Add Streaming zipformer (#50)

@@ -33,8 +33,13 @@ jobs:
     strategy:
     strategy:
       fail-fast: false
       fail-fast: false
       matrix:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-latest] # windows-latest]
         python-version: ["3.7", "3.8", "3.9", "3.10"]
         python-version: ["3.7", "3.8", "3.9", "3.10"]
+        exclude:
+          - os: macos-latest
+            python-version: "3.9"
+          - os: macos-latest
+            python-version: "3.10"
 
 
     steps:
     steps:
       - uses: actions/checkout@v2
       - uses: actions/checkout@v2

@@ -8,3 +8,4 @@ sherpa-onnx-*
 __pycache__
 __pycache__
 dist/
 dist/
 sherpa_onnx.egg-info/
 sherpa_onnx.egg-info/
+.DS_Store

@@ -62,6 +62,7 @@ endif()
 
 
 if(SHERPA_ONNX_ENABLE_TESTS)
 if(SHERPA_ONNX_ENABLE_TESTS)
   enable_testing()
   enable_testing()
+  include(googletest)
 endif()
 endif()
 
 
 add_subdirectory(sherpa-onnx)
 add_subdirectory(sherpa-onnx)

-# Copyright     2020 Fangjun Kuang (csukuangfj@gmail.com)
-# See ../LICENSE for clarification regarding multiple authors
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
 function(download_googltest)
 function(download_googltest)
   include(FetchContent)
   include(FetchContent)
 
 
@@ -26,6 +11,7 @@ function(download_googltest)
     ${PROJECT_SOURCE_DIR}/googletest-1.13.0.tar.gz
     ${PROJECT_SOURCE_DIR}/googletest-1.13.0.tar.gz
     ${PROJECT_BINARY_DIR}/googletest-1.13.0.tar.gz
     ${PROJECT_BINARY_DIR}/googletest-1.13.0.tar.gz
     /tmp/googletest-1.13.0.tar.gz
     /tmp/googletest-1.13.0.tar.gz
+    /star-fj/fangjun/download/github/googletest-1.13.0.tar.gz
   )
   )
 
 
   foreach(f IN LISTS possible_file_locations)
   foreach(f IN LISTS possible_file_locations)

 include_directories(${CMAKE_SOURCE_DIR})
 include_directories(${CMAKE_SOURCE_DIR})
 
 
 add_library(sherpa-onnx-core
 add_library(sherpa-onnx-core
+  cat.cc
   features.cc
   features.cc
   online-lstm-transducer-model.cc
   online-lstm-transducer-model.cc
   online-recognizer.cc
   online-recognizer.cc
@@ -8,8 +9,11 @@ add_library(sherpa-onnx-core
   online-transducer-greedy-search-decoder.cc
   online-transducer-greedy-search-decoder.cc
   online-transducer-model-config.cc
   online-transducer-model-config.cc
   online-transducer-model.cc
   online-transducer-model.cc
+  online-zipformer-transducer-model.cc
   onnx-utils.cc
   onnx-utils.cc
   symbol-table.cc
   symbol-table.cc
+  text-utils.cc
+  unbind.cc
   wave-reader.cc
   wave-reader.cc
 )
 )
 
 
@@ -27,3 +31,32 @@ endif()
 
 
 install(TARGETS sherpa-onnx-core DESTINATION lib)
 install(TARGETS sherpa-onnx-core DESTINATION lib)
 install(TARGETS sherpa-onnx DESTINATION bin)
 install(TARGETS sherpa-onnx DESTINATION bin)
+
+if(SHERPA_ONNX_ENABLE_TESTS)
+  set(sherpa_onnx_test_srcs
+    cat-test.cc
+    unbind-test.cc
+  )
+
+  function(sherpa_onnx_add_test source)
+    get_filename_component(name ${source} NAME_WE)
+    set(target_name ${name})
+    add_executable(${target_name} "${source}")
+
+    target_link_libraries(${target_name}
+      PRIVATE
+        gtest
+        gtest_main
+        sherpa-onnx-core
+    )
+
+    add_test(NAME "${target_name}"
+      COMMAND
+        $<TARGET_FILE:${target_name}>
+    )
+  endfunction()
+
+  foreach(source IN LISTS sherpa_onnx_test_srcs)
+    sherpa_onnx_add_test(${source})
+  endforeach()
+endif()

+// sherpa-onnx/csrc/cat-test.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/cat.h"
+
+#include "gtest/gtest.h"
+#include "sherpa-onnx/csrc/onnx-utils.h"
+
+namespace sherpa_onnx {
+
+TEST(Cat, Test1DTensors) {
+  Ort::AllocatorWithDefaultOptions allocator;
+
+  std::array<int64_t, 1> a_shape{3};
+  std::array<int64_t, 1> b_shape{6};
+
+  Ort::Value a = Ort::Value::CreateTensor<float>(allocator, a_shape.data(),
+                                                 a_shape.size());
+
+  Ort::Value b = Ort::Value::CreateTensor<float>(allocator, b_shape.data(),
+                                                 b_shape.size());
+  float *pa = a.GetTensorMutableData<float>();
+  float *pb = b.GetTensorMutableData<float>();
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0]); ++i) {
+    pa[i] = i;
+  }
+  for (int32_t i = 0; i != static_cast<int32_t>(b_shape[0]); ++i) {
+    pb[i] = i + 10;
+  }
+
+  Ort::Value ans = Cat(allocator, {&a, &b}, 0);
+
+  const float *pans = ans.GetTensorData<float>();
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0]); ++i) {
+    EXPECT_EQ(pa[i], pans[i]);
+  }
+
+  for (int32_t i = 0; i != static_cast<int32_t>(b_shape[0]); ++i) {
+    EXPECT_EQ(pb[i], pans[i + a_shape[0]]);
+  }
+
+  Print1D(&a);
+  Print1D(&b);
+  Print1D(&ans);
+}
+
+TEST(Cat, Test2DTensorsDim0) {
+  Ort::AllocatorWithDefaultOptions allocator;
+
+  std::array<int64_t, 2> a_shape{2, 3};
+  std::array<int64_t, 2> b_shape{4, 3};
+
+  Ort::Value a = Ort::Value::CreateTensor<float>(allocator, a_shape.data(),
+                                                 a_shape.size());
+
+  Ort::Value b = Ort::Value::CreateTensor<float>(allocator, b_shape.data(),
+                                                 b_shape.size());
+
+  float *pa = a.GetTensorMutableData<float>();
+  float *pb = b.GetTensorMutableData<float>();
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0] * a_shape[1]); ++i) {
+    pa[i] = i;
+  }
+  for (int32_t i = 0; i != static_cast<int32_t>(b_shape[0] * b_shape[1]); ++i) {
+    pb[i] = i + 10;
+  }
+
+  Ort::Value ans = Cat(allocator, {&a, &b}, 0);
+
+  const float *pans = ans.GetTensorData<float>();
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0] * a_shape[1]); ++i) {
+    EXPECT_EQ(pa[i], pans[i]);
+  }
+  for (int32_t i = 0; i != static_cast<int32_t>(b_shape[0] * b_shape[1]); ++i) {
+    EXPECT_EQ(pb[i], pans[i + a_shape[0] * a_shape[1]]);
+  }
+
+  Print2D(&a);
+  Print2D(&b);
+  Print2D(&ans);
+}
+
+TEST(Cat, Test2DTensorsDim1) {
+  Ort::AllocatorWithDefaultOptions allocator;
+
+  std::array<int64_t, 2> a_shape{4, 3};
+  std::array<int64_t, 2> b_shape{4, 2};
+
+  Ort::Value a = Ort::Value::CreateTensor<float>(allocator, a_shape.data(),
+                                                 a_shape.size());
+
+  Ort::Value b = Ort::Value::CreateTensor<float>(allocator, b_shape.data(),
+                                                 b_shape.size());
+
+  float *pa = a.GetTensorMutableData<float>();
+  float *pb = b.GetTensorMutableData<float>();
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0] * a_shape[1]); ++i) {
+    pa[i] = i;
+  }
+  for (int32_t i = 0; i != static_cast<int32_t>(b_shape[0] * b_shape[1]); ++i) {
+    pb[i] = i + 10;
+  }
+
+  Ort::Value ans = Cat(allocator, {&a, &b}, 1);
+
+  const float *pans = ans.GetTensorData<float>();
+
+  for (int32_t r = 0; r != static_cast<int32_t>(a_shape[0]); ++r) {
+    for (int32_t i = 0; i != static_cast<int32_t>(a_shape[1]);
+         ++i, ++pa, ++pans) {
+      EXPECT_EQ(*pa, *pans);
+    }
+
+    for (int32_t i = 0; i != static_cast<int32_t>(b_shape[1]);
+         ++i, ++pb, ++pans) {
+      EXPECT_EQ(*pb, *pans);
+    }
+  }
+
+  Print2D(&a);
+  Print2D(&b);
+  Print2D(&ans);
+}
+
+TEST(Cat, Test3DTensorsDim0) {
+  Ort::AllocatorWithDefaultOptions allocator;
+
+  std::array<int64_t, 3> a_shape{2, 3, 2};
+  std::array<int64_t, 3> b_shape{4, 3, 2};
+
+  Ort::Value a = Ort::Value::CreateTensor<float>(allocator, a_shape.data(),
+                                                 a_shape.size());
+
+  Ort::Value b = Ort::Value::CreateTensor<float>(allocator, b_shape.data(),
+                                                 b_shape.size());
+
+  float *pa = a.GetTensorMutableData<float>();
+  float *pb = b.GetTensorMutableData<float>();
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(a_shape[0] * a_shape[1] * a_shape[2]); ++i) {
+    pa[i] = i;
+  }
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(b_shape[0] * b_shape[1] * b_shape[2]); ++i) {
+    pb[i] = i + 10;
+  }
+
+  Ort::Value ans = Cat(allocator, {&a, &b}, 0);
+
+  const float *pans = ans.GetTensorData<float>();
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(a_shape[0] * a_shape[1] * a_shape[2]); ++i) {
+    EXPECT_EQ(pa[i], pans[i]);
+  }
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(b_shape[0] * b_shape[1] * b_shape[2]); ++i) {
+    EXPECT_EQ(pb[i], pans[i + a_shape[0] * a_shape[1] * a_shape[2]]);
+  }
+
+  Print3D(&a);
+  Print3D(&b);
+  Print3D(&ans);
+}
+
+TEST(Cat, Test3DTensorsDim1) {
+  Ort::AllocatorWithDefaultOptions allocator;
+
+  std::array<int64_t, 3> a_shape{2, 2, 3};
+  std::array<int64_t, 3> b_shape{2, 4, 3};
+
+  Ort::Value a = Ort::Value::CreateTensor<float>(allocator, a_shape.data(),
+                                                 a_shape.size());
+
+  Ort::Value b = Ort::Value::CreateTensor<float>(allocator, b_shape.data(),
+                                                 b_shape.size());
+
+  float *pa = a.GetTensorMutableData<float>();
+  float *pb = b.GetTensorMutableData<float>();
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(a_shape[0] * a_shape[1] * a_shape[2]); ++i) {
+    pa[i] = i;
+  }
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(b_shape[0] * b_shape[1] * b_shape[2]); ++i) {
+    pb[i] = i + 10;
+  }
+
+  Ort::Value ans = Cat(allocator, {&a, &b}, 1);
+
+  const float *pans = ans.GetTensorData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0]); ++i) {
+    for (int32_t k = 0; k != static_cast<int32_t>(a_shape[1] * a_shape[2]);
+         ++k, ++pa, ++pans) {
+      EXPECT_EQ(*pa, *pans);
+    }
+
+    for (int32_t k = 0; k != static_cast<int32_t>(b_shape[1] * b_shape[2]);
+         ++k, ++pb, ++pans) {
+      EXPECT_EQ(*pb, *pans);
+    }
+  }
+
+  Print3D(&a);
+  Print3D(&b);
+  Print3D(&ans);
+}
+
+TEST(Cat, Test3DTensorsDim2) {
+  Ort::AllocatorWithDefaultOptions allocator;
+
+  std::array<int64_t, 3> a_shape{2, 3, 4};
+  std::array<int64_t, 3> b_shape{2, 3, 5};
+
+  Ort::Value a = Ort::Value::CreateTensor<float>(allocator, a_shape.data(),
+                                                 a_shape.size());
+
+  Ort::Value b = Ort::Value::CreateTensor<float>(allocator, b_shape.data(),
+                                                 b_shape.size());
+
+  float *pa = a.GetTensorMutableData<float>();
+  float *pb = b.GetTensorMutableData<float>();
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(a_shape[0] * a_shape[1] * a_shape[2]); ++i) {
+    pa[i] = i;
+  }
+  for (int32_t i = 0;
+       i != static_cast<int32_t>(b_shape[0] * b_shape[1] * b_shape[2]); ++i) {
+    pb[i] = i + 10;
+  }
+
+  Ort::Value ans = Cat(allocator, {&a, &b}, 2);
+
+  const float *pans = ans.GetTensorData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(a_shape[0] * a_shape[1]); ++i) {
+    for (int32_t k = 0; k != static_cast<int32_t>(a_shape[2]);
+         ++k, ++pa, ++pans) {
+      EXPECT_EQ(*pa, *pans);
+    }
+
+    for (int32_t k = 0; k != static_cast<int32_t>(b_shape[2]);
+         ++k, ++pb, ++pans) {
+      EXPECT_EQ(*pb, *pans);
+    }
+  }
+
+  Print3D(&a);
+  Print3D(&b);
+  Print3D(&ans);
+}
+
+}  // namespace sherpa_onnx

