devaudio.c

著名操作系统Plan 9的第三版的部分核心源代码。现在很难找到了。Plan 9是bell实验室开发的Unix后继者。

	void *p;

	for(i=0; i<Nbuf; i++) {
		p = xspanalloc(Bufsize, CACHELINESZ, 64*1024);
		dcflush(p, Bufsize);
		audio.buf[i].virt = UNCACHED(uchar, p);
		audio.buf[i].phys = (ulong)PADDR(p);
	}
}

static	void
setempty(void)
{
	int i;

	ilock(&blaster);
	audio.empty.first = 0;
	audio.empty.last = 0;
	audio.full.first = 0;
	audio.full.last = 0;
	audio.current = 0;
	audio.filling = 0;
	for(i=0; i<Nbuf; i++)
		putbuf(&audio.empty, &audio.buf[i]);
	audio.totcount = 0;
	audio.tottime = 0LL;
	iunlock(&blaster);
}

static	void
resetlevel(void)
{
	int i;

	for(i=0; volumes[i].name; i++) {
		audio.lovol[i] = volumes[i].ilval;
		audio.rovol[i] = volumes[i].irval;
		audio.livol[i] = volumes[i].ilval;
		audio.rivol[i] = volumes[i].irval;
	}
}

static int
ess1688(ISAConf* sbconf)
{
	int i, major, minor;

	/*
	 * Try for ESS1688.
	 */
	sbcmd(0xE7);			/* get version */
	major = sbread();
	minor = sbread();
	if(major != 0x68 || minor != 0x8B){
		print("#A: model 0x%.2x 0x%.2x; not ESS1688 compatible\n", major, minor);
		return 1;
	}

	ess1688reset();

	switch(sbconf->irq){
	case 2:
	case 9:
		i = 0x50|(0<<2);
		break;
	case 5:
		i = 0x50|(1<<2);
		break;
	case 7:
		i = 0x50|(2<<2);
		break;
	case 10:
		i = 0x50|(3<<2);
		break;
	default:
		print("#A: bad ESS1688 irq %lud\n", sbconf->irq);
		return 1;
	}
	ess1688w(0xB1, i);

	switch(sbconf->dma){
	case 0:
		i = 0x50|(1<<2);
		break;
	case 1:
		i = 0xF0|(2<<2);
		break;
	case 3:
		i = 0x50|(3<<2);
		break;
	default:
		print("#A: bad ESS1688 dma %lud\n", sbconf->dma);
		return 1;
	}
	ess1688w(0xB2, i);

	ess1688reset();

	blaster.startdma = ess1688startdma;
	blaster.intr = ess1688intr;

	return 0;
}

static void
audioinit(void)
{
	ISAConf sbconf;
	int i, x;
	static int irq[] = {2,5,7,10};

	sbconf.port = 0x220;
	sbconf.dma = Dma;
	sbconf.irq = IrqAUDIO;
	if(isaconfig("audio", 0, &sbconf) == 0)
		return;
	if(cistrcmp(sbconf.type, "sb16") != 0 && cistrcmp(sbconf.type, "ess1688") != 0)
		return;
	switch(sbconf.port){
	case 0x220:
	case 0x240:
	case 0x260:
	case 0x280:
		break;
	default:
		print("#A: bad port 0x%lux\n", sbconf.port);
		return;
	}
	switch(sbconf.irq){
	case 2:
	case 5:
	case 7:
	case 9:
	case 10:
		break;
	default:
		print("#A: bad irq %lud\n", sbconf.irq);
		return;
	}

	blaster.reset = sbconf.port + 0x6;
	blaster.read = sbconf.port + 0xa;
	blaster.write = sbconf.port + 0xc;
	blaster.wstatus = sbconf.port + 0xc;
	blaster.rstatus = sbconf.port + 0xe;
	blaster.mixaddr = sbconf.port + 0x4;
	blaster.mixdata = sbconf.port + 0x5;
	blaster.clri8 = sbconf.port + 0xe;
	blaster.clri16 = sbconf.port + 0xf;
	blaster.clri401 = sbconf.port + 0x100;
	blaster.dma = sbconf.dma;

	blaster.startdma = sb16startdma;
	blaster.intr = sb16intr;

	audio.amode = Aclosed;
	resetlevel();

	outb(blaster.reset, 1);
	delay(1);			/* >3 υs */
	outb(blaster.reset, 0);
	delay(1);

	i = sbread();
	if(i != 0xaa) {
		print("#A: no response #%.2x\n", i);
		return;
	}

	sbcmd(0xe1);			/* get version */
	audio.major = sbread();
	audio.minor = sbread();

	if(audio.major != 4) {
		if(audio.major != 3 || audio.minor != 1 || ess1688(&sbconf)){
			print("#A: model 0x%.2x 0x%.2x; not SB 16 compatible\n",
				audio.major, audio.minor);
			return;
		}
		audio.major = 4;
	}

	/*
	 * initialize the mixer
	 */
	mxcmd(0x00, 0);			/* Reset mixer */
	mxvolume();

