)
             {
                 throw new NotImplementedException("Floating-point trap handling.");
             }