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using Ryujinx.HLE.Exceptions;
using Ryujinx.HLE.HOS.Tamper.Operations;
namespace Ryujinx.HLE.HOS.Tamper.CodeEmitters
{
/// <summary>
/// Code type 6 allows writing a fixed value to a memory address specified by a register.
/// </summary>
class StoreConstantToMemory
{
private const int OperationWidthIndex = 1;
private const int AddressRegisterIndex = 3;
private const int IncrementAddressRegisterIndex = 4;
private const int UseOffsetRegisterIndex = 5;
private const int OffsetRegisterIndex = 6;
private const int ValueImmediateIndex = 8;
private const int ValueImmediateSize = 16;
public static void Emit(byte[] instruction, CompilationContext context)
{
// 6T0RIor0 VVVVVVVV VVVVVVVV
// T: Width of memory write(1, 2, 4, or 8 bytes).
// R: Register used as base memory address.
// I: Increment register flag(0 = do not increment R, 1 = increment R by T).
// o: Offset register enable flag(0 = do not add r to address, 1 = add r to address).
// r: Register used as offset when o is 1.
// V: Value to write to memory.
byte operationWidth = instruction[OperationWidthIndex];
Register sourceRegister = context.GetRegister(instruction[AddressRegisterIndex]);
byte incrementAddressRegister = instruction[IncrementAddressRegisterIndex];
byte useOffsetRegister = instruction[UseOffsetRegisterIndex];
ulong immediate = InstructionHelper.GetImmediate(instruction, ValueImmediateIndex, ValueImmediateSize);
Value<ulong> storeValue = new(immediate);
Pointer destinationMemory;
switch (useOffsetRegister)
{
case 0:
// Don't offset the address register by another register.
destinationMemory = MemoryHelper.EmitPointer(sourceRegister, context);
break;
case 1:
// Replace the source address by the sum of the base and offset registers.
Register offsetRegister = context.GetRegister(instruction[OffsetRegisterIndex]);
destinationMemory = MemoryHelper.EmitPointer(sourceRegister, offsetRegister, context);
break;
default:
throw new TamperCompilationException($"Invalid offset mode {useOffsetRegister} in Atmosphere cheat");
}
InstructionHelper.EmitMov(operationWidth, context, destinationMemory, storeValue);
switch (incrementAddressRegister)
{
case 0:
// Don't increment the address register by operationWidth.
break;
case 1:
// Increment the address register by operationWidth.
IOperand increment = new Value<ulong>(operationWidth);
context.CurrentOperations.Add(new OpAdd<ulong>(sourceRegister, sourceRegister, increment));
break;
default:
throw new TamperCompilationException($"Invalid increment mode {incrementAddressRegister} in Atmosphere cheat");
}
}
}
}
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