ref: 783f6d8fcd85aaa04d843d3ac282b7dc238b4c2c
dir: /beep.c/
// produce waveform for a "beep" #include <u.h> #include <libc.h> void usage(void) { fprint(2, "usage: %s [-f hz] [-d decay] [-l samples] [-s slide] [-v volume]\n", argv0); exits("usage"); } void main(int argc, char **argv) { char *buffer; short s; int i; double hz = 440; double decay = 0.9998; int samples = 11025; double slide = 1.0001; double volume = 0.33; double *table; ARGBEGIN{ case 'f': hz = atof(EARGF(usage())); break; case 'd': decay = atof(EARGF(usage())); break; case 'l': samples = atoi(EARGF(usage())); break; case 's': slide = atof(EARGF(usage())); break; case 'v': volume = atof(EARGF(usage()))/100.0; break; default: usage(); }ARGEND volume = volume < 0? 0: volume > 1? 1: volume; table = malloc(6283 * sizeof(double)); for (i = 0; i < 6283; i++) { table[i] = cos(i/1000.0); } buffer = malloc(samples * 4); for (i = 0; i < samples; i++) { s = table[(int)(fmod(((double)i/44100*2*PI*(hz-pow(slide,i))),6.283)*1000.0)] * 32767 * volume * pow(decay,i); buffer[i*4+0] = buffer[i*4+2] = s & 0xFF; buffer[i*4+1] = buffer[i*4+3] = (s >> 8) & 0xFF; } write(1, buffer, samples * 4); }