Usage conversion

output.txt

$ python3 wfrac.py
usage:     0 kWh (  0) | origbytes:     [0, 0, 0, 0] | vals:      [0, 0, 0, 0] => orig:    0.0, glsf91:    0.0, new:    0.0
usage:     1 kWh (  4) | origbytes:     [0, 0, 4, 0] | vals:      [0, 0, 4, 0] => orig:    1.0, glsf91:    1.0, new:    1.0
usage:    30 kWh (120) | origbytes:   [0, 0, 120, 0] | vals:    [0, 0, 120, 0] => orig:   30.0, glsf91:   58.0, new:   30.0
usage:    31 kWh (124) | origbytes:   [0, 0, 124, 0] | vals:    [0, 0, 124, 0] => orig:   31.0, glsf91:   59.0, new:   31.0
usage:    32 kWh (128) | origbytes:   [0, 0, 128, 0] | vals:   [0, 0, -128, 0] => orig:   None, glsf91:   32.0, new:   32.0
usage:    33 kWh (132) | origbytes:   [0, 0, 132, 0] | vals:   [0, 0, -124, 0] => orig:   None, glsf91:   33.0, new:   33.0
usage:    63 kWh (252) | origbytes:   [0, 0, 252, 0] | vals:     [0, 0, -4, 0] => orig:   None, glsf91:   91.0, new:   63.0
usage:    64 kWh (256) | origbytes:     [0, 0, 0, 1] | vals:      [0, 0, 0, 1] => orig:    0.0, glsf91:   0.25, new:   64.0
usage:    65 kWh (260) | origbytes:     [0, 0, 4, 1] | vals:      [0, 0, 4, 1] => orig:    1.0, glsf91:   1.25, new:   65.0
usage:   128 kWh (512) | origbytes:     [0, 0, 0, 2] | vals:      [0, 0, 0, 2] => orig:    0.0, glsf91:    0.5, new:  128.0
usage:   129 kWh (516) | origbytes:     [0, 0, 4, 2] | vals:      [0, 0, 4, 2] => orig:    1.0, glsf91:    1.5, new:  129.0

test.py

for usage in [0, 1, 30, 31, 32, 33, 63, 64, 65, 128, 129]:
    vals_orig = [ 0x00, 0x00, *int.to_bytes(usage * 4, 2, 'little', signed=False)]
    vals = [
        (256 - a) * (-1) if a > 127 else a for a in vals_orig
    ]

    i = 0
    orig, glsf91, new = None, None, None
    try:
        orig = int.from_bytes(vals[i + 2: i + 3], "little", signed=False ) * 0.25
    except: pass
    try:
        glsf91 = ( ((vals[i + 3] & 0x7f) + (vals[i + 3] & 0xF0) * 64) + (vals[i + 2] & 0x7f) + (vals[i + 2] & 0xF0) )* 0.25
    except: pass
    try:
        new = int.from_bytes([(256 + v) % 256 for v in vals[i + 2: i + 4]], "little", signed=False ) * 0.25
    except:
        pass

    print(f"usage: {usage:5g} kWh ({usage*4:3g}) | origbytes: {str(vals_orig): >16} | vals: {str(vals): >17} => orig: {str(orig): >6}, glsf91: {str(glsf91): >6}, new: {str(new): >6}")