Add helper class for ARM/Thumb assembly functions (#127)

Replaces static helper functions in
    Sdk5DsiSdCardRedirectPatch.cpp
    LastWindowCrcPatch.h
    CardiTryReadCardDmaPatch.cpp

arm9/source/patches/arm7/sdk5/Sdk5DsiSdCardRedirectPatch.cpp

@@ -1,4 +1,5 @@
 #include "common.h"
+#include "ArmHelper.h"
 #include "sharedMemory.h"
 #include "ndsHeader.h"
 #include "moduleParams.h"
@@ -12,11 +13,6 @@ static const u32 sAttachFunctionPatternThumb[] = { 0xB0FFB518u, 0xB0DFB0FFu, 0x4
 #define BL_TO_GET_DRIVE_STRUCT_OFFSET       (-0x20)
 #define BL_TO_GET_DRIVE_STRUCT_OFFSET_ALT   0x88
 
-static bool isArmUnconditionalBl(u32 armInstruction)
-{
-    return (armInstruction >> 24) == 0xEB;
-}
-
 bool Sdk5DsiSdCardRedirectPatch::FindPatchTarget(PatchContext& patchContext)
 {
     _attachFunction = patchContext.FindPattern32Twl(sAttachFunctionPattern, sizeof(sAttachFunctionPattern));
@@ -32,10 +28,10 @@ bool Sdk5DsiSdCardRedirectPatch::FindPatchTarget(PatchContext& patchContext)
     {
         LOG_DEBUG("Found FATFSi_sdmcRtfsAttach at %p\n", _attachFunction);
         _blToGetDriveStructOffset = BL_TO_GET_DRIVE_STRUCT_OFFSET;
-        if (!_thumb && !isArmUnconditionalBl(*(u32*)((u8*)_attachFunction + _blToGetDriveStructOffset)))
+        if (!_thumb && !ArmHelper::IsArmUnconditionalBl(*(u32*)((u8*)_attachFunction + _blToGetDriveStructOffset)))
         {
             _blToGetDriveStructOffset = BL_TO_GET_DRIVE_STRUCT_OFFSET_ALT;
-            if (!isArmUnconditionalBl(*(u32*)((u8*)_attachFunction + _blToGetDriveStructOffset)))
+            if (!ArmHelper::IsArmUnconditionalBl(*(u32*)((u8*)_attachFunction + _blToGetDriveStructOffset)))
             {
                 LOG_WARNING("Unsupported arm7 version for SD redirection patches\n");
                 _attachFunction = nullptr;
@@ -50,19 +46,6 @@ bool Sdk5DsiSdCardRedirectPatch::FindPatchTarget(PatchContext& patchContext)
     return _attachFunction != nullptr;
 }
 
-static u32 getArmBlAddress(const u32* instructionPointer)
-{
-    u32 blInstruction = *instructionPointer;
-    return (u32)instructionPointer + 8 + ((int)((blInstruction & 0xFFFFFF) << 8) >> 6);
-}
-
-static u32 getThumbBlAddress(const u32* instructionPointer)
-{
-    u32 blInstruction1 = ((u16*)instructionPointer)[0];
-    u32 blInstruction2 = ((u16*)instructionPointer)[1];
-    return (u32)instructionPointer + 5 + ((int)((((blInstruction1 & 0x7FF) << 11) | (blInstruction2 & 0x7FF)) << 10) >> 9);
-}
-
 void Sdk5DsiSdCardRedirectPatch::ApplyPatch(PatchContext& patchContext)
 {
     if (!_attachFunction)
@@ -71,11 +54,11 @@ void Sdk5DsiSdCardRedirectPatch::ApplyPatch(PatchContext& patchContext)
     u32 getDriveStructAddress;
     if (_thumb)
     {
-        getDriveStructAddress = getThumbBlAddress((u32*)((u8*)_attachFunction + _blToGetDriveStructOffset));
+        getDriveStructAddress = ArmHelper::GetThumbCallAddress((u32*)((u8*)_attachFunction + _blToGetDriveStructOffset));
     }
     else
     {
-        getDriveStructAddress = getArmBlAddress((u32*)((u8*)_attachFunction + _blToGetDriveStructOffset));
+        getDriveStructAddress = ArmHelper::GetArmCallAddress((u32*)((u8*)_attachFunction + _blToGetDriveStructOffset));
     }
 
     auto arm7iAutoload = patchContext.GetAutoloadAdjusterTwl();

