feat: offset + CTCSS tone BCD codecs (provisional encodings)

civ.py

@@ -24,6 +24,17 @@ SUB_SQL_LEVEL = 0x03
 SUB_SQL_STATUS = 0x01
 SUB_SMETER = 0x02
 
+# --- repeater config (candidate commands; verify on live radio) ---
+CMD_OFFSET = 0x0D       # set duplex offset frequency
+CMD_DUPLEX = 0x0F       # set duplex direction
+DUP_SIMPLEX = 0x10
+DUP_MINUS = 0x11
+DUP_PLUS = 0x12
+CMD_TONE_PARAM = 0x1B   # sub 0x00 = repeater (TX) tone frequency
+SUB_RPT_TONE = 0x00
+CMD_TONE_SWITCH = 0x16  # sub 0x42 = tone encode on/off
+SUB_TONE_ENC = 0x42
+
 Frame = namedtuple("Frame", "to frm cn data")
 
 
@@ -66,6 +77,41 @@ def bcd_to_level(data):
     return value
 
 
+def offset_to_bcd(hz):
+    """Duplex offset Hz -> 3-byte little-endian BCD in 100 Hz units (PROVISIONAL)."""
+    if hz < 0:
+        raise ValueError(f"offset {hz} must be >= 0")
+    units = round(hz / 100)
+    digits = f"{units:06d}"
+    out = bytearray()
+    for i in range(0, 6, 2):
+        out.append((int(digits[4 - i]) << 4) | int(digits[5 - i]))
+    return bytes(out)
+
+
+def bcd_to_offset(data):
+    """3-byte little-endian BCD (100 Hz units) -> Hz (PROVISIONAL)."""
+    units = 0
+    for i, byte in enumerate(data[:3]):
+        units += (byte & 0x0F) * (10 ** (2 * i)) + (byte >> 4) * (10 ** (2 * i + 1))
+    return units * 100
+
+
+def tone_to_bcd(hz):
+    """CTCSS tone Hz -> 2-byte BCD of tone*10 (88.5 -> 08 85)."""
+    digits = f"{round(hz * 10):04d}"
+    return bytes([(int(digits[0]) << 4) | int(digits[1]),
+                  (int(digits[2]) << 4) | int(digits[3])])
+
+
+def bcd_to_tone(data):
+    """2-byte BCD of tone*10 -> CTCSS tone Hz."""
+    t = 0
+    for byte in data[:2]:
+        t = t * 100 + (byte >> 4) * 10 + (byte & 0x0F)
+    return t / 10.0
+
+
 def build_frame(cmd, data=b"", to=RADIO_ADDR, frm=CTRL_ADDR):
     """Assemble FE FE <to> <from> <cmd> [data] FD."""
     return PREAMBLE + bytes([to, frm, cmd]) + bytes(data) + bytes([EOM])