finish trainer protocol update

BasaltTrainer/pipe_operator.py

@@ -1,8 +1,10 @@
 import os
 import sys
-from typing import Optional, Any
+import struct
+from typing import Optional, Any, ClassVar
 
 IS_WINDOWS: bool = sys.platform == "win32"
+IS_LITTLE_ENDIAN: bool = sys.byteorder == "little"
 
 if IS_WINDOWS:
     import win32pipe
@@ -151,3 +153,43 @@ class PipeOperator:
                     total_written += bytes_written
                 except OSError as e:
                     raise RuntimeError(f"Failed to write to named pipe: {e}")
+
+    def read_pod(self, pattern: struct.Struct) -> tuple[Any, ...]:
+        return pattern.unpack(self.read(pattern.size))
+
+    def write_pod(self, pattern: struct.Struct, *args) -> None:
+        self.write(pattern.pack(*args))
+
+    STR_LEN_PACKER: ClassVar[struct.Struct] = struct.Struct("=N")
+
+    def read_string(self) -> str:
+        (length,) = self.read_pod(PipeOperator.STR_LEN_PACKER)
+        str_bytes = self.read(length)
+        return str_bytes.decode("utf-8")
+
+    def write_string(self, s: str) -> None:
+        str_bytes = s.encode("utf-8")
+        self.write_pod(PipeOperator.STR_LEN_PACKER, len(str_bytes))
+        self.write(str_bytes)
+
+    def read_bsstring(self) -> str:
+        (length,) = self.read_pod(PipeOperator.STR_LEN_PACKER)
+        str_bytes = self.read(length)
+        return self.__decode_bsstring(str_bytes)
+
+    def write_bsstring(self, s: str) -> None:
+        str_bytes = self.__encode_bsstring(s)
+        self.write_pod(PipeOperator.STR_LEN_PACKER, len(str_bytes))
+        self.write(str_bytes)
+
+    def __encode_bsstring(self, s: str) -> bytes:
+        if IS_LITTLE_ENDIAN:
+            return s.encode("utf_16_le")
+        else:
+            return s.encode("utf_16_be")
+
+    def __decode_bsstring(self, b: bytes) -> str:
+        if IS_LITTLE_ENDIAN:
+            return b.decode("utf_16_le")
+        else:
+            return b.decode("utf_16_be")