sndiod: Use the channel mapping code of aucat

For now sndiod uses only a subset of the available channel mappings.
It gives the same result as the previous one, but having the same
in both programs makes code review and testing easier.

1 files changed, 30 insertions, 28 deletions

diff --git a/usr.bin/sndiod/dsp.c b/usr.bin/sndiod/dsp.c
index f3420d151cd..2aa1cb143fa 100644
--- a/usr.bin/sndiod/dsp.c
+++ b/usr.bin/sndiod/dsp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dsp.c,v 1.20 2024/04/22 11:07:42 ratchov Exp $	*/
+/*	$OpenBSD: dsp.c,v 1.21 2024/04/22 14:11:35 ratchov Exp $	*/
 /*
  * Copyright (c) 2008-2012 Alexandre Ratchov <alex@caoua.org>
  *
@@ -834,33 +834,35 @@ cmap_init(struct cmap *p,
     int imin, int imax, int isubmin, int isubmax,
     int omin, int omax, int osubmin, int osubmax)
 {
-	int cmin, cmax;
-
-	cmin = -NCHAN_MAX;
-	if (osubmin > cmin)
-		cmin = osubmin;
-	if (omin > cmin)
-		cmin = omin;
-	if (isubmin > cmin)
-		cmin = isubmin;
-	if (imin > cmin)
-		cmin = imin;
-
-	cmax = NCHAN_MAX;
-	if (osubmax < cmax)
-		cmax = osubmax;
-	if (omax < cmax)
-		cmax = omax;
-	if (isubmax < cmax)
-		cmax = isubmax;
-	if (imax < cmax)
-		cmax = imax;
-
-	p->ostart = cmin - omin;
-	p->onext = omax - cmax;
-	p->istart = cmin - imin;
-	p->inext = imax - cmax;
-	p->nch = cmax - cmin + 1;
+	int inch, onch, nch;
+
+	/*
+	 * Ignore channels outside of the available sets
+	 */
+	if (isubmin < imin)
+		isubmin = imin;
+	if (isubmax > imax)
+		isubmax = imax;
+	if (osubmin < omin)
+		osubmin = omin;
+	if (osubmax > omax)
+		osubmax = omax;
+
+	/*
+	 * Shrink the input or the output subset to make both subsets of
+	 * the same size
+	 */
+	inch = isubmax - isubmin + 1;
+	onch = osubmax - osubmin + 1;
+	nch = (inch < onch) ? inch : onch;
+	isubmax = isubmin + nch - 1;
+	osubmax = osubmin + nch - 1;
+
+	p->ostart = osubmin - omin;
+	p->onext = omax - osubmax;
+	p->istart = isubmin - imin;
+	p->inext = imax - isubmax;
+	p->nch = nch;
 #ifdef DEBUG
 	if (log_level >= 3) {
 		log_puts("cmap: nch = ");