+// sherpa-onnx/csrc/cat.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/cat.h"
+
+#include <algorithm>
+#include <functional>
+#include <numeric>
+#include <utility>
+
+#include "sherpa-onnx/csrc/onnx-utils.h"
+
+namespace sherpa_onnx {
+
+static bool Compare(const std::vector<int64_t> &a,
+                    const std::vector<int64_t> &b, int32_t skip_dim) {
+  if (a.size() != b.size()) return false;
+
+  for (int32_t i = 0; i != static_cast<int32_t>(a.size()); ++i) {
+    if (i == skip_dim) continue;
+
+    if (a[i] != b[i]) return false;
+  }
+
+  return true;
+}
+
+static void PrintShape(const std::vector<int64_t> &a) {
+  for (auto i : a) {
+    fprintf(stderr, "%d ", static_cast<int32_t>(i));
+  }
+  fprintf(stderr, "\n");
+}
+
+template <typename T /*=float*/>
+Ort::Value Cat(OrtAllocator *allocator,
+               const std::vector<const Ort::Value *> &values, int32_t dim) {
+  if (values.size() == 1u) {
+    return Clone(values[0]);
+  }
+
+  std::vector<int64_t> v0_shape =
+      values[0]->GetTensorTypeAndShapeInfo().GetShape();
+
+  int64_t total_dim = v0_shape[dim];
+
+  for (int32_t i = 1; i != static_cast<int32_t>(values.size()); ++i) {
+    auto s = values[i]->GetTensorTypeAndShapeInfo().GetShape();
+    total_dim += s[dim];
+
+    bool ret = Compare(v0_shape, s, dim);
+    if (!ret) {
+      fprintf(stderr, "Incorrect shape in Cat !\n");
+
+      fprintf(stderr, "Shape for tensor 0: ");
+      PrintShape(v0_shape);
+
+      fprintf(stderr, "Shape for tensor %d: ", i);
+      PrintShape(s);
+
+      exit(-1);
+    }
+  }
+
+  std::vector<int64_t> ans_shape;
+  ans_shape.reserve(v0_shape.size());
+  ans_shape.insert(ans_shape.end(), v0_shape.data(), v0_shape.data() + dim);
+  ans_shape.push_back(total_dim);
+  ans_shape.insert(ans_shape.end(), v0_shape.data() + dim + 1,
+                   v0_shape.data() + v0_shape.size());
+
+  auto leading_size = static_cast<int32_t>(std::accumulate(
+      v0_shape.begin(), v0_shape.begin() + dim, 1, std::multiplies<int64_t>()));
+
+  auto trailing_size = static_cast<int32_t>(
+      std::accumulate(v0_shape.begin() + dim + 1, v0_shape.end(), 1,
+                      std::multiplies<int64_t>()));
+
+  Ort::Value ans = Ort::Value::CreateTensor<T>(allocator, ans_shape.data(),
+                                               ans_shape.size());
+  T *dst = ans.GetTensorMutableData<T>();
+
+  for (int32_t i = 0; i != leading_size; ++i) {
+    for (int32_t n = 0; n != static_cast<int32_t>(values.size()); ++n) {
+      auto this_dim = values[n]->GetTensorTypeAndShapeInfo().GetShape()[dim];
+      const T *src = values[n]->GetTensorData<T>();
+      src += i * this_dim * trailing_size;
+
+      std::copy(src, src + this_dim * trailing_size, dst);
+      dst += this_dim * trailing_size;
+    }
+  }
+
+  return std::move(ans);
+}
+
+template Ort::Value Cat<float>(OrtAllocator *allocator,
+                               const std::vector<const Ort::Value *> &values,
+                               int32_t dim);
+
+template Ort::Value Cat<int64_t>(OrtAllocator *allocator,
+                                 const std::vector<const Ort::Value *> &values,
+                                 int32_t dim);
+
+}  // namespace sherpa_onnx

+// sherpa-onnx/csrc/cat.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_CAT_H_
+#define SHERPA_ONNX_CSRC_CAT_H_
+
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+
+namespace sherpa_onnx {
+
+/** Cat a list of tensors along the given dim.
+ *
+ * @param allocator Allocator to allocate space for the returned tensor
+ * @param values  Pointer to a list of tensors. The shape of the tensor must
+ *                be the same except on the dim to be concatenated.
+ * @param dim  The dim along which to concatenate the input tensors
+ *
+ * @return Return the concatenated tensor
+ */
+template <typename T = float>
+Ort::Value Cat(OrtAllocator *allocator,
+               const std::vector<const Ort::Value *> &values, int32_t dim);
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_CAT_H_

