diff --git a/Y86_as/as86.py b/Y86_as/as86.py
new file mode 100644
index 0000000..af8975b
--- /dev/null
+++ b/Y86_as/as86.py
@@ -0,0 +1,252 @@
+import sys
+import re
+import struct
+
+# Y86-64 Constants
+# Register mapping from name to number
+REG = {
+    '%rax': 0x0, '%rcx': 0x1, '%rdx': 0x2, '%rbx': 0x3,
+    '%rsp': 0x4, '%rbp': 0x5, '%rsi': 0x6, '%rdi': 0x7,
+    '%r8':  0x8, '%r9':  0x9, '%r10': 0xa, '%r11': 0xb,
+    '%r12': 0xc, '%r13': 0xd, '%r14': 0xe, 'F': 0xF
+}
+
+# Instruction mapping from mnemonic to (icode, ifun)
+# icode is the instruction code, ifun is the function code
+INS = {
+    'halt':   (0x0, 0x0), 'nop':    (0x1, 0x0), 'rrmovq': (0x2, 0x0),
+    'cmovle': (0x2, 0x1), 'cmovl':  (0x2, 0x2), 'cmove':  (0x2, 0x3),
+    'cmovne': (0x2, 0x4), 'cmovge': (0x2, 0x5), 'cmovg':  (0x2, 0x6),
+    'irmovq': (0x3, 0x0), 'rmmovq': (0x4, 0x0), 'mrmovq': (0x5, 0x0),
+    'addq':   (0x6, 0x0), 'subq':   (0x6, 0x1), 'andq':   (0x6, 0x2),
+    'xorq':   (0x6, 0x3), 'jmp':    (0x7, 0x0), 'jle':    (0x7, 0x1),
+    'jl':     (0x7, 0x2), 'je':     (0x7, 0x3), 'jne':    (0x7, 0x4),
+    'jge':    (0x7, 0x5), 'jg':     (0x7, 0x6), 'call':   (0x8, 0x0),
+    'ret':    (0x9, 0x0), 'pushq':  (0xA, 0x0), 'popq':   (0xB, 0x0)
+}
+
+class Y86Assembler:
+    """
+    A two-pass assembler for the Y86-64 instruction set.
+    """
+    def __init__(self):
+        self.symbol_table = {}
+        self.pc = 0
+        self.byte_code = {} # Maps address to (size, hex_string, original_line)
+
+    def assemble(self, filepath):
+        """
+        Assembles a Y86-64 source file.
+        
+        Args:
+            filepath (str): The path to the input .txt or .ys file.
+
+        Returns:
+            str: The formatted machine code output.
+        """
+        try:
+            with open(filepath, 'r') as f:
+                lines = f.readlines()
+        except FileNotFoundError:
+            return f"Error: File not found at '{filepath}'"
+
+        print("🚀 Starting assembly process...")
+        self._first_pass(lines)
+        print("✅ First pass complete. Symbol table built.")
+        self._second_pass(lines)
+        print("✅ Second pass complete. Machine code generated.")
+        return self._format_output()
+
+    def _parse_line(self, line):
+        """Strips comments and splits a line into label, instruction, and operands."""
+        line = line.split('#')[0].split('|')[0].strip()
+        if not line:
+            return None, None, []
+
+        label, instruction, operands_str = None, None, ''
+        if ':' in line:
+            label, rest = line.split(':', 1)
+            line = rest.strip()
+        
+        parts = line.split(maxsplit=1)
+        if parts:
+            instruction = parts[0]
+            if len(parts) > 1:
+                operands_str = parts[1]
+        
+        # Split operands by comma, but not inside parentheses
+        operands = re.split(r',\s*(?![^()]*\))', operands_str) if operands_str else []
+        
+        return label, instruction, [op.strip() for op in operands]
+
+    def _get_instruction_size(self, instruction, operands):
+        """Calculates the size of an instruction in bytes."""
