usbaudioctl.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

					return -1;
			return 0;
		}
		if (c->value[0] != value[0])
			return -1;
		return 0;
	}
	if (c->chans){
		value[0] = 0;	// set to average
		m = 0;
		for (i = 1; i < 8; i++)
			if (c->chans & 1 << i){
				if (c->min != Undef && value[i] < c->min)
					value[i] = c->min;
				if (c->max != Undef && value[i] > c->max)
					value[i] = c->max;
				value[0] += value[i];
				m++;
			} else
				value[i] = Undef;
		if (m) value[0] /= m;
	}else{
		if (c->min != Undef && value[0] < c->min)
			value[0] = c->min;
		if (c->max != Undef && value[0] > c->max)
			value[0] = c->max;
	}
	req = SET_CUR;
	count = 1;
	switch(ctl){
	default:
		if (debug & Dbgcontrol) fprint(2, "setcontrol: can't happen\n");
		return -1;
	case Speed_control:
		if ((value[0] = setspeed(rec, value[0])) < 0)
			return -1;
		c->value[0] = value[0];
		return 0;
	case Equalizer_control:
		/* not implemented */
		return -1;
	case Resolution_control:
		control = findalt(rec, controls[rec][Channel_control].value[0], value[0], defaultspeed[rec]);
		if(control < 0 || setaudioalt(rec, c, control) < 0){
			if (debug & Dbgcontrol) fprint(2, "setcontrol: can't find setting for %s\n",
				c->name);
			return -1;
		}
		c->value[0] = value[0];
		controls[rec][Speed_control].value[0] = defaultspeed[rec];
		return 0;
	case Volume_control:
	case Delay_control:
		count = 2;
		/* fall through */
	case Mute_control:
	case Bass_control:
	case Mid_control:
	case Treble_control:
	case Agc_control:
	case Bassboost_control:
	case Loudness_control:
		type = RH2D|Rclass|Rinterface;
		control = ctl<<8;
		index = featureid[rec]<<8;
		break;
	case Selector_control:
		type = RH2D|Rclass|Rinterface;
		control = ctl<<8;
		index = selectorid[rec];
		break;
	case Channel_control:
		control = findalt(rec, value[0], controls[rec][Resolution_control].value[0], defaultspeed[rec]);
		if(control < 0 || setaudioalt(rec, c, control) < 0){
			if (debug & Dbgcontrol) fprint(2, "setcontrol: can't find setting for %s\n",
				c->name);
			return -1;
		}
		c->value[0] = value[0];
		controls[rec][Speed_control].value[0] = defaultspeed[rec];
		return 0;
	}
	if(c->chans){
		for (i = 1; i < 8; i++)
			if (c->chans & 1 << i){
				switch(count){
				case 2:
					buf[1] = value[i] >> 8;
				case 1:
					buf[0] = value[i];
				}
				if (setupcmd(ad->ep[0], type, req, control | i, index, buf, count) < 0){
					if (debug & Dbgcontrol) fprint(2, "setcontrol: setupcmd %s failed\n",
						controls[rec][ctl].name);
					return -1;
				}
				c->value[i] = value[i];
			}
	}else{
		switch(count){
		case 2:
			buf[1] = value[0] >> 8;
		case 1:
			buf[0] = value[0];
		}
		if (setupcmd(ad->ep[0], type, req, control, index, buf, count) < 0){
			if (debug & Dbgcontrol) fprint(2, "setcontrol: setupcmd %s failed\n",
				c->name);
			return -1;
		}
	}
	c->value[0] = value[0];
	return 0;
}

int
getspecialcontrol(int rec, int ctl, int req, long *value)
{
	byte buf[3];
	int m, n, i;
	int type, control, index, count;
	short svalue;

	count = 1;
	switch(ctl){
	default:
		return Undef;
	case Speed_control:
		value[0] =  getspeed(rec, req);
		return 0;
	case Channel_control:
	case Resolution_control:
		if (req == GET_MIN)
			value[0] = controls[rec][ctl].min;
		if (req == GET_MAX)
			value[0] = controls[rec][ctl].max;
		if (req == GET_RES)
			value[0] = controls[rec][ctl].step;
		if (req == GET_CUR)
			value[0] = controls[rec][ctl].value[0];
		return 0;
	case Volume_control:
	case Delay_control:
		count = 2;
		/* fall through */
	case Mute_control:
	case Bass_control:
	case Mid_control:
	case Treble_control:
	case Equalizer_control:
	case Agc_control:
	case Bassboost_control:
	case Loudness_control:
		type = RD2H|Rclass|Rinterface;
		control = ctl<<8;
		index = featureid[rec]<<8;
		break;
	case Selector_control:
		type = RD2H|Rclass|Rinterface;
		control = ctl<<8;
		index = selectorid[rec];
		break;
	}
	if (controls[rec][ctl].chans){
		m = 0;
		value[0] = 0; // set to average
		for (i = 1; i < 8; i++){
			value[i] = Undef;
			if (controls[rec][ctl].chans & 1 << i){
				if (setupreq(ad->ep[0], type, req, control | i, index, count) < 0)
					return Undef;
				n = setupreply(ad->ep[0], buf, count);
				if (n != count)
					return -1;
				switch (count) {
				case 2:
					svalue = buf[1] << 8 | buf[0];
					if (req == GET_CUR){
						value[i] = svalue;
						value[0] += svalue;
						m++;
					}else
						value[0] = svalue;
					break;
				case 1:
					if (req == GET_CUR){
						value[i] = buf[0];
						value[0] += buf[0];
						m++;
					}else
						value[0] = buf[0];
				}
			}
		}
		if (m) value[0] /= m;
		return 0;
	}
	value[0] = Undef;
	if (setupreq(ad->ep[0], type, req, control, index, count) < 0)
		return -1;
	n = setupreply(ad->ep[0], buf, count);
	if (n != count)
		return -1;
	switch (count) {
	case 2:
		svalue = buf[1] << 8 | buf[0];
		value[0] = svalue;
		break;
	case 1:
		value[0] = buf[0];
	}
	return 0;
}

