dsound: Allow mixing the same buffer multiple times if we are looping

[Maarten Lankhorst]

This fixes the fahrenheit bug (#8908) which creates a 441 byte mono 8
bit buffer, and always underruns in <10 ms, so sound never starts.
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>From 3f0bfcfe1d9d26d546a9cb32929099d2f7470ce4 Mon Sep 17 00:00:00 2001
From: Maarten Lankhorst <m.b.lankhorst at gmail.com>
Date: Thu, 12 Jul 2007 13:21:43 +0200
Subject: [PATCH] dsound: Allow mixing the same buffer multiple times if we are looping

This fixes the Fahrenheit bug
---
 dlls/dsound/mixer.c |   46 ++++++++++++++++++++++++++++++----------------
 1 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/dlls/dsound/mixer.c b/dlls/dsound/mixer.c
index f2bee0d..4f7291d 100644
--- a/dlls/dsound/mixer.c
+++ b/dlls/dsound/mixer.c
@@ -543,6 +543,12 @@ static DWORD DSOUND_MixInBuffer(IDirectSoundBufferImpl *dsb, DWORD writepos, DWO
 		dsb->leadin = FALSE;
 	}
 
+	/* check for notification positions */
+	if (dsb->dsbd.dwFlags & DSBCAPS_CTRLPOSITIONNOTIFY &&
+	    dsb->state != STATE_STARTING) {
+		DSOUND_CheckEvent(dsb, dsb->buf_mixpos, ilen);
+	}
+
 	dsb->buf_mixpos += ilen;
 
 	if (dsb->buf_mixpos >= dsb->buflen) {
@@ -557,6 +563,9 @@ static DWORD DSOUND_MixInBuffer(IDirectSoundBufferImpl *dsb, DWORD writepos, DWO
 		}
 	}
 
+	/* increase mix position */
+	dsb->primary_mixpos += len;
+	dsb->primary_mixpos %= dsb->device->buflen;
 	return len;
 }
 
@@ -607,27 +616,32 @@ static DWORD DSOUND_MixOne(IDirectSoundBufferImpl *dsb, DWORD playpos, DWORD wri
 	}
 
 	/* take into acount already mixed data */
-	mixlen = mixlen - primary_done;
+	mixlen -= primary_done;
 
-	TRACE("mixlen (primary) = %i\n", mixlen);
+	TRACE("primary_done=%d, mixlen (primary) = %i\n", primary_done, mixlen);
+
+	if ((dsb->playflags & DSBPLAY_LOOPING) && mixlen > buflen)
+	{
+		while (mixlen > buflen)
+		{
+			DWORD mixedlength = DSOUND_MixInBuffer(dsb, dsb->primary_mixpos, buflen);
+			mixlen -= buflen;
+			if (!mixedlength)
+			{
+				mixlen = 0;
+				break;
+			}
+		}
+		
+	}
 
 	/* clip to valid length */
 	mixlen = (buflen < mixlen) ? buflen : mixlen;
+	TRACE("mixlen (buffer)=%d\n", mixlen);
 
-	TRACE("primary_done=%d, mixlen (buffer)=%d\n", primary_done, mixlen);
-
-	/* mix more data */
-	mixlen = DSOUND_MixInBuffer(dsb, dsb->primary_mixpos, mixlen);
-
-	/* check for notification positions */
-	if (dsb->dsbd.dwFlags & DSBCAPS_CTRLPOSITIONNOTIFY &&
-	    dsb->state != STATE_STARTING) {
-		DSOUND_CheckEvent(dsb, writepos, mixlen	/ dsb->device->pwfx->nBlockAlign * dsb->pwfx->nBlockAlign);
-	}
-
-	/* increase mix position */
-	dsb->primary_mixpos += mixlen;
-	dsb->primary_mixpos %= dsb->device->buflen;
+	if (mixlen)
+		/* mix more data */
+		mixlen = DSOUND_MixInBuffer(dsb, dsb->primary_mixpos, mixlen);
 
 	TRACE("new primary_mixpos=%d, mixed data len=%d, buffer left = %d\n",
 		dsb->primary_mixpos, mixlen, (dsb->buflen - dsb->buf_mixpos));
-- 
1.4.4.2