"""Interpret the admitted FW 5.02 PPM input before its firmware deadband.

app_ppm.c publishes input_val before utils_deadband. A nonzero decoded value
inside app_ppm_conf.hyst is therefore not a motor command. Do not infer radio
link presence from this value: the receiver can keep emitting failsafe pulses.
"""
import math


def neutral_band(application):
    band = application["app_ppm_conf.hyst"]
    if (application["app_to_use"] not in (1, 4)
            or application["app_ppm_conf.ctrl_type"] != 4
            or not math.isfinite(band) or not .01 <= band <= .3):
        raise ValueError("Unsupported PPM neutral configuration")
    return band


def active(level, band):
    if not math.isfinite(level) or not math.isfinite(band) or not .01 <= band <= .3:
        raise ValueError("Invalid PPM level or neutral band")
    return abs(level) > band