DHT12 - Evaluating negative temperatures

- Arduino board: Not relevant (based on visual inspection of code)

- Arduino IDE version (found in Arduino -> About Arduino menu): Also not relevant (based on visual inspection of code

- List the steps to reproduce the problem below (if possible attach a sketch or
copy the sketch code in too):

In file: DHT.cpp,
In function: float DHT::readTemperature(bool S, bool force)
While handling the DHT12 (extracting the float value from the 5-byte data received from the device
Code lines 100-105 are:
case DHT12:
f = data[2];
f += (data[3] & 0x0f) * 0.1;
if (data[2] & 0x80) {
f *= -1;
}

Bit 7 of data[2] is included in the float value, AND is used as a sign bit.
Surely this can't be right.
E.g. if data[2] = 0x80 and data[3]=0x00
then this will return a temperature of -128.0 degreesC

Read DHT.cpp and inspect DHT::readTemperature(bool S, bool force), especially the DHT12 handling at lines 100-105. Reproduce the reported case with data[2] = 0x80 and data[3] = 0x00, then verify that the decoded negative temperature no longer includes the sign bit in its magnitude.

Written by the indexing model from the issue text.