Fix a bug when mixing a data source using mmap mode.

This was causing mmaped data sources to not loop if they coincidentally
reached the end at the same time as the final output frame was written.

research/ma_mixing.h

@@ -2557,10 +2557,14 @@ static ma_result ma_mixer_mix_data_source_mmap(ma_mixer* pMixer, ma_data_source*
             result = ma_data_source_unmap(pDataSource, framesMapped);   /* Do this last because the result code is used below to determine whether or not we need to loop. */
         }
 
+        totalFramesProcessed += framesToProcess;
+        pRunningAccumulationBuffer = ma_offset_ptr(pRunningAccumulationBuffer, framesToProcess * ma_get_accumulation_bytes_per_frame(pMixer->format, pMixer->channels));
+
         if (result != MA_SUCCESS) {
             if (result == MA_AT_END) {
                 if (loop) {
                     ma_data_source_seek_to_pcm_frame(pDataSource, 0);
+                    result = MA_SUCCESS;    /* Make sure we don't return MA_AT_END which will happen if we conicidentally hit the end of the data source at the same time as we finish outputting. */
                 } else {
                     break;  /* We've reached the end and we're not looping. */
                 }
@@ -2568,9 +2572,6 @@ static ma_result ma_mixer_mix_data_source_mmap(ma_mixer* pMixer, ma_data_source*
                 return result;  /* An error occurred. */
             }
         }
-        
-        totalFramesProcessed += framesToProcess;
-        pRunningAccumulationBuffer = ma_offset_ptr(pRunningAccumulationBuffer, framesToProcess * ma_get_accumulation_bytes_per_frame(pMixer->format, pMixer->channels));
     }
 
     return result;