Commit int packer with dbg to keep it in history

Results match expectation

twnet_parser/packer.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+
+from textwrap import wrap
+
+def dbg(raw: bytearray) -> None:
+    bits_str = ''
+    annotation_str = ''
+    for byte in raw:
+        bits_str += ' '.join(wrap(f"{byte:08b} ", 2))
+        annotation_str += 'ES DD DD DD '
+    print(f"  {bits_str}   {bytes(raw)!r}")
+    print(f"  {annotation_str}")
+
+def pack_int(num: int) -> bytes:
+    print(f"packing {num}")
+    res: bytearray = bytearray(b'\x00')
+    if num < 0:
+        res[0] |= 0x40 # set sign bit
+        print(f"num={num}")
+        num = ~num
+        # print(f"num num={num}")
+
+    # print("--- signed:")
+    # dbg(res)
+
+    res[0] |= num & 0x3F # pack 6bit into res
+    num >>= 6 # discard 6 bits
+
+    print("--- pack 6 bit:")
+    dbg(res)
+
+    i = 0
+    while num != 0:
+        res[i] |= 0x80 # set extend bit
+        i += 1
+        res.extend(bytes([num & 0x7F])) # pack 7 bit
+        num >>= 7 # discard 7 bits
+        print(num)
+
+    return bytes(res)
+
+print(pack_int(63))
+print(pack_int(64))
+print(pack_int(65))
+