0
mirror of https://github.com/sampletext32/ParkanPlayground.git synced 2025-05-19 03:41:18 +03:00

88 lines
2.8 KiB
C#

namespace X86Disassembler.X86.Handlers.FloatingPoint.Comparison;
using X86Disassembler.X86.Operands;
/// <summary>
/// Handler for FUCOM ST(i) instruction (DD E0-E7)
/// </summary>
public class FucomHandler : InstructionHandler
{
/// <summary>
/// Initializes a new instance of the FucomHandler class
/// </summary>
/// <param name="decoder">The instruction decoder that owns this handler</param>
public FucomHandler(InstructionDecoder decoder)
: base(decoder)
{
}
/// <summary>
/// Checks if this handler can decode the given opcode
/// </summary>
/// <param name="opcode">The opcode to check</param>
/// <returns>True if this handler can decode the opcode</returns>
public override bool CanHandle(byte opcode)
{
// FUCOM ST(i) is DD E0-E7
if (opcode != 0xDD) return false;
if (!Decoder.CanReadByte())
{
return false;
}
// Check if the ModR/M byte has reg field = 4 and mod = 3
byte modRm = Decoder.PeakByte();
byte reg = (byte)((modRm >> 3) & 0x7);
byte mod = (byte)((modRm >> 6) & 0x3);
// Only handle register operands (mod = 3) with reg = 4
return reg == 4 && mod == 3;
}
/// <summary>
/// Decodes a FUCOM ST(i) instruction
/// </summary>
/// <param name="opcode">The opcode of the instruction</param>
/// <param name="instruction">The instruction object to populate</param>
/// <returns>True if the instruction was successfully decoded</returns>
public override bool Decode(byte opcode, Instruction instruction)
{
if (!Decoder.CanReadByte())
{
return false;
}
// Read the ModR/M byte
var (mod, reg, rm, _) = ModRMDecoder.ReadModRM();
// Set the instruction type
instruction.Type = InstructionType.Fucom;
// Map rm field to FPU register index
FpuRegisterIndex stIndex = rm switch
{
RegisterIndex.A => FpuRegisterIndex.ST0,
RegisterIndex.C => FpuRegisterIndex.ST1,
RegisterIndex.D => FpuRegisterIndex.ST2,
RegisterIndex.B => FpuRegisterIndex.ST3,
RegisterIndex.Sp => FpuRegisterIndex.ST4,
RegisterIndex.Bp => FpuRegisterIndex.ST5,
RegisterIndex.Si => FpuRegisterIndex.ST6,
RegisterIndex.Di => FpuRegisterIndex.ST7,
_ => FpuRegisterIndex.ST0 // Default case, should not happen
};
// Create the FPU register operand
var fpuRegisterOperand = OperandFactory.CreateFPURegisterOperand(stIndex);
// Set the structured operands
instruction.StructuredOperands =
[
fpuRegisterOperand
];
return true;
}
}