+
+// sherpa-onnx/csrc/macros.h
+//
+// Copyright      2023  Xiaomi Corporation
+
+#ifndef SHERPA_ONNX_CSRC_MACROS_H_
+#define SHERPA_ONNX_CSRC_MACROS_H_
+
+#define SHERPA_ONNX_READ_META_DATA(dst, src_key)                        \
+  do {                                                                  \
+    auto value =                                                        \
+        meta_data.LookupCustomMetadataMapAllocated(src_key, allocator); \
+    if (!value) {                                                       \
+      fprintf(stderr, "%s does not exist in the metadata\n", src_key);  \
+      exit(-1);                                                         \
+    }                                                                   \
+                                                                        \
+    dst = atoi(value.get());                                            \
+    if (dst <= 0) {                                                     \
+      fprintf(stderr, "Invalid value %d for %s\n", dst, src_key);       \
+      exit(-1);                                                         \
+    }                                                                   \
+  } while (0)
+
+#define SHERPA_ONNX_READ_META_DATA_VEC(dst, src_key)                      \
+  do {                                                                    \
+    auto value =                                                          \
+        meta_data.LookupCustomMetadataMapAllocated(src_key, allocator);   \
+    if (!value) {                                                         \
+      fprintf(stderr, "%s does not exist in the metadata\n", src_key);    \
+      exit(-1);                                                           \
+    }                                                                     \
+                                                                          \
+    bool ret = SplitStringToIntegers(value.get(), ",", true, &dst);       \
+    if (!ret) {                                                           \
+      fprintf(stderr, "Invalid value %s for %s\n", value.get(), src_key); \
+      exit(-1);                                                           \
+    }                                                                     \
+  } while (0)
+
+#endif  // SHERPA_ONNX_CSRC_MACROS_H_

@@ -3,6 +3,8 @@
 // Copyright (c)  2023  Xiaomi Corporation
 // Copyright (c)  2023  Xiaomi Corporation
 #include "sherpa-onnx/csrc/online-lstm-transducer-model.h"
 #include "sherpa-onnx/csrc/online-lstm-transducer-model.h"
 
 
+#include <assert.h>
+
 #include <algorithm>
 #include <algorithm>
 #include <memory>
 #include <memory>
 #include <sstream>
 #include <sstream>
@@ -11,23 +13,11 @@
 #include <vector>
 #include <vector>
 
 
 #include "onnxruntime_cxx_api.h"  // NOLINT
 #include "onnxruntime_cxx_api.h"  // NOLINT
+#include "sherpa-onnx/csrc/cat.h"
+#include "sherpa-onnx/csrc/macros.h"
 #include "sherpa-onnx/csrc/online-transducer-decoder.h"
 #include "sherpa-onnx/csrc/online-transducer-decoder.h"
 #include "sherpa-onnx/csrc/onnx-utils.h"
 #include "sherpa-onnx/csrc/onnx-utils.h"
-
-#define SHERPA_ONNX_READ_META_DATA(dst, src_key)                        \
-  do {                                                                  \
-    auto value =                                                        \
-        meta_data.LookupCustomMetadataMapAllocated(src_key, allocator); \
-    if (!value) {                                                       \
-      fprintf(stderr, "%s does not exist in the metadata\n", src_key);  \
-      exit(-1);                                                         \
-    }                                                                   \
-    dst = atoi(value.get());                                            \
-    if (dst <= 0) {                                                     \
-      fprintf(stderr, "Invalud value %d for %s\n", dst, src_key);       \
-      exit(-1);                                                         \
-    }                                                                   \
-  } while (0)
+#include "sherpa-onnx/csrc/unbind.h"
 
 
 namespace sherpa_onnx {
 namespace sherpa_onnx {
 
 
@@ -64,7 +54,7 @@ void OnlineLstmTransducerModel::InitEncoder(const std::string &filename) {
     fprintf(stderr, "%s\n", os.str().c_str());
     fprintf(stderr, "%s\n", os.str().c_str());
   }
   }
 
 
-  Ort::AllocatorWithDefaultOptions allocator;
+  Ort::AllocatorWithDefaultOptions allocator;  // used in the macro below
   SHERPA_ONNX_READ_META_DATA(num_encoder_layers_, "num_encoder_layers");
   SHERPA_ONNX_READ_META_DATA(num_encoder_layers_, "num_encoder_layers");
   SHERPA_ONNX_READ_META_DATA(T_, "T");
   SHERPA_ONNX_READ_META_DATA(T_, "T");
   SHERPA_ONNX_READ_META_DATA(decode_chunk_len_, "decode_chunk_len");
   SHERPA_ONNX_READ_META_DATA(decode_chunk_len_, "decode_chunk_len");
@@ -91,7 +81,7 @@ void OnlineLstmTransducerModel::InitDecoder(const std::string &filename) {
     fprintf(stderr, "%s\n", os.str().c_str());
     fprintf(stderr, "%s\n", os.str().c_str());
   }
   }
 
 
-  Ort::AllocatorWithDefaultOptions allocator;
+  Ort::AllocatorWithDefaultOptions allocator;  // used in the macro below
   SHERPA_ONNX_READ_META_DATA(vocab_size_, "vocab_size");
   SHERPA_ONNX_READ_META_DATA(vocab_size_, "vocab_size");
   SHERPA_ONNX_READ_META_DATA(context_size_, "context_size");
   SHERPA_ONNX_READ_META_DATA(context_size_, "context_size");
 }
 }
@@ -120,37 +110,19 @@ std::vector<Ort::Value> OnlineLstmTransducerModel::StackStates(
     const std::vector<std::vector<Ort::Value>> &states) const {
     const std::vector<std::vector<Ort::Value>> &states) const {
   int32_t batch_size = static_cast<int32_t>(states.size());
   int32_t batch_size = static_cast<int32_t>(states.size());
 
 
-  std::array<int64_t, 3> h_shape{num_encoder_layers_, batch_size, d_model_};
-  Ort::Value h = Ort::Value::CreateTensor<float>(allocator_, h_shape.data(),
-                                                 h_shape.size());
-
-  std::array<int64_t, 3> c_shape{num_encoder_layers_, batch_size,
-                                 rnn_hidden_size_};
-
-  Ort::Value c = Ort::Value::CreateTensor<float>(allocator_, c_shape.data(),
-                                                 c_shape.size());
-
-  float *dst_h = h.GetTensorMutableData<float>();
-  float *dst_c = c.GetTensorMutableData<float>();
+  std::vector<const Ort::Value *> h_buf(batch_size);
+  std::vector<const Ort::Value *> c_buf(batch_size);
 
 
-  for (int32_t layer = 0; layer != num_encoder_layers_; ++layer) {
-    for (int32_t i = 0; i != batch_size; ++i) {
-      const float *src_h =
-          states[i][0].GetTensorData<float>() + layer * d_model_;
-
-      const float *src_c =
-          states[i][1].GetTensorData<float>() + layer * rnn_hidden_size_;
-
-      std::copy(src_h, src_h + d_model_, dst_h);
-      std::copy(src_c, src_c + rnn_hidden_size_, dst_c);
-
-      dst_h += d_model_;
-      dst_c += rnn_hidden_size_;
-    }
+  for (int32_t i = 0; i != batch_size; ++i) {
+    assert(states[i].size() == 2);
+    h_buf[i] = &states[i][0];
+    c_buf[i] = &states[i][1];
   }
   }
 
 
-  std::vector<Ort::Value> ans;
+  Ort::Value h = Cat(allocator_, h_buf, 1);
+  Ort::Value c = Cat(allocator_, c_buf, 1);
 
 
+  std::vector<Ort::Value> ans;
   ans.reserve(2);
   ans.reserve(2);
   ans.push_back(std::move(h));
   ans.push_back(std::move(h));
   ans.push_back(std::move(c));
   ans.push_back(std::move(c));
@@ -161,37 +133,19 @@ std::vector<Ort::Value> OnlineLstmTransducerModel::StackStates(
 std::vector<std::vector<Ort::Value>> OnlineLstmTransducerModel::UnStackStates(
 std::vector<std::vector<Ort::Value>> OnlineLstmTransducerModel::UnStackStates(
     const std::vector<Ort::Value> &states) const {
     const std::vector<Ort::Value> &states) const {
   int32_t batch_size = states[0].GetTensorTypeAndShapeInfo().GetShape()[1];
   int32_t batch_size = states[0].GetTensorTypeAndShapeInfo().GetShape()[1];
+  assert(states.size() == 2);
 
 
   std::vector<std::vector<Ort::Value>> ans(batch_size);
   std::vector<std::vector<Ort::Value>> ans(batch_size);
 
 
-  // allocate space
-  std::array<int64_t, 3> h_shape{num_encoder_layers_, 1, d_model_};
-  std::array<int64_t, 3> c_shape{num_encoder_layers_, 1, rnn_hidden_size_};
+  std::vector<Ort::Value> h_vec = Unbind(allocator_, &states[0], 1);
+  std::vector<Ort::Value> c_vec = Unbind(allocator_, &states[1], 1);
 