int
getcontrol(int rec, char *name, long *value)
{
	int i;

	for (i = 0; i < Ncontrol; i++){
		if (strcmp(name, controls[rec][i].name) == 0)
			break;
	}
	if (i == Ncontrol)
		return -1;
	if (controls[rec][i].readable == 0)
		return -1;
	if(getspecialcontrol(rec, i, GET_CUR, value) < 0)
		return -1;
	memmove(controls[rec][i].value, value, sizeof controls[rec][i].value);
	return 0;
}

void
getcontrols(void)
{
	int rec, ctl, i;
	Audiocontrol *c;
	long v[8];

	for (rec = 0; rec < 2; rec++)
		for (ctl = 0; ctl < Ncontrol; ctl++){
			c = &controls[rec][ctl];
			if (c->readable){
				if (verbose)
					fprint(2, "%s %s control",
						rec?"Record":"Playback", controls[rec][ctl].name);
				c->min = (getspecialcontrol(rec, ctl, GET_MIN, v) < 0) ? Undef : v[0];
				if (verbose && c->min != Undef)
					fprint(2, ", min %ld", c->min);
				c->max = (getspecialcontrol(rec, ctl, GET_MAX, v) < 0) ? Undef : v[0];
				if (verbose && c->max != Undef)
					fprint(2, ", max %ld", c->max);
				c->step = (getspecialcontrol(rec, ctl, GET_RES, v) < 0) ? Undef : v[0];
				if (verbose && c->step != Undef)
					fprint(2, ", step %ld", c->step);
				if (getspecialcontrol(rec, ctl, GET_CUR, c->value) == 0){
					if (verbose) {
						if (c->chans){
							fprint(2, ", values");
							for (i = 1; i < 8; i++)
								if (c->chans & 1 << i)
									fprint(2, "[%d] %ld  ", i, c->value[i]);
						}else
							fprint(2, ", value %ld", c->value[0]);
					}
				}
				if (verbose)
					fprint(2, "\n");
			} else {
				c->min = Undef;
				c->max = Undef;
				c->step = Undef;
				c->value[0] = Undef;
				if (debug & Dbgcontrol)
					fprint(2, "%s %s control not settable\n",
						rec?"Playback":"Record", controls[rec][ctl].name);
			}
		}
}

int
ctlparse(char *s, Audiocontrol *c, long *v)
{
	int i, j, nf, m;
	char *vals[9];
	char *p;
	long val;

	nf = tokenize(s, vals, nelem(vals));
	if (nf <= 0)
		return -1;
	if (c->chans){
		j = 0;
		m = 0;
		SET(val);
		v[0] = 0;	// will compute average of v[i]
		for (i = 1; i < 8; i++)
			if (c->chans & 1 << i) {
				if (j < nf){
					val = strtol(vals[j], &p, 0);
					if (val == 0 && *p != '\0' && *p != '%')
						return -1;
					if (*p == '%' && c->min != Undef)
						val = (val*c->max + (100-val)*c->min)/100;
					j++;
				}
				v[i] = val;
				v[0] += val;
				m++;
			} else
				v[i] = Undef;
		if (m) v[0] /= m;
	} else {
		val = strtol(vals[0], &p, 0);
		if (*p == '%' && c->min != Undef)
			val = (val*c->max + (100-val)*c->min)/100;
		v[0] = val;
	}
	return 0;
}

int
Aconv(Fmt *fp)
{
	char str[256];
	Audiocontrol *c;
	int fst, i;
	char *p;

	c = va_arg(fp->args, Audiocontrol*);
	p = str;
	if (c->chans) {
		fst = 1;
		for (i = 1; i < 8; i++)
			if (c->chans & 1 << i){
				p = seprint(p, str+sizeof str, "%s%ld", fst?"'":" ", c->value[i]);
				fst = 0;
			}
		seprint(p, str+sizeof str, "'");
	} else
		seprint(p, str+sizeof str, "%ld", c->value[0]);
	return fmtstrcpy(fp, str);
}