IMDv3 prep

docs/source/protocol_proposed.rst

@@ -20,14 +20,13 @@ The suggested changes to the protocol are as follows:
         <val> (bit) (imdpull: true or false)
         <val> (bit) (imdwait: true or false)
         <val> (bit) (imdterm: true or false)
-        <val> (bit) (wrapped positions: true or false)
-        <val> (bit) (energies included: true or false)
-        <val> (bit) (dimensions included: true or false)
-        <val> (bit) (positions included: true or false)
-        <val> (bit) (velocities included: true or false)
-
-        <val> (bit) (forces included: true or false)
-        <val> (7 bits) (unused)
+        <val> (bit) (wrapped positions: true or false. if positions rate is 0, this is a placeholder value)
+
+        <val> (int32) (energies rate: number of steps that elapse between steps that contain energy data. 0 means never)
+        <val> (int32) (dimensions rate: number of steps that elapse between steps that contain dimension data. 0 means never)
+        <val> (int32) (positions rate: number of steps that elapse between steps that contain position data. 0 means never)
+        <val> (int32) (velocities rate: number of steps that elapse between steps that contain velocity data. 0 means never)
+        <val> (int32) (forces rate: number of steps that elapse between steps that contain force data. 0 means never)
 
    "wrapped positions" will be a new ``.mdp`` setting which specifies whether the atoms' positions
    should be adjusted to fit within the simulation box before sending. This is useful for visualization purposes.

imdreader/IMDProtocol.py

@@ -2,6 +2,10 @@
 import struct
 import logging
 from enum import Enum, auto
+from typing import Union
+from dataclasses import dataclass
+import abc
+import threading
 
 """
 IMD Packets have an 8 byte header and a variable length payload 
@@ -17,7 +21,8 @@
 """
 IMDHEADERSIZE = 8
 IMDENERGYPACKETLENGTH = 40
-IMDVERSION = 2
+IMDBOXPACKETLENGTH = 36
+IMDVERSIONS = {2, 3}
 
 
 class IMDType(Enum):
@@ -31,6 +36,11 @@ class IMDType(Enum):
     IMD_PAUSE = 7
     IMD_TRATE = 8
     IMD_IOERROR = 9
+    # New in IMD v3
+    IMD_BOX = 10
+    IMD_VELS = 11
+    IMD_FORCES = 12
+    IMD_EOS = 13
 
 
 class IMDHeader:
@@ -41,6 +51,32 @@ def __init__(self, msg_type: IMDType, length: int):
         self.length = length
 
 
+@dataclass
+class IMDSessionInfo:
+    """Convenience class to represent the session information of an IMD connection
+
+    '<' represents little endian and '>' represents big endian
+
+    Data should be loaded into and out of buffers in the order of the fields in this class
+    if present in the session for that step, i.e.
+        1. energies,
+        2. dimensions,
+        etc.
+    """
+
+    version: int
+    endianness: str
+    imdterm: Union[bool, None]
+    imdwait: Union[bool, None]
+    imdpull: Union[bool, None]
+    wrapped_coords: bool
+    energies: int
+    dimensions: int
+    positions: int
+    velocities: int
+    forces: int
+
+
 def create_header_bytes(msg_type: IMDType, length: int):
     # NOTE: add error checking for invalid packet msg_type here
     type = msg_type.value