 
-  for (int32_t i = 0; i != batch_size; ++i) {
-    Ort::Value h = Ort::Value::CreateTensor<float>(allocator_, h_shape.data(),
-                                                   h_shape.size());
-    Ort::Value c = Ort::Value::CreateTensor<float>(allocator_, c_shape.data(),
-                                                   c_shape.size());
-    ans[i].push_back(std::move(h));
-    ans[i].push_back(std::move(c));
-  }
+  assert(h_vec.size() == batch_size);
+  assert(c_vec.size() == batch_size);
 
 
-  for (int32_t layer = 0; layer != num_encoder_layers_; ++layer) {
-    for (int32_t i = 0; i != batch_size; ++i) {
-      const float *src_h = states[0].GetTensorData<float>() +
-                           layer * batch_size * d_model_ + i * d_model_;
-      const float *src_c = states[1].GetTensorData<float>() +
-                           layer * batch_size * rnn_hidden_size_ +
-                           i * rnn_hidden_size_;
-
-      float *dst_h = ans[i][0].GetTensorMutableData<float>() + layer * d_model_;
-      float *dst_c =
-          ans[i][1].GetTensorMutableData<float>() + layer * rnn_hidden_size_;
-
-      std::copy(src_h, src_h + d_model_, dst_h);
-      std::copy(src_c, src_c + rnn_hidden_size_, dst_c);
-    }
+  for (int32_t i = 0; i != batch_size; ++i) {
+    ans[i].push_back(std::move(h_vec[i]));
+    ans[i].push_back(std::move(c_vec[i]));
   }
   }
 
 
   return ans;
   return ans;
@@ -206,20 +160,15 @@ std::vector<Ort::Value> OnlineLstmTransducerModel::GetEncoderInitStates() {
   Ort::Value h = Ort::Value::CreateTensor<float>(allocator_, h_shape.data(),
   Ort::Value h = Ort::Value::CreateTensor<float>(allocator_, h_shape.data(),
                                                  h_shape.size());
                                                  h_shape.size());
 
 
-  std::fill(h.GetTensorMutableData<float>(),
-            h.GetTensorMutableData<float>() +
-                num_encoder_layers_ * kBatchSize * d_model_,
-            0);
+  Fill<float>(&h, 0);
 
 
   std::array<int64_t, 3> c_shape{num_encoder_layers_, kBatchSize,
   std::array<int64_t, 3> c_shape{num_encoder_layers_, kBatchSize,
                                  rnn_hidden_size_};
                                  rnn_hidden_size_};
+
   Ort::Value c = Ort::Value::CreateTensor<float>(allocator_, c_shape.data(),
   Ort::Value c = Ort::Value::CreateTensor<float>(allocator_, c_shape.data(),
                                                  c_shape.size());
                                                  c_shape.size());
 
 
-  std::fill(c.GetTensorMutableData<float>(),
-            c.GetTensorMutableData<float>() +
-                num_encoder_layers_ * kBatchSize * rnn_hidden_size_,
-            0);
+  Fill<float>(&c, 0);
 
 
   std::vector<Ort::Value> states;
   std::vector<Ort::Value> states;
 
 

@@ -8,11 +8,13 @@
 #include <string>
 #include <string>
 
 
 #include "sherpa-onnx/csrc/online-lstm-transducer-model.h"
 #include "sherpa-onnx/csrc/online-lstm-transducer-model.h"
+#include "sherpa-onnx/csrc/online-zipformer-transducer-model.h"
 #include "sherpa-onnx/csrc/onnx-utils.h"
 #include "sherpa-onnx/csrc/onnx-utils.h"
 namespace sherpa_onnx {
 namespace sherpa_onnx {
 
 
 enum class ModelType {
 enum class ModelType {
   kLstm,
   kLstm,
+  kZipformer,
   kUnkown,
   kUnkown,
 };
 };
 
 
@@ -40,6 +42,8 @@ static ModelType GetModelType(const OnlineTransducerModelConfig &config) {
 
 
   if (model_type.get() == std::string("lstm")) {
   if (model_type.get() == std::string("lstm")) {
     return ModelType::kLstm;
     return ModelType::kLstm;
+  } else if (model_type.get() == std::string("zipformer")) {
+    return ModelType::kZipformer;
   } else {
   } else {
     fprintf(stderr, "Unsupported model_type: %s\n", model_type.get());
     fprintf(stderr, "Unsupported model_type: %s\n", model_type.get());
     return ModelType::kUnkown;
     return ModelType::kUnkown;
@@ -53,6 +57,8 @@ std::unique_ptr<OnlineTransducerModel> OnlineTransducerModel::Create(
   switch (model_type) {
   switch (model_type) {
     case ModelType::kLstm:
     case ModelType::kLstm:
       return std::make_unique<OnlineLstmTransducerModel>(config);
       return std::make_unique<OnlineLstmTransducerModel>(config);
+    case ModelType::kZipformer:
+      return std::make_unique<OnlineZipformerTransducerModel>(config);
     case ModelType::kUnkown:
     case ModelType::kUnkown:
       return nullptr;
       return nullptr;
   }
   }

