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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/SubImmFromRm32SignExtendedHandler.cs
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@ -11,11 +11,11 @@ public class SubImmFromRm32SignExtendedHandler : 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 SubImmFromRm32SignExtendedHandler(byte[] codeBuffer, InstructionDecoder decoder, int length)
public SubImmFromRm32SignExtendedHandler(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 SubImmFromRm32SignExtendedHandler : InstructionHandler
{
if (opcode != 0x83)
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, imm8 (sign-extended) instruction
/// </summary>
@ -47,49 +47,41 @@ public class SubImmFromRm32SignExtendedHandler : 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);
var (mod, reg, rm, destOperand) = ModRMDecoder.ReadModRM();
// 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);
// Get the updated position after ModR/M decoding
position = Decoder.GetPosition();
// Read the immediate value
if (position >= Length)
{
return false;
}
// Read the immediate value as a signed byte and sign-extend it to 32 bits
sbyte imm8 = (sbyte)CodeBuffer[position++];
sbyte imm8 = (sbyte) Decoder.ReadByte();
int imm32 = imm8; // Automatic sign extension from sbyte to int
Decoder.SetPosition(position);
// Format the immediate value based on the operand type and value
string immStr;
// For memory operands, use a different format as expected by the tests
if (mod != 3) // Memory operand
{
// For memory operands, use the actual value as specified in the test
immStr = $"0x{(byte)imm8:X2}";
immStr = $"0x{(byte) imm8:X2}";
}
else // Register operand
{
@ -97,18 +89,18 @@ public class SubImmFromRm32SignExtendedHandler : InstructionHandler
if (imm8 < 0)
{
// For negative values, show the full 32-bit representation with 8-digit padding
immStr = $"0x{(uint)imm32:X8}";
immStr = $"0x{(uint) imm32:X8}";
}
else
{
// For positive values, just show the value with 2-digit padding for consistency
immStr = $"0x{(byte)imm8:X2}";
immStr = $"0x{(byte) imm8:X2}";
}
}
// Set the operands
instruction.Operands = $"{destOperand}, {immStr}";
return true;
}
}
}