	/*
	 * Attempt to set IRQ/DMA channels.
	 * On old ISA boards, these registers are writable.
	 * On Plug-n-Play boards, these are read-only.
	 *
	 * To accomodate both, we write to the registers,
	 * but then use the contents in case the write is
	 * disallowed.
	 */
	mxcmd(0x80,			/* irq */
		(sbconf.irq==2)? 1:
		(sbconf.irq==5)? 2:
		(sbconf.irq==7)? 4:
		(sbconf.irq==9)? 1:
		(sbconf.irq==10)? 8:
		0);
	mxcmd(0x81, 1<<blaster.dma);	/* dma */

	x = mxread(0x81);
	for(i=5; i<=7; i++)
		if(x & (1<<i)){
			blaster.dma = i;
			break;
		}

	x = mxread(0x80);
	for(i=0; i<=3; i++)
		if(x & (1<<i)){
			sbconf.irq = irq[i];
			break;
		}

	seteisadma(blaster.dma, audiodmaintr);
	setvec(Int0vec+sbconf.irq, pcaudiosbintr, 0);
}

static Chan*
audioattach(char *param)
{
	return devattach('A', param);
}

static int
audiowalk(Chan *c, char *name)
{
	return devwalk(c, name, audiodir, nelem(audiodir), devgen);
}

static void
audiostat(Chan *c, char *db)
{
	devstat(c, db, audiodir, nelem(audiodir), devgen);
}

static Chan*
audioopen(Chan *c, int omode)
{
	int amode;

	if(audio.major != 4)
		error(Emajor);

	switch(c->qid.path & ~CHDIR) {
	default:
		error(Eperm);
		break;

	case Qstatus:
		if((omode&7) != OREAD)
			error(Eperm);
	case Qvolume:
	case Qdir:
		break;

	case Qaudio:
		amode = Awrite;
		if((omode&7) == OREAD)
			amode = Aread;
		qlock(&audio);
		if(audio.amode != Aclosed){
			qunlock(&audio);
			error(Einuse);
		}
		if(audio.bufinit == 0) {
			audio.bufinit = 1;
			sbbufinit();
		}
		audio.amode = amode;
		setempty();
		audio.curcount = 0;
		qunlock(&audio);
		mxvolume();
		break;
	}
	c = devopen(c, omode, audiodir, nelem(audiodir), devgen);
	c->mode = openmode(omode);
	c->flag |= COPEN;
	c->offset = 0;

	return c;
}

static void
audioclose(Chan *c)
{
	Buf *b;

	switch(c->qid.path & ~CHDIR) {
	default:
		error(Eperm);
		break;

	case Qdir:
	case Qvolume:
	case Qstatus:
		break;

	case Qaudio:
		if(c->flag & COPEN) {
			qlock(&audio);
			if(audio.amode == Awrite) {
				/* flush out last partial buffer */
				b = audio.filling;
				if(b) {
					audio.filling = 0;
					memset(b->virt+audio.curcount, 0, Bufsize-audio.curcount);
					swab(b->virt);
					putbuf(&audio.full, b);
				}
				if(!audio.active && audio.full.first)
					pokeaudio();
			}
			audio.amode = Aclosed;
			if(waserror()){
				qunlock(&audio);
				nexterror();
			}
			while(audio.active)
				waitaudio();
			setempty();
			poperror();
			qunlock(&audio);
		}
		break;
	}
}

static long
audioread(Chan *c, void *v, long n, vlong off)
{
	int liv, riv, lov, rov;
	long m, n0;
	char buf[300];
	Buf *b;
	int j;
	ulong offset = off;
	char *a;

	n0 = n;
	a = v;
	switch(c->qid.path & ~CHDIR) {
	default:
		error(Eperm);
		break;

	case Qdir:
		return devdirread(c, a, n, audiodir, nelem(audiodir), devgen);

	case Qaudio:
		if(audio.amode != Aread)
			error(Emode);
		qlock(&audio);
		if(waserror()){
			qunlock(&audio);
			nexterror();
		}
		while(n > 0) {
			b = audio.filling;
			if(b == 0) {
				b = getbuf(&audio.full);
				if(b == 0) {
					waitaudio();
					continue;
				}
				audio.filling = b;
				swab(b->virt);
				audio.curcount = 0;
			}
			m = Bufsize-audio.curcount;
			if(m > n)
				m = n;
			memmove(a, b->virt+audio.curcount, m);

			audio.curcount += m;
			n -= m;
			a += m;
			if(audio.curcount >= Bufsize) {
				audio.filling = 0;
				putbuf(&audio.empty, b);
			}
		}
		poperror();
		qunlock(&audio);
		break;

	case Qstatus:
		buf[0] = 0;
		snprint(buf, sizeof(buf), "bytes %lud\ntime %lld\n",
			audio.totcount, audio.tottime);
		return readstr(offset, a, n, buf);

