alloc_soundbuf
static void alloc_soundbuf(struct tone_data *, double, int);
alloc_soundbuf(&tone_dot, dot_clock, 1);
alloc_soundbuf(&tone_dash, DASH_LEN * dot_clock, 1);
alloc_soundbuf(&tone_silence, dot_clock, 0);
alloc_soundbuf(&tone_letter_silence, word_clock, 0);