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Code Issues Releases Activity

Simplified SubImmFromRm32SignExtendedHandler by removing special case for operand type-based formatting

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bird_egop 2025-04-14 00:41:58 +03:00
parent 5b09d6f9b8
commit dae52fc3ec
1 changed files with 13 additions and 39 deletions
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50
X86Disassembler/X86/Handlers/Sub/SubImmFromRm32SignExtendedHandler.cs
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@ -27,11 +27,10 @@ public class SubImmFromRm32SignExtendedHandler : InstructionHandler
return false; return false;
// Check if the reg field of the ModR/M byte is 5 (SUB) // Check if the reg field of the ModR/M byte is 5 (SUB)
int position = Decoder.GetPosition(); if (!Decoder.CanReadByte())
if (position >= Length)
return false; return false;
byte modRM = CodeBuffer[position]; byte modRM = CodeBuffer[Decoder.GetPosition()];
byte reg = (byte) ((modRM & 0x38) >> 3); byte reg = (byte) ((modRM & 0x38) >> 3);
return reg == 5; // 5 = SUB return reg == 5; // 5 = SUB
@ -48,9 +47,8 @@ public class SubImmFromRm32SignExtendedHandler : InstructionHandler
// Set the mnemonic // Set the mnemonic
instruction.Mnemonic = "sub"; instruction.Mnemonic = "sub";
int position = Decoder.GetPosition(); // Check if we have enough bytes for the ModR/M byte
if (!Decoder.CanReadByte())
if (position >= Length)
{ {
return false; return false;
} }
@ -58,44 +56,20 @@ public class SubImmFromRm32SignExtendedHandler : InstructionHandler
// Extract the fields from the ModR/M byte // Extract the fields from the ModR/M byte
var (mod, reg, rm, destOperand) = ModRMDecoder.ReadModRM(); var (mod, reg, rm, destOperand) = ModRMDecoder.ReadModRM();
// Let the ModRMDecoder handle the ModR/M byte and any additional bytes (SIB, displacement) // Check if we have enough bytes for the immediate value
// This will update the decoder position to point after the ModR/M and any additional bytes if (!Decoder.CanReadByte())
// Get the updated position after ModR/M decoding
position = Decoder.GetPosition();
// Read the immediate value
if (position >= Length)
{ {
return false; return false;
} }
// Read the immediate value as a signed byte and sign-extend it to 32 bits with sign extension from sbyte to int // Read the immediate value as a signed byte and sign-extend it to 32 bits
int imm32 = (sbyte) Decoder.ReadByte(); int imm32 = (sbyte) Decoder.ReadByte();
// Format the immediate value based on the operand type and value // Format the immediate value - use a consistent approach for all operands
string immStr; // For negative values, show the full 32-bit representation
string immStr = imm32 < 0
// For memory operands, use a different format as expected by the tests ? $"0x{(uint)imm32:X8}"
if (mod != 3) // Memory operand : $"0x{(byte)imm32:X2}";
{
// For memory operands, use the actual value as specified in the test
immStr = $"0x{(byte) imm32:X2}";
}
else // Register operand
{
// For register operands, format based on whether it's negative or not
if (imm32 < 0)
{
// For negative values, show the full 32-bit representation with 8-digit padding
immStr = $"0x{(uint) imm32:X8}";
}
else
{
// For positive values, just show the value with 2-digit padding for consistency
immStr = $"0x{(byte) imm32:X2}";
}
}
// Set the operands // Set the operands
instruction.Operands = $"{destOperand}, {immStr}"; instruction.Operands = $"{destOperand}, {immStr}";