dsound: Add support for adjusting volume of more than 2 channels

[Donny Yang]

This was tested under wine 1.5.8 with Ubuntu 12.04 using both winealsa
and winepulse with 7.1 output channels and 1.0, 2.0, 5.1 and 7.1 file
input channels using foobar2000.
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From 7c4bfbc6da0bdb7f2ced78b7b9bdd5796e8a0a4e Mon Sep 17 00:00:00 2001
From: Donny Yang <xiao.tai.lang.de.email at gmail.com>
Date: Fri, 13 Jul 2012 17:14:38 +1000
Subject: dsound: Add support for adjusting volume of more than 2 channels

---
 dlls/dsound/mixer.c |   41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/dlls/dsound/mixer.c b/dlls/dsound/mixer.c
index 547c666..7d0dfa7 100644
--- a/dlls/dsound/mixer.c
+++ b/dlls/dsound/mixer.c
@@ -42,6 +42,11 @@
 #include "dsound_private.h"
 #include "fir.h"
 
+#define SPEAKERS_LEFT_MASK (SPEAKER_FRONT_LEFT | SPEAKER_BACK_LEFT | SPEAKER_FRONT_LEFT_OF_CENTER | \
+	SPEAKER_SIDE_LEFT | SPEAKER_TOP_FRONT_LEFT | SPEAKER_TOP_BACK_LEFT)
+#define SPEAKERS_RIGHT_MASK (SPEAKER_FRONT_RIGHT | SPEAKER_BACK_RIGHT | SPEAKER_FRONT_RIGHT_OF_CENTER | \
+	SPEAKER_SIDE_RIGHT | SPEAKER_TOP_FRONT_RIGHT | SPEAKER_TOP_BACK_RIGHT)
+
 WINE_DEFAULT_DEBUG_CHANNEL(dsound);
 
 void DSOUND_RecalcVolPan(PDSVOLUMEPAN volpan)
@@ -379,11 +384,26 @@ static void DSOUND_MixToTemporary(IDirectSoundBufferImpl *dsb, DWORD frames)
 	cp_fields(dsb, frames, &dsb->freqAcc);
 }
 
+static DWORD channel_number_to_speaker_position(DWORD channel, DWORD channelMask)
+{
+	DWORD result = 1;
+	while(channel > 0 && channelMask != 0){
+		channelMask >>= 1;
+		result <<= 1;
+		if(channelMask & 1)
+			--channel;
+	}
+	if (channelMask == 0 && channel != 0)
+		return 0;
+	return result;
+}
+
 static void DSOUND_MixerVol(const IDirectSoundBufferImpl *dsb, INT frames)
 {
 	INT	i;
-	float vLeft, vRight;
+	float vLeft, vRight, vCenter;
 	UINT channels = dsb->device->pwfx->nChannels, chan;
+	DWORD channelMask, speaker;
 
 	TRACE("(%p,%d)\n",dsb,frames);
 	TRACE("left = %x, right = %x\n", dsb->volpan.dwTotalLeftAmpFactor,
@@ -394,20 +414,29 @@ static void DSOUND_MixerVol(const IDirectSoundBufferImpl *dsb, INT frames)
 	     !(dsb->dsbd.dwFlags & DSBCAPS_CTRL3D))
 		return; /* Nothing to do */
 
-	if (channels != 1 && channels != 2)
-	{
-		FIXME("There is no support for %u channels\n", channels);
+	if (dsb->device->pwfx->wFormatTag == WAVE_FORMAT_EXTENSIBLE)
+		channelMask = ((WAVEFORMATEXTENSIBLE*)dsb->device->pwfx)->dwChannelMask;
+	else if (channels == 1)
+		channelMask = SPEAKER_FRONT_CENTER;
+	else if (channels == 2)
+		channelMask = SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT;
+	else {
+		FIXME("There is no support for %u channels without an extensible wave format\n", channels);
 		return;
 	}
 
 	vLeft = dsb->volpan.dwTotalLeftAmpFactor / ((float)0xFFFF);
 	vRight = dsb->volpan.dwTotalRightAmpFactor / ((float)0xFFFF);
+	vCenter = (vLeft + vRight) / 2.0;
 	for(i = 0; i < frames; ++i){
 		for(chan = 0; chan < channels; ++chan){
-			if(chan == 0)
+			speaker = channel_number_to_speaker_position(chan, channelMask);
+			if(speaker & SPEAKERS_LEFT_MASK)
 				dsb->device->tmp_buffer[i * channels + chan] *= vLeft;
-			else
+			else if(speaker & SPEAKERS_RIGHT_MASK)
 				dsb->device->tmp_buffer[i * channels + chan] *= vRight;
+			else
+				dsb->device->tmp_buffer[i * channels + chan] *= vCenter;
 		}
 	}
 }
-- 
1.7.9.5