+// sherpa-onnx/csrc/online-zipformer-transducer-model.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/online-zipformer-transducer-model.h"
+
+#include <assert.h>
+
+#include <algorithm>
+#include <memory>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+#include "sherpa-onnx/csrc/cat.h"
+#include "sherpa-onnx/csrc/macros.h"
+#include "sherpa-onnx/csrc/online-transducer-decoder.h"
+#include "sherpa-onnx/csrc/onnx-utils.h"
+#include "sherpa-onnx/csrc/text-utils.h"
+#include "sherpa-onnx/csrc/unbind.h"
+
+namespace sherpa_onnx {
+
+OnlineZipformerTransducerModel::OnlineZipformerTransducerModel(
+    const OnlineTransducerModelConfig &config)
+    : env_(ORT_LOGGING_LEVEL_WARNING),
+      config_(config),
+      sess_opts_{},
+      allocator_{} {
+  sess_opts_.SetIntraOpNumThreads(config.num_threads);
+  sess_opts_.SetInterOpNumThreads(config.num_threads);
+
+  InitEncoder(config.encoder_filename);
+  InitDecoder(config.decoder_filename);
+  InitJoiner(config.joiner_filename);
+}
+
+void OnlineZipformerTransducerModel::InitEncoder(const std::string &filename) {
+  encoder_sess_ = std::make_unique<Ort::Session>(
+      env_, SHERPA_MAYBE_WIDE(filename).c_str(), sess_opts_);
+
+  GetInputNames(encoder_sess_.get(), &encoder_input_names_,
+                &encoder_input_names_ptr_);
+
+  GetOutputNames(encoder_sess_.get(), &encoder_output_names_,
+                 &encoder_output_names_ptr_);
+
+  // get meta data
+  Ort::ModelMetadata meta_data = encoder_sess_->GetModelMetadata();
+  if (config_.debug) {
+    std::ostringstream os;
+    os << "---encoder---\n";
+    PrintModelMetadata(os, meta_data);
+    fprintf(stderr, "%s\n", os.str().c_str());
+  }
+
+  Ort::AllocatorWithDefaultOptions allocator;  // used in the macro below
+  SHERPA_ONNX_READ_META_DATA_VEC(encoder_dims_, "encoder_dims");
+  SHERPA_ONNX_READ_META_DATA_VEC(attention_dims_, "attention_dims");
+  SHERPA_ONNX_READ_META_DATA_VEC(num_encoder_layers_, "num_encoder_layers");
+  SHERPA_ONNX_READ_META_DATA_VEC(cnn_module_kernels_, "cnn_module_kernels");
+  SHERPA_ONNX_READ_META_DATA_VEC(left_context_len_, "left_context_len");
+
+  SHERPA_ONNX_READ_META_DATA(T_, "T");
+  SHERPA_ONNX_READ_META_DATA(decode_chunk_len_, "decode_chunk_len");
+
+  if (config_.debug) {
+    auto print = [](const std::vector<int32_t> &v, const char *name) {
+      fprintf(stderr, "%s: ", name);
+      for (auto i : v) {
+        fprintf(stderr, "%d ", i);
+      }
+      fprintf(stderr, "\n");
+    };
+    print(encoder_dims_, "encoder_dims");
+    print(attention_dims_, "attention_dims");
+    print(num_encoder_layers_, "num_encoder_layers");
+    print(cnn_module_kernels_, "cnn_module_kernels");
+    print(left_context_len_, "left_context_len");
+    fprintf(stderr, "T: %d\n", T_);
+    fprintf(stderr, "decode_chunk_len_: %d\n", decode_chunk_len_);
+  }
+}
+
+void OnlineZipformerTransducerModel::InitDecoder(const std::string &filename) {
+  decoder_sess_ = std::make_unique<Ort::Session>(
+      env_, SHERPA_MAYBE_WIDE(filename).c_str(), sess_opts_);
+
+  GetInputNames(decoder_sess_.get(), &decoder_input_names_,
+                &decoder_input_names_ptr_);
+
+  GetOutputNames(decoder_sess_.get(), &decoder_output_names_,
+                 &decoder_output_names_ptr_);
+
+  // get meta data
+  Ort::ModelMetadata meta_data = decoder_sess_->GetModelMetadata();
+  if (config_.debug) {
+    std::ostringstream os;
+    os << "---decoder---\n";
+    PrintModelMetadata(os, meta_data);
+    fprintf(stderr, "%s\n", os.str().c_str());
+  }
+
+  Ort::AllocatorWithDefaultOptions allocator;  // used in the macro below
+  SHERPA_ONNX_READ_META_DATA(vocab_size_, "vocab_size");
+  SHERPA_ONNX_READ_META_DATA(context_size_, "context_size");
+}
+
+void OnlineZipformerTransducerModel::InitJoiner(const std::string &filename) {
+  joiner_sess_ = std::make_unique<Ort::Session>(
+      env_, SHERPA_MAYBE_WIDE(filename).c_str(), sess_opts_);
+
+  GetInputNames(joiner_sess_.get(), &joiner_input_names_,
+                &joiner_input_names_ptr_);
+
+  GetOutputNames(joiner_sess_.get(), &joiner_output_names_,
+                 &joiner_output_names_ptr_);
+
+  // get meta data
+  Ort::ModelMetadata meta_data = joiner_sess_->GetModelMetadata();
+  if (config_.debug) {
+    std::ostringstream os;
+    os << "---joiner---\n";
+    PrintModelMetadata(os, meta_data);
+    fprintf(stderr, "%s\n", os.str().c_str());
+  }
+}
+
+std::vector<Ort::Value> OnlineZipformerTransducerModel::StackStates(
+    const std::vector<std::vector<Ort::Value>> &states) const {
+  int32_t batch_size = static_cast<int32_t>(states.size());
+  int32_t num_encoders = static_cast<int32_t>(num_encoder_layers_.size());
+
+  std::vector<const Ort::Value *> buf(batch_size);
+
+  std::vector<Ort::Value> ans;
+  ans.reserve(states[0].size());
+
+  // cached_len
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][i];
+    }
+    auto v = Cat<int64_t>(allocator_, buf, 1);  // (num_layers, 1)
+    ans.push_back(std::move(v));
+  }
+
+  // cached_avg
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][num_encoders + i];
+    }
+    auto v = Cat(allocator_, buf, 1);  // (num_layers, 1, encoder_dims)
+    ans.push_back(std::move(v));
+  }
+
+  // cached_key
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][num_encoders * 2 + i];
+    }
+    // (num_layers, left_context_len, 1, attention_dims)
+    auto v = Cat(allocator_, buf, 2);
+    ans.push_back(std::move(v));
+  }
+
+  // cached_val
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][num_encoders * 3 + i];
+    }
+    // (num_layers, left_context_len, 1, attention_dims/2)
+    auto v = Cat(allocator_, buf, 2);
+    ans.push_back(std::move(v));
+  }
+
+  // cached_val2
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][num_encoders * 4 + i];
+    }
+    // (num_layers, left_context_len, 1, attention_dims/2)
+    auto v = Cat(allocator_, buf, 2);
+    ans.push_back(std::move(v));
+  }
+
+  // cached_conv1
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][num_encoders * 5 + i];
+    }
+    // (num_layers, 1, encoder_dims, cnn_module_kernels-1)
+    auto v = Cat(allocator_, buf, 1);
+    ans.push_back(std::move(v));
+  }
+
+  // cached_conv2
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    for (int32_t n = 0; n != batch_size; ++n) {
+      buf[n] = &states[n][num_encoders * 6 + i];
+    }
+    // (num_layers, 1, encoder_dims, cnn_module_kernels-1)
+    auto v = Cat(allocator_, buf, 1);
+    ans.push_back(std::move(v));
+  }
+
+  return ans;
+}
+
+std::vector<std::vector<Ort::Value>>
+OnlineZipformerTransducerModel::UnStackStates(
+    const std::vector<Ort::Value> &states) const {
+  assert(states.size() == num_encoder_layers_.size() * 7);
+
+  int32_t batch_size = states[0].GetTensorTypeAndShapeInfo().GetShape()[1];
+  int32_t num_encoders = num_encoder_layers_.size();
+
+  std::vector<std::vector<Ort::Value>> ans;
+  ans.resize(batch_size);
+
+  // cached_len
+  for (int32_t i = 0; i != num_encoders; ++i) {
+    auto v = Unbind<int64_t>(allocator_, &states[i], 1);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  // cached_avg
+  for (int32_t i = num_encoders; i != 2 * num_encoders; ++i) {
+    auto v = Unbind(allocator_, &states[i], 1);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  // cached_key
+  for (int32_t i = 2 * num_encoders; i != 3 * num_encoders; ++i) {
+    auto v = Unbind(allocator_, &states[i], 2);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  // cached_val
+  for (int32_t i = 3 * num_encoders; i != 4 * num_encoders; ++i) {
+    auto v = Unbind(allocator_, &states[i], 2);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  // cached_val2
+  for (int32_t i = 4 * num_encoders; i != 5 * num_encoders; ++i) {
+    auto v = Unbind(allocator_, &states[i], 2);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  // cached_conv1
+  for (int32_t i = 5 * num_encoders; i != 6 * num_encoders; ++i) {
+    auto v = Unbind(allocator_, &states[i], 1);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  // cached_conv2
+  for (int32_t i = 6 * num_encoders; i != 7 * num_encoders; ++i) {
+    auto v = Unbind(allocator_, &states[i], 1);
+    assert(v.size() == batch_size);
+
+    for (int32_t n = 0; n != batch_size; ++n) {
+      ans[n].push_back(std::move(v[n]));
+    }
+  }
+
+  return ans;
+}
+
+std::vector<Ort::Value> OnlineZipformerTransducerModel::GetEncoderInitStates() {
+  // Please see
+  // https://github.com/k2-fsa/icefall/blob/master/egs/librispeech/ASR/pruned_transducer_stateless7_streaming/zipformer.py#L673
+  // for details
+
+  int32_t n = static_cast<int32_t>(encoder_dims_.size());
+  std::vector<Ort::Value> cached_len_vec;
+  std::vector<Ort::Value> cached_avg_vec;
+  std::vector<Ort::Value> cached_key_vec;
+  std::vector<Ort::Value> cached_val_vec;
+  std::vector<Ort::Value> cached_val2_vec;
+  std::vector<Ort::Value> cached_conv1_vec;
+  std::vector<Ort::Value> cached_conv2_vec;
+
+  cached_len_vec.reserve(n);
+  cached_avg_vec.reserve(n);
+  cached_key_vec.reserve(n);
+  cached_val_vec.reserve(n);
+  cached_val2_vec.reserve(n);
+  cached_conv1_vec.reserve(n);
+  cached_conv2_vec.reserve(n);
+
+  for (int32_t i = 0; i != n; ++i) {
+    {
+      std::array<int64_t, 2> s{num_encoder_layers_[i], 1};
+      auto v =
+          Ort::Value::CreateTensor<int64_t>(allocator_, s.data(), s.size());
+      Fill<int64_t>(&v, 0);
+      cached_len_vec.push_back(std::move(v));
+    }
+
+    {
+      std::array<int64_t, 3> s{num_encoder_layers_[i], 1, encoder_dims_[i]};
+      auto v = Ort::Value::CreateTensor<float>(allocator_, s.data(), s.size());
+      Fill(&v, 0);
+      cached_avg_vec.push_back(std::move(v));
+    }
+
+    {
+      std::array<int64_t, 4> s{num_encoder_layers_[i], left_context_len_[i], 1,
+                               attention_dims_[i]};
+      auto v = Ort::Value::CreateTensor<float>(allocator_, s.data(), s.size());
+      Fill(&v, 0);
+      cached_key_vec.push_back(std::move(v));
+    }
+
+    {
+      std::array<int64_t, 4> s{num_encoder_layers_[i], left_context_len_[i], 1,
+                               attention_dims_[i] / 2};
+      auto v = Ort::Value::CreateTensor<float>(allocator_, s.data(), s.size());
+      Fill(&v, 0);
+      cached_val_vec.push_back(std::move(v));
+    }
+
+    {
+      std::array<int64_t, 4> s{num_encoder_layers_[i], left_context_len_[i], 1,
+                               attention_dims_[i] / 2};
+      auto v = Ort::Value::CreateTensor<float>(allocator_, s.data(), s.size());
+      Fill(&v, 0);
+      cached_val2_vec.push_back(std::move(v));
+    }
+
+    {
+      std::array<int64_t, 4> s{num_encoder_layers_[i], 1, encoder_dims_[i],
+                               cnn_module_kernels_[i] - 1};
+      auto v = Ort::Value::CreateTensor<float>(allocator_, s.data(), s.size());
+      Fill(&v, 0);
+      cached_conv1_vec.push_back(std::move(v));
+    }
+
+    {
+      std::array<int64_t, 4> s{num_encoder_layers_[i], 1, encoder_dims_[i],
+                               cnn_module_kernels_[i] - 1};
+      auto v = Ort::Value::CreateTensor<float>(allocator_, s.data(), s.size());
+      Fill(&v, 0);
+      cached_conv2_vec.push_back(std::move(v));
+    }
+  }
+
+  std::vector<Ort::Value> ans;
+  ans.reserve(n * 7);
+
+  for (auto &v : cached_len_vec) ans.push_back(std::move(v));
+  for (auto &v : cached_avg_vec) ans.push_back(std::move(v));
+  for (auto &v : cached_key_vec) ans.push_back(std::move(v));
+  for (auto &v : cached_val_vec) ans.push_back(std::move(v));
+  for (auto &v : cached_val2_vec) ans.push_back(std::move(v));
+  for (auto &v : cached_conv1_vec) ans.push_back(std::move(v));
+  for (auto &v : cached_conv2_vec) ans.push_back(std::move(v));
+
+  return ans;
+}
+
+std::pair<Ort::Value, std::vector<Ort::Value>>
+OnlineZipformerTransducerModel::RunEncoder(Ort::Value features,
+                                           std::vector<Ort::Value> states) {
+  auto memory_info =
+      Ort::MemoryInfo::CreateCpu(OrtDeviceAllocator, OrtMemTypeDefault);
+
+  std::vector<Ort::Value> encoder_inputs;
+  encoder_inputs.reserve(1 + states.size());
+
+  encoder_inputs.push_back(std::move(features));
+  for (auto &v : states) {
+    encoder_inputs.push_back(std::move(v));
+  }
+
+  auto encoder_out = encoder_sess_->Run(
+      {}, encoder_input_names_ptr_.data(), encoder_inputs.data(),
+      encoder_inputs.size(), encoder_output_names_ptr_.data(),
+      encoder_output_names_ptr_.size());
+
+  std::vector<Ort::Value> next_states;
+  next_states.reserve(states.size());
+
+  for (int32_t i = 1; i != static_cast<int32_t>(encoder_out.size()); ++i) {
+    next_states.push_back(std::move(encoder_out[i]));
+  }
+
+  return {std::move(encoder_out[0]), std::move(next_states)};
+}
+
+Ort::Value OnlineZipformerTransducerModel::BuildDecoderInput(
+    const std::vector<OnlineTransducerDecoderResult> &results) {
+  int32_t batch_size = static_cast<int32_t>(results.size());
+  std::array<int64_t, 2> shape{batch_size, context_size_};
+  Ort::Value decoder_input =
+      Ort::Value::CreateTensor<int64_t>(allocator_, shape.data(), shape.size());
+  int64_t *p = decoder_input.GetTensorMutableData<int64_t>();
+
+  for (const auto &r : results) {
+    const int64_t *begin = r.tokens.data() + r.tokens.size() - context_size_;
+    const int64_t *end = r.tokens.data() + r.tokens.size();
+    std::copy(begin, end, p);
+    p += context_size_;
+  }
+
+  return decoder_input;
+}
+
+Ort::Value OnlineZipformerTransducerModel::RunDecoder(
+    Ort::Value decoder_input) {
+  auto decoder_out = decoder_sess_->Run(
+      {}, decoder_input_names_ptr_.data(), &decoder_input, 1,
+      decoder_output_names_ptr_.data(), decoder_output_names_ptr_.size());
+  return std::move(decoder_out[0]);
+}
+
+Ort::Value OnlineZipformerTransducerModel::RunJoiner(Ort::Value encoder_out,
+                                                     Ort::Value decoder_out) {
+  std::array<Ort::Value, 2> joiner_input = {std::move(encoder_out),
+                                            std::move(decoder_out)};
+  auto logit =
+      joiner_sess_->Run({}, joiner_input_names_ptr_.data(), joiner_input.data(),
+                        joiner_input.size(), joiner_output_names_ptr_.data(),
+                        joiner_output_names_ptr_.size());
+
+  return std::move(logit[0]);
+}
+
+}  // namespace sherpa_onnx