arm9/source/patches/arm9/LastWindowCrcPatch.cpp

@@ -1,4 +1,5 @@
 #include "common.h"
+#include "ArmHelper.h"
 #include "patches/PatchContext.h"
 #include "LastWindowCrcPatchCode.h"
 #include "LastWindowCrcPatch.h"
@@ -13,6 +14,6 @@ void LastWindowCrcPatch::ApplyPatch(PatchContext& patchContext)
 {
     auto patchCode = patchContext.GetPatchCodeCollection().AddUniquePatchCode<LastWindowCrcPatchCode>(patchContext.GetPatchHeap());
     u32 patchAddr = (u32)patchCode->GetLastWindowCrcFunction();
-    *_getCrc16 = MakeBlxCall(patchAddr);
+    *_getCrc16 = ArmHelper::MakeArmCall((u32)_getCrc16, patchAddr);
 }
 

arm9/source/patches/arm9/LastWindowCrcPatch.h

@@ -32,9 +32,4 @@ public:
 
 private:
     u32* _getCrc16 = nullptr;
-
-    u32 MakeBlxCall(u32 patchAddr) const
-    {
-        return 0xFA000000 | (((patchAddr - (u32)_getCrc16 - 8) >> 2) & 0xFFFFFF);
-    }
 };

arm9/source/patches/arm9/sdk2to4/CardiTryReadCardDmaPatch.cpp

@@ -1,4 +1,5 @@
 #include "common.h"
+#include "ArmHelper.h"
 #include "patches/PatchContext.h"
 #include "thumbInstructions.h"
 #include "CardiSetCardDmaPatchCode.h"
@@ -169,17 +170,6 @@ bool CardiTryReadCardDmaPatch::FindPatchTarget(PatchContext& patchContext)
     return true; //_cardiTryReadCardDma != nullptr;
 }
 
-static s32 getArmBlOffset(u32 blInstruction)
-{
-    return 8 + ((int)((blInstruction & 0xFFFFFF) << 8) >> 6);
-}
-
-static u32 getArmBlAddress(const u32* instructionPointer)
-{
-    u32 blInstruction = *instructionPointer;
-    return (u32)instructionPointer + 8 + ((int)((blInstruction & 0xFFFFFF) << 8) >> 6) + ((blInstruction >> 24) == 0xFA ? 1 : 0);
-}
-
 void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
 {
     if (!_cardiTryReadCardDma)
@@ -204,7 +194,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
             {
                 cardiCommon = *(u32*)((u8*)_cardiTryReadCardDma + 0x134);
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x144);
-                cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x124));
+                cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x124));
                 if (*(u32*)cardiOnReadCard == 0xE92D40F0u)
                 {
                     cardiSetCardDmaDmaCopyCallOffset = 0x18;
@@ -222,7 +212,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
             {
                 cardiCommon = *(u32*)((u8*)_cardiTryReadCardDma + 0x140);
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x150);
-                cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x130));
+                cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x130));
                 cardiSetCardDmaDmaCopyCallOffset = 0x18;
                 cardiOnReadCardOffset = 0x40;
             }
@@ -230,7 +220,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
             {
                 cardiCommon = *(u32*)((u8*)_cardiTryReadCardDma + 0x148) + 4;
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x158);
-                cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x138));
+                cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x138));
                 cardiSetCardDmaDmaCopyCallOffset = 0x18;
                 cardiOnReadCardOffset = 0x40;
             }
@@ -240,11 +230,11 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x16C);
                 if (*(u32*)((u8*)_cardiTryReadCardDma + 0x158) == 0xE12FFF1E)
                 {
-                    cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x148));
+                    cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x148));
                 }
                 else
                 {
-                    cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x14C));
+                    cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x14C));
                 }
                 cardiSetCardDmaDmaCopyCallOffset = 0x18;
                 cardiOnReadCardOffset = 0x40;
@@ -253,7 +243,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
             {
                 cardiCommon = *(u32*)((u8*)_cardiTryReadCardDma + 0x160) + 4;
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x170);
-                cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x14C));
+                cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x14C));
                 cardiSetCardDmaDmaCopyCallOffset = 0x18;
                 cardiOnReadCardOffset = 0x40;
             }
@@ -261,7 +251,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
             {
                 cardiCommon = *(u32*)((u8*)_cardiTryReadCardDma + 0x178) + 4;
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x188);
-                cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x16C));
+                cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x16C));
                 cardiSetCardDmaDmaCopyCallOffset = 0x1C;
                 cardiOnReadCardOffset = 0x48;
             }
@@ -269,7 +259,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
             {
                 cardiCommon = *(u32*)((u8*)_cardiTryReadCardDma + 0x180) + 4;
                 cardiOnReadCard = *(u32*)((u8*)_cardiTryReadCardDma + 0x190);
-                cardiSetCardDma = getArmBlAddress((u32*)((u8*)_cardiTryReadCardDma + 0x174));
+                cardiSetCardDma = ArmHelper::GetArmCallAddress((u32*)((u8*)_cardiTryReadCardDma + 0x174));
                 cardiSetCardDmaDmaCopyCallOffset = 0x1C;
                 cardiOnReadCardOffset = 0x48;
             }
@@ -291,7 +281,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
 
