From 2bb4a947d4d55e605e6912dec3ff95fbe541615a Mon Sep 17 00:00:00 2001
From: Nao Pross <np@0hm.ch>
Date: Sat, 20 Nov 2021 17:05:04 +0100
Subject: Implement Frame Object

---
 src/gr-fadingui/python/frame_obj.py | 77 ++++++++++++++++++++++---------------
 1 file changed, 47 insertions(+), 30 deletions(-)

(limited to 'src/gr-fadingui/python/frame_obj.py')

diff --git a/src/gr-fadingui/python/frame_obj.py b/src/gr-fadingui/python/frame_obj.py
index b9dae70..136fce0 100644
--- a/src/gr-fadingui/python/frame_obj.py
+++ b/src/gr-fadingui/python/frame_obj.py
@@ -10,65 +10,82 @@ import numpy as np
 from gnuradio import gr
 
 
-class frame_obj(gr.basic_block):
+class frame_obj:
     """
     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 |
+      | k bytes  | 1 bit   | 5 bits | 21 bits     | 5 bits |         | if necessary |
       -------------------------------------------------------------------------------
-                           | (31, 26) Hamming code EC      |
-                           -----------------------------------
+                           | (31, 26) Hamming EC code      |
+                           ---------------------------------
 
     - 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.
+    - The ID (5 bits) + Data length (21 bits) together are a 26 bits, followed
+      by 5 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)
+      This constraints the maximum payload size to 2 MiB and the number IDs to
+      32, i.e. max file size is 64 MiB.
 
     """
     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 = np.array(preamble, dtype=np.uint8)
+        self._preamble_len = len(self._preamble)
+        self._payload_len = payload_len
 
-        self.preamble_len = len(self.preamble)
-        self.payload_len = payload_len
+    @property
+    def header_length(self) -> int:
+        """Get header length in bytes"""
+        # 4 is the number of bytes for the hamming part
+        return self._preamble_len + 4
+
+    @property
+    def payload_length(self) -> int:
+        return self._payload_len
+
+    @property
+    def length(self) -> int:
+        """Get frame lenght in bytes"""
+        # 8 is the size of the hamming ECC part + 1 bit
+        return self.header_length + self.payload_length
 
     @property
-    def length(self):
-        """Frame lenght in bytes"""
-        return self.preamble_len + self.payload_len + 8
+    def preamble(self):
+        """Get preamble"""
+        return self._preamble
 
     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)
+        # get lower 4 bits of idv
+        idv_bits = np.unpackbits([np.uint8(idv)])[:5]
+
+        # get lower 22 bits of data_len
+        data_len_bytes = list(map(np.uint8, data_len.to_bytes(4, byteorder='little')))
+        data_len_bits = np.unpackbits(data_len_bytes)[:21]
+
+        # compute 5 parity bits
+        metadata = np.concatenate([idv_bits, data_len_bits])
+        parity_bits = self.parity(metadata)
+
+        # add padding
+        hamming_bits = np.concatenate([[0], metadata, parity_bits])
+        assert(len(hamming_bits) == 32)
+
+        # pack 32 bits into 4 bytes and add the rest
+        hamming = np.packbits(hamming_bits)
+        return np.concatenate([self.preamble, 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;
-
-- 
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