diff options
Diffstat (limited to 'fw/hid-dials/tools/butter_filter_gen.py')
-rw-r--r-- | fw/hid-dials/tools/butter_filter_gen.py | 93 |
1 files changed, 0 insertions, 93 deletions
diff --git a/fw/hid-dials/tools/butter_filter_gen.py b/fw/hid-dials/tools/butter_filter_gen.py deleted file mode 100644 index 0bb81bc..0000000 --- a/fw/hid-dials/tools/butter_filter_gen.py +++ /dev/null @@ -1,93 +0,0 @@ -#!/usr/bin/env python3 - -import math -import sys -import contextlib - -import scipy.signal as sig -import numpy as np - - -@contextlib.contextmanager -def wrap(left='{', right='}', file=None, end=''): - print(left, file=file, end=end) - yield - print(right, file=file, end=end) - -@contextlib.contextmanager -def print_include_guards(macro_name): - print(f'#ifndef {macro_name}') - print(f'#define {macro_name}') - print() - yield - print() - print(f'#endif /* {macro_name} */') - -macro_float = lambda f: f'{f}'.replace('.', 'F').replace('-', 'N').replace('+', 'P') - -ordinal = lambda n: "%d%s" % (n,"tsnrhtdd"[(n//10%10!=1)*(n%10<4)*n%10::4]) - -SI_TABLE = {-18: 'a', -15: 'f', -12: 'p', -9: 'n', -6: 'ยต', -3: 'm', 0: '', 3: 'k', 6: 'M', 9: 'G', 12: 'T', 15: 'P', 18: 'E'} -def siprefix(x, space=' ', unit=''): - l = math.log10(x)//3*3 - if l in SI_TABLE: - return f'{x/10**l}{space}{SI_TABLE[l]}{unit}' - return f'{x}{space}{unit}' - -if __name__ == '__main__': - import argparse - parser = argparse.ArgumentParser() - parser.add_argument('-m', '--macro-name', default='butter_filter', help='Prefix for output macro names') - parser.add_argument('fc', type=float, help='Corner frequency [Hz]') - parser.add_argument('fs', type=float, help='Sampling rate [Hz]') - parser.add_argument('n', type=int, nargs='?', default=6, help='Filter order') - args = parser.parse_args() - - sos = sig.butter(args.n, args.fc, fs=args.fs, output='sos') - - print('/* THIS IS A GENERATED FILE. DO NOT EDIT! */') - print() - with print_include_guards(f'__BUTTER_FILTER_GENERATED_{args.n}_{macro_float(args.fc)}_{macro_float(args.fs)}__'): - - print(f'/* {ordinal(args.n)} order Butterworth IIR filter coefficients') - print(f' *') - print(f' * corner frequency f_c = {siprefix(args.fc)}Hz') - print(f' * sampling rate f_s = {siprefix(args.fs)}Hz') - print(f' */') - print() - print(f'#define {args.macro_name.upper()}_ORDER {args.n}') - print(f'#define {args.macro_name.upper()}_CLEN {(args.n+1)//2}') - - # scipy.signal.butter by default returns extremely small bs for the first biquad and large ones for subsequent - # sections. Balance magnitudes to reduce possible rounding errors. - first_biquad_bs = sos[0][:3] - approx_mag = round(math.log10(np.mean(first_biquad_bs))) - mags = [approx_mag // len(sos)] * len(sos) - mags[0] += approx_mag - sum(mags) - sos[0][:3] /= 10**approx_mag - sos = np.array([ sec * np.array([10**mag, 10**mag, 10**mag, 1, 1, 1]) for mag, sec in zip(mags, sos) ]) - - ones = np.ones([100000]) - _, steady_state = sig.sosfilt(sos, ones, zi=np.zeros([(args.n+1)//2, 2])) - - print(f'#define {args.macro_name.upper()}_COEFF ', end='') - for sec in sos: - bs, ases = sec[:3], sec[4:6] - - with wrap(): - print('.b=', end='') - with wrap(): - print(', '.join(f'{v}' for v in bs), end='') - print(', .a=', end='') - with wrap(): - print(', '.join(f'{v}' for v in ases), end='') - print(', ', end='') - print() - - print(f'#define {args.macro_name.upper()}_STEADY_STATE ', end='') - for sec in steady_state: - with wrap(): - print(', '.join(f'{v}' for v in sec), end='') - print(', ', end='') - print() - |