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Code Issues Releases Activity

Updated instruction handlers to use Type and StructuredOperands instead of Mnemonic and Operands

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This commit is contained in:
bird_egop
2025-04-14 22:08:50 +03:00
parent c516e063e7
commit 685eeda03d
136 changed files with 3694 additions and 2584 deletions
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83
X86Disassembler/X86/Handlers/Nop/MultiByteNopHandler.cs
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@ -1,41 +1,41 @@
namespace X86Disassembler.X86.Handlers.Nop;
using X86Disassembler.X86.Operands;
/// <summary>
/// Handler for multi-byte NOP instructions (0x0F 0x1F ...)
/// These are used for alignment and are encoded as NOP operations with specific memory operands
/// </summary>
public class MultiByteNopHandler : InstructionHandler
{
// NOP variant information (ModR/M byte, memory operand, and expected bytes pattern)
private static readonly (byte ModRm, string MemOperand, byte[] ExpectedBytes)[] NopVariants =
// NOP variant information (ModR/M byte, expected bytes pattern, and operand creation info)
private static readonly (byte ModRm, byte[] ExpectedBytes, RegisterIndex BaseReg, RegisterIndex? IndexReg, int Scale)[] NopVariants =
{
// 8-byte NOP: 0F 1F 84 00 00 00 00 00 (check longest patterns first)
(0x84, "[eax+eax*1]", new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00 }),
(0x84, new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00 }, RegisterIndex.A, RegisterIndex.A, 1),
// 7-byte NOP: 0F 1F 80 00 00 00 00
(0x80, "[eax]", new byte[] { 0x00, 0x00, 0x00, 0x00 }),
(0x80, new byte[] { 0x00, 0x00, 0x00, 0x00 }, RegisterIndex.A, null, 0),
// 6-byte NOP: 0F 1F 44 00 00 00
(0x44, "[eax+eax*1]", new byte[] { 0x00, 0x00, 0x00 }),
(0x44, new byte[] { 0x00, 0x00, 0x00 }, RegisterIndex.A, RegisterIndex.A, 1),
// 5-byte NOP: 0F 1F 44 00 00
(0x44, "[eax+eax*1]", new byte[] { 0x00, 0x00 }),
(0x44, new byte[] { 0x00, 0x00 }, RegisterIndex.A, RegisterIndex.A, 1),
// 4-byte NOP: 0F 1F 40 00
(0x40, "[eax]", new byte[] { 0x00 }),
(0x40, new byte[] { 0x00 }, RegisterIndex.A, null, 0),
// 3-byte NOP: 0F 1F 00
(0x00, "[eax]", Array.Empty<byte>())
(0x00, Array.Empty<byte>(), RegisterIndex.A, null, 0)
};
/// <summary>
/// Initializes a new instance of the MultiByteNopHandler class
/// </summary>
/// <param name="codeBuffer">The buffer containing the code to decode</param>
/// <param name="decoder">The instruction decoder that owns this handler</param>
/// <param name="length">The length of the buffer</param>
public MultiByteNopHandler(byte[] codeBuffer, InstructionDecoder decoder, int length)
: base(codeBuffer, decoder, length)
public MultiByteNopHandler(InstructionDecoder decoder)
: base(decoder)
{
}
@ -59,7 +59,7 @@ public class MultiByteNopHandler : InstructionHandler
}
// Check if the second byte is 0x1F (part of the multi-byte NOP encoding)
byte secondByte = CodeBuffer[Decoder.GetPosition()];
byte secondByte = Decoder.PeakByte();
return secondByte == 0x1F;
}
@ -71,8 +71,8 @@ public class MultiByteNopHandler : InstructionHandler
/// <returns>True if the instruction was successfully decoded</returns>
public override bool Decode(byte opcode, Instruction instruction)
{
// Set the mnemonic
instruction.Mnemonic = "nop";
// Set the instruction type
instruction.Type = InstructionType.Nop;
// Skip the second byte (0x1F)
Decoder.ReadByte();
@ -87,27 +87,28 @@ public class MultiByteNopHandler : InstructionHandler
bool hasOperandSizePrefix = Decoder.HasOperandSizeOverridePrefix();
// Determine the size of the operand
string ptrType = hasOperandSizePrefix ? "word ptr" : "dword ptr";
int operandSize = hasOperandSizePrefix ? 16 : 32;
// Read the ModR/M byte but don't advance the position yet
int position = Decoder.GetPosition();
byte modRm = CodeBuffer[position];
byte modRm = Decoder.PeakByte();
// Default memory operand if no specific variant is matched
string memOperand = "[eax]";
// Default memory operand parameters
RegisterIndex baseReg = RegisterIndex.A;
RegisterIndex? indexReg = null;
int scale = 0;
int bytesToSkip = 1; // Skip at least the ModR/M byte
// Try to find a matching NOP variant (we check longest patterns first)
foreach (var (variantModRm, operand, expectedBytes) in NopVariants)
foreach (var (variantModRm, expectedBytes, variantBaseReg, variantIndexReg, variantScale) in NopVariants)
{
// Skip if ModR/M doesn't match
if (variantModRm != modRm)
{
continue;
}
// Check if we have enough bytes for this pattern
if (position + expectedBytes.Length >= Length)
if (!Decoder.CanRead(expectedBytes.Length + 1)) // +1 for ModR/M byte
{
continue;
}
@ -116,7 +117,9 @@ public class MultiByteNopHandler : InstructionHandler
bool isMatch = true;
for (int i = 0; i < expectedBytes.Length; i++)
{
if (position + i + 1 >= Length || CodeBuffer[position + i + 1] != expectedBytes[i])
// Check the byte at position
byte actualByte = Decoder.PeakByte();
if (actualByte != expectedBytes[i])
{
isMatch = false;
break;
@ -126,17 +129,41 @@ public class MultiByteNopHandler : InstructionHandler
// If we found a match, use it and stop checking
if (isMatch)
{
memOperand = operand;
baseReg = variantBaseReg;
indexReg = variantIndexReg;
scale = variantScale;
bytesToSkip = 1 + expectedBytes.Length; // ModR/M byte + additional bytes
break;
}
}
// Skip the bytes we've processed
Decoder.SetPosition(position + bytesToSkip);
Decoder.SetPosition(Decoder.GetPosition() + bytesToSkip);
// Set the operands with the appropriate size prefix
instruction.Operands = $"{ptrType} {memOperand}";
// Create the appropriate structured operand based on the NOP variant
if (indexReg.HasValue && scale > 0)
{
// Create a scaled index memory operand (e.g., [eax+eax*1])
instruction.StructuredOperands =
[
OperandFactory.CreateScaledIndexMemoryOperand(
indexReg.Value,
scale,
baseReg,
0,
operandSize)
];
}
else
{
// Create a simple base register memory operand (e.g., [eax])
instruction.StructuredOperands =
[
OperandFactory.CreateBaseRegisterMemoryOperand(
baseReg,
operandSize)
];
}
return true;
}