SPECTRAL_HT20_40_SAMPLE_LEN
sample = sample_end - SPECTRAL_HT20_40_SAMPLE_LEN + 1;
if (bytes_read < SPECTRAL_HT20_40_SAMPLE_LEN &&
sample_len = SPECTRAL_HT20_40_SAMPLE_LEN;
if (bytes_read < SPECTRAL_HT20_40_SAMPLE_LEN - 1)
#define SPECTRAL_SAMPLE_MAX_LEN SPECTRAL_HT20_40_SAMPLE_LEN