Frames

1 files changed, 74 insertions, 0 deletions

diff --git a/src/gr-fadingui/python/frame_obj.py b/src/gr-fadingui/python/frame_obj.py
new file mode 100644
index 0000000..b9dae70
--- /dev/null
+++ b/src/gr-fadingui/python/frame_obj.py
@@ -0,0 +1,74 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Copyright 2021 Naoki Pross.
+
+from functools import reduce
+import operator as op
+
+import numpy as np
+from gnuradio import gr
+
+
+class frame_obj(gr.basic_block):
+    """
+    Frame Object: Contains informations about a data frame.
+
+      -------------------------------------------------------------------------------
+      | Preamble | Padding | ID     | Data Length | Parity | Payload | Padding      |
+      | k bytes  | 1 bit   | 4 bits | 22 bits     | 5 bits |         | if necessary |
+      -------------------------------------------------------------------------------
+                           | (31, 26) Hamming code EC      |
+                           -----------------------------------
+
+    - The preamble is user defined.
+    - The ID (11 bits) + Data length (22 bits) together are a 31 bits, followed
+      by 26 parity bits computed using a (31,26) hamming code.
+
+      This constraints the maximum payload size to 64 MB and the number IDs to
+      1024 (i.e. max file size is 1 GB, more than enough for many thing)
+
+    """
+    def __init__(self, preamble, payload_len):
+        gr.basic_block.__init__(self, name="frame_obj",
+                in_sig=None, out_sig=None)
+
+        self.preamble = np.array(preamble, dtype=np.uint8)
+
+        self.preamble_len = len(self.preamble)
+        self.payload_len = payload_len
+
+    @property
+    def length(self):
+        """Frame lenght in bytes"""
+        return self.preamble_len + self.payload_len + 8
+
+    def parity(self, bits):
+        """Compute the 5 parity bits for an unpacked array of 26 bits"""
+        assert(len(bits) == 26)
+        # FIXME: does not work
+        # gen = np.array(
+        #     [[1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0],
+        #      [0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1],
+        #      [0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0],
+        #      [0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0],
+        #      [0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1]],
+        #     dtype=np.uint8)
+        # return np.matmul(bits, gen) % 2
+        return np.array([0, 0, 0, 0, 0])
+
+    def make(self, idv, data_len, data):
+        """Make a frame"""
+        return np.concatenate(self.preamble, np.packbits(hamming), data)
+
+    def syndrome(self, bits):
+        """Compute the syndrome (check Hamming code) for an unpacked array of 31 bits"""
+        assert(len(bits) == 31)
+        return reduce(op.xor, [i for i, bit in enumerate(bits) if bit])
+
+    def general_work(self, input_items, output_items):
+        """
+        This block has no inputs or output 
+        """
+        return 0;
+