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Code Issues Releases Activity

Refactor SUB handlers

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bird_egop
2025-04-13 18:22:44 +03:00
parent a04a16af7d
commit e91a0223f7
18 changed files with 493 additions and 200 deletions
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56
X86Disassembler/X86/Handlers/Sub/SubImmFromRm32Handler.cs
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@ -11,11 +11,11 @@ public class SubImmFromRm32Handler : InstructionHandler
/// <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 SubImmFromRm32Handler(byte[] codeBuffer, InstructionDecoder decoder, int length)
public SubImmFromRm32Handler(byte[] codeBuffer, InstructionDecoder decoder, int length)
: base(codeBuffer, decoder, length)
{
}
/// <summary>
/// Checks if this handler can decode the given opcode
/// </summary>
@ -25,18 +25,18 @@ public class SubImmFromRm32Handler : InstructionHandler
{
if (opcode != 0x81)
return false;
// Check if the reg field of the ModR/M byte is 5 (SUB)
int position = Decoder.GetPosition();
if (position >= Length)
return false;
byte modRM = CodeBuffer[position];
byte reg = (byte)((modRM & 0x38) >> 3);
byte reg = (byte) ((modRM & 0x38) >> 3);
return reg == 5; // 5 = SUB
}
/// <summary>
/// Decodes a SUB r/m32, imm32 instruction
/// </summary>
@ -47,53 +47,43 @@ public class SubImmFromRm32Handler : InstructionHandler
{
// Set the mnemonic
instruction.Mnemonic = "sub";
int position = Decoder.GetPosition();
if (position >= Length)
{
return false;
}
// Read the ModR/M byte
byte modRM = CodeBuffer[position++];
Decoder.SetPosition(position);
// Extract the fields from the ModR/M byte
byte mod = (byte)((modRM & 0xC0) >> 6);
byte reg = (byte)((modRM & 0x38) >> 3); // Should be 5 for SUB
byte rm = (byte)(modRM & 0x07);
// Let the ModRMDecoder handle the ModR/M byte and any additional bytes (SIB, displacement)
// This will update the decoder position to point after the ModR/M and any additional bytes
string destOperand = ModRMDecoder.DecodeModRM(mod, rm, false);
var (mod, reg, rm, destOperand) = ModRMDecoder.ReadModRM();
// Get the updated position after ModR/M decoding
position = Decoder.GetPosition();
// Read the immediate value
if (position + 3 >= Length)
{
return false;
}
// Read the immediate value in little-endian format
byte b0 = CodeBuffer[position];
byte b1 = CodeBuffer[position + 1];
byte b2 = CodeBuffer[position + 2];
byte b3 = CodeBuffer[position + 3];
// Format the immediate value as expected by the tests (0x12345678)
// Note: Always use the same format regardless of operand type to match test expectations
string immStr = $"0x{b3:X2}{b2:X2}{b1:X2}{b0:X2}";
var imm = Decoder.ReadUInt32();
// Format the immediate value
string immStr = $"0x{imm:X8}";
// Advance the position past the immediate value
position += 4;
Decoder.SetPosition(position);
// Set the operands
instruction.Operands = $"{destOperand}, {immStr}";
return true;
}
}
}