clarify variable names

include/libnyquist/IMA4Util.h

@@ -33,13 +33,11 @@ namespace nqr
 
     struct ADPCMState
     {
-        int nBlockAlign;
+        int frame_size;
         int firstDataBlockByte;
         int dataSize;
         int currentByte;
-        const uint8_t * currentDatablock; // A buffer containing the current encoded datablock.
-        int predict = 0;
-        int stepIndex = 0;
+        const uint8_t * inBuffer;
     };
 
     static const int ima_index_table[16] =
@@ -101,7 +99,7 @@ namespace nqr
     
     void decode_ima_adpcm(ADPCMState & state, int16_t * outBuffer, uint32_t num_channels)
     {
-        const uint8_t * data = state.currentDatablock;
+        const uint8_t * data = state.inBuffer;
         
         // Loop over the interleaved words
         for (int32_t ch = 0; ch < num_channels; ch++)
@@ -120,7 +118,7 @@ namespace nqr
             int idx = ch;
             
             // Decode each nibble of the current data word, containing 8 encoded samples, for the current channel
-            while (byteIdx < state.nBlockAlign)
+            while (byteIdx < state.frame_size)
             {
                 for (int j = 0; j < 4; j++)
                 {

src/WavDecoder.cpp

@@ -188,11 +188,11 @@ int WavDecoder::LoadFromBuffer(AudioData * data, const std::vector<uint8_t> & me
     if (adpcmEncoded)
     {
         ADPCMState s;
-        s.nBlockAlign = wavHeader.frame_size;
+        s.frame_size = wavHeader.frame_size;
         s.firstDataBlockByte = 0;
         s.dataSize = DataChunkInfo.size;
         s.currentByte = 0;
-        s.currentDatablock = const_cast<uint8_t*>(memory.data() + DataChunkInfo.offset);
+        s.inBuffer = const_cast<uint8_t*>(memory.data() + DataChunkInfo.offset);
         
         // An encoded sample is 4 bits that expands to 16
         size_t totalSamples = factChunk.sample_length * 4;
@@ -200,13 +200,13 @@ int WavDecoder::LoadFromBuffer(AudioData * data, const std::vector<uint8_t> & me
         
         uint32_t frameOffset = 0;
         
-        unsigned numFrames = DataChunkInfo.size / s.nBlockAlign;
+        unsigned numFrames = DataChunkInfo.size / s.frame_size;
         
         for (int i = 0; i < numFrames; ++i)
         {
             decode_ima_adpcm(s, adpcm_pcm16.data() + frameOffset, wavHeader.channel_count);
-            s.currentDatablock += s.nBlockAlign;
-            frameOffset += (wavHeader.channel_count * s.nBlockAlign);
+            s.inBuffer += s.frame_size;
+            frameOffset += (wavHeader.channel_count * s.frame_size);
         }
         
         data->lengthSeconds = ((float) totalSamples / (float) wavHeader.sample_rate) / wavHeader.channel_count;