import struct

def create_demod_info_packet():
    """创建解调信息报文(类型12)的内容"""
    # 模拟解调信息数据
    message_type = 12             # 消息类型 (1字节)
    satellite_id = 1               # 卫星ID (1字节)
    demodulator_id = 0             # 解调器编号 (1字节)
    demod_slot = 1234              # 解调时隙 (2字节)
    receive_delay = 5678           # 接收延迟 (2字节，单位us)
    snr = 25.75                    # 信噪比 (2字节，dB)
    
    # 处理信噪比 (高8位整数部分，低8位小数部分)
    snr_int = int(snr)
    snr_frac = int((snr - snr_int) * 100)  # 转换为0-99的小数部分
    snr_packed = (snr_int & 0xFF) << 8 | (snr_frac & 0xFF)
    
    # 打包为二进制 (大端字节序)
    content = struct.pack(
        '>BBBHHH',  # 格式: B(1),B(1),B(1),H(2),H(2),h(2)
        message_type,
        satellite_id,
        demodulator_id,
        demod_slot,
        receive_delay,
        snr_packed
    )
    return content

def create_tcp_packet(packet_type, content):
    """创建符合VDES TCP协议的报文"""
    # 报文帧头 (4字节)
    header = b'####'
    
    # 报文类型 (4字节，大端)
    type_field = struct.pack('>I', packet_type)
    
    # 报文长度 (4字节，大端，内容长度)
    length = len(content)
    length_field = struct.pack('>I', length)
    
    # 构建完整报文
    packet = header + type_field + length_field + content
    return packet



# 使用示例
demod_info_content = create_demod_info_packet()
demod_info_packet = create_tcp_packet(12, demod_info_content)

# 打印结果