170 lines
7.5 KiB
Python
170 lines
7.5 KiB
Python
from typing import Optional, Tuple
|
||
import logging
|
||
from frame import FrameFormat
|
||
|
||
class FrameFinder:
|
||
"""帧查找器 - 在数据缓冲区中查找符合帧格式的数据"""
|
||
|
||
def __init__(self):
|
||
"""初始化帧查找器"""
|
||
self.frame_length = FrameFormat.FIXED_SIZE + FrameFormat.DATA_SIZE
|
||
self.frame_header = FrameFormat.FRAME_HEADER
|
||
self.logger = logging.getLogger(__name__)
|
||
|
||
def find_frame_in_buffer(self, buffer: bytes, start_pos: int = 0) -> Tuple[Optional[bytes], int]:
|
||
"""
|
||
在给定的缓冲区数据中查找下一个有效帧
|
||
Args:
|
||
buffer: 要搜索的缓冲区数据
|
||
start_pos: 开始搜索的位置
|
||
Returns:
|
||
Tuple[Optional[bytes], int]:
|
||
- 找到的帧数据（如果没找到则为None）
|
||
- 下一次搜索的起始位置（如果找到帧，则是帧后的位置；如果没找到，则是需要保留的数据起始位置）
|
||
"""
|
||
buffer_size = len(buffer)
|
||
|
||
# 检查起始位置是否有效
|
||
if start_pos >= buffer_size:
|
||
self.logger.debug(f"起始位置无效: {start_pos} >= {buffer_size}，将移除所有数据")
|
||
return None, buffer_size
|
||
|
||
# 在缓冲区中查找帧头
|
||
header_pos = self._find_header(buffer, start_pos)
|
||
if header_pos is None:
|
||
self.logger.debug(f"未找到帧头，将移除所有数据 ({buffer_size} 字节)")
|
||
if buffer_size > 0:
|
||
self.logger.debug(f"移除的数据: {buffer.hex()}")
|
||
return None, buffer_size # 返回缓冲区末尾位置，表示当前数据都可以丢弃
|
||
|
||
self.logger.debug(f"找到帧头位置: {header_pos}")
|
||
if header_pos > start_pos:
|
||
removed_data = buffer[start_pos:header_pos]
|
||
self.logger.debug(f"将移除帧头前的无效数据: {removed_data.hex() if len(removed_data) > 0 else '无'} ({len(removed_data)} 字节)")
|
||
|
||
# 检查是否有完整帧的数据
|
||
if buffer_size - header_pos < self.frame_length:
|
||
self.logger.debug(f"帧头后数据不足: {buffer_size - header_pos} < {self.frame_length}")
|
||
self.logger.debug(f"保留从位置 {header_pos} 开始的数据: {buffer[header_pos:].hex()}")
|
||
return None, header_pos # 返回帧头位置，表示需要保留从这个位置开始的数据
|
||
|
||
# 提取并验证帧
|
||
frame_data = buffer[header_pos:header_pos + self.frame_length]
|
||
if self._verify_frame(frame_data):
|
||
self.logger.debug(f"找到有效帧: {frame_data.hex()}")
|
||
next_pos = header_pos + self.frame_length
|
||
remaining_data = buffer[next_pos:] if next_pos < buffer_size else b''
|
||
self.logger.debug(f"处理完帧后剩余数据: {remaining_data.hex() if remaining_data else '无'} ({len(remaining_data)} 字节)")
|
||
return frame_data, next_pos
|
||
else:
|
||
self.logger.debug(f"帧验证失败，从下一个位置继续查找")
|
||
# 防止在同一位置反复查找
|
||
next_search_pos = header_pos + len(self.frame_header)
|
||
if next_search_pos >= buffer_size:
|
||
self.logger.debug(f"搜索位置已到达缓冲区末尾，将移除所有数据")
|
||
return None, buffer_size
|
||
|
||
removed_data = buffer[header_pos:next_search_pos]
|
||
self.logger.debug(f"移除无效帧头数据: {removed_data.hex()} ({len(removed_data)} 字节)")
|
||
return self.find_frame_in_buffer(buffer, next_search_pos)
|
||
|
||
