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Code Issues Releases Activity

Refactor SUB handlers

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This commit is contained in:
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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61
X86Disassembler/X86/Handlers/Sub/SubImmFromRm16Handler.cs
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@ -36,32 +36,27 @@ public class SubImmFromRm16Handler : InstructionHandler
public override bool Decode(byte opcode, Instruction instruction)
{
int position = Decoder.GetPosition();
if (position >= Length)
{
return false;
}
// Read the ModR/M byte
byte modRM = CodeBuffer[position++];
// Extract the fields from the ModR/M byte
byte mod = (byte)((modRM & 0xC0) >> 6);
byte reg = (byte)((modRM & 0x38) >> 3);
byte rm = (byte)(modRM & 0x07);
var (mod, reg, rm, operand) = ModRMDecoder.ReadModRM();
// Check if this is a SUB instruction (reg field must be 5)
if (reg != 5)
{
return false;
}
// Set the mnemonic
instruction.Mnemonic = "sub";
// Update the decoder position
Decoder.SetPosition(position);
// For mod == 3, the r/m field specifies a register
string destination;
if (mod == 3)
@ -73,43 +68,37 @@ public class SubImmFromRm16Handler : InstructionHandler
{
// Get the memory operand string
destination = ModRMDecoder.DecodeModRM(mod, rm, false);
// Replace "dword" with "word" in the memory operand
destination = destination.Replace("dword", "word");
}
// Get the current position after processing the ModR/M byte
position = Decoder.GetPosition();
// Check if we have enough bytes for the immediate value
if (position + 1 >= Length)
{
return false;
}
// Read the immediate value (16-bit)
byte lowByte = CodeBuffer[position++];
byte highByte = CodeBuffer[position++];
// Combine the bytes into a 16-bit value
ushort immediate = (ushort)((highByte << 8) | lowByte);
// Update the decoder position
Decoder.SetPosition(position);
ushort immediate = Decoder.ReadUInt16();
// Set the operands (note: we use 32-bit register names to match the disassembler's output)
if (mod == 3)
{
// For register operands, use the 32-bit register name
string reg32Name = destination.Replace("ax", "eax")
.Replace("bx", "ebx")
.Replace("cx", "ecx")
.Replace("dx", "edx")
.Replace("sp", "esp")
.Replace("bp", "ebp")
.Replace("si", "esi")
.Replace("di", "edi");
string reg32Name = destination
.Replace("ax", "eax")
.Replace("bx", "ebx")
.Replace("cx", "ecx")
.Replace("dx", "edx")
.Replace("sp", "esp")
.Replace("bp", "ebp")
.Replace("si", "esi")
.Replace("di", "edi");
instruction.Operands = $"{reg32Name}, 0x{immediate:X4}";
}
else
@ -117,7 +106,7 @@ public class SubImmFromRm16Handler : InstructionHandler
// For memory operands, keep the memory operand as is
instruction.Operands = $"{destination}, 0x{immediate:X4}";
}
return true;
}
}
}