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dmid: better fnumber calculation and fix fine tuning for 2nd voice

--- a/sys/src/games/dmid.c

+++ b/sys/src/games/dmid.c

@@ -31,7 +31,7 @@

 struct Inst{

 	int fixed;

 	int dbl;

-	uchar fine;

+	int fine;

 	uchar n;

 	uchar i[13];

 	uchar i2[13];

@@ -225,13 +225,16 @@

 void

 setoct(Opl *o)

 {

-	int n, b, f;

+	int n, b, f, d;

+	double e;

-	n = o->n + o->c->bend / 0x1000 & 0x7f;

-	f = freq[n] + (o->c->bend % 0x1000) * (freq[n+1] - freq[n]) / 0x1000;

-	f = (f * (1 << 20)) / 49716;

-	//if(o->i == o->c->i->i2)

-	//	f += o->c->i->fine;	/* nope */

+	d = o->c->bend;

+	d += o->i == o->c->i->i2 ? o->c->i->fine : 0;

+	n = o->n + d / 0x1000 & 0x7f;

+	e = freq[n] + (d % 0x1000) * (freq[n+1] - freq[n]) / 0x1000;

+	if(o->c->i->fixed)

+		e = (double)(int)e;

+	f = (e * (1 << 20)) / 49716;

 	for(b=1; b<8; b++, f>>=1)

 		if(f < 1024)

 			break;

@@ -448,7 +451,7 @@

 		i->fixed = n & 1<<0;

 		i->dbl = opl2 ? 0 : n & 1<<2;

 		get8(nil);

-		i->fine = get8(nil) / 2 - 64;

+		i->fine = (get8(nil) - 128) * 64;

 		i->n = get8(nil);

 		bread(i->i, sizeof i->i);

 		get8(nil);