Add C++ Bus class for the physical layer interface

src/avclan/target/avr-attiny3216/phy_avr.c

@@ -3,48 +3,6 @@
 // Copyright (C) 2015 Allen Hill <allenofthehills@gmail.com>
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-/*
-                                AVC LAN Theory
-
-  The AVC LAN bus is an implementation of the IEBus (mode 1) which is a
-  differential signal; IEBus is electrically (but not logically) compatible with
-  CAN bus.
-
-  - Logical `1`: Potential difference between bus lines (BUS+ pin and BUS– pin)
-    is 20 mV or lower (floating).
-  - Logical `0`: Potential difference between bus lines (BUS+ pin and BUS– pin)
-    is 120 mV or higher (driving).
-
-  A nominal bit length is 39 us, composed of 3 periods: preparation,
-  synchronization, data.
-
-                                Figure 1. AVCLAN Bus bit format
-
-                             │ Prep │<─ Sync ─>│<─ Data ─>│ ...
-    Driving (logical `0`)           ╭──────────╮──────────╮
-                                    │          │          │
-    Floating (logical `1`) ─────────╯          ╰──────────╰─────────
-                             │ 6 μs │── 19 μs ─│─ 13 μs ──│
-
-  The logical value during the data period signifies the bit value, e.g. a bit
-  `0` continues the logical `0` (high potential difference between bus lines) of
-  the sync period thru the data period, and a bit `1` has a logical `1`
-  (low/floating potential between bus lines) during the data period. Using the
-  TCB pulse-width and frequency measure mode, the total bit length differs for
-  bit `1` and `0`; detailed bit timing can be found in "timing.h". The bus
-  idles at low potential (floating).
-
-  A start bit is nominally 169 us high followed by 20 us low.
-
-  A bit `0` is dominant on the bus, which is a design choice that affects
-  bit/interpretation:
-    - Low addresses have priority upon transmission conflicts
-    - The broadcast bit is `1` (floating, no effort) for normal communication
-    - For acknowledge bits, the receiver extends the logical '0' of the sync
-      period to the length of a normal bit `0`. Hence, a NAK (bit `1`) is
-      literally the absence of an ACK.
-*/
-
 #include <avr/interrupt.h>
 #include <avr/io.h>
 #include <avr/sfr_defs.h>