126 lines
4.3 KiB
Python
126 lines
4.3 KiB
Python
# -*- coding: utf-8 -*-
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import re
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"""
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LA32R Simple Assembler
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- Converts a simplified assembly language into 32-bit hexadecimal machine code.
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- Supports all 14 instructions required by the course design.
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- Handles register names like '$r4', '$r12' and immediate values.
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- Outputs a 'program.hex' file suitable for Verilog's $readmemh.
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- [FIXED] Corrected the encoding for ADDI.W to match the ISA specification
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(opcode 000000 + func4).
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- [FINAL FIX] Corrected the string formatting for 3R-type instructions, which
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was scrambling the register and function fields.
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"""
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# 指令编码定义
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OPCODES = {
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'add.w': '000000', 'sub.w': '000000', 'slt': '000000', 'sltu': '000000',
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'nor': '000000', 'and': '000000', 'or': '000000',
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'addi.w': '000000', 'lu12i.w': '000101', 'ld.w': '001010', 'st.w': '001010',
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'b': '010100', 'beq': '010110', 'blt': '011000'
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}
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FUNC_3R = {
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'add.w': ('01', '00000'), 'sub.w': ('01', '00010'), 'slt': ('01', '00100'),
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'sltu': ('01', '00101'), 'nor': ('01', '01000'), 'and': ('01', '01001'),
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'or': ('01', '01010')
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}
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FUNC_2RI12 = {
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'addi.w': '1010', 'ld.w': '0010', 'st.w': '0110'
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}
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def to_binary(value, bits):
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"""Converts an integer to a two's complement binary string of specified length."""
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if value >= 0:
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return format(value, 'b').zfill(bits)
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else:
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return format((1 << bits) + value, 'b')
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def parse_register(reg_str):
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"""Parses register string '$rX' to a 5-bit binary string."""
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return to_binary(int(reg_str.strip('$r')), 5)
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def assemble_line(line):
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"""Assembles a single line of assembly code into a 32-bit binary string."""
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line = line.lower().strip()
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parts = re.split(r'[\s,]+', line)
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op = parts[0]
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if op in FUNC_3R: # 3R-type
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rd, rj, rk = parse_register(parts[1]), parse_register(parts[2]), parse_register(parts[3])
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opcode = OPCODES[op]
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func2, func5 = FUNC_3R[op]
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# [THE FIX] Removed the erroneous hardcoded '00000' field.
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# The correct format for these 3R instructions is opcode | 0000 | func2 | func5 | rk | rj | rd
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return f"{opcode}0000{func2}{func5}{rk}{rj}{rd}"
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elif op in ['addi.w', 'ld.w', 'st.w']: # 2RI12-type
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rd = parse_register(parts[1])
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rj = parse_register(parts[2])
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imm = to_binary(int(parts[3], 0), 12)
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opcode = OPCODES[op]
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func4 = FUNC_2RI12[op]
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return f"{opcode}{func4}{imm}{rj}{rd}"
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elif op == 'lu12i.w': # 1RI20-type
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rd = parse_register(parts[1])
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imm = to_binary(int(parts[2], 0), 20)
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opcode = OPCODES[op]
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return f"{opcode}0{imm}{rd}"
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elif op in ['beq', 'blt']: # 2RI16-type
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rj, rd = parse_register(parts[1]), parse_register(parts[2])
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offset = int(parts[3], 0) >> 2
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imm = to_binary(offset, 16)
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opcode = OPCODES[op]
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return f"{opcode}{imm}{rj}{rd}"
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elif op == 'b': # I26-type
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offset = int(parts[1], 0) >> 2
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imm = to_binary(offset, 26)
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offs_25_16, offs_15_0 = imm[0:10], imm[10:26]
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opcode = OPCODES[op]
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return f"{opcode}{offs_15_0}{offs_25_16}"
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else:
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raise ValueError(f"Unknown instruction: {op}")
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def main():
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"""Main function to read assembly file and write hex file."""
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# 使用这个测试程序来验证CPU的功能
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# Use this test program to verify CPU functionality
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assembly_code = open("../program.asm", "r").read()
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output_filename = "program.hex"
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with open(output_filename, "w") as f:
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print(f"Assembling code into {output_filename}...")
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for line in assembly_code.split('\n'):
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line = line.strip()
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# 忽略注释和空行
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# Ignore comments and empty lines
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if not line or line.startswith('//'):
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continue
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try:
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# 移除行内注释
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# Remove inline comments
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line = line.split('//')[0].strip()
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binary_code = assemble_line(line)
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hex_code = f"{int(binary_code, 2):08x}"
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f.write(hex_code + '\n')
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print(f" {line:<30} -> {hex_code}")
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except Exception as e:
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print(f"Error assembling line: '{line}'")
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print(f" > {e}")
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return
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print("Assembly finished successfully.")
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if __name__ == "__main__":
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main()
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