Add flac buffer decoder

src/FlacDecoder.cpp

@@ -89,6 +89,63 @@ public:
         }
         
     }
+
+    FlacDecoderInternal(AudioData * d, const std::vector<uint8_t> & memory) : d(d), data(std::move(memory)), dataPos(0)
+    {
+        
+        /////////////////////////////
+        // Initialize FLAC library //
+        /////////////////////////////
+        
+        decoderInternal = FLAC__stream_decoder_new();
+        
+        FLAC__stream_decoder_set_metadata_respond(decoderInternal, FLAC__METADATA_TYPE_STREAMINFO);
+        
+        bool initialized = FLAC__stream_decoder_init_stream(
+          decoderInternal,
+          read_callback,
+          seek_callback,
+          tell_callback,
+          length_callback,
+          eof_callback,
+          s_writeCallback,
+          s_metadataCallback,
+          s_errorCallback,
+          this
+        ) == FLAC__STREAM_DECODER_INIT_STATUS_OK;
+        
+        FLAC__stream_decoder_set_md5_checking(decoderInternal, true);
+        
+        //////////////////////
+        // Read Stream Data //
+        /////////////////////
+        
+        if (initialized)
+        {
+            // Find the size and allocate memory
+            FLAC__stream_decoder_process_until_end_of_metadata(decoderInternal);
+            
+            // Read memory out into our temporary internalBuffer
+            FLAC__stream_decoder_process_until_end_of_stream(decoderInternal);
+
+            // Presently unneeded, but useful for reference
+            // FLAC__ChannelAssignment channelAssignment = FLAC__stream_decoder_get_channel_assignment(decoderInternal);
+            
+            // Fill out remaining user data
+            d->lengthSeconds = (float) numSamples / (float) d->sampleRate;
+            
+            auto totalSamples = numSamples * d->channelCount;
+
+            // Next, process internal buffer into the user-visible samples array
+            ConvertToFloat32(d->samples.data(), internalBuffer.data(), totalSamples, d->sourceFormat);
+        }
+        
+        else
+        {
+            throw std::runtime_error("Unable to initialize FLAC decoder");
+        }
+        
+    }
     
     ~FlacDecoderInternal()
     {
@@ -148,12 +205,51 @@ public:
     {
         std::cerr << "FLAC Decoder Error: " << FLAC__StreamDecoderErrorStatusString[status] << std::endl;
     }
+
+    static FLAC__StreamDecoderReadStatus read_callback(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], size_t *bytes, void *client_data) {
+      FlacDecoderInternal *decoderInternal = (FlacDecoderInternal *)client_data;
+      size_t readLength = std::min<size_t>(*bytes, decoderInternal->data.size() - decoderInternal->dataPos);
+      if (readLength > 0) {
+        memcpy(buffer, decoderInternal->data.data(), readLength);
+        decoderInternal->dataPos += readLength;
+        *bytes = readLength;
+        if (decoderInternal->dataPos < decoderInternal->data.size()) {
+          return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
+        } else {
+          return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
+        }
+      } else {
+        return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
+      }
+    }
+    static FLAC__StreamDecoderSeekStatus seek_callback(const FLAC__StreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data) {
+      FlacDecoderInternal *decoderInternal = (FlacDecoderInternal *)client_data;
+      size_t newPos = std::min<size_t>(absolute_byte_offset, decoderInternal->data.size() - decoderInternal->dataPos);
+      decoderInternal->dataPos = newPos;
+      return FLAC__STREAM_DECODER_SEEK_STATUS_OK;
+    }
+    static FLAC__StreamDecoderTellStatus tell_callback(const FLAC__StreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data) {
+      FlacDecoderInternal *decoderInternal = (FlacDecoderInternal *)client_data;
+      *absolute_byte_offset = decoderInternal->dataPos;
+      return FLAC__STREAM_DECODER_TELL_STATUS_OK;
+    }
+    static FLAC__StreamDecoderLengthStatus length_callback(const FLAC__StreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data) {
+      FlacDecoderInternal *decoderInternal = (FlacDecoderInternal *)client_data;
+      *stream_length = decoderInternal->data.size();
+      return FLAC__STREAM_DECODER_LENGTH_STATUS_OK;
+    }
+    static FLAC__bool eof_callback(const FLAC__StreamDecoder *decoder, void *client_data) {
+      FlacDecoderInternal *decoderInternal = (FlacDecoderInternal *)client_data;
+      return decoderInternal->dataPos == decoderInternal->data.size();
+    }
     
 private:
     
     NO_COPY(FlacDecoderInternal);
     
     FLAC__StreamDecoder * decoderInternal;
+    std::vector<uint8_t> data;
+    size_t dataPos;
     
     size_t bufferPosition = 0;
     size_t numSamples = 0;
@@ -174,7 +270,7 @@ void FlacDecoder::LoadFromPath(AudioData * data, const std::string & path)
 
 void FlacDecoder::LoadFromBuffer(AudioData * data, const std::vector<uint8_t> & memory)
 {
-    throw LoadBufferNotImplEx();
+    FlacDecoderInternal decoder(data, memory);
 }
 
 std::vector<std::string> FlacDecoder::GetSupportedFileExtensions()