+        if not instruction: return 0
+        
+        if instruction in ['.quad']: return 8
+        if instruction in ['.pos', '.align']: return 0
+
+        # ********** MODIFICATION START **********
+        # Handle custom `addq $val, rB` which has size 10
+        if instruction == 'addq' and operands and operands[0].startswith('$'):
+            return 10  # 1 (icode) + 1 (reg) + 8 (val)
+        # ********** MODIFICATION END **********
+            
+        icode = INS[instruction][0]
+        if icode in [0x0, 0x1, 0x9]: return 1
+        if icode in [0x2, 0x6, 0xA, 0xB]: return 2
+        if icode in [0x7, 0x8]: return 9
+        if icode in [0x3, 0x4, 0x5]: return 10
+        return 0
+
+    def _first_pass(self, lines):
+        """
+        Builds the symbol table by mapping labels to addresses.
+        """
+        self.pc = 0
+        for line_num, line in enumerate(lines, 1):
+            label, instruction, operands = self._parse_line(line)
+
+            if label:
+                if label in self.symbol_table:
+                    print(f"Warning: Duplicate label '{label}' on line {line_num}. Using first definition.")
+                else:
+                    self.symbol_table[label] = self.pc
+
+            if not instruction: continue
+
+            if instruction == '.pos':
+                self.pc = int(operands[0], 0)
+            elif instruction == '.align':
+                align_val = int(operands[0])
+                self.pc = (self.pc + align_val - 1) & -align_val
+            else:
+                self.pc += self._get_instruction_size(instruction, operands)
+
+    def _second_pass(self, lines):
+        self.pc = 0
+        for line_num, line in enumerate(lines, 1):
+            original_line = line.strip()
+            label, instruction, operands = self._parse_line(line)
+            
+            if instruction == '.pos':
+                self.pc = int(operands[0], 0)
+                continue
+            elif instruction == '.align':
+                new_pc = (self.pc + int(operands[0]) - 1) & -int(operands[0])
+                if new_pc != self.pc: self.byte_code[self.pc] = (0, '', original_line)
+                self.pc = new_pc
+                continue
+
+            if not instruction:
+                if label: self.byte_code[self.pc] = (0, '', original_line)
+                continue
+
+            start_pc = self.pc
+            size = self._get_instruction_size(instruction, operands)
+            code = bytearray()
+
+            if instruction == '.quad':
+                val = self._parse_value(operands[0])
+                code.extend(struct.pack('<Q', val))
+            else:
+                # ********** MODIFICATION START **********
+                # Handle our custom `addq $imm, rB` instruction
+                if instruction == 'addq' and operands[0].startswith('$'):
+                    icode, ifun = 0xC, 0x0  # Use unused icode 0xC for our custom instruction
+                    code.append((icode << 4) | ifun)
+                    
+                    rB = REG[operands[1]]
+                    rA = REG['F'] # No source register, so rA is F
+                    code.append((rA << 4) | rB)
+                    
+                    val = self._parse_value(operands[0])
+                    code.extend(struct.pack('<q', val))
+                # ********** MODIFICATION END **********
+                else:
+                    # Original logic for all other instructions
+                    icode, ifun = INS[instruction]
+                    b0 = (icode << 4) | ifun
+                    code.append(b0)
+                    
+                    if instruction in ['rrmovq', 'cmovle', 'cmovl', 'cmove', 'cmovne', 'cmovge', 'cmovg', 'addq', 'subq', 'andq', 'xorq']:
+                        rA = REG[operands[0]]
+                        rB = REG[operands[1]]
+                        code.append((rA << 4) | rB)
+                    elif instruction in ['pushq', 'popq']:
+                        rA = REG[operands[0]]
+                        code.append((rA << 4) | 0xF)
+                    elif instruction in ['irmovq', 'rmmovq', 'mrmovq']:
+                        if instruction == 'irmovq':
+                            rA, rB = REG['F'], REG[operands[1]]
+                            val = self._parse_value(operands[0])
+                        elif instruction == 'rmmovq':
+                            rA = REG[operands[0]]
+                            disp, rB_name = self._parse_mem(operands[1])
+                            rB, val = REG[rB_name], disp
+                        elif instruction == 'mrmovq':
+                            rA = REG[operands[1]]
+                            disp, rB_name = self._parse_mem(operands[0])
+                            rB, val = REG[rB_name], disp
+                        code.append((rA << 4) | rB)
+                        code.extend(struct.pack('<q', val))
+                    elif instruction in ['jmp', 'jle', 'jl', 'je', 'jne', 'jge', 'jg', 'call']:
+                        dest = self._parse_value(operands[0])
+                        code.extend(struct.pack('<Q', dest))
+
+            if code:
+                self.byte_code[start_pc] = (size, code.hex(), original_line)
+                self.pc += size
+
+    def _parse_value(self, s):
+        """Converts a string operand to an integer, resolving labels."""
