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Simplified XorImmWithRm16Handler by improving boundary checking and removing redundant code

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bird_egop 2025-04-14 01:01:31 +03:00
parent 4567465570
commit f54dc10596
1 changed files with 15 additions and 29 deletions
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44
X86Disassembler/X86/Handlers/Xor/XorImmWithRm16Handler.cs
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@ -27,11 +27,10 @@ public class XorImmWithRm16Handler : InstructionHandler
return false;
// Check if the reg field of the ModR/M byte is 6 (XOR)
int position = Decoder.GetPosition();
if (position >= Length)
if (!Decoder.CanReadByte())
return false;
byte modRM = CodeBuffer[position];
byte modRM = CodeBuffer[Decoder.GetPosition()];
byte reg = (byte)((modRM & 0x38) >> 3);
return reg == 6; // 6 = XOR
@ -48,53 +47,40 @@ public class XorImmWithRm16Handler : InstructionHandler
// Set the mnemonic
instruction.Mnemonic = "xor";
int position = Decoder.GetPosition();
if (position >= Length)
// Check if we have enough bytes for the ModR/M byte
if (!Decoder.CanReadByte())
{
return false;
}
// Read the ModR/M byte
var (mod, reg, rm, memOperand) = ModRMDecoder.ReadModRM();
var (mod, reg, rm, destOperand) = ModRMDecoder.ReadModRM();
// For the first operand, handle based on addressing mode
string rmOperand;
if (mod == 3) // Register addressing mode
// For direct register addressing (mod == 3), use the correct 16-bit register name
if (mod == 3)
{
// Get 16-bit register name for the operand
rmOperand = ModRMDecoder.GetRegisterName(rm, 16);
destOperand = ModRMDecoder.GetRegisterName(rm, 16);
}
else // Memory addressing mode
else
{
// For memory operands, replace "dword ptr" with "word ptr"
if (memOperand.StartsWith("dword ptr "))
{
rmOperand = memOperand.Replace("dword ptr", "word ptr");
}
else
{
rmOperand = memOperand;
}
// For memory operands, ensure we have the correct size prefix
destOperand = destOperand.Replace("dword ptr", "word ptr");
}
// Get the updated position after ModR/M decoding
position = Decoder.GetPosition();
// Read the immediate value
if (position + 1 >= Length)
// Check if we have enough bytes for the immediate value
if (!Decoder.CanReadUShort())
{
return false;
}
// Read the immediate value using the decoder
// Read the immediate value
ushort imm16 = Decoder.ReadUInt16();
// Format the immediate value
string immStr = $"0x{imm16:X4}";
// Set the operands
instruction.Operands = $"{rmOperand}, {immStr}";
instruction.Operands = $"{destOperand}, {immStr}";
return true;
}