From fb3a4e8b7016e27c326bc51e3b1484b4741d8b1c Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens@ladisch.de>
Date: Mon, 14 Jan 2008 08:52:16 +0100
Subject: [PATCH] pcm dmix plugin: fix generic direct remixing

In the case of the sum buffer being uninitialized, the source sample
must be negated not only when writing to the sum but also when writing
to the destination.
---
 src/pcm/pcm_dmix_generic.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/pcm/pcm_dmix_generic.c b/src/pcm/pcm_dmix_generic.c
index 29ea91a7..a1086c95 100644
--- a/src/pcm/pcm_dmix_generic.c
+++ b/src/pcm/pcm_dmix_generic.c
@@ -173,7 +173,7 @@ static void generic_remix_areas_16_native(unsigned int size,
 		sample = *src;
 		if (! *dst) {
 			*sum = -sample;
-			*dst = *src;
+			*dst = -sample;
 		} else {
 			*sum = sample = *sum - sample;
 			if (sample > 0x7fff)
@@ -238,7 +238,7 @@ static void generic_remix_areas_32_native(unsigned int size,
 		sample = *src >> 8;
 		if (! *dst) {
 			*sum = -sample;
-			*dst = *src;
+			*dst = -*src;
 		} else {
 			*sum = sample = *sum - sample;
 			if (sample > 0x7fffff)
@@ -303,7 +303,7 @@ static void generic_remix_areas_16_swap(unsigned int size,
 		sample = (signed short) bswap_16(*src);
 		if (! *dst) {
 			*sum = -sample;
-			*dst = *src;
+			*dst = (signed short) bswap_16((signed short) -sample);
 		} else {
 			*sum = sample = *sum - sample;
 			if (sample > 0x7fff)
@@ -368,7 +368,7 @@ static void generic_remix_areas_32_swap(unsigned int size,
 		sample = bswap_32(*src) >> 8;
 		if (! *dst) {
 			*sum = -sample;
-			*dst = *src;
+			*dst = bswap_32(-sample);
 		} else {
 			*sum = sample = *sum - sample;
 			if (sample > 0x7fffff)
@@ -434,7 +434,8 @@ static void generic_remix_areas_24(unsigned int size,
 	for (;;) {
 		sample = src[0] | (src[1] << 8) | (((signed char *)src)[2] << 16);
 		if (!(dst[0] | dst[1] | dst[2])) {
-			*sum = -sample;
+			sample = -sample;
+			*sum = sample;
 		} else {
 			*sum = sample = *sum - sample;
 			if (sample > 0x7fffff)
@@ -493,7 +494,8 @@ static void generic_remix_areas_u8(unsigned int size,
 	for (;;) {
 		register int sample = *src - 0x80;
 		if (*dst == 0x80) {
-			*sum = -sample;
+			sample = -sample;
+			*sum = sample;
 		} else {
 			*sum = sample = *sum - sample;
 			if (sample > 0x7f)
-- 
2.47.1