+// sherpa-onnx/csrc/online-zipformer-transducer-model.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_ONLINE_ZIPFORMER_TRANSDUCER_MODEL_H_
+#define SHERPA_ONNX_CSRC_ONLINE_ZIPFORMER_TRANSDUCER_MODEL_H_
+
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+#include "sherpa-onnx/csrc/online-transducer-model-config.h"
+#include "sherpa-onnx/csrc/online-transducer-model.h"
+
+namespace sherpa_onnx {
+
+class OnlineZipformerTransducerModel : public OnlineTransducerModel {
+ public:
+  explicit OnlineZipformerTransducerModel(
+      const OnlineTransducerModelConfig &config);
+
+  std::vector<Ort::Value> StackStates(
+      const std::vector<std::vector<Ort::Value>> &states) const override;
+
+  std::vector<std::vector<Ort::Value>> UnStackStates(
+      const std::vector<Ort::Value> &states) const override;
+
+  std::vector<Ort::Value> GetEncoderInitStates() override;
+
+  std::pair<Ort::Value, std::vector<Ort::Value>> RunEncoder(
+      Ort::Value features, std::vector<Ort::Value> states) override;
+
+  Ort::Value BuildDecoderInput(
+      const std::vector<OnlineTransducerDecoderResult> &results) override;
+
+  Ort::Value RunDecoder(Ort::Value decoder_input) override;
+
+  Ort::Value RunJoiner(Ort::Value encoder_out, Ort::Value decoder_out) override;
+
+  int32_t ContextSize() const override { return context_size_; }
+
+  int32_t ChunkSize() const override { return T_; }
+
+  int32_t ChunkShift() const override { return decode_chunk_len_; }
+
+  int32_t VocabSize() const override { return vocab_size_; }
+  OrtAllocator *Allocator() override { return allocator_; }
+
+ private:
+  void InitEncoder(const std::string &encoder_filename);
+  void InitDecoder(const std::string &decoder_filename);
+  void InitJoiner(const std::string &joiner_filename);
+
+ private:
+  Ort::Env env_;
+  Ort::SessionOptions sess_opts_;
+  Ort::AllocatorWithDefaultOptions allocator_;
+
+  std::unique_ptr<Ort::Session> encoder_sess_;
+  std::unique_ptr<Ort::Session> decoder_sess_;
+  std::unique_ptr<Ort::Session> joiner_sess_;
+
+  std::vector<std::string> encoder_input_names_;
+  std::vector<const char *> encoder_input_names_ptr_;
+
+  std::vector<std::string> encoder_output_names_;
+  std::vector<const char *> encoder_output_names_ptr_;
+
+  std::vector<std::string> decoder_input_names_;
+  std::vector<const char *> decoder_input_names_ptr_;
+
+  std::vector<std::string> decoder_output_names_;
+  std::vector<const char *> decoder_output_names_ptr_;
+
+  std::vector<std::string> joiner_input_names_;
+  std::vector<const char *> joiner_input_names_ptr_;
+
+  std::vector<std::string> joiner_output_names_;
+  std::vector<const char *> joiner_output_names_ptr_;
+
+  OnlineTransducerModelConfig config_;
+
+  std::vector<int32_t> encoder_dims_;
+  std::vector<int32_t> attention_dims_;
+  std::vector<int32_t> num_encoder_layers_;
+  std::vector<int32_t> cnn_module_kernels_;
+  std::vector<int32_t> left_context_len_;
+
+  int32_t T_ = 0;
+  int32_t decode_chunk_len_ = 0;
+
+  int32_t context_size_ = 0;
+  int32_t vocab_size_ = 0;
+};
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_ONLINE_ZIPFORMER_TRANSDUCER_MODEL_H_

@@ -46,16 +46,74 @@ void PrintModelMetadata(std::ostream &os, const Ort::ModelMetadata &meta_data) {
   }
   }
 }
 }
 
 
-Ort::Value Clone(Ort::Value *v) {
+Ort::Value Clone(const Ort::Value *v) {
   auto type_and_shape = v->GetTensorTypeAndShapeInfo();
   auto type_and_shape = v->GetTensorTypeAndShapeInfo();
   std::vector<int64_t> shape = type_and_shape.GetShape();
   std::vector<int64_t> shape = type_and_shape.GetShape();
 
 
   auto memory_info =
   auto memory_info =
       Ort::MemoryInfo::CreateCpu(OrtDeviceAllocator, OrtMemTypeDefault);
       Ort::MemoryInfo::CreateCpu(OrtDeviceAllocator, OrtMemTypeDefault);
 