             // MIi_CardDmaCopy32 is relative, but we need its final location to call it later
             u32 miiCardDmaCopy32CallLocation = cardiSetCardDma + cardiSetCardDmaDmaCopyCallOffset;
-            s32 miiCardDmaCopy32CallOffset = getArmBlOffset(*(u32*)miiCardDmaCopy32CallLocation);
+            s32 miiCardDmaCopy32CallOffset = ArmHelper::GetArmCallOffset(*(u32*)miiCardDmaCopy32CallLocation);
             if (autoloadAdjuster)
             {
                 miiCardDmaCopy32CallLocation = autoloadAdjuster->AdjustInitialToFinal(miiCardDmaCopy32CallLocation);
@@ -300,7 +290,7 @@ void CardiTryReadCardDmaPatch::ApplyPatch(PatchContext& patchContext)
 
             // same as above with OS_DisableIrqMask
             u32 osDisableIrqMaskCallLocation = cardiOnReadCard + cardiOnReadCardOffset + 4;
-            s32 osDisableIrqMaskCallOffset = getArmBlOffset(*(u32*)osDisableIrqMaskCallLocation);
+            s32 osDisableIrqMaskCallOffset = ArmHelper::GetArmCallOffset(*(u32*)osDisableIrqMaskCallLocation);
             if (autoloadAdjuster)
             {
                 osDisableIrqMaskCallLocation = autoloadAdjuster->AdjustInitialToFinal(osDisableIrqMaskCallLocation);

common/ArmHelper.h

@@ -0,0 +1,63 @@
+#pragma once
+
+/// @brief Class containing helper functions for manipulating ARM or Thumb assembly.
+class ArmHelper
+{
+public:
+    ArmHelper() = delete;
+
+    /// @brief Check if an ARM instruction is an unconditional bl call.
+    /// @param instruction The ARM instruction to check.
+    /// @return True if the instruction is an unconditional bl call, false otherwise.
+    static bool IsArmUnconditionalBl(u32 instruction)
+    {
+        return (instruction >> 24) == 0xEB;
+    }
+
+    /// @brief Get the offset of an ARM call (bl or blx).
+    /// @param callInstruction The ARM call instruction.
+    /// @return The offset to the destination function. +1 if Thumb.
+    static s32 GetArmCallOffset(u32 callInstruction)
+    {
+        return 8 + ((int)((callInstruction & 0xFFFFFF) << 8) >> 6)
+            + ((callInstruction >> 24) == 0xFA ? 1 : 0);
+    }
+
+    /// @brief Get the address of the callee in an ARM call (bl or blx).
+    /// @param instructionPointer Pointer to the ARM call instruction.
+    /// @return The address of the function being called. +1 if Thumb.
+    static u32 GetArmCallAddress(const void* instructionPointer)
+    {
+        auto pc = (const u32*)((u32)instructionPointer & ~3);
+        return (u32)pc + GetArmCallOffset(*pc);
+    }
+
+    /// @brief Create an ARM call instruction (bl or blx).
+    /// @param instructionAddress The address where the instruction is to be placed.
+    /// @param targetAddress The address of the function to call. +1 if Thumb.
+    /// @return The ARM call instruction to call the target.
+    static u32 MakeArmCall(u32 instructionAddress, u32 targetAddress)
+    {
+        u32 offset = targetAddress - instructionAddress - 8;
+        return ((targetAddress & 1) ? 0xFA000000 : 0xEB000000) | ((offset >> 2) & 0xFFFFFF);
+    }
+
+    /// @brief Get the offset of a Thumb call (bl or blx).
+    /// @param callInstruction1 The first Thumb call instruction.
+    /// @param callInstruction2 The second Thumb call instruction.
+    /// @return The offset to the destination function. +1 if Thumb.
+    static s32 GetThumbCallOffset(u16 callInstruction1, u16 callInstruction2)
+    {
+        return 4 + ((int)((((callInstruction1 & 0x7FF) << 11) | (callInstruction2 & 0x7FF)) << 10) >> 9)
+            + ((callInstruction2 >> 11) == 0x1F ? 1 : 0);
+    }
+
+    /// @brief Get the address of the callee in an Thumb call (bl or blx).
+    /// @param instructionPointer Pointer to the first Thumb call instruction.
+    /// @return The offset to the destination function. +1 if Thumb.
+    static u32 GetThumbCallAddress(const void* instructionPointer)
+    {
+        auto pc = (const u16*)((u32)instructionPointer & ~1);
+        return (u32)pc + GetThumbCallOffset(pc[0], pc[1]);
+    }
+};