Sync from upstream TF.

Author: TFLM-bot

tensorflow/lite/kernels/internal/portable_tensor_utils.cc

@@ -18,6 +18,7 @@ limitations under the License.
 #include "tensorflow/lite/kernels/internal/portable_tensor_utils.h"
 
 #include <algorithm>
+#include <cassert>
 #include <cmath>
 #include <cstdint>
 
@@ -92,6 +93,56 @@ void UnpackDenseInt4IntoInt8(const int8_t* src_buffer, int num_elements,
   }
 }
 
+void UnpackPackedIntToInt8(const int8_t* src_buffer, int num_elements,
+                           int bit_width, int8_t* dst_buffer) {
+  assert(bit_width == 2 || bit_width == 4);
+  if (bit_width == 4) {
+    // num_elements means the number of elements regardless of packed or
+    // unpacked. For example, 3 elements means both
+    //   1) Packed: 3 int4's = 12 bit -> 16 bits (padded) = 2 bytes.
+    //      stored in src_buffer[0] and src_buffer[1] (i = 0..1)
+    //   2) Unpacked: 3 int8's = 3 bytes.
+    //.     stored in dst_buffer[0], dst_buffer[1] and dst_buffer[2] (j = 0..2)
+    for (int i = 0; i < num_elements / 2; i++) {
+      int8_t byte = src_buffer[i];
+      // Shift left first so that sign is properly extended when shifted right
+      int8_t lower = static_cast<int8_t>(byte << 4) >> 4;
+      int8_t higher = byte >> 4;
+      dst_buffer[2 * i] = lower;
+      dst_buffer[2 * i + 1] = higher;
+    }
+
+    // If the buffer size is odd, extract the final lower nibble.
+    if (num_elements % 2 != 0) {
+      dst_buffer[num_elements - 1] =
+          static_cast<int8_t>(src_buffer[num_elements / 2] << 4) >> 4;
+    }
+  } else if (bit_width == 2) {
+    for (int i = 0; i < num_elements / 4; i++) {
+      int8_t byte = src_buffer[i];
+      // Shift left first so that sign is properly extended when shifted right
+      int8_t val1 = static_cast<int8_t>(byte << 6) >> 6;
+      int8_t val2 = static_cast<int8_t>((byte << 4) & 0xFF) >> 6;
+      int8_t val3 = static_cast<int8_t>((byte << 2) & 0xFF) >> 6;
+      int8_t val4 = byte >> 6;
+      dst_buffer[4 * i] = val1;
+      dst_buffer[4 * i + 1] = val2;
+      dst_buffer[4 * i + 2] = val3;
+      dst_buffer[4 * i + 3] = val4;
+    }
+
+    // Handle the remaining elements.
+    int remaining_elements = num_elements % 4;
+    if (remaining_elements > 0) {
+      int8_t byte = src_buffer[num_elements / 4];
+      for (int i = 0; i < remaining_elements; i++) {
+        dst_buffer[num_elements - remaining_elements + i] =
+            static_cast<int8_t>((byte << (6 - 2 * i)) & 0xFF) >> 6;
+      }
+    }
+  }
+}
+
 void PackInt8IntoDenseInt4(const int8_t* src_buffer, int num_elements,
                            int8_t* dst_buffer) {
   // num_elements means the number of elements regardless of packed or unpacked.

tensorflow/lite/kernels/internal/portable_tensor_utils.h

@@ -618,6 +618,23 @@ void ApplySignbitToVector(const float* __restrict__ vector, int v_size,
 void UnpackDenseInt4IntoInt8(const int8_t* src_buffer, int num_elements,
                              int8_t* dst_buffer);
 
+// Unpack or inflate `src_buffer` by taking each byte and splitting it into
+// multiple elements into `dst_buffer`. Supports 2-bit and 4-bit packed integers
+// Parameters:
+//   src_buffer   : Densely packed buffer containing int2 or int4 values.
+//   num_elements : Number of unpacked elements to be read from the buffer.
+//                  This should be equal to the size of `dst_buffer`.
+//   bit_width    : The bit width of the packed elements (either 2 or 4).
+//   dst_buffer   : Buffer to unpack into. Should be allocated by the caller.
+//                  Size should be at least `num_elements`.
+// Notes:
+//   For 4-bit unpacking: e.g., `src_buffer = {0x12, 0x34};` (num_elements = 4)
+//   will return `dst_buffer = {0x02, 0x01, 0x04, 0x03}`.
+//   For 2-bit unpacking: e.g., `src_buffer = {0x12};` (num_elements = 4)
+//   will return `dst_buffer = {0x02, 0x00, 0x01, 0x00}` (sign extended).
+void UnpackPackedIntToInt8(const int8_t* src_buffer, int num_elements,
+                           int bit_width, int8_t* dst_buffer);
+
 // Pack `src_buffer` into a densely packed buffer of int4 values.
 // Parameters:
 //   src_buffer   : Buffer containing int4 values stored in int8 memory.

tensorflow/lite/tools/visualize.py

@@ -33,7 +33,7 @@
   from tflite_micro.tensorflow.lite.python import schema_py_generated as schema_fb
 else:
   # This file is part of tflite_runtime package.
-  from tflite_runtime import schema_py_generated as schema_fb
+  from tflite_micro.tensorflow.lite_runtime import schema_py_generated as schema_fb
 
 # A CSS description for making the visualizer
 _CSS = """