Convert IR code into Hex code in MSB first format.

• https://techdocs.altium.com/display/FPGA/NEC+Infrared+Transmission+Protocol
• http://www.hifi-remote.com/infrared/IR-PWM.shtml

• pulse distance encoding of message bit
• standard frequency is 38 kHz, period is approx. 26.3 μs
• each pulse burst is 562.5 μs
• logic bits:
  • '0' --> 562.5 μs pulse burst followed by a 562.5 μs space; total = 1.125 ms
  • '1' --> 562.5 μs pulse burst followed by a 1687.5 μs space; total = 2.25 ms
• duration of single frame transmission = 108 ms (192 pulse burst and space)

• zero (0x00)
• IR frequency (see below)
• message code byte pairs (NEC: 34 byte pairs = 0x22)
• repeat code byte pairs (NEC: 2 byte pairs = 0x02)

hex_irFreq = 1000000 / 0.241246 / irFreq;

• leading pulse burst (16x = 9 ms)
• leading space (8x = 4.5 ms)
• 8-bit address
• logical inverse of 8-bit address
• 8-bit command
• logical inverse of 8-bit command
• end pulse burst (1x = 562.5 μs)
• end space (71x = 39.9375 ms)

address + command --> 96x = 54 ms

End space duration can vary if address or command has different formats, e.g:

• 8-bit address + 8-bit command (as shown above)
• 16-bit address + 8-bit command
• 16-bit address + 16-bit command

• leading pulse burst (16x = 9 ms)
• repeat space (4x = 2.25 ms)
• end pulse burst (1x = 562.5 μs)
• end space (171x = 96.1875 ms)

• CMake 3.22 or newer
• gcc toolchain
• make or Ninja

# configure project with make (default):
cmake -S . -B build/

# configure project with ninja:
cmake -GNinja -S . -B build/

# build project
cmake --build build/

# run test
cd build/ && ctest

Current implementation of NEC protocol uses LSB first format in data transmission,
but this code generate hex code in MSB first format for my use-case.
Changing the format will only require a simple modification of code.

Tested with Magic Lighting RGB LED.