shithub: pplay

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drawsamp: don't memcpy everything, just fetch chunk slices as intended

--- a/cmd.c

+++ b/cmd.c

@@ -256,6 +256,32 @@

 }

 uchar *

+getslice(Dot *d, usize n, usize *sz)

+{

+	usize Δbuf, Δloop, off;

+	Chunk *c;

+

+	if(d->pos >= totalsz){

+		*sz = 0;

+		return nil;

+	}

+	c = p2c(d->pos, &off);

+	Δloop = d->to.pos - d->pos;

+	Δbuf = c->bufsz - off;

+	if(n < Δloop && n < Δbuf){

+		*sz = n;

+		d->pos += n;

+	}else if(Δloop <= Δbuf){

+		*sz = Δloop;

+		d->pos = d->from.pos;

+	}else{

+		*sz = Δbuf;

+		d->pos += Δbuf;

+	}

+	return c->buf + off;

+}

+

+uchar *

 getbuf(Dot d, usize n, uchar *scratch, usize *boff)

 {

 	uchar *bp, *p;

--- a/draw.c

+++ b/draw.c

@@ -23,8 +23,6 @@

 static int bgscalyl, bgscalyr, bgscalf;

 static Channel *drawc;

 static usize T;

-static uchar *sbuf;

-static usize sbufsz;

 static int sampwidth = 1;

 static double zoom = 1.0;

@@ -67,7 +65,7 @@

 drawsamps(void*)

 {

 	int x, lmin, lmax, rmin, rmax;

-	usize n, m;

+	usize n, m, k;

 	s16int s;

 	uchar *p, *e;

 	Rectangle l, r;

@@ -77,50 +75,49 @@

 end:

 		recvul(drawc);

 again:

-		if(sbufsz < T * sampwidth){

-			sbuf = erealloc(sbuf, T * sampwidth, sbufsz);

-			sbufsz = T * sampwidth;

-		}

 		lockdisplay(display);

 		draw(viewbg, viewbg->r, col[Cbg], nil, ZP);

 		unlockdisplay(display);

+		d.from.pos = 0;

 		d.pos = views;

+		d.to.pos = totalsz;

 		m = viewe - views;

 		x = 0;

+		qlock(&lsync);

 		while(m > 0){

-			qlock(&lsync);

 			if(nbrecvul(drawc) == 1){

 				qunlock(&lsync);

 				goto again;

 			}

 			n = m < T * sampwidth ? m : T * sampwidth;

-			p = getbuf(d, n, sbuf, &n);

-			qunlock(&lsync);

-			if(p == nil){

-				if(n > 0)

-					fprint(2, "getbuf: %r\n");

-				goto end;

-			}

-			d.pos += n;

-			e = p + n;

 			lmin = lmax = 0;

 			rmin = rmax = 0;

-			while(p < e){

-				s = (s16int)(p[1] << 8 | p[0]);

-				if(s < lmin)

-					lmin = s;

-				else if(s > lmax)

-					lmax = s;

-				if(stereo){

-					s = (s16int)(p[3] << 8 | p[2]);

-					if(s < rmin)

-						rmin = s;

-					else if(s > rmax)

-						rmax = s;

+			while(n > 0){

+				p = getslice(&d, n, &k);

+				if(p == nil){

+					if(k > 0)

+						fprint(2, "getslice: %r\n");

+					goto end;

 				}

-				p += 4 * sampwidth;

+				e = p + k;

+				while(p < e){

+					s = (s16int)(p[1] << 8 | p[0]);

+					if(s < lmin)

+						lmin = s;

+					else if(s > lmax)

+						lmax = s;

+					if(stereo){

+						s = (s16int)(p[3] << 8 | p[2]);

+						if(s < rmin)

+							rmin = s;

+						else if(s > rmax)

+							rmax = s;

+					}

+					p += 4 * sampwidth;

+				}

+				n -= k;

+				m -= k;

 			}

-			m -= n;

 			l = Rect(x, bgscalyl - lmax / bgscalf,

 				x+sampwidth, bgscalyl - lmin / bgscalf);

 			r = Rect(x, bgscalyr - rmax / bgscalf,

@@ -132,6 +129,7 @@

 			unlockdisplay(display);

 			x = (d.pos - views) / T;

 		}

+		qunlock(&lsync);

 	}

 }

--- a/fns.h

+++ b/fns.h

@@ -14,6 +14,7 @@

 Chunk*	p2c(usize, usize*);

 void	setrange(usize, usize);

 int	setpos(usize);

+uchar*	getslice(Dot*, usize, usize*);

 uchar*	getbuf(Dot, usize, uchar*, usize*);

 int	loadin(int);

 void*	emalloc(usize);