def _find_header(self, buffer: bytes, start_pos: int) -> Optional[int]:
|
||
"""
|
||
在缓冲区中查找帧头
|
||
Args:
|
||
buffer: 要搜索的缓冲区数据
|
||
start_pos: 开始搜索的位置
|
||
Returns:
|
||
Optional[int]: 帧头位置，如果未找到则返回None
|
||
"""
|
||
header_len = len(self.frame_header)
|
||
for i in range(start_pos, len(buffer) - header_len + 1):
|
||
if buffer[i:i+header_len] == self.frame_header:
|
||
return i
|
||
return None
|
||
|
||
def _verify_frame(self, frame_data: bytes) -> bool:
|
||
"""
|
||
验证帧的有效性
|
||
Args:
|
||
frame_data: 要验证的帧数据
|
||
Returns:
|
||
bool: 帧是否有效
|
||
"""
|
||
# 使用FrameFormat验证帧
|
||
frame = FrameFormat.parse_frame(frame_data)
|
||
return frame is not None
|
||
|
||
if __name__ == "__main__":
|
||
# 使用示例
|
||
import logging
|
||
|
||
# 配置日志
|
||
logging.basicConfig(
|
||
level=logging.DEBUG,
|
||
format='%(asctime)s - %(levelname)s - %(message)s'
|
||
)
|
||
|
||
# 创建帧查找器实例
|
||
finder = FrameFinder()
|
||
|
||
# 测试数据：包含3个完整帧，中间夹杂一些无效数据
|
||
test_data = bytes.fromhex(
|
||
# 第一个有效帧
|
||
"1CDFAAAAAAAA0200000049000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000F3"
|
||
# 一些无效数据
|
||
"FFFF1234"
|
||
# 第二个有效帧
|
||
"1CDFAAAAAAAA0300000049000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000F4"
|
||
# 不完整的帧头
|
||
"1CDF12"
|
||
# 第三个有效帧
|
||
"1CDFAAAAAAAA0400000049000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000F5"
|
||
)
|
||
|
||
print("初始测试数据:")
|
||
print("总长度:", len(test_data))
|
||
print("数据:", test_data.hex())
|
||
print("\n开始查找帧:")
|
||
|
||
# 模拟实际使用场景，从不同位置开始查找
|
||
remaining_data = test_data
|
||
frame_count = 0
|
||
|
||
while len(remaining_data) > 0:
|
||
frame, next_pos = finder.find_frame_in_buffer(remaining_data)
|
||
if frame:
|
||
frame_count += 1
|
||
print(f"\n找到第 {frame_count} 个帧:")
|
||
print(f"帧数据: {frame.hex()}")
|
||
print(f"下一个搜索位置: {next_pos}")
|
||
|
||
# 解析帧内容
|
||
parsed_frame = FrameFormat.parse_frame(frame)
|
||
if parsed_frame:
|
||
print(f"命令码: 0x{parsed_frame.command:08X}")
|
||
print(f"长度: {parsed_frame.length}")
|
||
print(f"帧IDX: {parsed_frame.frame_idx}")
|
||
print("通道数据:")
|
||
for i, value in enumerate(parsed_frame.channels):
|
||
print(f"通道 {i+1}: 0x{value:08X}")
|
||
print(f"校验和: 0x{parsed_frame.checksum:02X}")
|
||
|
||
# 更新剩余数据
|
||
remaining_data = remaining_data[next_pos:]
|
||
print(f"\n剩余数据: ({len(remaining_data)} 字节)")
|
||
if remaining_data:
|
||
print(f"数据: {remaining_data.hex()}")
|
||
else:
|
||
# 如果没有找到帧，next_pos 表示需要保留的数据起始位置
|
||
if next_pos == len(remaining_data):
|
||
print("\n没有更多帧了")
|
||
break
|
||
else:
|
||
print(f"\n在当前位置未找到帧，移除 {next_pos} 字节无效数据")
|
||
remaining_data = remaining_data[next_pos:]
|
||
print(f"剩余数据: ({len(remaining_data)} 字节)")
|
||
if remaining_data:
|
||
print(f"数据: {remaining_data.hex()}")
|
||
|
||
print(f"\n总共找到 {frame_count} 个帧") |