revert to original Cadence bit width 4 code

tensorflow/lite/micro/kernels/xtensa/decompress.cc

@@ -43,11 +43,14 @@ struct DecompressionStateXtensa : DecompressionState {
       : DecompressionState(other) {}
 
   void DecompressToBufferWidth4_Xtensa(int8_t* buffer);
+  void DecompressToBufferWidth4_Xtensa_Old(int8_t* buffer);
 
   template <size_t N>
   void DecompressToBufferWidthAny_Xtensa(int8_t* buffer);
 };
 
+// TODO(ddavis-2015): unaligned/stride code has error, method not currently
+// used.
 void DecompressionStateXtensa::DecompressToBufferWidth4_Xtensa(int8_t* buffer) {
   MicroProfiler* profiler =
       static_cast<MicroProfiler*>(micro_context_->external_context());
@@ -105,6 +108,48 @@ void DecompressionStateXtensa::DecompressToBufferWidth4_Xtensa(int8_t* buffer) {
   }
 }
 
+void DecompressionStateXtensa::DecompressToBufferWidth4_Xtensa_Old(
+    int8_t* buffer) {
+  MicroProfiler* profiler =
+      static_cast<MicroProfiler*>(micro_context_->external_context());
+  ScopedMicroProfiler scoped_profiler(__func__, profiler);
+
+  char shuffle_pattern_1[8] = {0x08, 0x19, 0x2A, 0x3B, 0x4C, 0x5D, 0x6E, 0x7F};
+  ae_int8x8 d_shuffle_t = *(ae_int8x8*)&shuffle_pattern_1[0];
+
+  char shuffle_pattern_2[8] = {0xFB, 0x73, 0xEA, 0x62, 0xD9, 0x51, 0xC8, 0x40};
+  ae_int8x8 d_d_shuffle_t2 = *(ae_int8x8*)&shuffle_pattern_2[0];
+
+  ae_int8x8 d_out1, d_out2;
+  ae_int8x8 d_value_0, d_value_1;
+  ae_int8x8 d_index;
+
+  int elements_per_channel_t = elements_per_channel_;
+  int num_channels_t = num_channels_;
+  ae_int8x8* __restrict pIn_tmp = (ae_int8x8*)compressed_indices_;
+  ae_int8* __restrict p_out_tmp = (ae_int8*)buffer;
+
+  const size_t stride = comp_data_.data.lut_data->value_table_channel_stride;
+  const uint8_t* __restrict value_table =
+      static_cast<const uint8_t*>(comp_data_.data.lut_data->value_table);
+
+  for (int i = 0; i < num_channels_t; i++) {
+    ae_int8x8 d_value_0_t = *(ae_int8x8*)&value_table[0];
+    ae_int8x8 d_value_1_t = *(ae_int8x8*)&value_table[8];
+
+    AE_DSEL8X8(d_value_0, d_value_1, d_value_0_t, d_value_1_t, d_shuffle_t);
+
+    for (int j = 0; j < elements_per_channel_t; j += 16) {
+      AE_L8X8_IP(d_index, pIn_tmp, 8);
+      AE_DSEL8X8(d_out1, d_out2, d_value_0, d_value_1, d_index);
+      AE_DSEL8X8(d_out1, d_out2, d_out1, d_out2, d_d_shuffle_t2);
+      AE_S8X8X2_IP(d_out1, d_out2, (ae_int8x16*)p_out_tmp, 16);
+    }
+
+    value_table += stride;
+  }
+}
+
 template <size_t N>
 void DecompressionStateXtensa::DecompressToBufferWidthAny_Xtensa(
     int8_t* buffer) {
@@ -163,7 +208,12 @@ T* DecompressionState::DecompressToBuffer(void* buffer) {
   if (std::is_same<T, int8_t>::value &&
       comp_data_.data.lut_data->compressed_bit_width == 4 &&
       !comp_data_.data.lut_data->use_alternate_axis) {
-    dsx.DecompressToBufferWidth4_Xtensa(static_cast<int8_t*>(buffer));
+    if (!(elements_per_channel_ & 0x0F) &&
+        comp_data_.data.lut_data->value_table_channel_stride == 16) {
+      dsx.DecompressToBufferWidth4_Xtensa_Old(static_cast<int8_t*>(buffer));
+    } else {
+      DecompressToBufferWidth4_16(static_cast<int8_t*>(buffer));
+    }
   } else if (std::is_same<T, int8_t>::value &&
              comp_data_.data.lut_data->compressed_bit_width == 3 &&
              !comp_data_.data.lut_data->use_alternate_axis) {