Allow playback of slightly incorrect wav files.

It will now truncate wavs where metadata says the sample is longer than it actually is.

changelogs/maxw_changelog_1.txt

@@ -76,6 +76,25 @@ Add Plane_Copy. It copies slopes.
 Updated the credits screen to include myself, and amend Sarah Mancuso's name.
 The credits now have two names per column, and are separated down the middle.
 
+-------------------------------------------------------------------------------
+2017/01/08
+Fixed CMake for Windows VS2015 generation.
+
+-------------------------------------------------------------------------------
+2017/01/13
+Added thing specials, made them activate on death. Useable in UDMF and
+ExtraData.
+
+-------------------------------------------------------------------------------
+2017/01/14
+Added ZDoom codepointer, A_SetSpecial. Fixed x/y offsets on png's being broken.
+They're now no longer sunk into the floor.
+
+-------------------------------------------------------------------------------
+2017/01/21
+Allow playback of slightly faulty wav files, such as those in Darch's Preacher
+BOOM mapset.
+
 ================================================================================
 EOF
 ================================================================================

source/s_formats.cpp

@@ -264,10 +264,14 @@ static bool S_isWaveSample(byte *data, size_t len, sounddata_t &sd)
 
    r += 4;
    size_t bytes = GetBinaryUDWord(&r);
-   if(!bytes || bytes + totalMDSize > len) // empty or truncated sample stream
+   if(!bytes) // empty sample stream
       return false;
 
-   sd.samplecount = bytes / (bps/8);
+   if(bytes + totalMDSize > len) // truncated sample stream
+      sd.samplecount = (len - totalMDSize) / (bps / 8);
+   else
+      sd.samplecount = bytes / (bps / 8);
+
    sd.samplestart = data + sampleOffset;
 
    return true;