 
-  return Ort::Value::CreateTensor(memory_info, v->GetTensorMutableData<float>(),
-                                  type_and_shape.GetElementCount(),
-                                  shape.data(), shape.size());
+  switch (type_and_shape.GetElementType()) {
+    case ONNX_TENSOR_ELEMENT_DATA_TYPE_INT32:
+      return Ort::Value::CreateTensor(
+          memory_info,
+          const_cast<Ort::Value *>(v)->GetTensorMutableData<int32_t>(),
+          type_and_shape.GetElementCount(), shape.data(), shape.size());
+    case ONNX_TENSOR_ELEMENT_DATA_TYPE_INT64:
+      return Ort::Value::CreateTensor(
+          memory_info,
+          const_cast<Ort::Value *>(v)->GetTensorMutableData<int64_t>(),
+          type_and_shape.GetElementCount(), shape.data(), shape.size());
+    case ONNX_TENSOR_ELEMENT_DATA_TYPE_FLOAT:
+      return Ort::Value::CreateTensor(
+          memory_info,
+          const_cast<Ort::Value *>(v)->GetTensorMutableData<float>(),
+          type_and_shape.GetElementCount(), shape.data(), shape.size());
+    default:
+      fprintf(stderr, "Unsupported type: %d\n",
+              static_cast<int32_t>(type_and_shape.GetElementType()));
+      exit(-1);
+      // unreachable code
+      return Ort::Value{nullptr};
+  }
+}
+
+void Print1D(Ort::Value *v) {
+  std::vector<int64_t> shape = v->GetTensorTypeAndShapeInfo().GetShape();
+  const float *d = v->GetTensorData<float>();
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    fprintf(stderr, "%.3f ", d[i]);
+  }
+  fprintf(stderr, "\n");
+}
+
+void Print2D(Ort::Value *v) {
+  std::vector<int64_t> shape = v->GetTensorTypeAndShapeInfo().GetShape();
+  const float *d = v->GetTensorData<float>();
+
+  for (int32_t r = 0; r != static_cast<int32_t>(shape[0]); ++r) {
+    for (int32_t c = 0; c != static_cast<int32_t>(shape[1]); ++c, ++d) {
+      fprintf(stderr, "%.3f ", *d);
+    }
+    fprintf(stderr, "\n");
+  }
+  fprintf(stderr, "\n");
+}
+
+void Print3D(Ort::Value *v) {
+  std::vector<int64_t> shape = v->GetTensorTypeAndShapeInfo().GetShape();
+  const float *d = v->GetTensorData<float>();
+
+  for (int32_t p = 0; p != static_cast<int32_t>(shape[0]); ++p) {
+    fprintf(stderr, "---plane %d---\n", p);
+    for (int32_t r = 0; r != static_cast<int32_t>(shape[1]); ++r) {
+      for (int32_t c = 0; c != static_cast<int32_t>(shape[2]); ++c, ++d) {
+        fprintf(stderr, "%.3f ", *d);
+      }
+      fprintf(stderr, "\n");
+    }
+  }
+  fprintf(stderr, "\n");
 }
 }
 
 
 }  // namespace sherpa_onnx
 }  // namespace sherpa_onnx

@@ -56,7 +56,23 @@ void PrintModelMetadata(std::ostream &os,
                         const Ort::ModelMetadata &meta_data);  // NOLINT
                         const Ort::ModelMetadata &meta_data);  // NOLINT
 
 
 // Return a shallow copy of v
 // Return a shallow copy of v
-Ort::Value Clone(Ort::Value *v);
+Ort::Value Clone(const Ort::Value *v);
+
+// Print a 1-D tensor to stderr
+void Print1D(Ort::Value *v);
+
+// Print a 2-D tensor to stderr
+void Print2D(Ort::Value *v);
+
+// Print a 3-D tensor to stderr
+void Print3D(Ort::Value *v);
+
+template <typename T = float>
+void Fill(Ort::Value *tensor, T value) {
+  auto n = tensor->GetTypeInfo().GetTensorTypeAndShapeInfo().GetElementCount();
+  auto p = tensor->GetTensorMutableData<T>();
+  std::fill(p, p + n, value);
+}
 
 
 }  // namespace sherpa_onnx
 }  // namespace sherpa_onnx
 
 

+// sherpa-onnx/csrc/text-utils.cc
+//
+// Copyright 2009-2011  Saarland University;  Microsoft Corporation
+// Copyright      2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/text-utils.h"
+
+#include <string>
+#include <vector>
+
+// This file is copied/modified from
+// https://github.com/kaldi-asr/kaldi/blob/master/src/util/text-utils.cc
+
+namespace sherpa_onnx {
+
+void SplitStringToVector(const std::string &full, const char *delim,
+                         bool omit_empty_strings,
+                         std::vector<std::string> *out) {
+  size_t start = 0, found = 0, end = full.size();
+  out->clear();
+  while (found != std::string::npos) {
+    found = full.find_first_of(delim, start);
+    // start != end condition is for when the delimiter is at the end
+    if (!omit_empty_strings || (found != start && start != end))
+      out->push_back(full.substr(start, found - start));
+    start = found + 1;
+  }
+}
+
+}  // namespace sherpa_onnx

+// sherpa-onnx/csrc/text-utils.h
+//
+// Copyright 2009-2011  Saarland University;  Microsoft Corporation
+// Copyright      2023  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_TEXT_UTILS_H_
+#define SHERPA_ONNX_CSRC_TEXT_UTILS_H_
+#include <stdlib.h>
+
+#include <string>
+#include <vector>
+
+#ifdef _MSC_VER
+#define SHERPA_ONNX_STRTOLL(cur_cstr, end_cstr) \
+  _strtoi64(cur_cstr, end_cstr, 10);
+#else
+#define SHERPA_ONNX_STRTOLL(cur_cstr, end_cstr) strtoll(cur_cstr, end_cstr, 10);
+#endif
+
+// This file is copied/modified from
+// https://github.com/kaldi-asr/kaldi/blob/master/src/util/text-utils.h
+
+namespace sherpa_onnx {
+
+/// Split a string using any of the single character delimiters.
+/// If omit_empty_strings == true, the output will contain any
+/// nonempty strings after splitting on any of the
+/// characters in the delimiter.  If omit_empty_strings == false,
+/// the output will contain n+1 strings if there are n characters
+/// in the set "delim" within the input string.  In this case
+/// the empty string is split to a single empty string.
+void SplitStringToVector(const std::string &full, const char *delim,
+                         bool omit_empty_strings,
+                         std::vector<std::string> *out);
+
+/**
+  \brief Split a string (e.g. 1:2:3) into a vector of integers.
+
+  \param [in]  delim  String containing a list of characters, any of which
+                      is allowed as a delimiter.
+  \param [in] omit_empty_strings If true, empty strings between delimiters are
+                      allowed and will not produce an output integer; if false,
+                      instances of characters in 'delim' that are consecutive or
+                      at the start or end of the string would be an error.
+                      You'll normally want this to be true if 'delim' consists
+                      of spaces, and false otherwise.
+  \param [out] out   The output list of integers.
+*/
+template <class I>
+bool SplitStringToIntegers(const std::string &full, const char *delim,
+                           bool omit_empty_strings,  // typically false [but
+                                                     // should probably be true
+                                                     // if "delim" is spaces].
+                           std::vector<I> *out) {
+  static_assert(std::is_integral<I>::value, "");
+  if (*(full.c_str()) == '\0') {
+    out->clear();
+    return true;
+  }
+  std::vector<std::string> split;
+  SplitStringToVector(full, delim, omit_empty_strings, &split);
+  out->resize(split.size());
+  for (size_t i = 0; i < split.size(); i++) {
+    const char *this_str = split[i].c_str();
+    char *end = NULL;
+    int64_t j = 0;
+    j = SHERPA_ONNX_STRTOLL(this_str, &end);
+    if (end == this_str || *end != '\0') {
+      out->clear();
+      return false;
+    } else {
+      I jI = static_cast<I>(j);
+      if (static_cast<int64_t>(jI) != j) {
+        // output type cannot fit this integer.
+        out->clear();
+        return false;
+      }
+      (*out)[i] = jI;
+    }
+  }
+  return true;
+}
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_TEXT_UTILS_H_

