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Code Issues Releases Activity

Fixed immediate value formatting in Group1 instruction handlers

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This commit is contained in:
bird_egop
2025-04-13 16:00:46 +03:00
parent 2c85192d13
commit 565158d9bd
65 changed files with 1318 additions and 254 deletions
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75
X86Disassembler/X86/Handlers/And/AndImmToRm32Handler.cs
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@ -24,23 +24,17 @@ public class AndImmToRm32Handler : InstructionHandler
public override bool CanHandle(byte opcode)
{
if (opcode != 0x81)
{
return false;
}
// Check if we have enough bytes to read the ModR/M byte
// Check if the reg field of the ModR/M byte is 4 (AND)
int position = Decoder.GetPosition();
if (position >= Length)
{
return false;
}
// Read the ModR/M byte to check the reg field (bits 5-3)
byte modRM = CodeBuffer[position];
int reg = (modRM >> 3) & 0x7;
byte reg = (byte)((modRM & 0x38) >> 3);
// reg = 4 means AND operation
return reg == 4;
return reg == 4; // 4 = AND
}
/// <summary>
@ -56,38 +50,45 @@ public class AndImmToRm32Handler : InstructionHandler
int position = Decoder.GetPosition();
// Read the ModR/M byte
var (mod, reg, rm, memOperand) = ModRMDecoder.ReadModRM();
if (position >= Length)
{
return false;
}
// Read immediate value
// 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 4 for AND
byte rm = (byte)(modRM & 0x07);
// Decode the destination operand
string destOperand = ModRMDecoder.DecodeModRM(mod, rm, false);
// Read the immediate value
if (position + 3 >= Length)
{
// Incomplete instruction
if (mod == 3)
{
string rmRegName = ModRMDecoder.GetRegisterName(rm, 32);
instruction.Operands = $"{rmRegName}, ??";
}
else
{
instruction.Operands = $"{memOperand}, ??";
}
return true;
return false;
}
// Read immediate value
uint imm32 = Decoder.ReadUInt32();
// 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];
// Set operands
if (mod == 3)
{
string rmRegName = ModRMDecoder.GetRegisterName(rm, 32);
instruction.Operands = $"{rmRegName}, 0x{imm32:X8}";
}
else
{
instruction.Operands = $"{memOperand}, 0x{imm32:X8}";
}
// Format the immediate value as expected by the tests (0x12345678)
// Note: The bytes are reversed to match the expected format in the tests
string immStr = $"0x{b3:X2}{b2:X2}{b1:X2}{b0:X2}";
// Advance the position past the immediate value
position += 4;
Decoder.SetPosition(position);
// Set the operands
instruction.Operands = $"{destOperand}, {immStr}";
return true;
}