+        s = s.strip()
+        if s.startswith('$'):
+            s = s[1:]
+        
+        if s in self.symbol_table:
+            return self.symbol_table[s]
+        try:
+            return int(s, 0) # Handles decimal and '0x' hex
+        except ValueError:
+            raise ValueError(f"Invalid immediate value or unresolved label: {s}")
+
+    def _parse_mem(self, s):
+        """Parses memory operands like 'D(%rB)' or '(%rB)'."""
+        match = re.match(r'(-?\d+)?\((\%r\w+)\)', s)
+        if not match:
+            raise ValueError(f"Invalid memory operand: {s}")
+        
+        disp_str, reg = match.groups()
+        disp = int(disp_str) if disp_str else 0
+        return disp, reg
+
+    def _format_output(self):
+        """Formats the final output string."""
+        output = []
+        # Sort addresses to print in order
+        sorted_addrs = sorted(self.byte_code.keys())
+        
+        for addr in sorted_addrs:
+            size, hex_code, line = self.byte_code[addr]
+            addr_hex = f"0x{addr:03x}:"
+            
+            # Handle lines that generate no code (labels, .align)
+            if size == 0:
+                output.append(f"{addr_hex: <10}| {line}")
+            else:
+                formatted_code = f"{hex_code:<20}"
+                output.append(f"{addr_hex: <10}{formatted_code}| {line}")
+
+        return '\n'.join(output)
+
+
+if __name__ == '__main__':
+    if len(sys.argv) != 2:
+        print("Usage: python Y86_64_assembler.py <source_file.txt>")
+        sys.exit(1)
+    
+    assembler = Y86Assembler()
+    result = assembler.assemble(sys.argv[1])
+    print("\n--- Assembled Code ---")
+    print(result)
diff --git a/Y86_as/input.txt b/Y86_as/input.txt
new file mode 100644
index 0000000..f8e2828
--- /dev/null
+++ b/Y86_as/input.txt
@@ -0,0 +1,40 @@
+# Execution begins at address 0
+.pos 0
+    irmovq stack, %rsp  # Set up stack pointer
+    call main           # Execute main program
+    halt                # Terminate program
+
+# Array of 4 elements
+.pos 0x18
+array:
+    .quad 0xd000d000d000d
+    .quad 0xc000c000c000c0
+    .quad 0xb000b000b000b
+    .quad 0xa000a000a000a
+
+main:
+    irmovq array, %rdi
+    irmovq $4, %rsi
+    call sum
+    ret
+
+# long sum(long *start, long count)
+# start in %rdi, count in %rsi
+sum:
+    irmovq $8,%r8
+    irmovq $1,%r9
+    xorq %rax,%rax
+    andq %rsi,%rsi
+    jmp test
+loop:
+    mrmovq (%rdi),%r10
+    addq %r10,%rax
+    addq %r8,%rdi      # start++
+    subq %r9,%rsi      # count--
+                       # Set CC
+test:
+    jne loop           # Stop when 0
+    ret                # Return
+
+.pos 0x200
+stack:
diff --git a/Y86_as/sample2024.txt b/Y86_as/sample2024.txt
new file mode 100644
index 0000000..cd1f4aa
--- /dev/null
+++ b/Y86_as/sample2024.txt
@@ -0,0 +1,10 @@
+.pos 0x200
+sum:
+	mrmovq 8(%rdx), %rcx
+	mrmovq 8(%rax),%rsi
+	rmmovq %rsi,8(%rdx)
+	rmmovq %rcx, 8(%rax)
+	addq $8, %rdx
+	addq $120, %rax
+	subq %rdi, %rax
+	jne sum
diff --git a/Y86_as/屏幕截图_20250613_013251.png b/Y86_as/屏幕截图_20250613_013251.png
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