code: plan9front

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games/opl3: don't buffer output and simplify (thanks umbraticus)

this fixes real-time applications.

-n previously specified a rate divisor rather than the rate itself,
which was used for specific applications outside of 9front.  instead,
just set the rate directly, more useful and straightforward.

--- a/sys/man/1/opl3

+++ b/sys/man/1/opl3

@@ -4,7 +4,7 @@

 .SH SYNOPSIS

 .B opl3

 [

-.B -n

+.B -r

 .I rate

 ] [

 .I file

@@ -44,7 +44,7 @@

 chip may be sampled before processing the next command.

 The period itself is the inverse of the command rate, 44100 Hz by default.

 This rate can be set using the

-.B -n

+.B -r

 parameter.

 .SH SOURCE

 .B /sys/src/games/opl3

--- a/sys/src/games/opl3/opl3m.c

+++ b/sys/src/games/opl3/opl3m.c

@@ -6,14 +6,10 @@

 void	opl3wr(int, int);

 void	opl3init(int);

-enum{

-	Rate = 44100,

-};

-

 void

 usage(void)

 {

-	fprint(2, "usage: %s [-n nsamp] [file]\n", argv0);

+	fprint(2, "usage: %s [-r rate] [file]\n", argv0);

 	exits("usage");

 }

@@ -20,15 +16,15 @@

 void

 main(int argc, char **argv)

 {

-	int r, v, dt, nsamp, fd;

-	uchar *sb, u[5];

-	Biobuf *bi, *bo;

+	int rate, r, v, dt, fd;

+	uchar sb[65536 * 4], u[5];

+	Biobuf *bi;

 	fd = 0;

-	nsamp = 1;

+	rate = 44100;

 	ARGBEGIN{

-	case 'n':

-		nsamp = Rate / atoi(EARGF(usage()));

+	case 'r':

+		rate = atoi(EARGF(usage()));

 		break;

 	default:

 		usage();

@@ -37,21 +33,16 @@

 		if((fd = open(*argv, OREAD)) < 0)

 			sysfatal("open: %r");

 	bi = Bfdopen(fd, OREAD);

-	bo = Bfdopen(1, OWRITE);

-	if(bi == nil || bo == nil)

+	if(bi == nil)

 		sysfatal("Bfdopen: %r");

-	nsamp *= 4;

-	if((sb = malloc(nsamp)) == nil)

-		sysfatal("malloc: %r");

-	opl3init(Rate);

+	opl3init(rate);

 	while(Bread(bi, u, sizeof u) > 0){

 		r = u[1] << 8 | u[0];

 		v = u[2];

-		dt = u[4] << 8 | u[3];

 		opl3wr(r, v);

-		while(dt-- > 0){

-			opl3out(sb, nsamp);

-			Bwrite(bo, sb, nsamp);

+		if(dt = (u[4] << 8 | u[3]) * 4){	/* 16-bit stereo */

+			opl3out(sb, dt);

+			write(1, sb, dt);

 		}

 	}

 }