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

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

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]);
+    }
+};