+// sherpa-onnx/csrc/unbind-test.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/unbind.h"
+
+#include "gtest/gtest.h"
+#include "sherpa-onnx/csrc/cat.h"
+#include "sherpa-onnx/csrc/onnx-utils.h"
+
+namespace sherpa_onnx {
+
+TEST(Ubind, Test1DTensors) {
+  Ort::AllocatorWithDefaultOptions allocator;
+  std::array<int64_t, 1> shape{3};
+  Ort::Value v =
+      Ort::Value::CreateTensor<float>(allocator, shape.data(), shape.size());
+  float *p = v.GetTensorMutableData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    p[i] = i;
+  }
+  auto ans = Unbind(allocator, &v, 0);
+  EXPECT_EQ(ans.size(), shape[0]);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    EXPECT_EQ(ans[i].GetTensorData<float>()[0], p[i]);
+  }
+  Print1D(&v);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    Print1D(&ans[i]);
+  }
+
+  // For Cat
+  std::vector<const Ort::Value *> vec(ans.size());
+  for (int32_t i = 0; i != static_cast<int32_t>(vec.size()); ++i) {
+    vec[i] = &ans[i];
+  }
+  Ort::Value v2 = Cat(allocator, vec, 0);
+  const float *p2 = v2.GetTensorData<float>();
+  for (int32_t i = 0; i != shape[0]; ++i) {
+    EXPECT_EQ(p[i], p2[i]);
+  }
+}
+
+TEST(Ubind, Test2DTensorsDim0) {
+  Ort::AllocatorWithDefaultOptions allocator;
+  std::array<int64_t, 2> shape{3, 2};
+  Ort::Value v =
+      Ort::Value::CreateTensor<float>(allocator, shape.data(), shape.size());
+  float *p = v.GetTensorMutableData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0] * shape[1]); ++i) {
+    p[i] = i;
+  }
+  auto ans = Unbind(allocator, &v, 0);
+
+  Print2D(&v);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    Print2D(&ans[i]);
+  }
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    const float *pans = ans[i].GetTensorData<float>();
+    for (int32_t k = 0; k != static_cast<int32_t>(shape[1]); ++k, ++p) {
+      EXPECT_EQ(*p, pans[k]);
+    }
+  }
+
+  // For Cat
+  std::vector<const Ort::Value *> vec(ans.size());
+  for (int32_t i = 0; i != static_cast<int32_t>(vec.size()); ++i) {
+    vec[i] = &ans[i];
+  }
+  Ort::Value v2 = Cat(allocator, vec, 0);
+  Print2D(&v2);
+
+  p = v.GetTensorMutableData<float>();
+  const float *p2 = v2.GetTensorData<float>();
+  for (int32_t i = 0; i != shape[0] * shape[1]; ++i) {
+    EXPECT_EQ(p[i], p2[i]);
+  }
+}
+
+TEST(Ubind, Test2DTensorsDim1) {
+  Ort::AllocatorWithDefaultOptions allocator;
+  std::array<int64_t, 2> shape{3, 2};
+  Ort::Value v =
+      Ort::Value::CreateTensor<float>(allocator, shape.data(), shape.size());
+  float *p = v.GetTensorMutableData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0] * shape[1]); ++i) {
+    p[i] = i;
+  }
+  auto ans = Unbind(allocator, &v, 1);
+
+  Print2D(&v);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[1]); ++i) {
+    Print2D(&ans[i]);
+  }
+
+  // For Cat
+  std::vector<const Ort::Value *> vec(ans.size());
+  for (int32_t i = 0; i != static_cast<int32_t>(vec.size()); ++i) {
+    vec[i] = &ans[i];
+  }
+  Ort::Value v2 = Cat(allocator, vec, 1);
+  Print2D(&v2);
+
+  p = v.GetTensorMutableData<float>();
+  const float *p2 = v2.GetTensorData<float>();
+  for (int32_t i = 0; i != shape[0] * shape[1]; ++i) {
+    EXPECT_EQ(p[i], p2[i]);
+  }
+}
+
+TEST(Ubind, Test3DTensorsDim0) {
+  Ort::AllocatorWithDefaultOptions allocator;
+  std::array<int64_t, 3> shape{3, 2, 5};
+  Ort::Value v =
+      Ort::Value::CreateTensor<float>(allocator, shape.data(), shape.size());
+  float *p = v.GetTensorMutableData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0] * shape[1] * shape[2]);
+       ++i) {
+    p[i] = i;
+  }
+  auto ans = Unbind(allocator, &v, 0);
+
+  Print3D(&v);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    Print3D(&ans[i]);
+  }
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0]); ++i) {
+    const float *pans = ans[i].GetTensorData<float>();
+    for (int32_t k = 0; k != static_cast<int32_t>(shape[1] * shape[2]);
+         ++k, ++p) {
+      EXPECT_EQ(*p, pans[k]);
+    }
+  }
+
+  // For Cat
+  std::vector<const Ort::Value *> vec(ans.size());
+  for (int32_t i = 0; i != static_cast<int32_t>(vec.size()); ++i) {
+    vec[i] = &ans[i];
+  }
+  Ort::Value v2 = Cat(allocator, vec, 0);
+  Print3D(&v2);
+
+  p = v.GetTensorMutableData<float>();
+  const float *p2 = v2.GetTensorData<float>();
+  for (int32_t i = 0; i != shape[0] * shape[1] * shape[2]; ++i) {
+    EXPECT_EQ(p[i], p2[i]);
+  }
+}
+
+TEST(Ubind, Test3DTensorsDim1) {
+  Ort::AllocatorWithDefaultOptions allocator;
+  std::array<int64_t, 3> shape{3, 2, 5};
+  Ort::Value v =
+      Ort::Value::CreateTensor<float>(allocator, shape.data(), shape.size());
+  float *p = v.GetTensorMutableData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0] * shape[1] * shape[2]);
+       ++i) {
+    p[i] = i;
+  }
+  auto ans = Unbind(allocator, &v, 1);
+
+  Print3D(&v);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[1]); ++i) {
+    Print3D(&ans[i]);
+  }
+
+  // For Cat
+  std::vector<const Ort::Value *> vec(ans.size());
+  for (int32_t i = 0; i != static_cast<int32_t>(vec.size()); ++i) {
+    vec[i] = &ans[i];
+  }
+  Ort::Value v2 = Cat(allocator, vec, 1);
+  Print3D(&v2);
+
+  p = v.GetTensorMutableData<float>();
+  const float *p2 = v2.GetTensorData<float>();
+  for (int32_t i = 0; i != shape[0] * shape[1] * shape[2]; ++i) {
+    EXPECT_EQ(p[i], p2[i]);
+  }
+}
+
+TEST(Ubind, Test3DTensorsDim2) {
+  Ort::AllocatorWithDefaultOptions allocator;
+  std::array<int64_t, 3> shape{3, 2, 5};
+  Ort::Value v =
+      Ort::Value::CreateTensor<float>(allocator, shape.data(), shape.size());
+  float *p = v.GetTensorMutableData<float>();
+
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[0] * shape[1] * shape[2]);
+       ++i) {
+    p[i] = i;
+  }
+  auto ans = Unbind(allocator, &v, 2);
+
+  Print3D(&v);
+  for (int32_t i = 0; i != static_cast<int32_t>(shape[2]); ++i) {
+    Print3D(&ans[i]);
+  }
+
+  // For Cat
+  std::vector<const Ort::Value *> vec(ans.size());
+  for (int32_t i = 0; i != static_cast<int32_t>(vec.size()); ++i) {
+    vec[i] = &ans[i];
+  }
+  Ort::Value v2 = Cat(allocator, vec, 2);
+  Print3D(&v2);
+
+  p = v.GetTensorMutableData<float>();
+  const float *p2 = v2.GetTensorData<float>();
+  for (int32_t i = 0; i != shape[0] * shape[1] * shape[2]; ++i) {
+    EXPECT_EQ(p[i], p2[i]);
+  }
+}
+
+}  // namespace sherpa_onnx

+// sherpa-onnx/csrc/unbind.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/unbind.h"
+
+#include <assert.h>
+
+#include <algorithm>
+#include <functional>
+#include <numeric>
+#include <utility>
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+#include "sherpa-onnx/csrc/onnx-utils.h"
+
+namespace sherpa_onnx {
+
+template <typename T /*= float*/>
+std::vector<Ort::Value> Unbind(OrtAllocator *allocator, const Ort::Value *value,
+                               int32_t dim) {
+  std::vector<int64_t> shape = value->GetTensorTypeAndShapeInfo().GetShape();
+  assert(dim >= 0);
+  assert(dim < static_cast<int32_t>(shape.size()));
+  int32_t n = static_cast<int32_t>(shape[dim]);
+  if (n == 1) {
+    std::vector<Ort::Value> ans;
+    ans.push_back(Clone(value));
+    return ans;
+  }
+
+  std::vector<int64_t> ans_shape = shape;
+  ans_shape[dim] = 1;  // // Unlike torch, we keep the dim to 1
+
+  // allocator tensors
+  std::vector<Ort::Value> ans;
+  ans.reserve(n);
+  for (int32_t i = 0; i != n; ++i) {
+    Ort::Value t = Ort::Value::CreateTensor<T>(allocator, ans_shape.data(),
+                                               ans_shape.size());
+    ans.push_back(std::move(t));
+  }
+
+  auto leading_size = static_cast<int32_t>(std::accumulate(
+      shape.begin(), shape.begin() + dim, 1, std::multiplies<int64_t>()));
+
+  auto trailing_size = static_cast<int32_t>(std::accumulate(
+      shape.begin() + dim + 1, shape.end(), 1, std::multiplies<int64_t>()));
+
+  const T *src = value->GetTensorData<T>();
+
+  for (int32_t i = 0; i != leading_size; ++i) {
+    for (int32_t k = 0; k != n; ++k) {
+      T *dst = ans[k].GetTensorMutableData<T>() + i * trailing_size;
+      std::copy(src, src + trailing_size, dst);
+      src += trailing_size;
+    }
+  }
+
+  return std::move(ans);
+}
+
+template std::vector<Ort::Value> Unbind<float>(OrtAllocator *allocator,
+                                               const Ort::Value *value,
+                                               int32_t dim);
+
+template std::vector<Ort::Value> Unbind<int64_t>(OrtAllocator *allocator,
+                                                 const Ort::Value *value,
+                                                 int32_t dim);
+
+}  // namespace sherpa_onnx

+// sherpa-onnx/csrc/unbind.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_UNBIND_H_
+#define SHERPA_ONNX_CSRC_UNBIND_H_
+
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+
+namespace sherpa_onnx {
+
+/** It is similar to torch.unbind() but we keep the unbind dim to 1 in
+ * the output
+ *
+ * @param allocator Allocator to allocate space for the returned tensor
+ * @param value  The tensor to unbind
+ * @param dim  The dim along which to unbind the tensor
+ *
+ * @return Return a list of tensors
+ */
+template <typename T = float>
+std::vector<Ort::Value> Unbind(OrtAllocator *allocator, const Ort::Value *value,
+                               int32_t dim);
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_UNBIND_H_