	case Qvolume:
		j = 0;
		buf[0] = 0;
		for(m=0; volumes[m].name; m++){
			liv = audio.livol[m];
			riv = audio.rivol[m];
			lov = audio.lovol[m];
			rov = audio.rovol[m];
			j += snprint(buf+j, sizeof(buf)-j, "%s", volumes[m].name);
			if((volumes[m].flag & Fmono) || liv==riv && lov==rov){
				if((volumes[m].flag&(Fin|Fout))==(Fin|Fout) && liv==lov)
					j += snprint(buf+j, sizeof(buf)-j, " %d", liv);
				else{
					if(volumes[m].flag & Fin)
						j += snprint(buf+j, sizeof(buf)-j,
							" in %d", liv);
					if(volumes[m].flag & Fout)
						j += snprint(buf+j, sizeof(buf)-j,
							" out %d", lov);
				}
			}else{
				if((volumes[m].flag&(Fin|Fout))==(Fin|Fout) &&
				    liv==lov && riv==rov)
					j += snprint(buf+j, sizeof(buf)-j,
						" left %d right %d",
						liv, riv);
				else{
					if(volumes[m].flag & Fin)
						j += snprint(buf+j, sizeof(buf)-j,
							" in left %d right %d",
							liv, riv);
					if(volumes[m].flag & Fout)
						j += snprint(buf+j, sizeof(buf)-j,
							" out left %d right %d",
							lov, rov);
				}
			}
			j += snprint(buf+j, sizeof(buf)-j, "\n");
		}
		return readstr(offset, a, n, buf);
	}
	return n0-n;
}

static long
audiowrite(Chan *c, void *vp, long n, vlong)
{
	long m, n0;
	int i, nf, v, left, right, in, out;
	char buf[255], *field[Ncmd];
	Buf *b;
	char *a;

	a = vp;
	n0 = n;
	switch(c->qid.path & ~CHDIR) {
	default:
		error(Eperm);
		break;

	case Qvolume:
		v = Vaudio;
		left = 1;
		right = 1;
		in = 1;
		out = 1;
		if(n > sizeof(buf)-1)
			n = sizeof(buf)-1;
		memmove(buf, a, n);
		buf[n] = '\0';

		nf = getfields(buf, field, Ncmd, 1, " \t\n");
		for(i = 0; i < nf; i++){
			/*
			 * a number is volume
			 */
			if(field[i][0] >= '0' && field[i][0] <= '9') {
				m = strtoul(field[i], 0, 10);
				if(left && out)
					audio.lovol[v] = m;
				if(left && in)
					audio.livol[v] = m;
				if(right && out)
					audio.rovol[v] = m;
				if(right && in)
					audio.rivol[v] = m;
				mxvolume();
				goto cont0;
			}

			for(m=0; volumes[m].name; m++) {
				if(strcmp(field[i], volumes[m].name) == 0) {
					v = m;
					in = 1;
					out = 1;
					left = 1;
					right = 1;
					goto cont0;
				}
			}

			if(strcmp(field[i], "reset") == 0) {
				resetlevel();
				mxvolume();
				goto cont0;
			}
			if(strcmp(field[i], "in") == 0) {
				in = 1;
				out = 0;
				goto cont0;
			}
			if(strcmp(field[i], "out") == 0) {
				in = 0;
				out = 1;
				goto cont0;
			}
			if(strcmp(field[i], "left") == 0) {
				left = 1;
				right = 0;
				goto cont0;
			}
			if(strcmp(field[i], "right") == 0) {
				left = 0;
				right = 1;
				goto cont0;
			}
			error(Evolume);
			break;
		cont0:;
		}
		break;

	case Qaudio:
		if(audio.amode != Awrite)
			error(Emode);
		qlock(&audio);
		if(waserror()){
			qunlock(&audio);
			nexterror();
		}
		while(n > 0) {
			b = audio.filling;
			if(b == 0) {
				b = getbuf(&audio.empty);
				if(b == 0) {
					waitaudio();
					continue;
				}
				audio.filling = b;
				audio.curcount = 0;
			}

			m = Bufsize-audio.curcount;
			if(m > n)
				m = n;
			memmove(b->virt+audio.curcount, a, m);

			audio.curcount += m;
			n -= m;
			a += m;
			if(audio.curcount >= Bufsize) {
				audio.filling = 0;
				swab(b->virt);
				putbuf(&audio.full, b);
			}
		}
		poperror();
		qunlock(&audio);
		break;
	}
	return n0 - n;
}

static	void
swab(uchar *a)
{
	ulong *p, *ep, b;

	if(!SBswab){
		USED(a);
		return;
	}
	p = (ulong*)a;
	ep = p + (Bufsize>>2);
	while(p < ep) {
		b = *p;
		b = (b>>24) | (b<<24) |
			((b&0xff0000) >> 8) |
			((b&0x00ff00) << 8);
		*p++ = b;
	}
}

Dev audiodevtab = {
	'A',
	"audio",

	devreset,
	audioinit,
	audioattach,
	devclone,
	audiowalk,
	audiostat,
	audioopen,
	devcreate,
	audioclose,
	audioread,
	devbread,
	audiowrite,
	devbwrite,
	devremove,
	devwstat,
};