From: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Date: Thu, 28 Apr 2022 16:17:27 +0000 (+0900)
Subject: pcm: dmix: fix wrong scaling in 32bits pcm mixing
X-Git-Tag: v1.2.7~11
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=b62fc061e4833b12286a5f9b2e78894b614ce3fb;p=alsa-lib.git

pcm: dmix: fix wrong scaling in 32bits pcm mixing

Generic mixing function for 32bits pcm has used 8bits right shift for
pre-scaling. But this is generating wrong result if pcm data is
negative value because return value type of bswap_32() is unsigned int.

This patch adds type cast bswap_32() result to signed int.

Fixes: https://github.com/alsa-project/alsa-lib/pull/222
Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
---

diff --git a/src/pcm/pcm_dmix_generic.c b/src/pcm/pcm_dmix_generic.c
index 8a5b6f14..701c66c9 100644
--- a/src/pcm/pcm_dmix_generic.c
+++ b/src/pcm/pcm_dmix_generic.c
@@ -330,7 +330,7 @@ static void generic_mix_areas_32_swap(unsigned int size,
 	register signed int sample;
 
 	for (;;) {
-		sample = bswap_32(*src) >> 8;
+		sample = (signed int) bswap_32(*src) >> 8;
 		if (! *dst) {
 			*sum = sample;
 			*dst = *src;
@@ -364,7 +364,7 @@ static void generic_remix_areas_32_swap(unsigned int size,
 	register signed int sample;
 
 	for (;;) {
-		sample = bswap_32(*src) >> 8;
+		sample = (signed int) bswap_32(*src) >> 8;
 		if (! *dst) {
 			*sum = -sample;
 			*dst = bswap_32(-sample);